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Homer
15-12-06, 22:29
Name:
BPU

Also known as:
Basic Performance Upgrade
Full decat

What is it?
BPU stands for “Basic Performance Upgrade”, a term coined by US firm Suprastore for a basic upgrade package for the TT Supra. BPU is essentially what other marques refer to as "Stage 1” engine modification.

The BPU upgrades allow the engine to produce more power by raising the boost pressure the turbos produce.

In stock form, the TT produces 0.76bar (11psi), however this can be raised; it's generally accepted that the stock ceramic Jspec turbos will handle 1.2bar (17.4psi). The Export spec (UK/Euro/US) has steel blades so will, in general, survive at higher boost pressures. 1.4bar (20.3psi) is not unheard of.

1.2bar is the "accepted" safe limit with regards to a) detonation, b) actually getting more power, and c) some level of longevity. It's also accepted that you're taking an allbeit very small risk each time you use full boost. 1.2 bar is generally safe, but at 1.4 you're pushing your luck.

There are limitations with pressures above 1.2bar, the turbos are already outside of their efficiency range and the additional heat generated will raise the intake air temperature considerably – thus negating the effect of increased boost pressure.

In both Jspec and export spec, BPU will raise engine power to around 400bhp. Not only will it release more power but it allows much quicker turbo spool-up, which vastly increases drivability.

How it works
In stock form, the boost pressure the turbos produce is controlled by back pressure in the exhaust system (I.e. highly restrictive catalytic converters and exhaust system). There are two approaches to BPU dependant on the model of car; as such the next section is split between Jspec and Export spec:


Fundamentals of BPU

Jspec:
To raise boost beyond the stock level the restrictive catalytic converters are removed, thus allowing the turbos to spin faster and produce more boost pressure.

There is a down side to this. With both cats removed the turbos will in fact over speed far past their safe limit and reach over 1.6bar (23.2psi). This is due to the small size of the jspec wastegate which cannot cope with the increase in exhaust gasses.
At these pressures the ceramic blades in the turbo can become detached from the shaft and therefore cause catastrophic failure of the turbo.

In order to add some restriction back in to the exhaust a restrictor ring is added to the exhaust system. A restrictor ring is simply a metal plate that fits normally between either between the 1st and 2nd decat pipes, or the 2nd decat and cat-back. The centre of the restrictor is drilled out to a smaller diameter than the exhaust itself (normally around 2inches). A properly sized restrictor should bring the maximum boost pressure down to 1.2 bar or less.

UK/Euro/US (Export) spec:
To raise boost beyond the stock level the restrictive catalytic converters are removed, thus allowing the turbos to spin faster and produce more boost pressure. Different to the jspec, the export spec has a larger wastegate which can handle the increase in exhaust gasses.
Therefore boost pressure will be maintained at only slightly above stock levels, typically 0.85bar (12.3psi). In order to raise this further it is necessary to install a Boost controller to change the way in which the wastegate opens.
A restrictor ring is not required on the export spec

Note: On both models it’s possible to raise the boost with simply adding a Boost controller or Bleed valve; however this is not recommended since the huge resistance of the cats is still in place. This will result in significant extra heat being generated in the manifold and could cause serious engine damage due to raised exhaust gas temperatures.


Parts required:

Obviously all that’s needed to raise the boost pressure is a double decat & restrictor ring (Jspec) or double decat & boost controller (export spec). However, it will not work without further modifications. The following will be required in both models:

1) Aftermarket cat-back exhaust
The stock cat back (the pipe after the 2nd decat pipe) is extremely restrictive. In order to allow a good free flowing system this needs to be replaced with an aftermarket system. There are a huge amount of systems available, but any good quality aftermarket system will be suitable for a BPU level of modification.

2) Fuel cut defender
The stock ecu will initiate fuel cut when boost pressure reaches 1 bar for a 3 second period. In order to stop this, a device is needed in order to trick the ecu into thinking the boost pressure is lower.
(See quick link for further details)

3) Updated fuel pump
The stock fuel pump in the jspecs is not considered suitable for BPU level power, the one in the export spec is higher specification and will be suitable. However as many of these cars are approaching 13 years old it should be standard practice to replace the fuel pump.
The Walbro pump is commonly used, however the standard pump that comes with the export spec is a better specification and has quieter operation (though considerably more costly).

4) Colder grade spark plug
With an increase in boost, a ‘colder’ grade plug is required with a closer gap. There are two basic options:
- Iridium IK22 plugs
- NGK BCPR7ES
The iridium’s will last longer (most people get >10k miles) but typically cost £60 a set
The NGK’s need replacing around 3k miles, but cost £14 a set


Recommended, but non-essential parts:

That’s it for the required parts, though there are two items which are highly recommended to ensure you can monitor the health of your engine:

1) Boost gauge
A simple electronic or mechanical boost gauge can be mounted in the dash to view the boost pressure. An electronic boost gauge is recommend as most will come with a peak hold or even playback function, thus allowing easier monitoring of maximum pressures

2) AFR gauge
Also known as Air/Fuel ratio. This has a wideband O2 sensor mounted in the 2nd decat which measures the air/fuel mixture of the exhaust gases. This is very important to monitor, otherwise you won't know if the air/fuel ratio runs lean under high boost (and therefore result in piston meltdown). Though it won’t allow adjustment, it will warn you that something is not right if it does go lean.

3) EGT gauge (optional to AFR gauge)
Also known as Exhaust Gas Temperature. This has a temperature probe fitted into one of the exhaust runners (as close to the cylinder as possible). It performs basically the same function as the AFR gauge by monitoring the condition of the exhaust gases. High temps (sensor mounted post turbo 950degrees is dodgy, >1000degrees is a very bad thing!) will likely result in engine damage due to lean mixture. However there are some cons when comparing this to the afr gauge:

- It is much slower to react
- Failure of the temp probe (i.e disintegration) will result in the particles entering the turbos potentially causing failure
- The exhaust runner requires drilling and tapping which can result in swarf entering the manifold before the turbo. This could result in damage to the turbo blades.

A safer place to tap the probe is in the exhaust or downpipe after the turbo. It will stop the risk of swarf ending up in the turbo and turbo damage in the event of probe failure. There is a downside - Installing it post-turbo introduces such a big and variable heatsink into the equation it's pretty much useless. People take anything from 100 to 250degC off the aforementioned maximum, meaning that your gauge could read 800degC and mean anything from imminent meltdown to running nicely. No-one has put an EGT sensor before and after the turbo and datalogged the variance so it's 100% guesswork, and that's the last thing you want on the ragged edge.

4) Intercooler
A replacement or aftermarket intercooler isn't required, however you need to ensure your current intercooler is in good condition and allows smooth airflow though the core. Many of the stock IC's on older cars are now in very poor condition and suffer from corroded fins, if yours is like this it should be replaced prior to going bpu.

Rayman
15-01-07, 19:40
Awesome thread this, makes BPU really easy to understand, is there not a typo under colder plugs, is it not Ik24 that are used for BPU rather than Ik22. It probably wont make much difference but i just thought thats what was generally recommended?

Andyhannah
16-01-07, 03:36
Very informative that darryl,very useful.

Jake
16-01-07, 03:50
is there not a typo under colder plugs, is it not Ik24 that are used for BPU rather than Ik22.No I think it's correct. IK22 are more than adequate for BPU. Running too cool a plug offers no benefit and they are more prone to fouling.

carl0s
16-01-07, 10:13
3) Updated fuel pump
however the Bosch 044 which comes with the export spec is a better specification and has quieter operation (though considerably more costly).

