Gas Porting pistons

[want-a-be]

Hello all,

I know what Gas Porting pistons are, But Ive not heard of any dyno proven numers. I'm mostly intrested in gas porting SBC pistons, and was wondering what kind of increase a person could expect in an engine putting out around 600hp. Then what I could expect by adding a vacuum pump on top of that. I'm sure I'd see more gain with the .043 rings but what can I expect by doing .0625 rings, as thats what I currently have.

Thanks, Don

[Awesome Bill]

Gas porting does very little under 7000 rpm if anything. A properly honed block, (with plates and fasteners your going to use along with your head gasket). will make more of a difference that gas porting a standard end gap rign. The heavier the ring along with more rpm over 7000 with help stabalize the ring after that rpm. The rpm x ring weight is what causes ring flutter along with other factors not getting into. The smaller the ring package the better the ring will stay on the cylinder wall. We only gas port a heavier ring package along with rpm over 7000. We also dyno tested a SBF making 720 on Billy Gliddens dyno, mine made 721 with 2 completely differnt corrections but the hp was corrected to within 1 hp between 2 dynos miles apart. with out the air pump, we were down to 701 hp @ 8800 rpm. With the air pump, right back to 720. Most engines will see 5-15 hp with an air pump especially over 6000 rpm. So take it from here.

[want-a-be]

Thanks Awesome,

8500 rpm is the upper target for this engine. Will more then likely be a 383 ci. the 600hp should be a conservative hp at only 1.6 hp per ci. I was just wondering where all I can squeeze out some "free", (as if), hp. Had heard some about the ring flutter. Especially with the pump. Thought the gas porting helped more with faster/better ring seal upon compression. Didn't quite get any numbers on the gas porting though. But did appreciate the vacuum numbers.


Here is another question. I had an intresting conversation with a guy last summer with a guy about ignitions. Acording to him, once 18-1 ish compression ,and up, is reached most cdi ignitions start having problems firing the cylinders. Not going that high but would like to expand on what I've learned from him.

Thanks, Don

[Awesome Bill]

we have run well over 25-1 with MSD 7 AlL3 and had no problems, we run a 16 volt also. when we stepped it up from there, it did not like it. We installed a 10 box and man did that wake it up. We picked up 3 tenths and over 4 MPH with a little 417 blown sbc. I would gas port those pistons if your rpm is going to be over 8000, that will help some. hthelps.