Afr heads with PAC 8002 spring upgrade.

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01-26-2017 | 10:41 PM

#191

getrdunn

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From: NW Michigan

Quote:

Originally Posted by MILD THUNDER

Pushrods. Don't forget the pushrods!

MT 100 % correct but you'd think most going to different ratio would consider such such. If they don't urn they don't belong changing ratio. Although I have to be honest on lower hp builds 550 and less ive done it with no changes. But that's pure luck perhaps or just the way alignment worked out and nothing changed on valve tip. But I will say lobe profiles etc have changed much since then but regardless anybody who doesn't check pushrods length even on stock rebuild is asking for trouble.

01-26-2017 | 10:42 PM

#192

MILD THUNDER

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From: chicago

I was meaning wall thickness/diameter in regards to pushrods . But yes, length too !

01-27-2017 | 09:33 AM

#193

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From: On A Dirt Floor

Quote:

Originally Posted by MILD THUNDER

Duration itself, is in a way a mathmatical result of what a particular engine may need, to operate at a given RPM.

Just fooling around, but for example, plugging in a 4.25 bore, x 4.60 engine, (565ci),

a 236* intake lobe, would max out at 5952 RPM. Adding 3* at .050, would make it a 239*, and now, that is good until 6067 RPM. So, RPM capability went up 100rpm, just from the rocker change.

For that engine to achieve 107% VE, you will need a cylinder head that can flow 345CFM, at peak piston demand or 74* crank angle.

I missed this earlier ^^^

I thought you ran FullForce's 540 motor on the sim and came out with around 250 at .050" ?

01-27-2017 | 09:40 AM

#194

MILD THUNDER

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From: chicago

Quote:

Originally Posted by SB

I missed this earlier ^^^

I thought you ran FullForce's 540 motor on the sim and came out with around 250 at .050" ?

Totally different programs . This calculation was using "pipemax". It was just for calculation. It does not factor in port speed, port cfm, and so on.