Re: Porting and relieving

["Tom Harais" <tjhemh@domain.elided>]

Doug:

That's true - For racing, highly polished exhaust ports to get the exhaust
gases out with the least amount of friction. Less polished intakes to
create some turbulence in the intake charge and help the mixture.

But, that's racing engines. The key factor here is throughput. As in WOT
and high RPMs and volumetric efficencies of 100% or better. Lots of air
moving through those engines.

Now think about an IH 345, maybe 74% vol eff, running 2000 RPM at partial
throttle. Not nearly such a high volume of gases passing through. I'm not
so sure that turbulence in the intake is going to be that beneficial.

Of course, I think you'll still find that any machine shop will polish your
exhausts "mirror smooth" and the intake ports sort of "brushed aluminum
smooth".

Tom H.