Is this definately correct? It's just that I'm trying to find more info on the 044 and I can see that some people are using it but there's a common conception that this pump doesn't do very well at lifting fuel out of the tank. So, is this the pump that the UK cars have fitted as standard then?

Sheefa
18-01-07, 22:56
Best guide I've read so far. Great job mate! :)

carl0s
19-02-07, 21:04
In answer to my own question..


The stock UK pump is most definitely NOT a Bosch 044, or anything like it. It's not even made by Bosch at all.

So, any chance of correcting the article?

Glosphil
19-02-07, 21:36
Well done mate, wish you'd of written that when I joined lol

carl0s
19-02-07, 21:37
FFS, everytime I point out this mistake, someone replies in front with a "great post!" thing, meaning I don't get noticed ;) :p

grrr.

:D

RobSheffield
19-02-07, 21:47
FFS, everytime I point out this mistake, someone replies in front with a "great post!" thing, meaning I don't get noticed ;) :p

grrr.

:D

Great post :D

Homer
19-02-07, 22:10
In answer to my own question..

So, any chance of correcting the article?

Cheers Carlos, I searched high and low and couldn't confirm or disprove the Export pump spec so left it as it was. Seeing as it's CW who posted that I'll correct the article ;)


Is anyone able to supply the model and type of pump used on the export spec?

SupraStar 3000
19-02-07, 22:14
great post.
thanks mate :)

carl0s
20-02-07, 10:31
Cheers Carlos, I searched high and low and couldn't confirm or disprove the Export pump spec so left it as it was. Seeing as it's CW who posted that I'll correct the article ;)


Is anyone able to supply the model and type of pump used on the export spec?

Everything I've found so far just says "Nippon", (that being Denso, right?)

I think I have a part number too: 23221-46110

carl0s
20-02-07, 16:04
It is a great post, btw. Thanks Homer ;)

Omlaysause
16-03-07, 19:24
Perfect .. this is exactly what I'm looking to do with mine, nothing radical but a bit more Oomph!!

So can someone enlighten to an approx cost for the BPU stuff. I already have a Cat back exhaust although I don't know if it has a restrictor ring in it. Everything else as far as I know is stock other than an induction kit, which doesn't do anything.
I'm near Edinburgh and wondered if anyone know's who could do the work. I've spoken to TDR but his Dad's unfortunately a bit busy just now :D

Homer
18-03-07, 01:16
So can someone enlighten to an approx cost for the BPU stuff. I already have a Cat back exhaust although I don't know if it has a restrictor ring in it. Everything else as far as I know is stock other than an induction kit, which doesn't do anything.
I'm near Edinburgh and wondered if anyone know's who could do the work. I've spoken to TDR but his Dad's unfortunately a bit busy just now :D

This isnn't really the right place to ask since its a tech discussion ;)

I recommend you contact some of our traders and look for the best deal: Envy, Miami-GT, Whifbitz, MVP, PHR - in no particular order!

tDR
18-03-07, 07:04
Homer - on the spark plug recommendation. BKR7E are the ones to recommend by default NGK wise. These are ISO fitment as per the OEM plugs. The BCPR7ES will work but they're very slightly longer from the base of the insulator to the tip where the coil pack seats, since they are the older JSO fitment standard. In practice these are a good bet when you have old and worn coil packs and are suffering misfires as a result - the snugger fit helps.

Also, perhaps mention the NGKs should be gapped at 0.9mm at BPU level and that iridium plugs come pre-gapped at a smaller gap than stock so don't touch as you risk damaging their fragile very thin centre electrodes if you try to gap them. Also there is no mention that IK22's are made by Denso.

Otherwise - excellent article! :)

Cheers,

Brian.

carl0s
18-03-07, 10:10
Homer - on the spark plug recommendation. BKR7E are the ones to recommend by default NGK wise. These are ISO fitment as per the OEM plugs. The BCPR7ES will work but they're very slightly longer from the base of the insulator to the tip where the coil pack seats, since they are the older JSO fitment standard. In practice these are a good bet when you have old and worn coil packs and are suffering misfires as a result - the snugger fit helps.

Also, perhaps mention the NGKs should be gapped at 0.9mm at BPU level and that iridium plugs come pre-gapped at a smaller gap than stock so don't touch as you risk damaging their fragile very thin centre electrodes if you try to gap them. Also there is no mention that IK22's are made by Denso.

Otherwise - excellent article! :)

Cheers,

Brian.

How about BKR7E-VX? I've always just fitted them - it says not to regap them on the box, and I haven't actually checked them with a feeler gauge. All OK? (car not gone bang yet anyway.. ;) )

nick_t
18-03-07, 13:20
how much difference does bpu make with regards performance and number of horses cheers

tDR
18-03-07, 13:43
How about BKR7E-VX? I've always just fitted them - it says not to regap them on the box, and I haven't actually checked them with a feeler gauge. All OK? (car not gone bang yet anyway.. ;) )


BKR7EVX are a discontinued line - these were platinum plugs (extended service intervals) at around 4 times the price of the copper BKR7E's. There isn't a problem gapping platinum plugs as far as I'm aware so always worth a check with a set of feeler gauges although I suspect they will be around 0.8mm from the factory given the print on the box. They are the grade 7 heat range still so will be fine at BPU level since they are also one heat range colder than stock but for me I've never had issues with the good old NGK coppers so why change when they're reliable and low cost? The VX have been replaced by the iridium IX range by the way, at similar cost.

Cheers,

Brian.

tDR
18-03-07, 13:44
how much difference does bpu make with regards performance and number of horses cheers

You awaken the beast and go from around 320bhp to around 390bhp.

Cheers,

Brian.

carl0s
18-03-07, 16:20
BKR7EVX are a discontinued line - these were platinum plugs (extended service intervals) at around 4 times the price of the copper BKR7E's. There isn't a problem gapping platinum plugs as far as I'm aware so always worth a check with a set of feeler gauges although I suspect they will be around 0.8mm from the factory given the print on the box. They are the grade 7 heat range still so will be fine at BPU level since they are also one heat range colder than stock but for me I've never had issues with the good old NGK coppers so why change when they're reliable and low cost? The VX have been replaced by the iridium IX range by the way, at similar cost.

Cheers,

Brian.

I didn't know that, thanks. I bought my last set of BKR7EVXs about four weeks ago, so I take it the discontinuation is a fairly recent thing? They were £4.54 + vat each from my local Partco.

AndyT
05-04-07, 06:06
Very nice sir. Thanks. I know what to look for, ask about to find out what's been done to the one I'm getting now.

TonyP
05-04-07, 07:20
Great post.:) Even I understood it! :nana: :thanks:

johnny
08-04-07, 19:51
that was good.this is my first supra its standard. dont think it that quick but will get a few mods and get it sorted... have a six speed box ready to go in to it soon

Geneb
08-04-07, 20:18
Thankyou very much bud it makes sense now:)

95tt
06-07-07, 04:11
Im bpu++. And I was wondering, My fuel pump is from 1995 so its getting old. but why replace something that works. Woud I see difference in my AFR readings when the pump starts to go bad ? or do i need to hook up a pressure gauge. My logic tells me that if my pump is starting to go bad i would read a leaning afr ? right or wrong ?

tDR
06-07-07, 17:10
Correct, you will see a lean AFR if your pump is dying but that one time on boost could be too late!

Best replacing as a service item, most economical performance pump is the walbro 341 255 ltr/hr

Cheers,

Brian.

supra61
06-07-07, 18:11
thanks homer it all makes more sence now.i'm just going bpu+ nice piece,many thanks.

Geneb
06-07-07, 22:35
thanks homer it all makes more sence now.i'm just going bpu+ nice piece,many thanks.

