Rb30det Not Making Power ? Any Ideas

[MR VLT]

hey guys, just after any ideas / help please....

I have an RB30DET with rb25det head.

fully built forged bottem end,

rb25det head , port , polish, 1mm over size valves, valve springs, head machined to fit bigger cams

cams tomei rb26 272 deg - 10mm lift inlet and exhaust machined to suit rb25 (tighe cams)

greddy genuine inlet plenum,

6boost merge collector exhaust manifold,

garrett gt4202r turbo, 48mm progate

100mm intercooler.

2 speed powerglide trans

had the car on the dyno the other night and made 242 rwkw on 15psi ..

power curve goes straight up to 240 and then goes straight across .....

making 500-550nm of torque

afr's 11.5-12.0,

stuffed around with cam timing and brought power on quicker and made 12rwkw more but

same thing happened.. will try get dyno print out

does any one have any idea on why ? been told should make 300- 350rwkw on that boost with the auto..

cheers

alex

[Guilt-Toy]

how does it feel on the street?

some of the time because your running a big auto box and stallie it might not be getting full load on the dyno.

Does it feel like its only got 200ish rwkw on the street or does it fry the tyres?

You might need to f**k with the ramp settings on the dyno so you can get proper dyno runs, also the rear wheels could be spinning?

[NYTSKY]

Turn the boost up.15psi is nothing for that turbo.But i wouldnt be doing it till you get some Ks up on the motor.

[MR VLT]

the car doesnt really feel like it has more than 250rwkw, the torque is there

motor is run in..

were tryin to find out why it isnt making much power on this boost b4 we wind it up

cheers

alex

[R33GTS25]

Compression test.... leak down test??.... no fkn idea what it means but my cuz said it might help since you did some head work.

8:1-8.5:1 compression: 150-170 psi per cylinder

8.5:1~9.5:1 compression: 170-210 psi per cylinder

9.5:1~11:1 compression: 210-275 psi per cylinder

also make sure there isnt more than +-20 psi difference between each cylinder

also he suggested pressure testing the intercooler system for leaks....

Edited February 22, 2008 by R33GTS25

[MR VLT]

did compression test all good same as leak down test...

[Guilt-Toy]

what if you got 120 in each cyl ?

Compression test.... leak down test??.... no fkn idea what it means but my cuz said it might help since you did some head work.

8:1-8.5:1 compression: 150-170 psi per cylinder

8.5:1~9.5:1 compression: 170-210 psi per cylinder

9.5:1~11:1 compression: 210-275 psi per cylinder

also make sure there isnt more than +-20 psi difference between each cylinder

also he suggested pressure testing the intercooler system for leaks....

[VB-]

8:1-8.5:1 compression: 150-170 psi per cylinder

8.5:1~9.5:1 compression: 170-210 psi per cylinder

9.5:1~11:1 compression: 210-275 psi per cylinder

^ i call bs. cant use compression test results to determine CR

anyway what valve springs are you running? might be starting to float

PS - have you got an pics of your ingnition timing maps? or any idea how much timing is in it at the top end?

PPS - turn the boost down as low as it will go and do another run (to check if its mechanical or tune) and keep turning the boost up till it starts to flatten out the graph again

Edited February 22, 2008 by VB-

[MR VLT]

valve springs are isky racing, no problems there ..

also tried it on 10psi and same thing....

[paulr33]

what is your full exhaust setup?

dump? gate? screamer? pipe sizes etc

also get a plot of exhaust pressure past the turbo outlet

[den001]

it may be your stallie like guilt toy has said

i recon stallie is slipping and not fully engaging thus you are not making more torque and any more power, you say that the torque sits there and holds deat flat on the same power, my friends car did the same and it was the stall converter.... back on dyno and got extra 60hp at wheels

[RB30-POWER]

drag it and check your mph.

[MR VLT]

yea i want to drag but no track in adelaide..

stall converter- trans.... - have a mate of mine with same trans and almost same stall conv,

his car makes 350rwkw on 16psi with tad smaller turbo and single cam head ???

my exhaust is 3 1/2 inch dump to half car then into 3 inch 1 straight thru muffler,,

48mm turbosmart progate, 2inch screamer

cheers

alex

[RB30-POWER]

ahh adelaide, then you would know of darrens/JetR31 sohc rb30 gt42 over 600hp at the treads on pump fuel r31 then?

did you buy this head of luke in qld at all?

Edited February 23, 2008 by RB30-POWER

[MR VLT]

yes i know darren, good mate...

he has the same trans but a little different stall converter i think

he made the 350rwkw on 16psi

no didnt by the head frm luke...

have seen everything that has been done to this head except cam machining..

[shanef]

exhaust could be ur problem

get it on the dyno, drop off the exhaust and see how it is then

[zertek]

dont know what the deal is with stallies but with clutches and brakes i know u have to wear them in on conservative driving for them to bed, other wise they get shagged real fast and can cause slippage

im guessing it would be the same deal with the stallie? though i hope that your stallie slipping isnt the case...

[VB-]

^ dont think it would be an issue

if your 100% sure its not springs, and it doesnt sound like it if the problem was still there at 10 pound, i would be looking at the tune, get a pic up of the ignition map if you can

Edited February 23, 2008 by VB-

[sky30]

Hey Alex, how u been?

What Rpm does it make peak power,then start to flatten off?

As NYTSKY said, id try some more boost, 15 psi aint much for that turbo.

[MR VLT]

will try get pics up...

hey carl, how u been mate? been alrite jus busy with work and over this car...

cant remember exactly what rpm will get the dyno print out, but it jus seems to go almost straight up to 245rwkw then flatten across, prob around 4500rpm not to sure tho..

also trying to figure out the problem on th lower boost, but might try 20psi and see what happens