Why So Low?

[camoo]

Ive got an R34 GTT that i bout a year ago that was stock besides a cat back.

Now ive done some minor mods, and its made 275 rwkw on a hub dyno, and 235 on rollers...

235 seems low for the mods ive completed.

Mods as follows:

GT3076 .63 ( exhaust housing outlet was around 2 3/4" for some reason??)

3" turbo back, custom dump, cat back fujitsubo giken exhaust

50mm synapse external gate

turbo technics MBC (soon to be profec b 2)

725cc experts injectors

bosch 044

Z32 AFM

cooling pro return cooler

NIStune ECU

Tuned by Garage 7

standard engine

standard exhaust and inlet manifold

Running 17 PSI, suffering boost drop down to around 13 which i am hoping to counteract with EBC???

Making bugger all torque too.... Cant remember figures on that though.

Anyone think that 235 rwkw on a set of rollers to low?

Any suggestions?

[elir32]

I'm no expert by any means... Here's a comparison to what I'm running very similar

Gt 3076 .82 internal

Nismo 420cc Injectors

Spitfire coilpacks

Pod filter induction

Blitz return flow fmic

Waulbro 500hp fuel pump

3" turbo back exhaust with 100cell high flow cat

Z32 afm

Nistune ecu

Nistune boost setup running high at 18pound making 304rwk mainline dyno making 248rwk runnig low boost on 14pound from memory

Rb25neo manual r34.--otherwise mostly standard under the engine bay. Tuned using bp98

tuned by Ashley from Adelaide classic performance-hackman.

Hope that helps a bit-others will have a lot more knowledge in this area.

Edited October 22, 2011 by elir32

[camoo]

hmm i was hoping to get just below those figures...

its does seem like something in my set up is letting me down..

any one else have a similar set up?

[Matty Sherlock]

Overall health of the motor? Pressure drop, dependant on the size of your ic? Saturation? If you're not happy with the result these would be some factors i'd consider.

Personally I reckon thats a respectable outright power figure, it is a fair whack of boost but after all it is only a 2.5 litre.

[camoo]

Motors in good condition, 110 xxx with good compression across the board.

Dosnt use oil or leave any in the catch can.

Cooler is 600 x 240 x 60mm... i thought it would be sufficient?

It does get pretty hot in there lol...

Was just expecting more at the end of it.

Before i put the turbo, injectors and fuel pump in it made just above 190 with nistune on rollers...

45 rwkw was a good gain.. but for some reason i was expecting more...

[elir32]

When I had the turbo etc installed and tuned-the hosing to pod all had to be customized-the factory pipes were sucked flat with the force- has yours been tuned to avoid this?i found this was an issue shortly after 240-250rwk, just a thought-another mate had much the same issue doing similar, is your cat converter too restrictive?Or as matty suggested your intercooler may not be sufficient. You can get both tested..

[Tangles]

the boost drop from 17 to 13psi is what's costing you the power.

It could be the return-flow design in itself (I wouldnt rate a return flow cooler to beyond 250kwaw); as matty suggested have the pressure drop tested between the Inlet & Outlet. You may need a 'proper' intercooler, but test first prior to spending further.

Elir32 is right with his suggestion; the intake pipe could be sucking closed if its still the standard black ribbed plastic unit.

"how to fix" here - http://www.skylinesaustralia.com/forums/topic/173016-rev210s-5min-5-intake-pipe-mod-for-your-stageaskyline/page__p__5261291__hl__%22intake+pipe%22__fromsearch__1#entry5261291

Definitely give the ProfecB spec-2 a go, a very good unit indeed. Once setup correctly could make a decent difference.

Diagnose why the boost pressure drops and you'll see a very good increase in power

[Madaz]

the boost drop from 17 to 13psi is what's costing you the power.

snip

bingo

[camoo]

elir32- not running the stock black intake, got a customized set up there, but ill check the silicon joins when i put it on the dyno next. as for the cat... wat cat.....lol

Tangles- ill be running a pressure test on the cooler in the next few days. i knew one day the return flow would bite me in the arse lol

Thanks for all the quick replies, really is greatly appreciated

[D_Stirls]

Is it an actual garrett 3076 in garrett housings or is it a high flowed turbo using garrett wheels.

[camoo]

its all genuine garrett, genuine housings and core

[rad100]

the hub result is more like the figure you should be at on rollers. thats more like the result you should get.

[Aberax]

My Old setup

GT3076 0.82 Internal Wastgate

Nismo 740cc Injectors

Bosch 040

Boost T off of ebay for $30

Haltech E11v2 with Map Sensor

Tuned at Horsepower In A Box on 14-15psi made 262.4rwkw with about 400nm torque on rollers.

New Setup

Same as old except the following.

CP RB26 86.5mm Pistons

R34 RB26 Crank

Tomei 256 8.5 Cam In/Ex

Performance Springs

Head Ported

Tuned at Horsepower In A Box on 8psi made 227rwkw with 400-500nm torque on rollers.

Same return flow intercooler used in both instances, ie input/output on the same side. Measurements not too sure of, but as intercooler sizes go, it's a medium size.

As said before the boost dropping off is killing the power, but the rear housing could also be holding you back, on 17psi you should be expecting about 260-280rwkw roughly.

[whatsisname]

Cam,

Get the boost drop issue sorted first, then begin the process of elimination from there - assuming after the boost drop is sorted it still falls sort of expectations.

You are basically getting 235rwkw @ 13psi, which is about what I'd expect from those modifications and a GT3076 with 0.63 exhaust housing, give or take 5-10rwkw. Get it to hold 17psi and it will gain quite a bit of addtional power at the top end of the rev' range.

Do you know what your external gate actuator spring is rated to, 10psi, 14psi? Running an external gate it really shouldn't struggle to hold boost, unless the turbine housing is simply too small (or the exhaust) and is choking it up - I doubt it.

A few years ago my 33 produced ~270rwkw at about 17-18psi. However, winding the boost down (or switching the EBC off and running off the aftermarket actuator ~13-14psi up top) it made 240ish.

[camoo]

whatsisname- hey mate, the spring in the wastegate is around 13- 14 psi

conveniently, the same guys that tuned my car tuned an r33 with the same cooler, turbo, wastegate and EBC- pretty much a carbon copy lol.

and would u believe it had a similar outcome with the boost drop issue.

As far as my tuner believs, the wastgate is the weak point, and we are going to try a heavier spring and a few other little tricks the the makers of the gate have

suggested.

If this fails, ill be getting a Tial

Out of curiosity, what size outlet did the exhaust housing have on your 3076?

The one i purchased was brand new, from a third party who has the turbo send directly from garrett, but the out let on mine was smaller than 3", which i thought was standard??

Thanks heaps for the reply

[rad100]

genuine gt3076 are a 4inch intake with surge slots.

[camoo]

yeh my compressor housing and cartridge are legit, i ment the exhaust housing outlet is not 3"

[camoo]

ok so anyone that was wondering, i installed a profec b 2, with no change in result.

Then i put a stiffer spring in the wastegate, and now with out a retune, the car makes 250 rwkw on rollers on 18 PSI with a drop to 16.5 PSI.

Im hoping with a slightly stiffer spring, the drop will be completely gone, and then a retune should see a bit more power.

So to all considering purchasing a 50mm synapse wastegate, go straight for a 120P spring.

Cheers all

[Jap_star]

id ditch the gate and go something smaller personally., 44mm perhaps

[Simon-S14]

50mm synaps is the best in the business. either way internal gates are shit for boost control :S

Edited November 11, 2011 by Simon-S14