So I was wondering why strokers ate up big cams and this is what I came up with, let me know how far off I am and how much is accurate and what is BS.

Every cam has a powerband which is primarily affected by (as well as other factors) velocity.

When you take two identical motors and add a longer stroke to one, the stroker will have a lower powerband because it is pulling more air in faster (effectively causing the same piston speed of the non-stroker at a lower RPM).

If you increase the size of the intake port, it decreases velocity and raises the powerband.

So.... (on with the main hypothesis)

If you increase the stroke by 11.35% (355 to 396) and increase the port size by the same amount, then the two motors will have similar powerbands.

Obviously there are other factors that affect the powerband (exhaust tuning, intake runner length, bolt ons....), but I was trying to understand the whole theory of "strokers eat up cams" because it is total BS that simple displacement makes a difference. If that were the case, hondas would have tiny cams (duration wise) and BBC would have gigantic cams.

 

anyone have an opinion?

 

There are a lot of variables, but basically; the larger the displacement the bigger the cam can be for a particular powerband.

 

Discoteque,

Not to come across the wrong way or anything but the points you're making are so mushy that I can't really tell if you're "getting it" or not.

Let me put it this way.... If I were your professor, and I'd asked you to write a technical paper about the function of camshaft overalap in relationship to cid, I'd hand this back to you and tell you to do some more research. It's very "safe".

One question... what happens when you change the stroke and the rod length so that both motors have the same rod/stroke ratio?

I'd start with studying anything you can find on camshaft events. How IVC, IVO, EVC, and EVO effect engine performance. With that understanding, you'll answer your own questions.

Good luck.

-Mindgame