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BPU Supra not boosting right...


Sean1933
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Im going to look at a BPU TT6 Supra tomorrow, it needs abit of work which im prepared/want to do...so its going cheap :)

 

The seller called me a couple of days ago and told me that the car was running 0.7 on 1st turbo and 1.0 on the second. He does not drive it much, when he does he does not drive it hard apart from on the odd occasion. He told me that he took it out to check it over and noted that it was only hitting 0.6 on 1st turbo and 0.8 on the 2nd, so standard boost. It still has one car in.

 

He has taken it to JPS this morning and apparently it could be a pipe going to the VSV that cannot be got at without taking the starter motor off (any ideas?, the starter is on the intake side of the gbox im sure...). If its not this then its probably the second turbo, or so the seller said. He seems pretty genuine though, he could of just not told me and i probably would not have noticed the boost peak issue.

 

Im not that fussed about this as it would be my single project anyway...but i would appreciate anyones views on what this could be. Thanks.

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Difficult to say but it may be a case of getting your head under the bonnet and checking for loose, or even split pipes - the later types are the biggest offenders in the turbo piping configuration! Age and pipe work degradation go hand in hand.

 

If 1 bar (and now 0.8 bar) is the best the car is producing then have both cats been removed etc etc. If anything the boost spike should increase now that the weather is turning quite nippy!

 

How long has the guy had it in BPU state Sean? His car may be telling him something?

 

What upgrades has the car got on top of standard spec mate?

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I dont know how long its been in BPU, but he does not drive it much or hard. It has 1 cat still in apparently.

 

Mods include cat back exhaust, filter, 1 decat, fuel cut defender, HKS AF Controller, HKS Boost Controller (not connected though). I think thats it to be honest.

 

So you think its probably just pipework, namely a split pipe thats only leaking enough to stop it going over 0.8, ie a very small hole!

What are the chanced of it being the turbo?

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TBH is that not about right the monet of boost your getting with 1 cat still in?

 

I would agree mate.

 

So you think its probably just pipework, namely a split pipe thats only leaking enough to stop it going over 0.8, ie a very small hole!

What are the chanced of it being the turbo?

 

 

 

Apart from the fact that the guy mentioned the original 1bar figure to you, the whole set-up seems OK. Don't forget that this BPU busness is no exact science. It depends on the condition of cars and their set-up configuration. If you genrally apply the same upgrades to the same cars then you won't get the same output performance figures. Having the 2nd cat removed and it tuned on the correct restrictor ring should see a suitable improvement.

 

Also, how did he record the 1-bar boost figure - his HKS BC (crap I may add) is not connected

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well that puts my mind at rest. He recorded it on a Greddy Boost Guage.

 

So why is the HKS boost controller crap?

 

Good news then Sean.

 

On the issue of BC's, there are some that best suit the Supra Sequential system and there are others that do not. The Blitz ID-III or the Blitz DSBC Type-R (not S variant though - more suited for single turbo applications) seem to have it bang on for supporting the Supe sequential system. I wouldn't touch the old HKS BC's (my own thoughts) but the new HKS seems OK. There is even a thread ongoing where Nic (Import Pimp) rates them quite highly so the likes of HKS are starting to evolve.

 

You can't go wrong with Blitz Sir IMHO!:) ;) :)

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Well i now have the car, and the seller was right about the boost changing.

 

Sometimes the 1st turbo would be at 0.7ish, then second turbo comes online and the pressure does not seem to change, if it does its only to like 0.8ish.

 

Then sometimes the 1st turbo would be at 0.7ish, second comes online and sweeps around to 1.0-1.1 which seems about right. I cant get an exact reading as the gauge is on its last legs, but i def notice the difference when the guage shows 1.0-1.1.

 

Any ideas? Possibly a VSV not opening properly or am i on the wrong path. I did wonder if it was a slightly split pipe but as its variable i cant see it being that.

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