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The mkiv Supra Owners Club

Boost Levels


Geezabloke

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Its been asked before, i know, I have been through the searches so no funny comments please:eek:

Theres lots of info out there but some of it is contradictory.

What is the safe level of boost for a UK Spec TT.

Its fully de-catted with a Blitz Nur spec system, Blitz SS Induction, HKS BOV, FCD and Blitz DSBC boost controller.

At present the max boost is @ 1.15 bar with a limit @ 1.2 bar, however ive read on past threads that UK spec cars can happily run @ 1.3 and even 1.4 bar?

Is this true or is it wise to stay as i have it set now?

I want the car as reliable as possible but obviously with as much performance as poss.

I have also read that the fuel i should now use should be Super Unleaded or better?

Cheers in advance for any advice.

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Most comments I heard was that its safe on stock fueling up to 18PSi which is 1.24 BAR.

 

I have mine set to 1.22 BAR, but I did hit 1.28 BAR twice.

(its a bleeder valve so dependend on the outside temp and pressure)

 

Cuba

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from what i have gathered, conventional wisdom has it at max 1.2 bar (i could well be wrong) with those mods, so it looks like if reliability is your goal, then you are bang on target. waiting to see if this is right cuz if not, i cud then up the boost on mine as well..:devil:

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Guest Usmann A

ummm.....for sure their is a difference as you know the Jspec turbos are ceramic, thus limiting thier ability to keep at high boost levels safely, although many on here seem to be running them at 1.2+bar fine, from what I have made out.

The UK specs are ovbiously steel, and therefore are more reliable at boost pressures above 1 bar....also they dont suffer boost creep,(Ithink this is because they are steel therefore heavier and cannot run away with boost as the lighter wheel ceramics,but they is also another reason...)

Having said that I rememebr reading somewhere that these turbos are designed to flow max at 1 BAR. But have also heard of people going bang at that level and lower.

So it seems that its a game of chance really, some guys last at 1.3 bar ceramics and some go bang at 1 bar....

 

 

 

Hope this helps.....waiting for someone to come and correct me....

 

 

 

 

 

Oh sorry...just read the postcard bit.....:innocent:

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U- baby,

 

supposedly the reason we "JAPPERS" can get boost-creep

is that the wastegate on the Jap' turbos is smaller than on the UK,

SO, if we increase boost past a 'certain' level it can't escape

quickly enough (from the 'engine' nor from the wastegate !)

[if it can't get out it raises the boost, if it raises the boost it

can't get out> > > > > > !]

 

on the UK's they have a bigger wastegate that can release a

larger 'flow' of air ie. cope with higher boost.

 

I THINK ? ?

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Theres lots of I thinks in there guys, whilst i appreciate the comments and replys, I was really hoping for concise answers ( dont mean any offence there):(

I dont want to turn it up unless im sure its safe to do so...........Im waiting for the Chicken comments now.....lol:flame Dev

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Guest Usmann A

Cheers steve-top man, i knew it was summin else, as referred to in me previous post,I was i me head just couldnt recall it.... :innocent:

Cheers STEVE-EE-WONDER:p

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Guest Usmann A

Someone sort Gezza out mann...I have said me bit and have been told by people on here that UK's at 1.2 are ok, so no-one ave a go at me now! :sly:

Our jap's gonna be running 1.2, thats if the tuner feels its safe.....altough hes not covering anything on it, incase it goes bang....and its a Jspec...

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The candle that burns twice as bright lasts half as long . . .

 

In short, it's highly unlikely that anything will suddenly go pop at 1.2-1.3 bar (although if it were me I'd get the fuelling checked with a wideband just in case the pump or something is showing it's age), but you have to bear in mind that you are working the turbos a fair bit harder than they would be at 1 bar and therefore you reduce their lifespan the higher you boost.

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Guest Usmann A

Exactly what I was thinking, its amazing how he makes comparisions(metaphors,similies) from such soft and nature like objects to dirty man mad car perfromance parts...utter class Adam... :p :thumbs:

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OK Guys - can someone with any real thoughts on this please come forward - as would be interested also (no offence to Shakespeare et al - LOL!)

 

Checked my gauges and realised that I had hiy a 1.38 Boost yesterday

 

J-Spec

Decatted

Blitz SBC-ID etc etc

 

Now this is not usual - every now and then - normaly kept around 1.15/1.20 max

 

 

Will this do real damage or as it is only for a short burst will withstand the extra?

 

Cheers

 

Paul

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Guest Martin F
Originally posted by Adam W

The candle that burns twice as bright lasts half as long . . .

 

 

Somebody been watching Bladerunner today ? :D

 

Geeza (or whatever your name maybe), there seems to be a lot of BS and 'I thinks' emanating from this thread, luckily Steve W has become the boost creep guru. :D and is spot on with his wastegate answer.

 

I am running a very similar setup to what you now have, the only difference i can see is i have water injection (when it decides to work) and hard piping (when it decides to stay on!). I am running 1.4kg\cm with my warnings set at 1.45kg\cm (close to 1.4 bar). I have been using this as my max setting for the last 2,000 miles or so with no real problems, although i'm still waiting to get my fuelling checked on a wideband. 1.4kg\cm is my max setting day to day and for cruising i use the lower setting on the DSBC which i have set close to 1 bar.

 

I hope this helps, but remember what may be ok for one car may not for another. Sorry forgot to mention mine is a UK spec as well.

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Guest Martin F
Originally posted by Steve W

[ps. 'copyright' royalties for the NUR avatar will be winging your

way shortly mate...:p ]

 

Could of waited till i cleaned it, it's gleaming now.

LOL

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Martin

Cheers for the info, you stated that you normally run close on 1.4bar, i take it this is in short bursts on occassion?

Are you running a standard head gasket?

Also what fuel do you use as up to now ive used UL..........Gonna start using SUL as no Shell garages nearby but im looking....

Just to confirm, i should therefore be safe running around 1.3bar?

Thanks Again

Dave (Geeza or whoever)

:flame Dev

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I run about 1.25bar with a peak/spike up to 1.33. Im slowly increasing the boost levels until I hit a 1.4 peak/spike. My car has 118,000 miles on it and the first mods were put on it at 116,000 miles so its not a massive amount of mileage at that boost.

 

UK spec turbos take more abuse due to steel internals, so where the j-specs run at 1.2bar for safety the UK specs can run at 1.3. BUT, do expect your turbos to have a shorter life running at higher boost levels.

 

JB

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mine have peaked at 1.4bar with cw de cats and nur spec exhaust.have fitted fmic now, and would like to fit water injection. will have to get fueling checked too.

you take a chance when running higher boost.dont drive at 1.4bar everywhere.

see how it goes on a j spec.

they say 1.2bar is a safe limit.

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Guest Martin F

Well my max is 1.4kg\cm which is around 1.4bar and like all max boost settings you will only hit this when your foot is flat to the floor. Yep still on stock metal head gasket which should be more than up to the job at 1.4kg\cm and i run Optimax all the time.

 

I would defenitely recommend you use Optimax or SUL.

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