Don Terrill’s Speed-Talk

Well we opened up bowl area on intake runners of a3 heads from 231cc to 244 and port matched tunnel ram. Seen slight increase in flow but only by 5 cfm at best from .400 up. Going to see where that gets us last dyno run saw 434 peak at 6900.

Steve.k wrote: ↑Mon Sep 17, 2018 1:15 pm Well we opened up bowl area on intake runners of a3 heads from 231cc to 244 and port matched tunnel ram. Seen slight increase in flow but only by 5 cfm at best from .400 up. Going to see where that gets us last dyno run saw 434 peak at 6900.

That should raise the RPM point of the peaks a bit; power may go up some because of a better port match.

Personally, in that case, I think the power will simply hang-on longer.

Walter R. Malik wrote: ↑Mon Sep 17, 2018 3:07 pm

Steve.k wrote: ↑Mon Sep 17, 2018 1:15 pm Well we opened up bowl area on intake runners of a3 heads from 231cc to 244 and port matched tunnel ram. Seen slight increase in flow but only by 5 cfm at best from .400 up. Going to see where that gets us last dyno run saw 434 peak at 6900.

That should raise the RPM point of the peaks a bit; power may go up some because of a better port match.

Personally, in that case, I think the power will simply hang-on longer.

It's possible it will quit earlier also. Port volume is more, because of bigger bowl, but if port cross section was small for combo and that was unchanged, it could peak sooner, may lose power. Or fill in some areas, but peak sooner, fall off harder if it's pulling on the port harder. Port match has to be WAAY off to gain power.

Just picked heads up. Turns out hes 250 cc from 231. Csa is alot bigger he says although didn't do before and after measurement. We will dyno this way and see where we get. We will also try setting intake centerline to 110 instead of 107.7. Get a little more pull on heads if you will.

Sorry to resurrect this thread, but what were the results?

No results yet. Engine just going together. Waiting on some parts