Jump to content
SAU Community

Recommended Posts

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.

Link to comment
https://www.sau.com.au/forums/topic/197240-boost-droping-away/
Share on other sites

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.

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.

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 ?

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Will have a look at that. I cant see any leaks 
    • Put another overflow bottle (ie, a 1.25 coke bottle or similar) under the overflow hose and see if it is being pushed out there or if it is disappearing into the engine.
    • Staring on a stand is no issue. You just have to wire everything up, give it fuel and cross your fingers that the stand is robust enough. Arranging the inlet plumbing is often the hardest part, without any surrounding structure to hand some of it from. No need for coolant if you only want to run it for <1 minute. As to the gearbox - I think the little Aisin box is a bit stronger than the other small Nissan boxes that went behind SRs, but I wouldn't be too keen to test its limits with the torque of a boosted 25. I don't know if you can retain the box and the tailshaft. The box won't connect to the RB without an adapter of some sort, which is either a plate that will push the engine forward (which is not good for fitting it into the bay's available space) or push the box back, which messes with the box position and tailshaft length - OR - cut and shut work on the bellhousing, which is a long way from "least modification". I'd be buying a new 370Z 6 speed or similar, doing what has to be done to that to make it fit RB (ie, cut and shut bellhousing) and the requisite tailshaft custom/mods.
    • Hi Everyone I am from West Pennant Hills in NSW. Been too busy until recently to attend to my RB25DET Series 2 engine until recently. I am planning to stick it into the S15 shell at this stage, unless a nice SR20DET turns up... For now, i am going to try and get the RB25 running and working well then decide what gearbox to use. My preference is to retain the SR20DET  6 speed gearbox and tail shaft to retain as much and least modifications as i can avoid. I am an old guy and won't be doing any heavy drifting so i don't need a bullet proof gearbox Does anyone have experience with starting the RB on a stand? I got everything setup as much as I can with the info i can find... endless searching and videos on Youtube I would be great to get some pointers Cheers Songo
    • Hey all, Recently have had my s1 r33 gtr serviced and noticed my coolant reservoir was topped up to the max line. Took the car out for 1 yesterday and noticed today the reservoir is completely empty.  Any ideas? Radiator is full
×
×
  • Create New...