Intake cam different to Exhaust cam ..

[PSIKO]

What is the advantage of choosing a different duration cam on the intake side to the exhaust ?

What combinations do people go for and for what reasons?

[Steve]

I went 256 inlet and 264 exhaust for the following reasons:

It is a commonly used combo in Japan, if it didnt work, it wouldnt be used

Less duration on the inlet as VVT advances the cam (until its retarded at 4500rpm). Too much duration on the inlet could cause problems with NVCS during advance - or so I was led to believe

256 was the only cam duration HKS used whilst being compatible with NVCS, but the bottom of the range exhaust cam was 264

Turbos make boost on the inlet side, the big trick is reducing back pressure on the exhaust side

My reasons anyway. The main one was the first one. I have looked to Japan in alot of ways for inspiration, they have been playing with these cars for alot longer than us.

I have also found that when I have deviated from what they do, not such nice things have followed.

Cams to me is somewhat black magic, too much cam and it can cause a whole heap of problems ( I found out this the hard way along time ago:)).

[RBVS]

great info steve , cheers.

[PSIKO]

Yeah cheers for that Steve

How bout on an RB20 though without the NVCS ?

[Steve]

Cant see why you couldnt use same duration both sides, same as RB26