Tuned a RB25DET - 265whp on stock boost

[onefastrb26]

Hi guys, we just tuned a RB25DET, and it put down some VERY good numbers. 265whp and 221ft lb torque.Mods:- 3" catback- custom front mount intercooler- z32 MAF- Apexi S-AFC- LESS THAN STOCK BOOST - there was a vacuum line from the boost source to the wastegate, so it was around 7psi or so??? No factory boost solenoid... No boost gauge...

We will post a dynochart tomorrow.

[Joe]

wait wait wait

no source to wastegate means FULL BOOST (17+psi). without a boost source the wastegate cant open

[Andrew85cm]

LOL good numbers but Kamin is right if it cant read boost or is reading atmospheric its thinking it needs to boost more so your wastegate wont open for a while. Be carefull running that much boost. I would check on that.

[onefastrb26]

Kamin:

"there was a vacuum line from the boost source to the wastegate" - yes, there was boost going to it, but no stock solenoid, no boost controller, nothing.

I run my RB26 the same way, and get 0.6bar :-( For now:-)

[cvc9216]

he's saying there was a boost source, just no factory boost regulator installed

[Joe]

hahaha wow i read that WAY wrong

my apologies

see, alll miscommunication

anyway, no boost solenoid on a RB25 = 5.5 psi!!! those are AWESOME numbers for 5PSI!!!!

[onefastrb26]

Yes, these numbers are great, I was pleasantly surprised.

The car came with a wrong wired z32 maf ( which came out bad, on top of the wrong wiring - the signal out and the 12V were switched), running on 5 cyl, fouled and rusted Denso iridiums, and a stock KA pump. After all that was fixed, it dynoed 254.xxrwhp. So I guess the engine was in a very good condition.

I bet it would put down like 100whp at best (in the condition it came in).

[Andrew85cm]

Oh my bad. I guess I should read more carefully. I was hoping you had a vac line hooked to it but it sounded like you hadn't. Good going on the numbers though. Keep us updated.

[Carl H]

this was done on a dynojet right?if so im not really impressed as my rb20 in STOCK form made 230whp..........also if it just has a boost source going to the wastegate then its boosting 7-8ish psi possibly nearer to 10 depending on how much exhaust work has been done.

[Wulfgang]

About a year ago on this forum people were talking about how much power could be gained on the stock engines by a little bit of tuning (leaning out the fuel curve mostly). IIRC, a few people got 30-40 bhp on RB20s (maybe frostedflakes?).

So your numbers aren't surprising although they are good.

[eh?]

IIRC, a few people got 30-40 bhp on RB20s (maybe frostedflakes?).

So your numbers aren't surprising although they are good.

He made 271 rwhp with an IHI turbo with 15psi, safc , 12:1 AFR.Now this guys is making 265 with an s-afc and ~5psi and it's not impressing you?

[Wulfgang]

No, not that time, you're looking at his more recent dyno. Somebody had an all-stock setup and got 30-40 bhp gain by tuning.

So 265 on an RB25 sounds reasonable.

[240sxed]

I thought withou the boost solenoid controller thingy, it stays at 7 psi? thats been my experience. My boost gauge reads to .5 bar without the solenoid? My understanding was that the solenoid kept it at 5 psi under 5000rpm, and over it went to 7

Oh yeah, great numbers, i hope to be putting down the same as soon as I can get to the dyno.

[Carl H]

ok it might be more impressive if we wernt guessing how much boost is being run.find out real boost and then tell us how much is being made.

[dekand]

well i have my profec b set on 0% for low boost which is the stock boost or lowest it can go i guess, and it turns out to be around 6 psi ... i need to get an safc and get my motor tuned sometime

[onefastrb26]

OK, I think boost was around 7psi( like some people said). My RB26 does 9psi(.6bar). 230whp on a stock RB20 on a dynojet might mean 230whp on one dynojet, and 200whp on another. No two dynos read the same. Ours reads less than FIS in Dallas, TX, and they have a Mustang dyno.

Here is the dynochart.

[onefastrb26]

An evo8 dynoed 476whp in a Ohio shop, and 367 at ours. That 367 is more close to the real power of the car now.

[240sxed]

I hate how different dyno's show so dramatically diff. I think on the AWD dyno it'd be even more of a dramatic diff. On single drive dynos I think its a lot less of a difference, maybe 30 hp diff.

An evo8 dynoed 476whp in a Ohio shop, and 367 at ours. That 367 is more close to the real power of the car now.

[Sukairain R-33]

actually its not surprising that you're getting more power at "less" boost. with your fmic and the exhaust you're moving air faster. im sure you'll find that even if you run stock boost with a massaged head and intake manifold since the air gets into and out of the cylinder faster your "boost" will show even lower despite the fact that you make more power.

what you should be measuring isn't psi but instead cfm.

[onefastrb26]

actually its not surprising that you're getting more power at "less" boost. with your fmic and the exhaust you're moving air faster. im sure you'll find that even if you run stock boost with a massaged head and intake manifold since the air gets into and out of the cylinder faster your "boost" will show even lower despite the fact that you make more power.

what you should be measuring isn't psi but instead cfm.

You are absolutely correct. I know the car made the extra power because of the fmic and the full exhaust, even at 2-3psi less than stock.

[240sxed]

gotta love them fmic's.... you gotta love um.

[fallen180sx]

sexay.. no matter the dissing.. all the 20 guys need be jealous. hehe, whats the point of the extra weight of a 6 cylinder with that little displacement? hehe.. j/k guys. i heart all the rb's. but yes.. good numbers onefast

[nissanparts.org]

what are some guesses of number this car would run at max boost? Im thinking 310 and 255

[240sxed]

what are some guesses of number this car would run at max boost? Im thinking 310 and 255

I've heard around 300 ballpark for 14 pounds. Thts what im hoping to hit...more or less 10 +/- hp.