BPU Full efficiency

I will wait for John A to jump in on this one, I have been trying to decide if to go full BPU or not as I cant justify the Price I may have to pay if the turbos give up on me, this is the only factor putting me off at the mo!!

I was wondering, obviously the turbos at 1.2 bar are working slightly outside there efficiency range and if I go down this route I want to make sure everything else can cope with extra boost levels so I can run the car as efficiently as possible at this power level!!

Any veiws or ideas would be great

Mike

Depends upon how well the car has been cared for, how it's been driven and how far.

No trader is going to gaurantee your turbos will be fine after decatting as like you say, they're operating out of manufacturer range.

General experience of club members says there should be good longevity at 1.2 bar (or why not 1.1 if you're worried?).

Myself, I'm resigned to the fact that I'll probably have to replace the turbos in a year or so, but that's the price you pay for power.

Over 1 bar ----> you're on your own.

You could have them operating at 1.4bar max and they might last for a year (of infrequent abuse)

You could have them set at 1.2bar and they could kick the bucket after a couple of weeks.

It really varies that much.

Everywhere seems to do a 1.2 bar restrictor ring, can you get a 1 bar ring? or 1.1?

Everywhere seems to do a 1.2 bar restrictor ring, can you get a 1 bar ring? or 1.1?

Yes. Chris Wilson does.

It really varies that much.

Very true! My turbo-seals started to fail after 10months going BPU .. that was at 1.2 Bar.

Whereas Oxygene's turbo's had a cardiac arrest .. and he was only running stock boost .. 0.8 Bar.

It's a lottery.

Everywhere seems to do a 1.2 bar restrictor ring, can you get a 1 bar ring? or 1.1?

depends on how restrictive the exhaust is aswell - mines never really went over 1 bar with a full decat - i even took the ring out....

I don't want to sound like I'm hijacking this thread, and I think this is all sort of related (but if it seems I am I will put this in a separate thread).

What would be the advantages \ disadvatages of using a 1 bar restrictor ring on a full decat and then upping the boost using a boost controller?

That way when you want that extra oomph you can turn the boost up, but for everyday nannying you run at the lower boost \ higher efficiency \ better reliability.

Also the title of this thread can be a bit misleading if one tries to look at it closer.

"Full efficiency" in what way?

combustion efficiency?

Fuel efficiency?

compressor efficiency?

...or is it really about bang/buck?

Or (risk of failure)/(extra oomph)?

Some of the possible 'efficiencies' are loosely related, and it's always a question of striking a balance different to that of the manufacturer.

I.e. there is no "free lunch", we always trade something for something else.

As a rule we only set the restrictor ring for 1.1 Bar unless Begged at!

Also the title of this thread can be a bit misleading if one tries to look at it closer.

 

"Full efficiency" in what way?

combustion efficiency?

Fuel efficiency?

compressor efficiency?

 

...or is it really about bang/buck?

Or (risk of failure)/(extra oomph)?

 

Some of the possible 'efficiencies' are loosely related, and it's always a question of striking a balance different to that of the manufacturer.

I.e. there is no "free lunch", we always trade something for something else.

aiming for maximum reliability and overall efficiency in all areas while being at BPU levels, ie fuelling, heat dicipitation etc

obviously the car will be not as Toyota had intended it to be, but how can I insure the car is as efficient and reliable as it can be at this level if you catch my drift, or am I going round in circles

In that case 1 Bar as John says and full Decat to get rid of all the heat.

Get it setup / checked at a Rolling Road so it is spot on.

More power will reduce the life of the engine...period! But saying that it would still last for many many years if looked after properly and supporting mods are looked into...J spec ceramics will eventually degrade quicker, go hybrids or single, you have to be prepared for them to fail, that way you can have funds set aside for when you go single etc.

What about 0.9 bar restrictor ring and then boost controller set up for 1 and 1.1 bar to be used only when needed .

What about 0.9 bar restrictor ring and then boost controller set up for 1 and 1.1 bar to be used only when needed .

Doesn't the aperture of the restrictor ring dictate EGT's ? If you have a 0.9 Bar restrictor ring .. doesn't it stand to reason that the EGTs will be higher (by how much I don't know) than a 1.1 or 1.2 Bar restrictor ring ?

If so, - then be interesting to see the EGT differences between a 1.0 restrictor ring & 1.2 Bar restrictor ring.

In the same boat, not sure whether double decat running at 1 bar would have any more power than one cat out and raising the boost to 1 bar???

In the same boat, not sure whether double decat running at 1 bar would have any more power than one cat out and raising the boost to 1 bar???

trouble with this is Tom that your then pushing your turbos against a resistance ie the cat left in place....this must have a detrimental effect on wear of the turbos??

So then is it safer (components lifetime wise) to have a full decat and run at 1 bar or leave the cats in and run at 1 bar (my setup)?

why de-cat if you worried about turbos blowing.you all know the ceramics are a weak point.you cant have your cake and eat it.if you are prepared to accept the turbos going to go sooner or later.you can pick up a set of stock turbos for 250 pounds.when i had a all in 1 3" decat pipe i was boosting to a crazy 1.5bar and knew it was mental so had to get boost down.

i used to get 1000 degrees egt`s with stock jap fuel pump.changed over to a walbro and egt`s have come down and feels safer.

if you worried about blowing your turbos just dont de-cat.

If I had a JSpec and wanted to keep reliability to max (and squeezing as much performance as poss) then I'd consider keeping the second cat.

No need for FCD, no need for rings, no need to muck about with fuelling at all, no need to worry about MOTs and/or roadside tests.

If the rear cat is in good shape (not melted, you can check this with a torch perhaps) it doesn't affect performance much at all - up until 1bar.

In certain revs it might even help *increase* torque after it has heated up, as it keeps the exh gases hot and moving fast.

Over 1 bar boost airflow starts to exceed the capacity of the cats and you also risk melting them -- then they have to go!

The first cat is very close to the turbos and has got to go.

Downpipe is best changed too.

But second cat I might keep for

On a J-spec I wouldn't personally go over 1.1bar without the following

1. A decent intercooler ie. either good condition stock or after market IC (actually anyone going over stock boost should make sure the IC is in good condition first).

2. More fueling, eg. adjustable fuel pressure regulator (so you can up the pressure), new higher flowing pump and possibly (although not absolutely necessary) bigger injectors.

3. Some way of controlling the fueling.

4. Dyno to set up the fueling correctly.

5. Someone with a lot of experience with Supras to advise.

Personally I fitted a FMIC, new fuel rail (not necessary really), FPR, bigger injectors, higher flowing fuel pump and an emanage. I have been running at 1.3bar (in parallel) for over 4 years now and (touch wood) turbos are still running strong.

My advice would be, if you're on a budget, limit the boost to around 1-1.1bar, anything more than this then make sure you have the supporting mods in place first.