Made It! But Only Just

[nathanway]

hello all

. ive just got my 08 fg turbo auto back from the shop , if anyone can remember I had a post up getting advice on what I should get done, original plan was to get my turbo front cover changed and upgrade the waste gate and actuator and go for 370-400rwkw but I ended up being about $1000 short so I coulnt afford to get the turbo and fuel pump done so I stuck with the stock turbo ,

the end result is impressive bottom end power but its a bit dull in the top end, I find that if I change gears at about 4500 rpm it gos way harder and will spin the tyres but it seems to drop away after 5000 , so the car apparently makes 302.9rwkw @about 4900rpm and 1226NM @ 3180rpm @ 20-21psi of boost no boost graphs were given so I cant confirm this its just what they said also cant see if its holding that pressure all the way through the rev range I suspect its dropping in the higher revs

mods include

rapid systems v2 pipe's cooler and turbo side intake

Exforce 4inch turbo back system mild steel

H/D valve springs

injectors ( doesn't say what size or brand)

x-cal 3 and dyno tune

now that you know how the cars set up my main concern is

boost pressure

lack of boost control ( max boost)

and lower than average power for more boost than most people with same power

more torque than most people with the same power (dyno run in 3rd)

dyno shop is known for good work and wasn't cheap

they said it was safe and that the auto box was the reason its not making the 320-330kw mark but at the same time ive got friends with similer mods making more but through different dyno companys with the auto + countless people on hear saying they made a little over 320 so im a little bit worried that somthings not quite right

any info or advice pointers would be would be sweet

Thanks

[Rab]

I'm sure I'm wrong, but that seems like a huge amount of torque (and drops off pretty quick)?

[fatz_f6_typhoon]

Hmmm maybe some advice from ratter May shed some light on it???.....

[ratter]

the small turbo will never hold boost in the top end on these engines, it's just too small

[hawlass]

Run done in 3rd accoring to the graph, hence mucho torquo, prob about 850nm in 4th at a guess.

[nathanway]

I asked him about doing the waste gate and the actuator and he said its not worth it ,

my understanding is limited but my thinking is

the hole and flapper are to small, down low rpms this causes spike because it cant divert the exhaust around the turbine fast enough ,

but once the motor starts to rev high and need large volumes of air it needs to close the gate to increase the turbine speed to increase the volume of air to maintain the pressure levels I know at this stage the turbo is starting to run out of puff but if the gate isn't fully closed that would cause the turbo to not hit max rpm/ flow and drop pressure a little earlier and more in the topend resulting in the lower peak output... but im no mechanic and don't realty know what im talking about but could just be the the actuator isn't right and that's the reason for the only 302kw instead of 320-330

its 20kw down on what everyone else's has made could it just be a low reading dyno +the auto but still seems a lot low, just a bit annoyed when others have only done the injectors and the tune and made 300

[sct911]

drag strip will tell the real story

[Ralph Wiggum]

the small turbo will never hold boost in the top end on these engines, it's just too small

Whats the max boost you tend to see them able to hold up top Mick?

Im playing around with one at the moment on a BF motor but haven't been able to wind it up due to a spongy stock actuator.

[nathanway]

ive had it down the strip when it was stock and got a 12.9@ 107mph with a 2.0 60foot

goal is to get a 11.xx but I don't think 302 is enough to , all the ones ive seen with 300 getting low 12 passes

[XtRmn8]

Whats the max boost you tend to see them able to hold up top Mick?

Im playing around with one at the moment on a BF motor but haven't been able to wind it up due to a spongy stock actuator.

+1 I too would like to know what the max boost a GT3576 can hold up top?

I have been keeping an eye on most of the stock turbo results posted here and it seems like the ones who run a completely stock GT3576 may hold 10-11psi max above 4500rpm and make around 300 at the wheels.

There have been a couple of example where actuators were done and they managed to hold 13-14psi and make around 330 at the wheels mark.

I guess there is a lot of other factors too, but am curious to know if a port job and actuator are worth it on a GT3576 to get that little extra top end?