Not Happy With My Rb25 Builds Figures

[chrislesnar]

Geez where to start.

Been in the process of modding my car and have just got it back all good to go. Just a little bit upset that the car only made 290rwhp on 16psi. Here is the list of mods on the car currently.

Car is a 87 VL Calais with rb25det

Arias Pistons 20 thou over and rods

ACL Main Bearings, head and main studs.

Cometic Head Gasket

Standard Head for now

Greddy Copy Manifold and 80mm throttle body

Sard 550cc injectors

Bosch 044, surge tank and new lift pump

FMIC

Z32 AFM

R34 OP6 Hypergear Standard Hi-flow Turbo

Power FC and AVCR

that is all the engine mods, i have also upgraded the brakes, axles and added an lsd.

Car made 260 on 14psi (low boost) and 290 on 16 psi (high boost). only think i can think to do is set high boost to 18psi and see what figures i pull. do you guys think that figures seems a bit low considering the mods i have.

[N1GTR]

Exhaust?

Auto?

[Trozzle]

whole exhaust and cat size? possible blocked/poor flow cat

[paulr33]

yep, what gearbox and diff gears?

that setup should make 260rwkw - what are you expecting

[chrislesnar]

sorry guys, car is manual, 3inch mandrel bent exhaust from turbo back and just stock vl diff gears. i was thinknig the diff gears might have a bit to do with it as it sits at no more then 2000 rpm when in 5th going 100k.

[rob82]

sorry guys, car is manual, 3inch mandrel bent exhaust from turbo back and just stock vl diff gears. i was thinknig the diff gears might have a bit to do with it as it sits at no more then 2000 rpm when in 5th going 100k.

Diff gears have no effect on power output.

[STATUS]

so 290 is about 215rwkw and realistically 240ish should be achievable so what comp pistons, HG thickness and was the pfc tuned via knock monitoring or just the handset??

[DVS JEZ]

^^^+ 1, how was it tuned? have you checked the cat?

pic of dyno graph? with AFR, boost and torque etc

[hypergear]

Well if pistons and head gaskets have dropped the engine compression then you will need more boost to make the same amount of power.

Make sure you have a 3inch metal intake pipe and a free flow exhaust. Try a run with dropped exhaust, high power gain means restrictive exhaust.

Also highly recommend a high pressure actuator if you are running a stock actuator. This turbo is capable of doing around 260rwkws.

[chrislesnar]

hey guys i now have dyno print out up. i drove the car before it was tuned and the turbo kicked in alot harder then.

[hypergear]

hey guys i now have dyno print out up. i drove the car before it was tuned and the turbo kicked in alot harder then.

You will need a high pressure actuator to hold boost up top. Should have no issues getting 260rwkws. are you running stock intake pipe?

[chrislesnar]

the guy that tuned my car took the actuator you supplied off and put a stock one on. he said it was jammed or something cause he didnt know when it was gonna open. im not sure what you mean by stock intake pipe, i have the normal exhaust manifold. here is a pic of my engine bay b4 injectors were fitted.

Edited December 1, 2010 by chrislesnar

[hypergear]

The the whole reason of having an high pressure actuator is to hold boost. Put it back the way it was, and go for another tune. I really don't like people tempering with the actuator as most people lefts them un-adjusted. it opens around 18~20psi without boost controller. It is not Jammed.

Intake pipe is the pipe that connects the turbo to the pod filter, it needs to be an hard pipe at least 3inch in length. If the turbo can not suck in or dispatch air then it will result in lag and lose in power.

[KiwiRS4T]

Sounds like a cr*p tuner although looking at their ad they seem big time. Maybe the person who did your tune is not theiir expert?

[GTScotT]

I can see a metal intake in there, so that issue is resolved.

Stao, the graph shows he is running roughly 1 bar at a minimum. Do you expect this result from the turbo in question at that boost level?

I think the result is more consistent with a stock op6 @ 14psi than it is a highflow with that sort of power. Someone correct me if I am wrong.

[STATUS]

needs boost, im sure godzilla had a reason for lower boost as they are very reputable have you spoken to them about your concerns?

[chrislesnar]

Yes, we had a chat today. I did advise before hand that i only wanted 16psi but i thought it would have pulled a bigger figure on that. I mentioned adding a high pressure actuator but he said that the 18psi actuator on it initially was to large and a 12-14psi actuator would be better suited for my build. Atm i happy with how the car is running but just think it could have pulled a larger figure. Will this high pressure actuator increase the hp by that much?

Edited December 2, 2010 by chrislesnar

[TiTAN]

a completely stock engine will take 18psi on a turbo of that size.

[Rolls]

You have a built motor, it can take 20psi all day everyday without issue if it was built and tuned properly

even a stock motor will hold together with 18psi with that turbo, was there another reason they said that?

running it at 18-20psi will make a large difference to power.

[chrislesnar]

the car was found to be low on compression while i was modding the car so i rebuilt the bottom end with forged internals old mate seems reluctant to up the boost due to the head being stock. with this actuator make a difference