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The mkiv Supra Owners Club

Boost levels on a Jspec TT


Paul R

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Hi,

 

I've heard a few times that the boost level automaticaly rises on an imported TT if you do such things as remove the cat, but the boost level wont rise on a UK TT?

 

Is this right?

 

What is the difference between the two cars??

 

 

Paul.

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I think Martin F may be along shortly to instruct you in the use of the search button, but...

 

It's something to do with the size of the wastegate on the J-Spec being not big enough to regulate the boost when the restriction of both cats is removed.

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It's something to do with the size of the wastegate on the J-Spec being not big enough to regulate the boost when the restriction of both cats is removed.

 

Spot-on Thorin-babes.....

 

the wastgate on my poor old J' is quite a bit smaller than a UK...

 

It can't cope with 'getting-rid' of as much excess boost as well as

the UK wastgate.....

 

UP TO THAT point it makes no difference but it's about the

level of BPU that it CAN occur....

[no idea why some J' cars suffer from it and others don't ? ?]

 

Having said that, mine's de-cat / NUR / NO restrictor, and is steady

at @1.1 at present......

 

FatS.

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Originally posted by Justin

When I fitted my Nur spec on my J spec TT and removed both cats my boost went up to 21.5 psi. I fitted the restrictor plate to get it down to 17.5/18.0 psi.

 

 

Is your car modified(in the internal department).

 

Isnt that a bit dodgy getting the boost up that high? what kinda RWHP you putting out??

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Originally posted by p_radbone

Is your car modified(in the internal department).

 

Isnt that a bit dodgy getting the boost up that high? what kinda RWHP you putting out??

 

When decatted with a aftermarket exhaust the boost can rise dramatically on a J-Spec, I too saw 1.5bar before fitting a restrictor ring. Justin is well aware that that was too high, hence him fitting a restrictor and now running ~18psi

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Originally posted by p_radbone

Ok sorry, didnt mean to sound patronising. I'm new to this supra thing!

 

i take it you all have boost guages fitted?

 

Perhaps that should be the first mod I do?

 

Paul.

 

Yep, good very good idea :D

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