Quote:
Originally Posted by garry viohl
482 FE with aluminum heads and 35 total timing.
Do you think it will ping? What happens if the air temp goes to 100?
Thanks.
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Lots of interesting suggestions and arguments. Unfortunatly, they're all based on too little information.
What's important is Dynamic Compression, which static compression plays a role in. Dynamic compression is the key.
The second most important component is intake valve closing point. The intake valve closes as the piston is coming up into the compression stroke. If it's very late, like 85* ABDC, then the piston doesn't compress much air/fuel. If the valves closes early, like 30* ABDC, then there's a lot of swept volume, and cylinder pressures will be high.
So, do a little more research, and find out what your compression really is. Fortunalty, it's pretty easy. On a warm engine do a compression check. If your cylinder pressures are low, like <170-180psi, you'll be fine on premium pump gas and a good tune. More than that, and you'll have some problems.
Case in point, I run 13.5:1 static on premium pump gas. But the rest of my engine build, and driving conditions support that. My dynamic compression is 8.449:1. When I got to the track, I know cylinder pressures will rise so I use 110 race fuel.
If you have more engine information, you can do some calculations here to see where you're at.
http://www.wallaceracing.com/Calculators.htm