Boost creep problem

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Jun 22, 2012 | 04:04 PM

#21

black98ws6ta

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From: louisville,ky

Redo the wastegate angle...it will fix it. A bigger gate might not fix it.

Jun 22, 2012 | 04:06 PM

#22

stevieturbo

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From: Norn Iron

Quote:

Originally Posted by boss79z

top port is to atmosphere.....bottom port is referenced to the turbo....other bottom port is closed.

And can you test it's operation with a known pressure source to see if its opening at the pressure you think it should be ?

Jun 22, 2012 | 04:41 PM

#23

Nitroused383

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From: Washington

Are you sure you have the correct diameter pipe for that 46mm gate? I believe standard size for 38-40mm gate is 1 3/4 but the 46mm gate needs 1-7/8 to 2".

Jun 22, 2012 | 04:48 PM

#24

boss79z

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Josh built everything....I just installed it. Not sure why it would be wrong since he has been building these for a while.

Jun 22, 2012 | 07:39 PM

#25

GrahamHill

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From: northeast Miss.

How high does it go with the thinner spring? And is that a constant creep with the little spring or does it ever flatline?

Jun 23, 2012 | 12:50 PM

#26

boss79z

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It never flat lined to 5k so we got out of it....it did that with the 4.5 and 7.5 springs.

Jun 23, 2012 | 06:18 PM

#27

got-a-ls1

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From: earth

my wastegate is at a 90 at the merge and seems fine... 9 lb spring made 9lbs. 10.5 lb springs make 10-11 pounds. One time i believe i installed one of the springs wrong (like it went sideways and got pinched when i bolted it together) and with 10.5 lbs of spring it would go to 15psi where i would let out of it.. running reference off the turbo.

Jun 23, 2012 | 06:53 PM

#28

Nitroused383

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From: Washington

When I ran the TC76 I could control boost down to 6lbs with a turbosmart 38mm gate. After I switched to the PT76 I could not control boost at all with the cutout open (15-16lbs). I installed a 46mm precision gate to try and solve the issue. With my cutout closed going through the factory slp dual dual exhaust I can run down to 6lbs, when I open the 4" cutout somedays when it's cooler it still creeps really bad, but somedays when it's not so cool it will run around 8-9lbs. The issue is less back pressure and not the greatest wastegate merge angle.

The more post turbine back pressure you have the higher pre turbine back pressure will be by an exponetial rate. Obviously lower back pressure makes controlling boost much more difficult. As the engine size decreases it's more difficult to control boost as a direct result of less back pressure.