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The mkiv Supra Owners Club

How long can the twins last on BPU 1.2 bar?


RB-GTE

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1.2 is the top limit, the 440cc injectors will be maxed out at this level

You can get round this to a dgree though by upping the fuel pressure cant you? Andy Blythe (I think) did a write up of his results experimenting with upping the fuel pressure and iirc the 440s responded well.

 

But back on subject re the life of the turbos, I am running just below 1.2 and have noticed that I am getting traces of oil in my intake now, so I guess thats a sign that the seals are starting to fail?

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Mine (j-spec) has lasted for 6+ years now. Soon 7. 50.000+ miles. Two yearly trips to The Ring through Germany not holding back on chasing top speed. A trackday or two on top of this each year.

The car has not skipped a beat. Still pulls strong. I see 1 bar in hot weather and 1.2 in cold (seen 1.3 once or twice, but avoid that)

 

From what I have heard, it is quite common for the tubbies to last for years if you use common sense. However, if people are looking to go single at some point, I guess they don't baby them too much..

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I've ran 1.2 bar on my uk spec for years but as to how long the turbo's have actually been at 1.2 bar

is anyones guess.

And that Dunk is a very valid point. Just because you have the max boost set to 1.2, doesn't mean that you are going to be sitting at that constantly, its just there when you need it and in day to day use how often is that with our roads. Edited by Shane
typo (see edit history)
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even when out for a spirited drive, 1.2 bar isnt seen for a huge amount of time, i mean if you can lay the full 1.2 bar down at WOT round bends then you're a much beter driver than me.

 

As above though, they'll last someone who uses their car daily and only drives it spiritedly a lot longer than someone that simply uses their car for thrash and track seeing the 1.2bar more often

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Can't you run slightly higher boost because they are steel and they wont shatter like the ceramic blades ?

 

They won't shatter, but they can still fail. At 1.4 they're outside their efficiency range and just generating more heat. IIRC Ian C did some testing years back and his car actually made less​ power at 1.4 bar than they did at 1.3.

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As I know nothing about this whole turbo setup and the constraints along with it, could you not just uprate the injectors to a higher flow? Ive seen members mention that the 440cc injectors will be maxed out so could you not just put (say) 600cc in and have a RR in place?

 

Apologies if that seems extremely silly but again, all I know is the GE engine.

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But wont the uk spec turbos handle 1.2bar better than ceramic jspecs's?

 

Bearing/oil seal wear seems to be more common with the UK spec turbos and the J-spec ceramic turbine wheels can shatter, running either turbos above the stock boost pressure will reduce their life. As Thorin says 1.2bar is accepted to be the maximum 'safe' boost pressure for both UK and J-spec turbos, above this and they start to generate high intake temperatures.

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As I know nothing about this whole turbo setup and the constraints along with it, could you not just uprate the injectors to a higher flow? Ive seen members mention that the 440cc injectors will be maxed out so could you not just put (say) 600cc in and have a RR in place?

 

Apologies if that seems extremely silly but again, all I know is the GE engine.

 

The stock J-spec 2JZ-GTE ECU is mapped to control the 440cc injectors, yes you can fit higher flowing injectors but you would also need some way of controlling them with either a standalone or piggyback ECU.

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Can't you run slightly higher boost because they are steel and they wont shatter like the ceramic blades ?

 

Look at it from this pov, the UK turbos internals are essentially steel versions of the ones from a 1JZ's turbos, so at 1.2 bar they are already beyond what would be considered safe on a ceramic CT12 (1.0 bar) so there's your ability to run higher boost in effect.

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If you are upping the boost on a tired old 100,000 mile plus engine and turbos you are just sailing very close to the wind, if you up the boost on a properly rebuilt engine and new (not rebuilt) genuine turbos, you are more likely to enjoy a long and reliable relationship :)

In my experience Jap spec turbos last far longer than UK spec ones without smoking or blowing up, at stock or modestly raised boost levels.

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