How much lift

[vwinnovator]

Whats the max runnable cam lift you'd run with a 40mm valve and an 87mm cylinder, 69mm stroke, normal aspirated.

specifically with panchito ports, out of the box

street engine

.500", .550", .600"??

Is there a lift where CFM becomes irrelevant to the cyl /stroke size?

[bugguy1967]

14 is a good general rule, where the flow gains begin to taper off based on the valve size. So for a 40mm valve, about .560" is where there are still gains to be made, but they become less and less, AND reliability continues to decrease (40x14=560). CNC'd Panchitos are about done at .600", but unmachined Panchitos are around .550".

A 87mm bore is small. Unless you're aiming for some high HP number at a very high rpm, I'd keep it at or below .500".
_________________
"A petrol engine can start readily, run smoothly and give every appearance of being in good order, without necessarily being in good tune." - Colin Campbell, "The Sportscar Engine"

[Dan Ruddock]

[vwinnovator]

Thanks guys,

I was thinking .500"ish would be about it as well.

[Dan Ruddock]

Your engine will be down on low end torque unless you add a bigger bore or run smaller heads like the Tims super stocks. What cam and rockers are you thinking about?
Dan

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