Small Cams = Rising Inlet Temps?

[Scooby]

Recently had my 26/30 tuned. Running R34N1s, Trust dumps, nismo pump and 600 inj, Vipec plug and play. Stock FMIC. Produced 370 rwhp at 15 psi and 11.2 afr. Power drops after 6250. A brief run at 17 psi produced 390 rwhp

Increasing boost above 15 psi makes intake temps rise dramatically. The tuner (a good one) claims this is due to the stock cams that are choking the inlet (cooling gas) and outlet (restricting hotside gas escape).

I know the cams are responsible for the power nosing over at 6250 but can't see anything else in the setup that should cause intlet temps to rise so dramatically in relation to boost.

Just wondering if anyone has seen this on their own car and noticed a big difference with cams.

Thanks.

[N1GTR]

Interesting topic. Got a dyno graph?

I bet the response is just pyscho

[Scooby]

Interesting topic. Got a dyno graph?

I bet the response is just pyscho

he really liked tuning it, said the feel even on the rollers was great, very torquey. no surprises there.

i do have a graph just need to get near the scanner.

[s13_Skyline_inside]

what cams are they? have you had any head work done? standard plenum?

[Scooby]

what cams are they? have you had any head work done? standard plenum?

cams are stock Rb26, so clearly too small for 26/30. mild head work / clean up. plenum is standard.

i think if his theory is correct it means that the 30 is producing enough exh to spin the R34s like mad but the cams are restricting air flow so the pressure just backs up, causing the over temp.

[rtune]

Recently had my 26/30 tuned. Running R34N1s, Trust dumps, nismo pump and 600 inj, Vipec plug and play. Stock FMIC. Produced 370 rwhp at 15 psi and 11.2 afr. Power drops after 6250. A brief run at 17 psi produced 390 rwhp

Increasing boost above 15 psi makes intake temps rise dramatically. The tuner (a good one) claims this is due to the stock cams that are choking the inlet (cooling gas) and outlet (restricting hotside gas escape).

I know the cams are responsible for the power nosing over at 6250 but can't see anything else in the setup that should cause intlet temps to rise so dramatically in relation to boost.

Just wondering if anyone has seen this on their own car and noticed a big difference with cams.

Thanks.

Does the stock intercooler get really hot on inlet, and therefore is unable to suck away enough heat

by the time the air gets to the outlet? if so, doesn't that indicate that the N1s are out of their efficiency island

and have begun turning into air heaters?

with an extra 400cc won't you be asking them to shift more

air at the same PSI (relative to a 2.6) therefore you get inefficient faster than a 2.6 application ?

[MBS206]

Does the stock intercooler get really hot on inlet, and therefore is unable to suck away enough heat

by the time the air gets to the outlet? if so, doesn't that indicate that the N1s are out of their efficiency island

and have begun turning into air heaters?

with an extra 400cc won't you be asking them to shift more

air at the same PSI (relative to a 2.6) therefore you get inefficient faster than a 2.6 application ?

I'd also be looking at the turbo maps of the N1s...

It's all about air flow, not boost where they become inefficient, so moneypit could be well on the money...

And getting bigger cams, is just going to make the problem worse if he's correct.

[R31Nismoid]

cams are stock Rb26, so clearly too small for 26/30. mild head work / clean up. plenum is standard.

'Clearly'... based on what?

Without going into too much detail, i know of two 26/30's 'in the build' at the moment that will be using stock cams @ ~380rwkw with -5's.

Also being that are a good number of stock cam RB26's with -5's also making 380rwkw...

Im inclined to be pretty confident these two 26/30's will not have an issue with the stock cams 'being' too small.

Have you measured the pressure & temp directly before & after the I/C and compared???

I'd check that before going much further, the cooler might have a bit of a pressure drop/blockage and so on which you might find the turbos are making 20+ psi before cooler, and 17psi after the cooler in which case indeed they will be blowing hot air around potentially

R34 N1s are good for 400-450rwhp around the 20psi on stock capacity... So i think perhaps something else is wrong at this stage, im not one bit convinced its cam related

[Scooby]

'Clearly'... based on what?

'clearly' based on the fact that the 3.0 is 15% larger than the 2.6. and the fact that the power drops off at 6250.

