[Stan Weiss]

Originally Posted by Chad Speier

It's all about RPM. You not going to achieve big hp/cid unless you have high RPM.

Just had a customer make 2.50 with a 349, at 9600 rpm.

Originally Posted by dci

I agree Bruce, The cam lobe profile is going to dictate the power potential and rpm for this type of engine. I think that an asymmetrical lobe will definitely need to be used to be able to control valve acceleration and bounce. Rocker ratio in my opinion is going to need to be 2.0-1 or 2.1-1 because of the traditional Pontiac's cam core limitation. The only problem with that is. The amount of load they will put on the cam and pushrods. Flex in these two areas might be an issue. I think that we can get a 60 mm core in there, but the journal in the back of the block will need to be smaller (50-55mm). Maybe with a little creative cam relocating we could possibly get a 65 mm core to fit. A short deck block will definitely help with the pushrod lengths, but for the cu in we are speculating. The rod to stroke ratio is going to pose a problem with the piston at the bottom of the cylinder bore possibly. That would have to be looked at for sure. I think the longest rod you could use and still be able to have enough room for the ring package would be 5.70"-5.850". If the wrist pin gets below the cylinder it will not live long.

JC, Did you guy's do any spintron testing with your combo?


Chad, If that 349 needed 9600 rpm to make that level of power. What rpm do you speculate a 500 cu in would need? With the assumed optimal csa for this engine of course.



Don Johnston
DCI MOTORSPORTS INC.
330-850-5050 shop
330-628-3354 cell
Designer of the DCI Tiger Heads and the NEW DCI Ram Air 5 Heads !!!!!

HP is about mass air flow / fuel, or you can think about it as VE and power cycles. Lets take a 499 ci engine, bore = 4.44", stroke = 4.03" @ 125% VE and 9600 RPM it will have around 7938 lbs / hr mass air flow. At 8600 RPM to get the same mass air flow the engine would need just about 136% VE.

Stan