Camshafts

[Guest Nismo_Freak]

What kind of gains are seen from a bump in duration and lift?

RB26DETT

Say using the 272 duration / 10.5mm lift, w/ valve springs on a fairly standard motor using only intake, 12 psi boost, full turbo back exhaust, fmic, and a HKS AVC (the fuel controller).

I would also swap the cam gears for adjustables and go with a 4 degree retard on the exhaust with a 1 degree advance on the intake.

Assuming fuel was optimized for the added airflow and tuned properly.

[Guest Nismo_Freak]

anyone? ... take an educated guess?

[GTS-t VSPEC]

The gains are huge, it will be one of the most important factors in getting huge horsepower. Without decent cams then the potential of any turbo is not used. I would only tend to use cams like that with a bigger turbo, but even without it a 10-15% increase in power is possible.

See'ya:burnout:

[Guest Nismo_Freak]

Sounds about right I suppose... the camshafts only increase the efficiency of the motor at the higher revolutions with a slight drop at lower rpms. This in turn creates lag as noted. But the end result is more power produced at lower boost levels. The requirement for octane however goes up because the dynamic compression increases, the same when boosting more. I just needed some numbers to go by. The stock cams are as follows, I believe:

Intake: 240 duration w/ .338 lift (8.58mm)

Exhaust: 236 duration w/ .326 lift (8.28mm)

The use of the cam gears will allow me to maintain the midrange and gain back some of the boost threashold lost when I moved to the hotter cams.

[GTS-t VSPEC]

Yeah, I would either use the HKS 256's or 264's, they should provide a heap more power without too rough an idle.

See'ya:burnout:

[rev210]

The 272's will kick in at around 4000+rpm and give the motor more legs to 8000+rpm. Something around 250 or so duration would be a better choice for a streeter. I think there are a few around 254 duration.

Most aftermaket cams need to 'dialed in' according to the motor. The factory usually designs them for a 0 deg fit but, depending on what you have done they may benifit with various timing settings.ie: don't take 4 degrees as gospel if you use non factory cams.

[lowlux]

when changing cams,is there anything needed to be adjusted? i heard that with the rb20's they have hydraulic lash adjusters,which means no adjustment, does this mean u can just wack the cam in with no probs?

[Guest Nismo_Freak]

Hydrolic means you dont use shims... so you dont need to adjust anything

[lowlux]

ok then that might be so for a new cam,but what if u get a cam ground? then would u need to adjust it or whould they adjust themselves?

[meggala]

low lux your boss should know

are they in yet

[lowlux]

nah not yet meggala but my boss doesent actually know much about the Jap side of things,there only now starting to get into it, but ill find out tomorrow which grind im gonna use on them

[Xeron]

Performance cams dont always increase your dynamic compression, that depends soley on the grind of the cam. Infact you might find a few drop the compression a tad to allow more boost with less chance of pre detonation.

[JH32]

Could you just go to Crow Cams or any one of the aussie dudes and get one of their cams?

Or does it have to be a Jap item?

[lowlux]

lol i work for crow cams, but the thing is the billets are very expensive, but im buying them anyways and grinding my cams to the same size as the tomei cams

[Zdenko]

thats what i was gonna sk

how big of a cam can u actually go with the rb25's?