Crap power out of my new turbo

[manna_s15]

hey guys already posted this on NS.com thought id post here to see what u guys think. i got my garret gt3071r internal wastegate, 0.64, installed few months ago but after spending so much it only made 276rwhp. i got all the supporting mods for it 740cc inj, nismo pump, fmic, pfc ecu, list goes on. have since taken it back to the workshop which was a waste of money yet again cause they didnt find nething. im running stock manifold cause i heard people making good power with it. should i invest in an aftermarket? was gonna go steam pipe which is $$$.

ok possible causes:
clutch slip
boost leak
tune
actuator?

if anyone here can help me out or has experienced the same prob and found the solution pls let me know!!
thanks guys

 

[Dazz0i]

what pressure is that running???


the turbo you have is just more capable of providing more boost.... doesn't actually mean that you will run more boost though! just cause it's bigger, doesn't mean more power!

 

[mitch]

im running stock manifold cause i heard people making good power with it. should i invest in an aftermarket?

I was told that the stock manifold would be restrictive at around 320bhp at the flywheel.

 

[manna_s15]

running 18psi atm. theres some guys with same turbo running like 1 bar and making at least 300hp+. hmmm might just be the choice of turbo.

 

[Dazz0i]

optimistic dyno?

276rwhp is about 330bhp at the fly.....

size of turbo won't effect the power it's making as such... it's the pressure of boost that turbo is pushing that effects the power.....

18psi from a T28 is exactly the same as 18psi from a T30.... it's just the T30 is more capable of pushing more boost as the T28 is on the limit at about 18psi.

 

[manna_s15]

optimistic dyno?

276rwhp is about 330bhp at the fly.....

size of turbo won't effect the power it's making as such... it's the pressure of boost that turbo is pushing that effects the power.....

18psi from a T28 is exactly the same as 18psi from a T30.... it's just the T30 is more capable of pushing more boost as the T28 is on the limit at about 18psi.

hmm the turbo must make some diff. thought t28 limits would be around 14-15 psi. so must not be a boost leak cause was pulling hard with the t28. possibly the tune. might take to a diff tuner get different opinion.

 

[Dazz0i]

T28's will run 1.2bar... which is about 18psi

the turbo size won't make any difference in power unless you're running more boost.... it will have more lag though when you start getting bigger.

could be worth testing for leaks, after that, take it else where.

 

[slammedmind]

i disagree, 18 psi on a small turbo is totally different then 18psi on a larger turbo. I have alot of experience tuning starlets and as an example the standard ct-9 tubby at 1 bar made 193 at the fly. Then a kkk k26 turbo was bolted on with external wastegate and a new mani and tuned to 0.8bar the car now runs 243bhp at the fly. Was the turbo new mate? Did you uprate the clutch or do any internal work? What milege is on the engine?

 

[Dazz0i]

but you've also changed the manifold at the same time...

you're not just changing one thing.....the pressure is the same, the fueling is the same.... the flow though is different....

 

[slammedmind]

yes the mani was changed but even with perfect flow the most a mani will give in theory is 15-20bhp. The flow rate depends on the size of the compressor mate

 

[slammedmind]

i wont argue that 18ps is 18psi but in theory a larger turbo will be more efficient at making the power, just imagine a small desk fan and a large desk fan next to each other, it will take alot less effort for the big fan to generate the same amount or air.

 

[oilrag22]

What does the turbo says on the housing?? the A/R ratio for the compressor and for the turbine???

 

[j@garagemac]

T28's will run 1.2bar... which is about 18psi

the turbo size won't make any difference in power unless you're running more boost.... it will have more lag though when you start getting bigger.

could be worth testing for leaks, after that, take it else where.

if for arument sake the 3071r is 15% bigger than a t28 at 1bar it will flow 15% more air at 1bar than the t28 so should make more power as thats the idea more airflow more power obviously with supporting mods feul-ignition .

 

[manna_s15]

i disagree, 18 psi on a small turbo is totally different then 18psi on a larger turbo. I have alot of experience tuning starlets and as an example the standard ct-9 tubby at 1 bar made 193 at the fly. Then a kkk k26 turbo was bolted on with external wastegate and a new mani and tuned to 0.8bar the car now runs 243bhp at the fly. Was the turbo new mate? Did you uprate the clutch or do any internal work? What milege is on the engine?

turbos new mate got it from a NS.com sponsor. no internal work has been done to the car. clutch still standard. i was intending on getting stage 1 cams but dont want to spend money on them to get the same result. the reason i kept the stock manifold was to reduce lag and thought the stockos are quite good.

 

[Dazz0i]

but, boost is limited on S15's from the throttle side of the turbo.... so going on a 15% increase in size on exhaust side. doesn't mean an increase in power .....

the efficency of the turbo may well be more suit or not, which will change the power delivery and feel...

 

[slammedmind]

what history do you have on the car mate? Engine and maintainence wise? What milege was on the engine? Personally, stock components in most cases are only a comprimise hence the reason why the aftermarket was born in some cases that is.

 

[manna_s15]

i purchased the car stock standard. with bout 60k on the clock. i do oil and filter change every 5000km and service every 10000km. very well maintained with quality oils.

 

[manna_s15]

also cars been compression tested everying is in good wokring order

 

[j@garagemac]

what dyno was it on and do you have the print out because the 3071 @18psi is pushing between 30-33 lb of air a min so is making about 330bhp@fly which sounds right so 270ish atw is about right

was it a dyno dynamics ??? if so post the graphs up im used t working with these machines

 

[j@garagemac]

but, boost is limited on S15's from the throttle side of the turbo.... so going on a 15% increase in size on exhaust side. doesn't mean an increase in power .....

the efficency of the turbo may well be more suit or not, which will change the power delivery and feel...

the whole turbo is bigger both sides, so it flows more air so it will make more power i belive the potential problem lies with another component or the tune on the ecu

the volumetric amount of air is increased with the bigger turbo but its at the same preasure as befor just there is lots more of it so unless its leaking or he has a restrictive intercooler or exhaust its the tune
kind regards jamie@garagemac