Will you shut up about your "BPU+" you old Tart:p

im going "BPU+1" with shiny brass knobs on!

supra_surj
07-07-07, 12:20
A quick question about the decats for bpu....if i have a 3" cat back exhaust do i need to get a 3" decat or would a 2.5" fit ok?

Mas
07-07-07, 12:21
you would be ok with 2.5inch one Surj, although you usually need an adaptor, most of the members have such set up anyway ;)

tDR
07-07-07, 15:39
Nah no adapter necessary - the flanges mate up fine 2.5" decats to 3" cat back system. I have 2.5" decats into my Blitz Nur Spec R.

I'd always recommend 2.5" decats for J Spec owners on standard turbos - keeps a bit more backpressure meaning you don't need such a small diameter restrictor ring.

Cheers,

Brian.

supra_surj
07-07-07, 16:39
Thanks guys! ;)

Mas
07-07-07, 16:57
Nah no adapter necessary - the flanges mate up fine 2.5" decats to 3" cat back system. I have 2.5" decats into my Blitz Nur Spec R.

I'd always recommend 2.5" decats for J Spec owners on standard turbos - keeps a bit more backpressure meaning you don't need such a small diameter restrictor ring.

Cheers,

Brian.

I used an adaptor maybe cos I have a 4" cat back!!! ;)

tDR
07-07-07, 19:17
I used an adaptor maybe cos I have a 4" cat back!!! ;)

That'd do it! :blink:

Mas
07-07-07, 19:24
That'd do it! :blink:

I'm sure I have 2.5" decats and Mark used an adaptor to fit them to my decat! I know its a different case but though same thing happeneds with 3" systems too! ;)

Dash Rendar
29-09-07, 17:46
Like everyone has already said... This is a great article.

I'm trying to find a thread that describes the difference between the various BPU+ levels (since a couple of people have already mentioned it in this thread). I'm sure I stumbled across one once, but I can't find it now.

Steve
29-09-07, 19:12
Theres a bit over on mkiv.com (http://www.mkiv.com/techarticles/index.html#bpu+) that has the differences between bpu+ and bpu++

:)

Homer
30-09-07, 21:16
In addition to Steve's post, the difference in the + and ++ terms of the orignal "BPU" packages marketed is explained here: http://www.suprastore.com/450hppackage.html

I seriously doubt their claims of performance differences between BPU and BPU++. The HP claims are also not comparable, whether it be due to the US Spec difference or 'eager' dyno's, who knows...

Dash Rendar
30-09-07, 21:40
I see what you mean... How many BPU Supras out there have 430RWHP? Seems a bit optimistic to me!

amigo5
26-10-07, 12:24
i have one question regarding the exhaust
shall i fit the downpipe with the width of 3" and length of only 1 m and no more from the turbos till under the seat
and
the rest of the exhaust should be 2" after the down pipe

amigo5
27-10-07, 21:06
??

carl0s
27-10-07, 21:56
i have one question regarding the exhaust
shall i fit the downpipe with the width of 3" and length of only 1 m and no more from the turbos till under the seat
and
the 4rest of the exhaust should be 2" after the down p41ipe

Most people fit 3" decat and 3" exhaust, or all 2.5".

aussie_supra
13-01-08, 04:31
If I do a full BPU as said here and just remove one CAT will I still get around 400HP?

aussie_supra
13-01-08, 04:36
And if I do remove both CATs how can I pass MOT?

AndyT
13-01-08, 06:45
Friendly MOT man ;) or put one back. About 15 minutes work.

miko_supra
13-01-08, 09:26
If I do a full BPU as said here and just remove one CAT will I still get around 400HP?

no both need removing. too restrictive otherwise. i think you can install a high flow performance cat if you wish

aussie_supra
13-01-08, 11:21
If I install high flow performance cat will I pass MOT and get desired rwhp? or bhp

aussie_supra
13-01-08, 11:32
And how did u guys pass MOT after decat?

miko_supra
13-01-08, 12:22
If I install high flow performance cat will I pass MOT and get desired rwhp? or bhp

should pass the mot, not sure how much it affects the bhp though



And how did u guys pass MOT after decat?

most guys just put the second cat back in for the mot

Kim1978
10-06-08, 09:56
in addtion to the four item listed by homer, isn't a aftermarket BOV also necessary? I was told the stock one can only hold 1bar

tDR
10-06-08, 18:38
in addtion to the four item listed by homer, isn't a aftermarket BOV also necessary? I was told the stock one can only hold 1bar

I've never heard that and still run my stock BOV with 1.2bar boost.

Cheers,

Brian.

Kim1978
11-06-08, 10:36
I've never heard that and still run my stock BOV with 1.2bar boost.

Cheers,

Brian.

thanks. It was the first time I heard that too.

I will stay with stock BOV.

ST1
07-07-08, 12:16
How do we get passed the Feul Cut Defender?

Deacon2k
14-08-08, 12:17
i am pritty new to the supra scene just had my over 2months now. i am wanting to remove both cats what else do i need this is what i am going to purchase.

1. blitz nur r
2. restrictor ring
3. walbro fuel pump
4. boost gauge
5. greddy boost limit cut controller
6. IK22 spark plugs

now what else do i need to remove the two cats can anyone advise me.

cheers :)

hadyn
14-08-08, 12:21
Possibly a boost controller (electronic or manual) if your car wont boost upto 1.2bar without the cats in.

Thorin
14-08-08, 12:23
I was under the impression that this thread was to help do away with all the "what do I need to go BPU?" type posts. Looks like it failed.

What it needs is a bit saying which parts are needed for BPU... oh wait, it has that.

Deacon2k
14-08-08, 12:26
what i was gettin at was will that exhaust system remove both cats?

MarkR
14-08-08, 12:27
i am pritty new to the supra scene just had my over 2months now. i am wanting to remove both cats what else do i need this is what i am going to purchase.

1. blitz nur r
2. restrictor ring
3. walbro fuel pump
4. boost gauge
5. greddy boost limit cut controller
6. IK22 spark plugs

now what else do i need to remove the two cats can anyone advise me.

cheers :)

To remove the cats you need to buy decat pipes (exhaust pipes with no cats to replace the section of pipe that has a cat). Read the first thread very carefully. It's all in there. Otherwise, use the search button near the top of the page and search for decat or bpu or other key words and have a good read. Most of these questions have been asked before and answered numerous time so you'll save yourself a lot of time (and people won't be mean to you ;) )

Thorin
14-08-08, 12:27
To remove the cats, you need de-cat pipes.

MarkR
14-08-08, 12:30
what i was gettin at was will that exhaust system remove both cats?

No. From the standard turbos, you get a small pipe with a cat, then another slightly longer pipe with another cat, and after that you get your cat-back exhaust system (clue is in the name). The Nur Spec will be from there back, and you'll still need to buy the 2 decat pipes.

Here's a pic of the 2 decat pipes

http://www.sonicsausage.com/Sections/Hobbies/TheCar/Images/CWDecatPipes.jpg

Deacon2k
14-08-08, 12:36
ah right i see thanks alot for the help guys
tis me first car so i ain't too clued up.
cheers :D

RobSheffield
14-08-08, 12:42
Wait, your first car?

*Alarm bells*

hadyn
14-08-08, 12:45
Its alright, its only an ancient Toyota that nobody wants :)

Deacon2k
14-08-08, 13:04
well ive drove me fathas car for a while this is me first performace car always wanted one of these :D

madwoody1
14-08-08, 22:24
get in there what a first car lol
mine was a opel kaddet 1.3 estate lol

jonte_j
17-10-08, 09:58
Where can i purchase this restrictor ring? Or do i have to make one myself? Where in the exhaust is it placed? I understand its in front section but is it before the 1st decat, between them or after?

