Rb30det Not Making Power ? Any Ideas

[RB30-POWER]

last time i heard this sort of problem was here

http://www.performanceforums.com/forums/sh...light=2jz+power

possibly no relation to your fault but...

[Cubes]

Alex you wouldn't have the cam spec sheet on hand?

I'm curious as to what centerlines they have set them up with out of the box. I've got engine analyzer setup which aids in selecting cam centerlines.

[MR VLT]

hey joel, i didnt get any cam specs and dnt think shaun got them either...

im pulling cams out later today or tomorow.. can u check them ??

[Cubes]

Sorry bud, I don't have the machine to check them out.

Tighe cams usually send out a cam spec sheet with the cams.

Have you spoke to the trans/stall people to see what they think?

[MR VLT]

not yet will do tomorow..

thanks

[GeeTR]

Odd. I doubt the 3.5 zhaust will limit flow at 250 powers.

The only time iv seen something like this, is from fast ramping cam lobes and lazy springs.

[Simon-S14]

seen a 3 inch exhaust flow well over 350 rwkw.... just needs to be a quality system.

[VB-]

seen a 3" exhaust make 893rwhp, so that wont be an issue

[The Mafia]

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.

At 15psi this should make at least 300rwkw, a T78 can make 300rwkw at 15psi. Boost is definately not the problem.

In saying that, maybe is a high pressure boost leak? Can you check the plumbing? Use a compressor, and pressurise the system. Go right up to 30psi and see if you can hear anything. You'll need to fabricate some sort of inlet that you can hook the compressor up to.

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....

rofl, who told you this? A Brand new RB25 makes 172psi and its comp ratio is 9:1. Its definately not accurate. What if the engine is worn?

Also, there shouldn't be any more than 5psi variance between the cylinders. 20psi? haha. If my engine had even 15psi variance, I'll pull it down..

[Lunatikk]

seen a 3" exhaust make 893rwhp, so that wont be an issue

You're right, a 3" ex should flow the numbers no probs BUT if the cat substrate has collapsed, coked up etc (same for the muffler/s) there's a good chance it won't. Spend the time, drop the ex in front of the cat & at least then you'll know one way or the other for sure. Assumptions can very easily lead to f**k-ups & waste a whole lotta time

[MR VLT]

thanks for replies guys and info..

have pulled cams out and getting them checked.

will then run car without exhaust and see if there's any diff there..

cheers

alex

[VB-]

You're right, a 3" ex should flow the numbers no probs BUT if the cat substrate has collapsed, coked up etc (same for the muffler/s) there's a good chance it won't. Spend the time, drop the ex in front of the cat & at least then you'll know one way or the other for sure. Assumptions can very easily lead to f**k-ups & waste a whole lotta time

yeah soory, should said i was sorta referring in general to the flow of the exhaust, not allowing for blockages

[MR VLT]

whilst im getting specs on cams we thought we'd throw in sum standard rb25det ones

to see i that would make a difference..

tried to start it tonite and engine had nothing, sounded like no compression..

motor would spin but not normal sounding at all ?????

mayb cams not opening valves ??

[rob82]

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

Usually it shouldn't be an issue going from a large lift cam to a small lift cam but did you bleed down the lifters before you put the cams in?

[Cubes]

I believe the head has been converted to solid lifters?

Have you checked the clearances?

The joy of modifying cars; if its not one thing its another. :S

[OFENSV]

if it has solid lifters and fitting the standard cams which may have a larger base circle might be causing the valves to stay open slightly making the cylinders lose compression.. as cube said, check the clearence.

[Adriano]

If the head has been converted to solids, and now has hydraulic cams, the the opening ramps designed to close the lifter will be opening the valve and therefore the duration of the valve lift will be huge, causing it to bleed off compression.

[MR VLT]

lifters are hydraulic

got my spec sheet on cams today, not to sure on what it all means.

someone here might ??

had to go ova in pen to see numbers

[MR VLT]

any ideas anyone??

[nugget400hp]

Kyle 6boost should be able to answer your questions mate, he made your manifold, jump on the blower.