boost fluctuation

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boost fluctuation

Postby avinesh » Fri Jun 20, 2008 11:38 pm

ok guys i put a single turbo on my 1jz soarer the turbo is a dsr 430 which is close in specs to a gt30-40 turbo, it has a internal waste gate, when i try to increase boost with a manual boost controller to say 12 psi from 8psi it doesnt work an the car seems to have boost fluctuation the boost would fluctuate in the high revs......any ideas
220.1 rwkw
jzz30 bpu soarer auto = 13.3 @ 171 km/h
jza80 supra = 11.7

jza80 apu supra manual = 400rwkw
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Postby MAGN1T » Sat Jun 21, 2008 12:14 am

leak in the exhaust manifold.

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Postby avinesh » Sat Jun 21, 2008 1:35 am

MAGN1T wrote:leak in the exhaust manifold.

Steve


dont think so coz on idle its really quiet you cannot hear any leaking sound
220.1 rwkw
jzz30 bpu soarer auto = 13.3 @ 171 km/h
jza80 supra = 11.7

jza80 apu supra manual = 400rwkw
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Postby MAGN1T » Sat Jun 21, 2008 10:16 am

Think again.

You won't hear it off boost and if the hole is small. In fact there might not even be a hole until it gets hot.

Anyway, If you think about the problem the correct way round,

IF you have a small leak,
You WONT hear it.
The end result will be low boost and fluctuating boost at high revs.

Most likely warpage where the manifold bolts to the head. Machining will fix it. Could be anywhere though. Blackening at the leak is the givaway.

Steve
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Postby evil_si » Sat Jun 21, 2008 11:52 am

does the car run ok at 8psi thru the rev range? or does it fluctuate as well

at 12psi what does it do? does it spike? surge? black smoke?


as steve said check for signs of carbon around the turbo and manifold, if there is there is a leak, that would be the first thing to rectify
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