MarkR
17-10-08, 10:32
Where can i purchase this restrictor ring? Or do i have to make one myself? Where in the exhaust is it placed? I understand its in front section but is it before the 1st decat, between them or after?

You can get them from some of the traders on the forum. Place a wanted ad, and I'm sure someone will respond.

Mine is between the cat back exhaust and the last cat.. Not sure if that's the correct place but it seems to work.

jonte_j
17-10-08, 17:20
thanks!

Duffman
17-10-08, 17:44
Where can i purchase this restrictor ring? Or do i have to make one myself? Where in the exhaust is it placed? I understand its in front section but is it before the 1st decat, between them or after?

Further back the better mate I think...maybe between 2nd decat and exhaust?

Anyone 2nd this?

MarkR
17-10-08, 18:00
You can get them from some of the traders on the forum. Place a wanted ad, and I'm sure someone will respond.

Mine is between the cat back exhaust and the last cat.. Not sure if that's the correct place but it seems to work.

Actually, I think you just seconded it... ;)

jonte_j
17-10-08, 19:40
Is there any welding needed for this?

MarkR
19-10-08, 23:06
Nope, its a gasket that fits inline with the pipes.

Suprafly
02-11-09, 01:22
Right I'm currently ordering parts from whifbitz for a full BPU.

I've got a 96 J-spec RZ-S, I already have a Blitz Nur spec cat back system fitted, so I'm after:

HKS FCD
Walbro fuel pump
Both decat pipes
Restrictor ring
NGK Iridium plugs

Question is what grade plugs do I go for?

tDR
02-11-09, 09:43
Right I'm currently ordering parts from whifbitz for a full BPU.

I've got a 96 J-spec RZ-S, I already have a Blitz Nur spec cat back system fitted, so I'm after:

HKS FCD

Question is what grade plugs do I go for?

Grade 7's. Check out the spark plug FAQ for well documented info on the subject.

I'd always go with a GReddy BCC (another name for an FCD) over the HKS FCD because of the method it uses to fool the stock ECU on the airflow signal.

Cheers,

Brian.

deathmonkey
05-02-10, 00:44
Massive apologies if this has been answered either on this thread or elsewhere, I've searched solid, I promise :innocent:!

Anyway, as I'm hoping to go BPU by the summer, I was just wondering what type of fuel I should be aiming to use? Does it not change from what I've always done - use the best at whatever station I'm at, or should I really be looking to use v-power for example, when I do eventually go BPU.

Thanks guys, again apologies if already answered.

Homer
05-02-10, 01:06
Simply use the higest octane fuel available to you. Shell v-power, BP Ultimate, etc. As always, ensure you have an AFR (worry gauge) to keep an eye on the levels and if it gets beyond limits back off.

I wouldn't recommend it though if only low octane is avaiable, unless the car has an aftermarket ECU & map at higher boost pressures (1.1 and above) it's *needed* to use high octane fuel. Peak power is not the issue, it's the switch-over point that causes det.

deathmonkey
05-02-10, 11:33
Simply use the higest octane fuel available to you. Shell v-power, BP Ultimate, etc. As always, ensure you have an AFR (worry gauge) to keep an eye on the levels and if it gets beyond limits back off.

I wouldn't recommend it though if only low octane is avaiable, unless the car has an aftermarket ECU & map at higher boost pressures (1.1 and above) it's *needed* to use high octane fuel. Peak power is not the issue, it's the switch-over point that causes det.

Thanks for the reply Homer, good to know :).

BABZ988
11-03-10, 23:36
i think:
if i buy a tanabe full decat system (usually a 4"); i'll need a restrictor ring !
but if i buy a 2.5 decat system from whifbitz ; will still need a ring?
looking for BPU at the moment!

Homer
12-03-10, 00:36
If it'a a jspec then yes, you will need the restrictor ring and the other mods before decatting, regardless of the exhuast diameter.

Pudsey
14-05-10, 17:15
Can someone answer me this, as there seems to be some differences of opinion.

I am BPU'ing my 1998 VTT-i Twin Turbo.

I need to know if I need a Fuel Cut Defender or not.

If I don't fit it and run the car without it will it get damaged?

Any advice would be appreciated and is rather urgent due to attending Japfest tomorrow.

Thorin
14-05-10, 17:34
You need one, otherwise you'll hit fuel cut >1.0bar

Shane
18-05-10, 16:07
Just about to go BPU and I have a couple of questions both relating to the ristrictor ring.

With the restrictor ring in with a hole of say 2 inches, is there any real point or advantage with a 3" exhaust, surely the ring becomes the most restrictive point and any advantage of a big bore exhaust after the ring is lost?

If I use 3" decat pipes and then have the ring between the second decat and the exhaust, surely when the engine is suddenley revved hard, until the pressure is built up between the turbos and the restrictor ring it is possible to overboost?

I know this is all proven territory and don't question it works as of course it does but as I was looking at the 3" decat pipes I bought for mine these questions just sprang to mind.

supra-ireland
29-06-10, 20:20
I've a question about my BPU setup.
I've got an Apexi S-AFC, it came with the car uninstalled.
I'm happy to install it myself but having read through the foum some people suggest that there's no point fitting one with a BPU setup.
Can the S-AFC improve things or should I just forget about it?

I've got stock turbos and was hoping to usually limit boost to 1.0 bar and occasionally go up to 1.2 bar.

tDR
29-06-10, 23:26
Sell it and do things properly if you want to get into tweaking maps IMO.

supra-ireland
29-06-10, 23:31
Sell it and do things properly if you want to get into tweaking maps IMO.

Ok, thanks.
So at a BPU level is there much point with aftermarket ECUs and the like
or are you as well to stay with stock?

tDR
29-06-10, 23:32
I'd say there's definitely gains to be had but the ECU or piggyback needs to have decent resolution mapping wise to really get the most out of the sequential setup to optimise the fuelling and timing across the rev range.

supra-ireland
29-06-10, 23:58
I'd say there's definitely gains to be had but the ECU or piggyback needs to have decent resolution mapping wise to really get the most out of the sequential setup to optimise the fuelling and timing across the rev range.

Is there anything you could recommend?
I want to keep costs down but at the same time I'm willing to spend enough to get something proper.
Thanks for the advice.

Peter P
30-06-10, 00:08
Is there anything you could recommend?
I want to keep costs down but at the same time I'm willing to spend enough to get something proper.
Thanks for the advice.

Would recommend looking at one of the SYVEC ECU's that Ryan does as these seem very comprehensive and would be future proofed if you went single at a later date.

The Whifbitz Time Attack cars both run this ECU to good effect and it also has goodies such as traction control and boost control involved.

Have a look under 2 bar tuning as a trader and see what you think.

There are other options but Ryan sets these up perfectly and the piece of mind having UK support both with the manufacturer and tuner appeals to me.

Will be what I go for when I get my next one! :)

Just my opinion by the way.

Pete

tDR
30-06-10, 09:18
Syvecs is an excellent choice if you're going standalone, also with good recent write-ups is the AEM piggyback which is probably more appropriate if you're auto. RyanG on this forum likes to map both of those choices.

Other piggybacks I like are the GReddy emanage ultimate and the MAP-ECU2.

supra-ireland
30-06-10, 09:46
Cheers Peter.
TDR, you got it just before me. :)
I've just read all of Ryan's threads on the Solaris and the AEM FIC.
I agree with you, I think the AEM is much more suitable for me.
My aim is for a good, reliable BPU setup giving me around 400BHP.
I may go for a single setup in the future but it's a long way off.

