H.O motor question

[MiracleMax]

Well lesse your engine displaces 308 cubes (3.07.7) and the roush heads feature 2.24 sq. in. of port area.

These heads in this application are good for about a peak torque value of 5100 rpm and since HP is a mathematical function of torque (I think peak HP is 1500 rpm higher than peak torque) then your looking at a peak HP value coming in around 6600 rpm.

here is the tech document on the Roush 200 heads from World Products.

http://www.worldcastings.com/tech/ro...inderheads.doc

this is a handy reference page for getting an idea about how to go about things.

http://www.newcovenant.com/speedcraf...ors/intake.htm

Conclusion

You at the very least need to make a manifold change to better take advantage of the heads and the ??cam??

The only easy info on manifolds I can find is from Edelbrock. Using the same calcultor suggests using the Performer 5.0 RPM (Which has an exiting port area designed for about 200 higher RPM)

so less'see a visit to the comp cams website and a check on the catalog suggests something in the 280 +/- adv degree range.

BTW, another rough estimation calculator for header length based on primary pipe O.D engine size and max revs fond here

http://www.bgsoflex.com/bestheader.html

suggests using a header with an 1-5/8 primary tube 31 inches in length.

Hooker makes a header with those dimensions as a regular stocking item.

Interestingly if you up the dia to 1-3/4 and bump the engine size to 347 then the pipe length remains about the same.

if anybody has flow figures for the Roush Heads (about 6 to 8 points preferably from .050 or .100 lift on up) I can plug these into a dyno sim for a rough idea on power. As well as compression ratio for 64cc heads and flat-top pistons.