Various Cih Camshaft Specifications

[Stev0]

Hi guys,

I've been looking into camshaft options for my CIH project and the info that I have found seems completely off base with what i'm used to..

In OHC convention, the durations are usually as follows:

standard: 240deg - 264deg

mild road: 270deg - 276deg

fast road: 280deg - 296deg

full race: 300deg +

Now i'm thinking, according to that I'd like something between a mild and a fast road cam, I can safely persue a higher duration because of my butterfly-per-cylinder setup, 288deg ideally, but now i'm looking at the cam specs for CIH engines, and it completely blows my conventional thinking out of the water..

according to this website (http://tekenaar.opelgt.com/Opel%20CIH%20Cams/gtcamspecs.html),

standard CIH 19S: 308deg and 9.95mm

now, Monzta mentioned that ENEM's Y12 (288deg, 11.1mm) would give a power increase of 10-20hp, but this seems impossible when you compare the specs of the std (308deg) vs Y12 (288deg).

am i missing something?

Also, I'm having difficulty understanding the @ 0.50" classification for camshafts.. the yanks all have these @ 0.50" denotions for the cams and I don't have a clue how to compare those to the conventional duration spec that i'm used to..

How does one convert:

Torquer cam: .407" lift, 216° @ .050"
Combo cam: .430" lift, 228° @ .050"
Max Comp cam: .430" lift, 248° @ .050"

... into something I can understand?

[lamchop77]

Stevo

One thing you ate missing is you are dealing with a completely different engine. The cih motors, especially the larger capacity ones, soak up cam duration so you can go wilder with the cams. 2.5 race motors need 324 deg duration cams to get anywhere near working properly. I,'ve tried getting into the cam theory bit and it is baffling although you apply some of what's mention on the net to see if your moving in the right direction. The 19s cam may have 308 degrees but it may have a wide lsa with little overlap, it's designed for a head with smaller valves and low lift and different flow figures. The law determines how the power is delivered, think wide angle gives more torque narrow gives power further up the rev range, couple that with the higher lift, bigger valves and bring exhaust scavenging dragging more air in into it and a smaller duration cam can produce more power.

For what your after I'd go with a Kent 234 gives good power and is readily available, most of the time you don't need to mod the piston pockets. If you don't fancy that use the info from the Kent catalogue and compare that cam with other makes. Look at the difference between a 214 and 234 and see if another make does something inbetween. Ring up the cam manufacturers with your engine spec and what you want to achieve and they will advise you. Kent were good when I did it as were Catcams.

Everyone will have a different opinion as to what works. I like Kent cams I've always had good results with them. I've had probs with piper cams so don't use them. I'll be using a high speed racing mega 10 cam (I think that's the one) for my 2.5, 304 bhp from a single cam 2.5 cih na motor. His cams are ground by Kent, speaks volumes to me. If you want to check out how well they go look on youtube and search 2.5 cih and look for vagoszx11.

Hth

Chris