PDowdy
02-08-10, 12:59
sorry if this is an obvious question but I wasn't totally sure after reading through this.
Does a jspec require a restrictor ring if you're fitting an electronic boost controller ??
Is it ok to run both ?? (I'm guessing yes but just want to double check)

Mcgoo
02-08-10, 13:21
sorry if this is an obvious question but I wasn't totally sure after reading through this.
Does a jspec require a restrictor ring if you're fitting an electronic boost controller ??
Is it ok to run both ?? (I'm guessing yes but just want to double check)

It's 'best' to run both really. Most people will fit a 1.0 or 1.1 bar restrictor ring and then use the EBC to raise it to 1.2 bar when required.
Without a restrictor ring the boost can go through the roof causing your turbos to pop.

TonytotheB
20-09-10, 09:05
Very simple to understand. Thanks Homer.

SupraDan24
07-11-10, 00:10
Do either the Iridiums on NGK's need to be gapped? I remember reading it on a thread somewhere a while back but i cant find it again. I'm going to be ordering some next week so i'll order which ever ones dont need gapping.

Jake
07-11-10, 00:30
Iridium plugs mustn't be re-gapped.

damadom
24-03-11, 15:25
can this work on the n/a?

Gaz6002
24-03-11, 15:30
can this work on the n/a?

You can decat the NA, but it's not known as BPU as you'll rarely see any 'upgrade'. You certainly won't see anywhere close to 400bhp on an NA.

Clancy2k
29-04-11, 16:00
I'm getting an RZ Twin-Turbo next week, i would just like to know how much this BPU costs parts + labour? I'm hoping it's £1000 or less, thanks.

johnny g
29-04-11, 16:57
Around £1000 will get you the decat pipes + exhaust + restrictor ring + plugs. Then you need to think about the intercooler, gauges, boost controller.

Budget for around £1600-1700 IMO

Clancy2k
29-04-11, 16:59
Around £1000 will get you the decat pipes + exhaust + restrictor ring + plugs. Then you need to think about the intercooler, gauges, boost controller.

Budget for around £1600-1700 IMO

well the good news is i think the Supra i'm getting already has an aftermarket de-cat exhasut, it looks that way from the pics anyway, so that should save me £500

Suprakeith
30-05-11, 19:48
can i ask whats the best mods to improve porfomance on the n/a please? will do complete engine rebuild next year i hope with single set up just got to the fund, but would like to do few bits to n/a for now so have more power and drive

Josh
30-05-11, 19:55
can i ask whats the best mods to improve porfomance on the n/a please? will do complete engine rebuild next year i hope with single set up just got to the fund, but would like to do few bits to n/a for now so have more power and drive

There's not a lot you can do. There are a few threads covering it but for the £ per horsepower, it's not really worth it IMO. Save up and get a TT :)

Suprakeith
30-05-11, 20:19
i not going to save up for TT am planing to do few mods to n/a then get head reworked and new cams then next year pull block out and fit new uprated pistons and conrods then fit single turbo,am thinking of having 100 shot of nos put on n/a aswell,was also looking at bigger throttle body for now as that can be used on n/a and can also be used when turbo her, well thats the plan any way, any help would be greatful and by help i dont mean save for TT,lol

scotty71
30-05-11, 22:35
There's not a lot you can do. There are a few threads covering it but for the £ per horsepower, it's not really worth it IMO. Save up and get a TT :)

but dont take 10 sheets about it :p

Thorin
31-05-11, 09:47
i not going to save up for TT am planing to do few mods to n/a then get head reworked and new cams then next year pull block out and fit new uprated pistons and conrods then fit single turbo,am thinking of having 100 shot of nos put on n/a aswell,was also looking at bigger throttle body for now as that can be used on n/a and can also be used when turbo her, well thats the plan any way, any help would be greatful and by help i dont mean save for TT,lol


Don't.

Either sell the NA and buy a TT, or do TT engine swap. Tuning the NA engine will be more costly, more complicated, and even if you fit a turbo you'll still not make much (if any) power over a BPU TT. Of course you could choose to ignore the advice of long standing members who've seen and done it all before...

Suprakeith
31-05-11, 11:25
i like the sound of doing engine swap as have found a company in japan that will send a TT engine with turbos to me for 2k which has just had rebuild including all bearing and seals so that could be the sensible path to take,thanx for the advice

Thorin
31-05-11, 11:34
i like the sound of doing engine swap as have found a company in japan that will send a TT engine with turbos to me for 2k which has just had rebuild including all bearing and seals so that could be the sensible path to take,thanx for the advice

I'd advise sourcing one through the forum, you'd have fun trying to deal with a company in Japan if the engine they sent turned out to be junk or incomplete.

Suprakeith
31-05-11, 12:54
that makes sense to me bud,thanx again for help,well best start saving some dosh for new engine then,lol

SamuraiFlash
03-07-11, 23:39
Just wanted to know if 0.9bar restrictor rings are available and what will be the outcome of removing the 1st cat, but keeping the 2nd one in?

Will this increase boost pressure and will it alow the turbo's to spool up quicker? I would like to only raise my boost pressure to 0.9 bar.

I would like to keep the 2nd cat in to avoid installing cats for MOT's etc, and I dont really want to raise the boost too high as I don't want to reduce the longetivity of the stock turbo's. If 0.9bar give's me a quick spool up and a little bit of extrapower then I'll be a happy fella :)

pezzler
03-07-11, 23:51
I would like to only raise my boost pressure to 0.9 bar.

0.2 bar probably wont give you a great deal of performance increase, but you will get faster spool from losing the cats. I have both cats out of my car and it has only failed 1 MOT for emissions, and that was due to an o2 sensor failure. If youre that bothered though, you could keep hold of the 2nd cat and fit it at MOT time (should only take 1/2 an hour to refit)

If you're going to do it, the go the whole hog. Full BPU conversion including boost controller, and boost gauge. And if you dont want to nail the turbo's then dont nail the car..... too much

SamuraiFlash
03-07-11, 23:57
Thanks for the info bud :) yes i'm going to get the whole kit off a friend on this forum. I'll be getting both de-cats, boost controller, 1bar RR, Thor FCD. All i need after that are plugs and maybe a fuel pump & filter.

I undertand what you are saying, but I would like to put my foot down once in a while, but only at a slightly higher boost pressure than stock. I've had a new o2 sensor fitted so I guess i can have a full decat done, but I just want to know how I can get the car running at max boost of 0.9bar with a full decat, RR and boost controller.

scotty71
04-07-11, 00:06
floor it :D

pezzler
04-07-11, 00:12
If you're fitting a 1 bar ring, then that will be the maximum boost pressure available - an electronic boost controller will allow you to increase on this.

If you're looking to hit a maximum of 0.9 bar, then you will have to fit a smaller diameter restrictor ring; something that will restrict the flow of exhaust gasses more. This in itself will only be possibly by a lot of trial and error, fabricating up numerous restrictor rings of different sizes then fitting them and testing them to see what the restrict the full boost pressure to. The problem with this will be that the ring you fabricate to restrict the boost to 0.9 bar now, will more that likely allow the boost to creep up when the weather changes ***somebody jump in and correct me if im wrong***

I'd definately change the fuel pump, and if you havent already then i'd look at renewing the intercooler. And if you really want some peace of mind, look into investing in an AFR or EGT gauge

SamuraiFlash
04-07-11, 00:19
Ok pezzler, I'll get in contact with Chris Wilson to see if he can make a 0.9bar RR for me.

I have recently purchased and fitted a Greddy FMIC, so it will be more efficient than my old and tatty stock SMIC I had previously.

Won't a Boost Controller stop the boost from creeping up regardless of conditions? Well I hope so!

