Technical > Matt Shaff's Engine Shop
Basic 355 combo
Roger:
Looking at your combination of weight, gear,tire diameter, and an engine like yours making 400-425 hp, car should run the eighth mile in about 5.70 seconds at about 120 mph. Give or take. That's puts your finish line engine speed at about 6300-6400 rpm.
With that said, use your rpm heads, the savings in weight will offset any hp gain from increased compression from a smaller chamber. And you already have them.
Since your are using zoomies and aren't killing the engine with rpms, there might not be a big difference with cam timing. Since you will get no inertia scavenging or wave scavenging as collector headers would give you above maybe 5000rpm, I'd suggest giving the cam at least a 108*lsa and at lease 6 more degrees duration on the exhaust as compared to the intake. That will cause the exhaust valve to open earlier to aid in clearing the exhaust gas out and it will minimize the valve overlap to help defeat exhaust reversion into the intake manifold. Invest in a good torque convertor that stalls about 4000-4500 rpm and see what happens.
Most of all, get it running and enjoy!
opa1:
Good info, Thanks. I'll look and see what cam profiles I can find. I'll post up my selections.
jeff/21:
it was a few years ago rpm was just under 7000 and speed was 125-6 the biggest was going from a big box Chinese torque to a name brand was good for .500 and easier to drive
Frontenginedragsters:
I agree with Roger, 108* LSA if I was to do it again.
You will also get tired of gas real quick.
Alcohol is the way to fly.
Matt
opa1:
Looking at @jeff/21 rpm #7000 and what @Roger calculated 6300/6400 is a big difference in cam choices. With the low compression I was looking at this to keep cylinder pressure up. I'm not sure it will rpm enough. The figures I calculated were closer to @roger rpm's.
Howards solid 110102-08, http://www.competitionproducts.com/Howards-Cams-Mechanical-Flat-Tappet-Camshaft-Chevy-Small-Block-240_246-050-505_520-108/productinfo/110102-08/#.Wr25DExFw2w
240/246@.050, 505/520@1.5, 108/104 3000/6200
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