just looking at a set of pistons for a na 370ci with 12.5 compression. thoughts on pump gas?

 

A lot of it depends on the DCR based on your cam. As long as you keep that below about 9 to 1 you should be fine.

 

ok ill keep that in mind

 

to get the most power out of it tho wont you have to put a cam in it that will not be around 9 to 1? So you'll be leaving power on the table, therefore kind of voiding you having the extra compression? So it would be better to try and get it down to under 12 or run race gas?

 

Youll make more power with timing vrs compression. If the pistons have a solid dome you can mill them down to whatever you want. But in the end everything comes down to cam selection.

 

In the end everything comes down to the limits of the fuel. It has been shown that high compression and not able to run a lot of timing is not as good as slightly less compression and more timing....this is assuming the same fuel. Now if the OP was running e85 it would be a different story and he could run plenty of timing on a high compression ratio and have the best of both worlds.

 

There is a lot that comes into play here. One I haven't heard yet is rod length and crank stroke.... My last combo in my car ran on pump gas and it is a cast iron headed engine running 12.8:1 compression. We tried race gas on the dyno, and the pump gas made the most ponies still.

-Kenny

 

is it possible? i don't think so
if it was possible in a truck
you'd want flat top 2vr pistons coated .030 max quench wider ring gap and p-w clearance
peanut shaped dual quench chambers sanded and coated with thermal barrier coating
Big Intake Runners with Slower Air Speed
A cam Big Enough to use A Large 250+cc Cyl head and provide a late enough ivc to get running compression down, early evo point 9.3:1 dcr max
A Good Exhaust Port with Good low lift flow
spot on tune, 93 octane leaded
have to be a stalled auto with no lock up, steep gears
light truck/car
this would be a max effort pump gas engine aka engine masters challenge type deal 3500-8000rpm and even with everything perfect you'd still probably pull timing jmho

 

For pump gas nothing over 11.0 c/ r if so its time to do 50/50 with race fuel and 12.5-13.0 and higher jet fuel

 

The 416 in my Vette is 11.45:1 static compression ration with a DCR of 8.78. No issues after being tuned for 91oct for over 5+ years