I will be purchasing a Fuel Pump, which will you recommend if I'm only going to be going upto 0.9bar max? I'd also like recommendations on the Plugs too.

Thank you :)

scotty71
04-07-11, 07:36
boost controllers can only up the boost not lower it Flash ;)

Thorin
04-07-11, 09:23
If you're leaving the second cat in you'll only hit around 0.9bar anyway, no need for a restrictor ring.

SamuraiFlash
04-07-11, 09:35
If you're leaving the second cat in you'll only hit around 0.9bar anyway, no need for a restrictor ring.

That's great! Will keeping the 2nd cat is cause exhaust gas temp to rise? Are there any concerns about running the car this way?

Thorin
04-07-11, 09:37
That's great! Will keeping the 2nd cat is cause exhaust gas temp to rise? Are there any concerns about running the car this way?

No, plenty of people have run with just the second cat in place.

SamuraiFlash
04-07-11, 09:51
No, plenty of people have run with just the second cat in place.

Is it still a good idea to use a boost controller to negate the chance of a boost spike or will this not happen with 2nd cat in place.

Also with this set up will the car spool up quicker without the 1st cat?

Thank you :)

SupraDan24
04-07-11, 12:51
No because a boost controller can't lower boost. Yes it will spool faster. I run mine with 2nd cat in, and get around 0.9bar so just go with that, no need for a boost controller or a RR. If for some reason the boost does go above that, install a RR but i wouldnt have thought it will.

SamuraiFlash
04-07-11, 13:24
Thanks for the reply dan. So how long have you been running your car like this? Do you have an EGT or an AFR guage installed? If so, have the readings been stable?

I think I'm getting a little confused with the boost controller business lol. I know you can't lower the boost if you have a 1bar RR, you can only keep it there or increase it. However I'm actually increasing my boost pressure from stock so can I just use the boost controller to keep stable at 0.9bar?

Josh
04-07-11, 13:40
Thanks for the reply dan. So how long have you been running your car like this? Do you have an EGT or an AFR guage installed? If so, have the readings been stable?

I think I'm getting a little confused with the boost controller business lol. I know you can't lower the boost if you have a 1bar RR, you can only keep it there or increase it. However I'm actually increasing my boost pressure from stock so can I just use the boost controller to keep stable at 0.9bar?

You can set the EBC to 0.9bar but if the boost wants to creep above that, it will do. You'd require a smaller RR to keep boost constantly as stock pressure then raise it to 0.9bar.

You'd have to just try it and see I reckon.

SamuraiFlash
04-07-11, 21:45
I guess even though I nay not to, but out of being cautious I'll get chris Wilson to make me a 0.9bar rr and have a boost controller fitted.

Just uncertain whether or not to remove the 2nd cat?

pezzler
04-07-11, 22:38
Up to you my friend, but as a couple of members have already stated - they have/do run cars with the 2nd cat in place, and their cars are making around 0.9 bar

I think you may be getting a little hung up on this magic 0.9 bar figure. Think you should either drop both cats, fit a 1 bar ring, and a decent EBC as many many people have done before.... or, lose the 1st cat and run a decent boost gauge just to monitor whats happening in your manifold - if you're finding that the boost is creeping past what you're happy with, then look at fitting a RR

The FMIC is a step in the right direction though

mwilkinson
04-07-11, 22:48
Kamal my opinion is you should go full BPU.

1.2 bar giving it the beans. Far more fun and what owning these cars is all about.

If you do it you will never look back. :)

SamuraiFlash
05-07-11, 11:56
Kamal my opinion is you should go full BPU.

1.2 bar giving it the beans. Far more fun and what owning these cars is all about.

If you do it you will never look back. :)

thanks matt, I guess I'll have to think this through once I have all the parts off you :)

SJMKIV
21-10-11, 13:54
Is there any benefit or drawback fitting 650cc injectors to a j-spec bpu supra?

I know this question might be a bit silly, but I have a set of 650cc injectors with me, and not sure if I should use them or try and sell them. Any advice is much appreciated!

Thanks!

SJ

dive_popo
21-10-11, 13:58
Is there any benefit or drawback fitting 650cc injectors to a j-spec bpu supra?

I know this question might be a bit silly, but I have a set of 650cc injectors with me, and not sure if I should use them or try and sell them. Any advice is much appreciated!

Thanks!

SJ

will need mapping...

grumps2JZ
24-07-12, 07:46
is there such a thing as a midpipe for the supra? i have the autobahn88 3" downpipe for mine but i'm pressuming this only removes the first cat. i would like to be able to remove the second set of cats but cant really afford to buy a decent full exhaust system right now, and dont want to bother with a crappy cheap system that i then have to replace again at a later date.

Geo
24-07-12, 08:22
^^^ see my reply in your other thread, :D

RZtwin
02-08-12, 08:12
Would it be wise to fit bigger injectors to my j-spec before going full bpu?

tDR
02-08-12, 09:23
Would it be wise to fit bigger injectors to my j-spec before going full bpu?

Not necessary - there's too much fuel available even at BPU, there are gains to be had by being able to trim out fuel mapping wise. For safety you want to be retarding timing in places at BPU level rather than adding more fuel than is available with the standard injectors.

Spend your cash on a decent piggyback or ideally standalone ECU rather than larger injectors out of the block.

Cheers,

Brian.

RZtwin
03-08-12, 21:14
Not necessary - there's too much fuel available even at BPU, there are gains to be had by being able to trim out fuel mapping wise. For safety you want to be retarding timing in places at BPU level rather than adding more fuel than is available with the standard injectors.

Spend your cash on a decent piggyback or ideally standalone ECU rather than larger injectors out of the block.

Cheers,

Brian.


My local tuner tells me the injectors will be around 80% duty cycle at bpu, roughly 400bhp, 16psi on my jdm
2jz?

carl0s
04-08-12, 01:34
My local tuner tells me the injectors will be around 80% duty cycle at bpu, roughly 400bhp, 16psi on my jdm
2jz?

I vaguely remember it being observed (Ian C?) that above a set boost pressure point, which may be 15 or 17psi, the Ecu runs the injectors at 100% DC just to be on the safe side.

tDR
04-08-12, 09:06
I vaguely remember it being observed (Ian C?) that above a set boost pressure point, which may be 15 or 17psi, the Ecu runs the injectors at 100% DC just to be on the safe side.

Correct - stock JDM ECU opens the taps 100% just before fuel cut, when the stock MAP sensor sees pressure equating to a voltage above ~ 4v. Hence you use a mappable ECU to never let these things happen until unsafe boost levels where you can still have safety cuts.

An FCD is cruder though is effective - it just caps the voltage the stock ECU sees.

carl0s
04-08-12, 09:47
Correct - stock JDM ECU opens the taps 100% just before fuel cut, when the stock MAP sensor sees pressure equating to a voltage above ~ 4v. Hence you use a mappable ECU to never let these things happen until unsafe boost levels where you can still have safety cuts.

An FCD is cruder though is effective - it just caps the voltage the stock ECU sees.

but the point at which the FCD caps the voltage, is the point at which the taps are open 100%, right?
So, a typical BPU car which uses an FCD, would generally be running 100% duty cycle at high rpm WOT?

tDR
05-08-12, 08:04
but the point at which the FCD caps the voltage, is the point at which the taps are open 100%, right?
So, a typical BPU car which uses an FCD, would generally be running 100% duty cycle at high rpm WOT?

Typically yes, although there is adjustment in some I've seen - GReddy BCC for example. The lower the voltage you set them to clamp at, the less fuel your injectors will put out as a maximum.

