More Cam Thoughts

[gregrob]

Ok after talking some more with my buddy in SC who I consider to be very knowledgeable. I have come up with a custom grind that might look something like this.

230/234 - .570/.570 - 112 LSA

This is basically AI's 226/234 cam with the intake duration raised because of my altitude, to get a little more air in, and the LSA bumped up accordingly.

Now, I might actually go 113 because theoretically I would be just matching the valve overlap when bumping up the intake duration 4deg, and the LSA 2deg accordingly.

So on 112 it would idle about the same as AI's normal grind. 113 might tame it down a little bit.

First of all give me your thoughts..

and secondly, do I have an advance put on it, such as 113+2?

This would be ran with 1.6 RR's of course.

If the idle is a little much, Oh well, I'll put another muffler on it and have it tuned best I can. That's what cutouts are for anyway, right

Thanx

[96lt1m6]

cam discussion should really be left to those that specialize in the field. i spoke to Lloyd and i spoke to Phil at AI.. GREAT ,KNOWLEDGABLE ,PROFESSIONAL guys to discuss your combo with and express your concerns with your altitude. i am sure you will be suprised about that.......

[joelster]

I think you are REALLY over-thinking this issue. I would LOVE to see a back-to-back dyno test of those 2 grinds, one on a 112, and the other on a 113. Maybe 1-2 hp difference if that. Custom ginds are fine and dandy, but you are really wasting your money if you are simply building a mild motor with nothing out of the ordinary. Those AI and LE off the shelf grinds will be excellent.

[Puck]

I would just call AI or LE, or use one of their "pre-designed" cams.

There is more to specc'ing a cam then duration, lift, and LSA. You need the proper ramp rates and valve timing events to get what you want out of a certain engine combo. There can be a ton of cams with the exact specs you listed that all perform differently. You also have to ask yourself a lot of questions that need to be answered - why would you change the LSA? Why raise the intake duration instead of intake lift? Why not raise intake duration AND the lift? Will you keep similar IVO/IVC EVO/EVC numbers? What lobes would you be using - aggressive ramp rates to get the valve off the seat faster but require better springs, or slower ramps that would be less stressful on your valvetrain? What is your target dynamic CR? etc...

I would leave the cam designing to the pros.

[gregrob]

LOL I'm not trying to design a cam from the ground up. Maybe just tweak a proven grind to work a little better for my situation, which I see nothing wrong with...

Although my buddy is very familiar with all the terminology you used^^ and how the cam size affects it, and took that into consideration when making his recommendation.

At any rate, I'll let you guys know how it turns out.

Thanks