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The mkiv Supra Owners Club

UK Boost??????


Scooby

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Lee, did you have an AFR gauge fitted at the time for 1.3 bar ?

 

Brad,

I have it in my head from when I first joined here that 18psi / 1.24 bar was the max you could run with the stock fuelling map on UK spec. I could be wrong but, I'm sure some of the old posts would answer this for you.

 

IMO if you want to enjoy BPU keeping the turbo's lifespan in mind, 1.2 bar max.

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Afternoon all,

 

I have a UK 6 speed and I am about to fit a boost controller, does anyone know what I can allow my turbos to boost to??

I think I herd a rumor they were ok at 1.4 Bar but I wanted to check.

 

Brad

*Anything above stock levels will reduce the life of the turbos, I hope that much is clear*

 

I run mine currently at 1.5 - max possible without an extra spring in the wastegate.

 

They are more resilient than the JSpec ones - they haven't got the ceramic turbine glued on, so it cannot break loose.

 

As for overspeeding damage to the shaft ---- well that's another story. Change your oil often, that helps a bit.

 

Fuelling is surprisingly adequate as well, remember that the UKSpec has 550cc injectors as stock, plus a stronger fuel pump.

 

Even at these levels, I use the AFCII to actually pull out fuel:d

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id imagine he doesn't have an egt problem with the various injection methods he's employed :)

True, mine is unconventional and doesn't mean for a moment that it's safe to take a stock car, boost it to 1.5bar and take fuel off at the same time. That would be unwise:blink:

 

But it indicates the resilience of UKSpec turbos. They just won't die, he he...

 

Some of my "boost" is pure steam, so no oxygen molecules there (hence no need to pair them with fuel molecules;) )

This 'deadweight' steam pays for itself earlier on though, as it increases the efficiency of the compressors and drops charge temps *below* the theoretical figure. That is equivalent to having compressor efficiency ~ 130% - by cheating ofcourse (the laws of thermodynamics have not been amended lately), but the discharge temps are low all the same.

 

Stock SMIC is having a very easy life, like freakin walking in the park:)

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John, your running stock uk tubbies at 1.5 bar? hell i was worried about going too 1.1, .

Boost is not a good indicator, beware.

* Just adding heat will show as more boost, so there's a big gotcha;)

* Adding restrictions to airflow will show as more boost, that's another nail in the 'boost' coffin.

* Higher airflow (what really makes power) won't necessarily show as more boost

* Fast-expanding steam (as in my case) creates pressure that shows as boost - yet if you find any way to combust steam, please let me know, lol...

 

So don't be in awe with fancy boost figures thrown around (for more, also read the 'boost is good' page on my site)

 

 

.

so how does that work, the steam thing.

 

It allows the turbo shaft speeds to be lower for the same total airflow, which is good (cannot tell exactly how much though without measuring shaft rpm)

It also allows operation at lower temps all the way from the diffuser onwards, another good thing.

Intercooling needs are much reduced, to the point that a good SMIC is more than adequate (I had plans to augment it with a chargecooler, but these are shelved since charge temps are laughably low)

You need to replenish the tank often though (it is lossy). After every boosted ride it has drunk 0.5-1litre.

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