headers vs manifolds on a 318 2bbl difference ????

mgoblue9798 said
I agree on all your points. Considering this van engine is a stockish 318 that would be pressed to spin to 5k rpm, a dyno of this engine would give more usable info if started at a lower rpm.

Dynos are generally dealing with performance engines, usually means higher stall and shift points drops are generally above 3000 rpm. Plus dyno pulls only works well over a fairly narrow rpms so they favor top end.

Unless your running a big cam and or race intake downstairs is fine. Plus hp as a % tq is 25 to 50 % from 1313 to 2626 rpm you need to do bigger tq changes to effect power down there vs 75 to 125 % from 3939 to 6565 rpm.

mgoblue9798 said
Even then we don't get much info about part throttle driveability from dyno testing.

Richard Holdener did a half throttle dyno run, I forget the exact % but was like 80% of the power and a similar curve wish he did a 25 % throttle my guess curve would be similar still and power % above throttle %.