We havent even got into the effects of valve lash yet.

I really don't know , how we ended up here, in a Full Force Spring upgrade thread.

He's gotta be sitting back having a beer probably laughing at us.

probably should just start a catch all thread that might go on for years titled ENGINE STUFF

That's funny that you say this. Jim and I were at the shop a few years ago and he was degreeing a cam. Degree wheel, dial indicator and such. We actually started writing down cam events, looking at piston position in the cylinder, lift at those positions, calculating RPM vs piston velocity, piston dwell and other crap. It's scientific black magic, he could see how the air entered and exited the cylinder. I not so much. Now give me some non-Newtonian fluids... I can see them flow.

Also, Jim ports for below 0.700" for the marine customer that is why you will always see a 0.650" flow #. You can really hurt the lower #'s trying to achieve good 0.800".
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SB
Oh, the difference of the integrals. Why didn't you say that to begin with... lol
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I was gonna mention that. I noticed he shows the flow at 650 lift. Most dont.

Thats pretty much what my local head guy says too. Sometimes to get flow at .800 to improve, you can hurt the low lift flow.

Its guys like him and jimv, who set the parameters for which these software programs to operate.

Its pretty cool to have a buddy to do that kind of stuff with at the shop

I would say that depends on single engine vs twin and many other factors like slip getting on plane. In a twin, there's plenty of torque between the two engines to get on plane.

One example I can give is when I built the upgraded small block for my 22' Apache. The stock 350MPI got on plane very easily and cruised very nicely with a top speed of 63mph. The 355" making 435hp fully dressed was a little doggy out of hole and the mid-range cruise under 3500 rpm was a few mph slower then with the MPI and it was the same exact prop and setup. However, once over 3500 the boat was faster and top end netted just under 74mph. Again, running the same prop as the MPI, turning about 700-800 more rpm on the big end.

Good stuff. I'd imagine most guys would take a little less "low rpm" power, to gain 11mph at the big end. Thats a nice gain.

What sucks is, when you build a new engine package, and lose power everywhere !

This is kind of the the question I axed a few cam...motion threads ago, if more ratio vs less cam could result in a quieter less destructive valve train. Sb's pic really expained a lot to me and made sense, as iwas having a hard time grasping what was being said. Still don't know, but the conversation is very interesting. :):cool-smiley-011:

^^^More rocker ratio is harder on the valvetrain^^^^

Sorry to side track for a second...forget what you had for a prop Panther on Lil Mo.