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Boost Droping Away

33drifta

By 33drifta,
in Engines & Forced Induction

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33drifta Community Regular

33drifta

Posted
Posted

hey guys, i have recently made the following upgrades...

high flow turbo

fmic

cat, dump and front pipe

600cc injectors

ebc

pfc

fuel pump upgrade

z32 afm

problem is, boost only hold 13psi then at around 4000rpm drops off to about 9psi.

we have tested...

boost controler, actuator, bov, intercooler pipe leaks and all seem fine. my next step is to take the turbo back off and have it looked at (got it second hand of sau). does anyone have any idea what it might be if its not the turbo? also, what rwkws should this set up achieve? only getting 165rwkws which i know is WAY low. thanx guys.

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Dose Pipe Sutututu Grand Master

Dose Pipe Sutututu

Posted
Posted

Intake pipe collapsing by any chance?

I bought one of those silicon intake pipes, and they are the biggest waste of money, when the pipe warms up, it collapses and I get a massive boost drop as well from 15PSI -> 13PSI.

But fixed that, stuffed the inside with some stainless steel offcuts.

stolen_s15 Mentor

stolen_s15

Posted
Posted

It's probably your actuator opening slightly when the volume of exhaust gasses increases (due to higher rpm), your using teh rb25 actuator I assume?

Your best bet is to use an RB20 w/g actuator, and increase the preload slightly. (Do a search for 'ghetto actuator mod')

It could be your inlet pipe, but I doubt it, any tuner should be able to diagnose that on a dyno though.

Strik3r Experienced

Strik3r

Posted
Posted

it could also be the exhaust itself not flowing enough.. my old exhaust used to hold 11psi till about 5k and then drop down to 9 psi by redline. got a new highflow cat and muffler and now boost holds all the way through.

edit: only 165rwkw.. thats at least 50 below what it should be. should be pulling 220-240 with that setup depending on how happy your dyno is and how much boost your pushing through. the low power reading suggests an underlying problem so its probably not just a restrictive exhaust. maybe a collapsed cat ?

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