Ported Dart pro 1 pre platinum

[Carnut1]

0110171600a.jpg

center of cylinder side

[Carnut1]

0110171557.jpg

Chamber / ssr notice ssr bias.

[Carnut1]

0110171559.jpg

Flange view

[Carnut1]

0110171547.jpg

Port fit with 1 7/8" pipe.

[Carnut1]

0110171555.jpg

View of widened ssr

[groberts101]

0110171555.jpg

View of widened ssr

Charlie, I see a wider floor and short turn overall.. but IMO you didn't break the floors corners soon enough. Too much straight section after the minor choke point. That's what I was pointing at with the "assymetrical throat" comments. The corners start VERY subtle at the bottom of the seat and start to lay back from there. Start forming the corners of the floor from the bottom of the seat and make it more pronounced to blend into the floors corners. Either side, not too much center, of the apex gets layed back towards the seat.. like small spillways to help gas navigate the turn. I'm tight on time right now but this was a quick grab of one of Chad's exhaust ports.

Hard to see in the pic but even still.. notice Chads corner layback, his whole short turn really, starts considerably earlier than it looks like your port does. Well.. at least from the perspective I can see. One of the reasons I wanted a good shot straight and up into the bowl from the combustion chamber side. Another dead straight down into the bowl for better seeing choke shape would help us determine how you have the choke/short side formed.

Speier exhaust port 2.jpg

PS. won;t be till later but I will snap some pic's of a few heads I have laying around here that will point out the shape I'm getting at here. One's a little d-ported Vortec head that takes a 1.625" OD 16 gauge match formed pipe that flowed 247'ish @.700". 1.54" valve size. Might have been 243 cfm.. have to find my flow sheets to be sure. Hardly did any major work to it.. well, blew the cealing out around the guide and thinned it pretty substantially.. but mostly floor widening and SSR work to settle the floor speeds down was all that it took.

[groberts101]

How's it going today, Charlie? Any more updates on this project?

Buried in snow here lately but I can still dig some heads out if you want. I remembered that I scrapped out my old LT1 heads. That one had a nice D-port exhaust design too(240'ish cfm@.700 with over 500 horses from a typical medium size cammed 350) but the intake ports had been puttied up so excessively from all of those sudden water passage intrusions. Probably also one of the most extreme short side laybacks on any head I've ever done too. It kept responding, so I kept cutting.

[Carnut1]

How's it going today, Charlie? Any more updates on this project?

Buried in snow here lately but I can still dig some heads out if you want. I remembered that I scrapped out my old LT1 heads. That one had a nice D-port exhaust design too(240'ish cfm@.700 with over 500 horses from a typical medium size cammed 350) but the intake ports had been puttied up so excessively from all of those sudden water passage intrusions. Probably also one of the most extreme short side laybacks on any head I've ever done too. It kept responding, so I kept cutting.

Took a step back and started a new port. I want to get an idea what gains you get from each part of the port. Don't dig out anything for me. You have been a great help so far. Some interesting stuff coming I hope. Thanks, Charlie

[Carnut1]

0110171822.jpg

Port #8 stock 2.08/1.6 combo

[Carnut1]

0111171903.jpg

Port#8 stock flows

[Carnut1]

0111171909.jpg

Port #8 gasket match to 1205 and open pinch. This pic shows bowl work for next test.

[Carnut1]

0111171739.jpg

Port #8 exhaust radius exit shape.

[Carnut1]

0111171936.jpg

Port #8 gasket match open pinch and radius exhaust exit flows. I am surprised at 18.6cfm intake increase @.5" lift and 10 cfm exhaust increase at .5" lift. About 25 min porting time.

[Carnut1]

0111171747.jpg

Stock bowl

[Carnut1]

0111171802.jpg

Deep bowl cut, about 15 min.