[Cliff R]

You just have to figure out how the cam plays into this deal. At that point it becomes more about the actual compression (dynamic) that the engine sees and not about the static compression ratio.

If you don't take anything else away from this thread, remember my first response:

"The cam is equally as important as the static compression ratio. The 9.5 to 1 limit we keep seeing regirgitated on this website is absolutely a retarded statement, IMHO."

There is little if any difference between a 455 with a 204/214/112 cam in it with an 8 to 1 compression ratio than a 455 with a 234/244/112 cam in it at 10 to 1 compression. At least in terms of cranking compression, compression at low rpms (keep in mind here idle quality and low speed manners follow effective compression at low engine speeds) and the ability of that engine to effectively manage pump fuel on a daily basis.

Sit back for a second and calculate the power production from each of those engines, and convince me the jump from 8 to 1 up to 10 to 1 compression is just worth 6 to 7 percent more power.

Where folks screw this deal up is using a fast ramp cam ground on a tighter LSA, when they should have used a cam with more seat to seat timing, more overlap, and wider LSA instead.

We continue to hear all about how the cam events play into this deal. Meaningless if you look at them on paper (static). You've got to figure the dynamics of the engine process into this deal.

Another factor seldom if ever mentioned is engine RPM's. The N/A engine quickly looses is ability to fill the cylinders as the rpms increase. It will see the most cylinder pressure at or very close to peak torque. Choose a cam that pulls power down to lower rpm's, and narrows up the torque curve, and quess what? You've just dramatically increased the engines octane requirements and potential for detonation, all else being equal.

When you carry an engine to the dyno, and it cranks out 550 ft lbs torque from the start of the pulls clear out past 5000rpm's, with a damn near flat torque curve, the octane requirements for that engine are less than a much less powerful (average power) engine pulling the torque curve down with a BIG spike in peak torque right in the mid-range.

I see this ALL the time, and EXACTLY why the 455 brought to us to "tune" with the 9.5 to 1 CR and 224/230/110 HR camshaft was a TURD everyplace. It was WAY too good at cylinder filling at low rpms. We've built engines with higher compression and larger cams on wider LSA's with ZERO issues anyplace, and they made more power everywhere.

Being an engine builder and DIRECTLY involved with tuning butt-loads of these engines, we've moved to even wider LSA cams and finding even better results. The next cam for my own engine will be bigger, and ground on a 114 LSA. I'm expecting little if any difference in idle quality, low speed manners, or low speed power. I do expect to makes some additional upper mid-range and top end power and not have the car slow down anyplace. Well, it's good thought, we'll see how it works when we get it installed and do some testing?

As always, with this topic, we get PLENTY of theory, and great responses from folks who haven't built an engine in at least 10 years, or had a car running for at least 20.

If you aren't out there building these engines, taking them to the dyno, then installing them in cars and street/track testing, well, your comments are mostly opinion(s), or information you've "Googled" up someplace, or cranked out of your desk top dyno with all the free time you've got that could have been put into actually building and testing one instead.

Like everything else associated with this hobby, to really know what's going on with these things, at some point you've just got to get out from behind your keyboard and get your hands dirty....FWIW.....Cliff