Boost Dropping

[Chris_Beli]

I recently had my stag on a dyno to see what sort of power it is making at the wheels, unfortunately the figure was considerably less them expected, around 130kw at the wheels, the car is set to run around 12psi using a turbo smart bleed valve however when approaching redline boost at the manifold was dropping to around 7 psi, I was told the two most likely reasons are that the bleed valve can't hold the boost, or the turbo is running out of puff, which do guys think is the first point of call? Turbo upgrade or an ebc? The turbo is believed to be from an r33 rb25 as the stock one was blown and replaced by previous owner, other mods on the car are fmic, full hks exhaust and apexi pod filter, cheers for your opinions, oh and it's a 99 auto c34

[Johny Bravo]

EBC isn't nessasary, just get a good manual boost controller, EBC is only really better if you wish to change your peak boost. As for other info i'm of no use.

[slippylotion]

I would guess at an exhaust restriction, maybe drop the cat and see what difference it makes.

[AAA34T]

I recently had my stag on a dyno to see what sort of power it is making at the wheels, unfortunately the figure was considerably less them expected, around 130kw at the wheels, the car is set to run around 12psi using a turbo smart bleed valve however when approaching redline boost at the manifold was dropping to around 7 psi, I was told the two most likely reasons are that the bleed valve can't hold the boost, or the turbo is running out of puff, which do guys think is the first point of call? Turbo upgrade or an ebc? The turbo is believed to be from an r33 rb25 as the stock one was blown and replaced by previous owner, other mods on the car are fmic, full hks exhaust and apexi pod filter, cheers for your opinions, oh and it's a 99 auto c34

hi so my stagea in stock form on the dyno made 115kwatw. So 130 and all u have is pod boost and exaughst is ok maby a touch more is avaliable but the stageas run ritch from standard but get to about 5 grand and lean out a little and the standad turbos max should be 12psi i had the same issue then put a fuel pressure gauge in and found out the pressure was low and the pump could not keep up and i fitted a new pump and it fixed the problem.

[KiwiRS4T]

If you have an R33 turbo on a Neo motor you are being short changed right there.. The solutions depend on your plans for the car - if you are looking for 260kw or so let us know! If you just want another 20 or 30 kw for now look for a good R34 turbo and an R32 10psi actuator for a start.

Oh and if you still have the stock airbox and snorkel put that back on and get a high flow panel filter such as a pipercross or K & N.

[pipster11]

i have a dyno sheet for 134awkw and it shows on 7psi

i think that was just with a pod and a catback exhaust

as perviously said, the r33 turbo will be holding you back, maybe try and find a blown r34 one for cheap and get it highflowed by hypergear (about $8-900)

also, a nistune will get you a decent improvement in both power, torque and economy (won't go so crazy rich on boost)

[Chris_Beli]

Cheers everyone, I don't want to male massive power but I was hoping for more around the 180kw mark, it shouldn't be an exhaust issue as I already had a high flow cat put in, also it shouldn't be running rich I forgot mention it's running am safc 2 to lean it out and save my wallet, and I already do plan to get the original neo turbo rebuilt I should have phrased the question better I ment more like which should come first better boost control or turbo, for instance if I get my turbo highflowed and increase the boost will the bleed valve be able to cope? And would simply adding better boost control make much more power? The guy who dynoed it isn't my normal mechanic he said it would whereas my mechanic said it's probably the turbo that's why I wanted more opinions haha also Johnny bravo u say use better manual control, are u talking about changing to a different actuator like also mentioned?

[lachlanw]

r33 turbo needs gone

get a r34 turbo at least

[lilcrash]

Bleed valve doesn't really create any restriction, it just controls the wastegate opening, if the turbo can't make the air it just keeps trying and eventually fails. Just get a bigger turbo or highflow then get it tuned to suit. The stock turbo will be better then an r33 item but they still loose boost as rpm rises.

[KiwiRS4T]

An electronic boost controller is not a necessity but in my experience can improve driveability. I ran a Jaycar IEBC but if you can't be bothered making one have a read of the reviews and threads in here and on Google and choose a good ebc. The SAFC is better than nothing but it will not control timing so its definitely a good idea to get a Nistune chip when you get your R34 turbo back and with an ebc and and a GOOD TUNE you should notice a significant improvement. I can't emphasise enough the value of a good tuner in making your car fast, driveable and keeping your engine safe... but you will need more than an safc if you increase the boost to 1 bar or more.

[Chris_Beli]

Cheers everyone guess turbo rebuild is the next thing on my list