Jump to content
SAU Community

Recommended Posts

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

Link to comment
https://www.sau.com.au/forums/topic/207289-rb30det-not-making-power-any-ideas/
Share on other sites

  • Replies 41
  • Created
  • Last Reply

Top Posters In This Topic

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?

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 by R33GTS25

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....

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 by VB-

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

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

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..

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 :banana:

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

^ 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 by VB-

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

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



  • Similar Content

  • Latest Posts

    • Check the injectors flow evenly, and are actually flowing what you and the ECU think they should be flowing. If it's starting up on starter fluid, you have a fuel issue. Is it possible under cranking your fuel pump is turning off?   The harness you replaced, is that the whole engine harness? Do yourself a test, and drop the old harness on and plug it into the Z32 ECU. It's possible they've wired things different. From memory S1 to S2 is different in RB25 and you may have a wrong loom
    • I haven’t pulled the injectors to watch them spray yet but they are clicking from the cas and all of the spark plugs are wet with fuel. I’ve thought the cylinders were being flooded from the beginning and was hoping fuel pressure would fix it. Tonight I am going to pull the rail and watch the injectors spray. Don’t know how to test/diagnose if the plugs are firing in correct sequence but that should be a timing thing and as far as timing goes my car still has the half moon for the cas can only install it 1 way. And my mechanical timing is 100% correct I posted photos above. Confirmed with the balancer on and off. 
    • I checked spark on all cylinders and they all visually have spark with the plug pulled and grounded, but plug 1 is the only one that fouled. This was a running swap that blew up and was rebuilt by a machine shop, put a new wiring specialties harness and did all gaskets, studs, and bolts while it was out.  compression is 135-150 across all cylinders. Aside from that from my understanding with the z32 ecu and maf the car should start regardless. The wiring for TPS and the dual 02 sensor/ dual knock sensor stuff shouldn’t actually stop the car from starting or even running well, (just slightly rich)  they just give fault codes. Car supposedly is supposed to start as long as you have z32 afm and ecu with the nistune base map and that’s info coming from a well known and trusted tuner who does a lot with SR/RB (Rsenthalpy). After more trouble shooting today where I’m at right now is that the cas is sending signal to the injectors they click while spinning the rotor, Fuel pressure is now set at 43psi, all cylinders have good compression and all of the plugs looked great (just wet with fuel) except for cylinder 1 which was very black (cylinder 1 has 150psi compression). all of the coils generate spark if pulled out and grounded out on the head. On the fuel pump car just pops into the exhaust. On starting fluid car will fire off. Hard to tell if all cylinders are firing off but definitley a couple. sounds like all of them but it’s only for 3-5 seconds hard to tell. 
    • Final update!!! Got the front bar fitted and sprayed and all sorted now. My cutouts worked great and the indicators aren’t just falling off. 😂  
    • Is this a brand new LSD? if so, have you followed any break/bed in procedure for it? Usually involves heaps of figure 8 patterns, a fluid flush.
×
×
  • Create New...