Exhaust Porting Help

[maxracesoftware]

My ex ports are also biased to the SSR and are oval in shape. I make them almost striate on the chamber wall side. If you think in terms of how much the gasses have to turn and bias the throat ( intake and exhaust) to the air flow, it will move more air every time. My intake throats are biased .050 to the SSR! That is trade secret not many people want us to talk about isn't it Bill.

Secret
yeah, i didn't want to mention it

i start off boring the seat insert area .90 % PerCent of Exh valve OD
but hand blend the radius seat , biasing the width along the lengthwise of the Head making it "Oval-Shape" or sort of "D-Shape" with the Short Turn Radius approx. .020" to .030" smaller across Long-Turn -to- Short Turn distance than the insert's width is to the lengthwise.
..so the insert is approx .91-.92 % in width (lengthwise to Head)
and about .905 - .91 sometimes Long Turn -to- Short Turn across insert
..this has to be done very careful , or port noise & turbulence can appear


in other words, removing more metal from sides (lengthwise) to long turn
, keeping the short turn radius fatter than the other 3/4 of the insert,
something like a D-Shaped Oval

maybe more like Bill was describing ????

you can create a very smooth Flowing/Sounding Exhaust port
using .88 -to- .89 % PerCent of Exhaust valve OD
and handworking/blending a sort of small venturi effect just under the .89 % percent bore area (not in the Long Turn Area), but if you need a little more Flow ,
you can go towards the .90-.91-.92 percent and Oval-D-Shape insert area

[bill jones]

-Whatever the outcome of our ports, it's basically like an art, and it takes some years of practice, good eyesight and excellent dexterity, for right handed guys.
-You guys that can port great heads and do it left handed are extremely gifted in my book.

[Rick360]

Darin,
In your Speedtalk interview you mention the exhaust flow on your Pro-Stock head. I can't make out for sure whether you say 315 of 350 cfm. Which is it
I've only listened to it 100 times so far.
Rick

[Darin Morgan]

Darin,
In your Speedtalk interview you mention the exhaust flow on your Pro-Stock head. I can't make out for sure whether you say 315 of 350 cfm. Which is it
I've only listened to it 100 times so far.
Rick

I try and maintain an exit velocity of 300 to 315 ft/sec. The Nextel cup engines or just about any engine with a full exhaust system will want the ports a little larger. They like it so I don't question it. The Nextel cup engines have exit velocities in the 285-290 range. Engines that operate at high to very high engine speeds like an exit speed of 300 to 315ft/sec @ .800 lift 28". I also flow them at 45 inches and make sure they don't go nuts. A little bit of turbulence at 28" can turn into a LOT of turbulence at 45".
I have had some exhaust ports on the bench that popped like fire crackers! The monometer jumped over three inches. Having little to no turbulence is just as important as the air flow and the air speed.