"Huge gains" I think we're losing track this is a slant 6 we're talkin about. IMO, unless you're racing for money or points, it's splittin hairs what lobe you go with. All things equal, how much do you think a .903 specific lobe will net?
It’s not just about peak horsepower (it just KILLS me to say that) but it’s about power under the curve, manners, driveability, idle quality…things like that that don’t show up on a dyno.
My math above comes right off the Howard’s lobe list.
Both lobes are the exact same at .050 but the .904 lobe has less seat to seat timing (better idle and more idle vacuum) and by .200 lift the .904 lobe has far more area under the curve.
When you are laying out an engine build the .904 lobe allows you to do more without sacrificing the above mentioned things.
