Don Terrill’s Speed-Talk

in a stock class SBC is there an advantage to using these? what if any considerations go into bulding amotor with these pistons.

Is the expense worth the gain for a circle track stock engine? .420 lift rule

I like to run the JE "super fly-weight" lateral gas ported pistons. The big advantage to the gas ports is they help the rings seal and you can run a thinner cross-section ring with less drag. Couple that with a slipper skirt piston and a low-tension oil ring and there is a considerable increase in power to be had if utilized properly. In the 2bbl classes we struggle for every hp so you really have to look closely at valvetrain control, harmonics, and friction reduction.

900HP wrote:I like to run the JE "super fly-weight" lateral gas ported pistons. The big advantage to the gas ports is they help the rings seal and you can run a thinner cross-section ring with less drag. Couple that with a slipper skirt piston and a low-tension oil ring and there is a considerable increase in power to be had if utilized properly. In the 2bbl classes we struggle for every hp so you really have to look closely at valvetrain control, harmonics, and friction reduction.

Im with 900, making a good, thin ring work, will help any engine.

X3 on the gas ported pistons.
In a 2bbl engine you have to use every advantage to gain HP and a perfectly prepared bore with the extra sealing ability of a thinner ring in conjunction with lateral gas ports reduces friction loss and seals the cylinder from pressure loss's a win win in any case.
The lighter the piston weight the more power can be gained as there is no need for extra strength because there is not the load exerted on the piston like a higher HP application.
I think Mahle now offeres a power pak piston that is gas ported for 2bbl engine applications.

Thanks guys.

Additional question: Can they be run with gapless upper rings? Any reason to?

NO...................

Tony B wrote:NO...................

That's kinda what I figured but I had to ask

The engines you see run 4 hours every Sunday on TV run ring packs smaller than .030, and they will have just as much power at the end of the race as the first, and not a SINGLE one of them uses gapless.TB

swatson454 wrote:Additional question: Can they be run with gapless upper rings? Any reason to?

Yes , they flat work.

Tony B wrote:NO...................

Separating out the question of " do gapless rings work" at all, is there some reason they don't work or won't work with a gas ported piston?

Abbottracingheads wrote:

swatson454 wrote:Additional question: Can they be run with gapless upper rings? Any reason to?

Yes , they flat work.

Are you referring to gapless rings alone or in combination with gas ports.
Thanks

I'm not going to say anything more to get this drawn out over 10 pages, but like I stated, the BEST engine builders in the country don't run them, put you hard earned dollar toward something else. (Marketing is a powerfull thing, huh??)TB


P.S. NOBODY has EVER been able to show how much is being lost past a tiny ring gap, in the micro second of the combustion process, just hipe. My 2 cents, but it didn't cost you a dime.

I agree we don't need 10 more pages on the ring thing, but.................... No one has ever shown that there is a power LOSS by running a gapless ring either. Plus, you don't have to fit your ring gaps super tight because there just isn't any difference because gapless is still gapless. My theory is (this is just a theory, I have no proof) that a gapless top ring will seal for a longer period of time as the bore wears than a conventional ring. Not important in an engine that only goes 500 miles, more important on an engine that's supposed to go 50,000 miles or more.

Good point, 900HP. I really like the idea of not killing an engine because I got a touch too tight with my ring gap.

i believe hendren racing engines did back to back tests with gapless vs standard rings with gas ported pistons and did find a substantial power loss with gapless rings. iirc it was a dirt late model engine.