RZtwin
05-08-12, 15:31
So what should I do fellas so.I don't lean out at WOT? I plan to bpu my 93 jdm tt and use it as a track car.

carl0s
05-08-12, 16:13
So what should I do fellas so.I don't lean out at WOT? I plan to bpu my 93 jdm tt and use it as a track car.

just BPU it™

RZtwin
06-08-12, 02:22
Should I worry at top boost at WOT?

tDR
06-08-12, 11:59
Should I worry at top boost at WOT?

Like I said, the real concern is detonation with increased boost. The only way to fix that is with a mappable piggyback or standalone ECU. This will lower the risk you run of engine damage. That said, most BPU cars run for many miles without lunching their engines. How hard they are driven is anyone's guess.

The most common failure with increased boost is the Turbos themselves.

As a side note - if you're still on your original fuel pump it's worth replacing to ensure a consistent fuel supply. Typically people switch to a higher flow item like that on the UK MKIV Supra or a Walbro 255 LPH job.

carl0s
06-08-12, 12:21
As tDR says: BPU itself generally comprises of: walbro pump (if existing is jdm), decat, suitable restrictor, colder plugs, thor FCD. Basically just raise boost and sort the fuel pump.
ECU modifications aren't normally done and it's not normal for the engines to break.
I'm sure somewhere in this 10 page thread entitled "BPU (Basic Performance Upgrade)" it will explain what the general BPU practice is.

arne
07-05-13, 18:24
I have a J-spec model and I'm wondering if there's any thing that I can change that makes it possible to remove the restrictor ring without having any problems or overspeeding turbos?

Budz86
07-05-13, 18:49
I have a J-spec model and I'm wondering if there's any thing that I can change that makes it possible to remove the restrictor ring without having any problems or overspeeding turbos?

Depends on your boost controller really (assuming you have one) - most will cut the boost pressure by a set amount if it detects the pressure exceeding a set limit. If you've not got a BC then don't remove the ring as they will spin way too fast! Generally it's not advisable to remove it at all; best thing would be to get it drilled out a touch more if it's too restrictive. Remember you also need some back pressure to keep the turbo's spinning. Why do you want to remove it completely?

listy
07-05-13, 19:02
Why even think of removing it? Its a cheap safety feature which helps stop your turbos going bang.

arne
07-05-13, 19:16
I have a gizzmo Boostcontroller and also a mapped piggyback (running 1.05bar)

mellonman
07-05-13, 19:48
Leave the ring in and up the boost with the controller, a boost controler can only make boost not make it less and needs a marging to work correctly,
If you have a piggy back ecu get it mapped for 1.2 boost and enjoy

ellis
07-05-13, 19:50
I run with 1st cat out, 2nd cat in and found mine hit fuel cut easily (in the colder winter period) and have since put an RR in - all good now and still lots of grunt plus the tubbies are safe.

arne
10-05-13, 08:39
what's the diameter of a 1bar RR?
or does it only makes a difference without BC?

Budz86
10-05-13, 08:56
Strangely it varies depending on the car. Think Whifbitz have a few different sizes so may be worth speaking to Paul

tony tt
10-05-13, 10:35
If go for a 1 bar restrictor ring to be safe then raise to 1.2 with a bc. Paul whiffin sells both sizes I'm sure.

arne
10-05-13, 11:35
I don't get why to run on 1.2bar with a 1bar RR?

Wez
10-05-13, 11:56
This whole debate is as old as this forum :lol:

A restrictor ring is not an exact science and is a bodge to fix the simple flaw that the internal wastegates are not able to control boost properly on the JSpec units. RR are sold as 1bar but do not guarantee 1bar boost, there are lots of factors, ie the weather, on a hot day it will make less and a cold frosty morning it will make more due to the dense air. Its long been said that 1.2bar is the max safe boost on the JSpec turbos, to safely achieve this fitting a restrictor ring to give approx 1bar allows for variables like the mentioned weather, you can then safely raise the boost to 1.2bar with a boost controller.

If for example you fitted a 1.2bar restrictor ring on a nice warm day, 100% guaranteed when you went out on a nice cold morning and booted it you would overshoot and possibly det the engine, blow the turbos or cause any other number of damage.

Now some people ask, why 1.2bar, I see two reasons for this, firstly the JSpec ceramic units do not like overspeed and tend to fail, secondly the JSpec is MAP not MAF and the stock MAP sensor reads to just over 1.2bar, therefore when you are out of the MAP range you are leaving your fueling to the hands of the gods and relying on your fuel reg to supply more fuel with higher boost, not an ideal situation.

arne
10-05-13, 12:05
do you mean that if my BC is running 1.2 bar and I have a 1bar RR that my TURBO'S will never reach 1.2bar but rather 1bar?
if so, does this mean that running 1.4 bar boost with a 1.2 bar RR is also safe?

Wez
10-05-13, 12:18
do you mean that if my BC is running 1.2 bar and I have a 1bar RR that my TURBO'S will never reach 1.2bar but rather 1bar?
if so, does this mean that running 1.4 bar boost with a 1.2 bar RR is also safe?

That is not what I mean at all.

I assume you have a boost gauge, with a 1 Bar restrictor ring and boost controller set 1.2bar you should be running 1.2bar as verified by the boost gauge read out, if you didnt have a 1 bar restrictor ring you would not be able to run 1.2bar safely, boost controllers can only increase boost, not reduce it, without the 1 bar restrictor your boost would over shoot 1.2 bar and your controller would be useless ;)

arne
12-05-13, 14:51
I'm running 1.05 bar and I don't know what restrictor ring I have...
I was wondering if I make the hole bigger... will it be safe? And what will be the best diameter of the "hole" to have max power but be safe enough...?

Toddzor
02-10-13, 04:51
Hey guys,

Sorry to revive a somewhat older thread.

Just a quick question on the topic of the BPU. I own JDM - so, I'm going to need to restrictive ring.

My question is in regards to the boost controller. Although not necessary - wouldn't a constant 1.2 bar eventually put strain on the jdm turbos? Or are they perfectly fine running at 1.2 bar all day every day?

Would you suggest getting a smaller ring for say 0.9 bar, and getting a boost controller to up the boost to 1.2? I'll stick with just the RR if anyone can confirm that 1.2 bar is perfectly safe to run daily.

listy
02-10-13, 07:36
Read the thread ;)

Get a 1 bar restrictor ring, not a 1.2 bar one.
I run just a 1 bar RR at the moment, as my Boost Controller gave up a while back. On colder days, I boost to 1.1 bar (ish), so having a 1 bar RR as apposed to a 1.2 bar RR is saving my tubbies.

A RR and boost controller is the safest way to run higher boost. I would never dream of runng at 1.2 bar with no boost controller.

1.2 bar is the recognised safe limit for J Spec turbos, so should be fine at 1.2 bar. Don't forget, you will only hit 1.2 bar when you're going some.

To sum up: Fit a 1 bar RR, and a boost controller. Set the BC to 1.2 bar, and enjoy :D

Toddzor
02-10-13, 07:50
No worries! Thanks for that Listy

p1RATE
05-11-13, 16:38
I thought this would be the best place to ask as i know this is a common topic but i cant find much information on this.

I have seen in a number of places people talking about a BPU N/A.

What would this consist of? i was under the impression that there was not much that you could do with an N/A other than fit a less restrictive exhaust.

Gaz6002
05-11-13, 16:55
You can do similar mods on an NA - and almost any car, actually - but you won't see the same gains.

BPU is a term coined for TT Supras, NA owners just like to kid themselves about what they're driving :)

Toddzor
15-01-14, 09:25
Just a quick question.

I have a FMIC intercooler, and have deleted the first CAT with a 3' pipe. This leaves the stock midpipe in place.