Also being that are a good number of stock cam RB26's with -5's also making 380rwkw...

and you are absolutely certain that they are using stock cams?

Have you measured the pressure & temp directly before & after the I/C and compared???

I'd check that before going much further, the cooler might have a bit of a pressure drop/blockage and so on which you might find the turbos are making 20+ psi before cooler, and 17psi after the cooler in which case indeed they will be blowing hot air around potentially

not yet but it is on my list of things to do; cooler is No1 suspect

R34 N1s are good for 400-450rwhp around the 20psi on stock capacity... So i think perhaps something else is wrong at this stage, im not one bit convinced its cam related

i am getting 390 at 17 psi so presumably this means they are on track for that power range.

[Scooby]

I'd also be looking at the turbo maps of the N1s...

It's all about air flow, not boost where they become inefficient, so moneypit could be well on the money...

And getting bigger cams, is just going to make the problem worse if he's correct.

the N1s should be fine. exhaust flow is exhaust flow whether it's from an RB26 or RB30. if the RB30 was spinning the turbos so hard they were backing up, they would be producing a lot more than 17 psi.

[N1GTR]

So, a bit off topic, but hows the response?

Are you in Sydney by any chance?

You say 390 at 17psi, just to confirm, thats KW or HP? AWKW or RWKW?

[R31Nismoid]

1- 'clearly' based on the fact that the 3.0 is 15% larger than the 2.6. and the fact that the power drops off at 6250.

2- and you are absolutely certain that they are using stock cams?

3- not yet but it is on my list of things to do; cooler is No1 suspect

4- i am getting 390 at 17 psi so presumably this means they are on track for that power range.

I numbered - easier

1- You said for a 26/30, and that setup. There is no way, if anything the turbos are the limit, no where near the cams

2- 110% sure mate, one of them is my own. It will use stock cams, it will make 380rwkw. A similar setup was done late last year, same power stock cams

My build will be similar

3- The cooler itself is fine for over 350rwkw if OK (some cars i know are even closer to 400rwkw)... So there could be a blockage or part of it damaged even?

4- Yeah, you're on the marker almost as the 400-450rwkw comes 18-20psi on a 2.6ltr (well, its more like 2.55)

Steve - 390 is HP dude, no way N1's are making 390rwkw.

[N1GTR]

Steve - 390 is HP dude, no way N1's are making 390rwkw.

Yeah just wanted to check

[Scooby]

I numbered - easier

1- You said for a 26/30, and that setup. There is no way, if anything the turbos are the limit, no where near the cams

Steve - 390 is HP dude, no way N1's are making 390rwkw.

So the 2.6 is actually over cammed for its capacity?

Steve that IS 390 rwkw (and on stock injectors). Lol first posts states rwhp.

I am in Canberra but the car was tuned at Insight Motorsport. The Superlap Tilton Evo was there while my car was getting tuned. Thing is a weapon (obviously) and beautifully put together.

[R31Nismoid]

Have a look through the RB26 dyno sticky. there are a lot of people over 350rwkw stock cams

[N1GTR]

Ok, so 390kw from 34N1's.....surely not stock N1's?

I originally wanted to do either 34N1's or GTSS's for my RB2630 for hill runs. If you're in Sydney and have time, please drop me a PM and take me for a ride. Ill repay the favour with a ride in mine if you like

Ash - VERY glad to see you're still doing the RB30 bottom end, good stuff mate!

[Scooby]

Ok, so 390kw from 34N1's.....surely not stock N1's?

I originally wanted to do either 34N1's or GTSS's for my RB2630 for hill runs. If you're in Sydney and have time, please drop me a PM and take me for a ride. Ill repay the favour with a ride in mine if you like

Steve it's hp not kw. To answer your question the response is very sharp. I'll let you know when I'm in Syd next.

[wolverine]

what (if any) changes have been made to cam gears?

[N1GTR]

Steve it's hp not kw. To answer your question the response is very sharp. I'll let you know when I'm in Syd next.

Cool cool

[Scooby]

what (if any) changes have been made to cam gears?

we were able to move the power curve using the adj wheels but with a 6250 redline there's not much to play with so we left them centred.

Edited March 31, 2009 by Scooby