I am still overboosting and am getting 22psi which is obviously hurting my AFR (12.7 to be exact). I thought maybe the stock midpipe would be small enough, and therefore wouldnt need a restrictor ring. Does anyone know the size of the stock midpipe?



Thanks

supra&starlet
26-02-14, 22:58
i had an aftermarket fuel pump in my gas tank, and i got that removed (the shop kept the aftermarket pump :( , ) anyways. Right now is a healthy J-spec fuel pump in the tank. Car is bpu, i am just wondering if i will be safe with this fuel pump for running no more than 1.0BAR of boost?? Or will i need to change the fuel pump if i plan to run that


OR, What is the boost range that the JDM fuel pump will take before you start running lean, ect..

Budz86
26-02-14, 23:27
You could be running quite lean at some points on WOT so it would be safer to upgrade the pump. Was the J spec pump new or second hand? Stock boost cut was set at 1 bar due to lack of fuel beyond that. Bear in mind that on some days (cold ones mostly) you may exceed 1 bar. How are you controlling and measuring boost? Do you have an AFR gauge?

Silece2k6
03-07-14, 14:03
Sorry, maybe I dont understand.
Ive got a 95 Jspec TT 6Spd with Catback, HKS Intake and Greddy Intercooler.

What can I expect if I only decat the 1st or 2nd Cat? (not both, because of Police :innocent:)

Provided FCD, Plugs and Fuelpump

thank you Patrick

pete.osborne69
29-11-14, 17:44
So I'm going bpu, but I am waiting on a fcd and boost gauge to arrive, I have everything else, would I be able to fit everything and still be able to drive the car or should I wait until the fcd arrives (no ETA) and if it is safe to drive what would I be limited to so I don't hit fuel cut, I assume no putting foot down for a long period of time but how hard do I have to accelerate to hit this fuel cut (not that I want to, just need some space in my living room for Xmas but this car is my only means of transportation)

Thanks
Pete

Grasmt
29-11-14, 21:17
The restrictor ring in the exhaust will hold the boost to 1bar, you dont need the fcd to run at 1bar as it cuts when boost exceeds that. Im running bpu @1bar with no fuel cut no boost controller only the restrictor ring in the exhaust and ive had no issues

pete.osborne69
30-11-14, 05:53
Thanks will get it all fitted today then :)

pete.osborne69
30-11-14, 12:33
does anybody know how to fit walbro pumps to the stock hanger

Nic
30-11-14, 15:40
does anybody know how to fit walbro pumps to the stock hanger

Which Walbro pump have you bought? if it's the correct one it should be a straight swap, the UK and J-spec hangers are different so you'll need the right pump for your car.

J-spec = GSS342 Walbro Fuel Pump
UK Spec = GSS341 Walbro Fuel Pump

pete.osborne69
30-11-14, 16:09
Thant explains a lot I have bought the UK spec one off someone on here and I have j-spec, explains why it didn't fit, and now I know there are two different types

Mk4Gaz
30-11-14, 16:11
It does fit a jspec Pete, I had it on mine. What bit are you struggling with?

Nic
30-11-14, 16:43
The fit is back to front on a UK spec, you can make it fit but I think you'll need a jubilee clip around the pump to hold it onto the hanger.

Mk4Gaz
30-11-14, 16:50
The fit is back to front on a UK spec, you can make it fit but I think you'll need a jubilee clip around the pump to hold it onto the hanger.
That's exactly what I done.

To be honest, when I bought it, I wasn't even aware that there were different types for the supra?

I just ordered it, and fitted it.

Being an aftermarket/generic item, I didn't expect it to fit exactly as a stock one would, but it went in fine and worked perfectly

pete.osborne69
04-12-14, 06:01
Thanks I managed to get it attached to the hanger but what have you guys used to insulate the wiring after it has been soldered together

Thanks again for the help

AshtonC
22-09-15, 07:56
Can some one explain why you need a restrictor ring? I don't have one on my supra and it runs 3" from the turbos back.. peak boost is about 1.1 bar and hits boost cut, motor is a vvti out of an aristo, cheers!

pete.osborne69
22-09-15, 08:03
Only j spec turbos need a restrictor ring due to the Turbo fans being made from ceramic and not steel (different melting points) smaller Turbo fans as well compared to stock which makes them spool faster then the UK ones so a restrictor ring prevents the Turbo from spooling to fast and melting the ceramic blades

Hope this helps (think I got it right)
If not someone will correct me

Ric
22-09-15, 08:29
Only j spec turbos need a restrictor ring due to the Turbo fans being made from ceramic and not steel (different melting points) smaller Turbo fans as well compared to stock which makes them spool faster then the UK ones so a restrictor ring prevents the Turbo from spooling to fast and melting the ceramic blades

Hope this helps (think I got it right)
If not someone will correct me

Almost.

The Jspec turbos wastegate is not man enough to the task, so if you take away the restriction of the cats, the wastegate can't control the turbo's boost, making it overboost way past it's "safe" limits (around 1.2bar) some Jspec turbos could boost upto 1.8 bar, albeit not very long.

The ceramic blades tend to detach from the turbine, chaos and screaming ensue.

AshtonC
22-09-15, 08:36
I live in NZ and mine doesn't have any restrictor rings and it boosts fine "custom made 3" so was just wondering what i'm missing

Ric
22-09-15, 08:40
I live in NZ and mine doesn't have any restrictor rings and it boosts fine "custom made 3" so was just wondering what i'm missing

Is yours a USDM model? similar to our UK / Euro Spec's they have the steel turbos with larger waste gates, you don't need the restrictor ring.

A picture of your engine bay would be able to tell, due to the injectors resistor pack.

AshtonC
22-09-15, 08:45
It has an aristo engine which is vvti I believe it's a jap spec as it has 440cc injectors

ashloys
20-10-16, 12:29
I'm about to fit UK turbos to my jspec engine with 440cc injectors. What is the maximum boost I can run? Still 1.2 or can I up it to 1.3/1.4bar?

Airwolf
07-05-17, 03:39
uk steel turbos are stronger than the jap ceramic versions. That being said with your injectors and not knowing your spec list. I would be safe and keep the boost at 1.2 bar (make sure you have a RR)
if you live a little on the wild side then you could up the boost to 1.3 or 1.4 and usually you would be ok but your risk is a bit higher.

fullrespect
02-04-19, 14:50
Guys, i am new here, and just wonder, if you do BPU which means removing catalytic converters - is it street legal ?

carl0s
02-04-19, 15:30
Guys, i am new here, and just wonder, if you do BPU which means removing catalytic converters - is it street legal ?

If I recall correctly, you'll still pass an MOT with the second CAT removed, but for BPU and the extra boost, you want to remove the first CAT, which would make it not street legal and you'd need to find a friendly MOT-friend, or swap out that CAT/de-cat pipe at MOT time.

Dnk
02-04-19, 16:27
If you got caught it could get silly, ie your insurance would be i'd imagine invalid as your car
wouldn't pass the mot, or shouldn't pass the mot unless one is fitted, saying that i know someone
who has given his insurance all of his mods, one being the cars de catted and they have insured him
which makes no sense to me if it can't pass the mot

nigelboyne
02-04-19, 18:27
If I recall correctly, you'll still pass an MOT with the second CAT removed, but for BPU and the extra boost, you want to remove the first CAT, which would make it not street legal and you'd need to find a friendly MOT-friend, or swap out that CAT/de-cat pipe at MOT time.

To pass emissions yes your correct will pass with just 2nd cat in , however you need the car very hot to pass at idle, so once your nct/mot passed that should be fine ie road worthy and hence no problems with insurance