im runing 11 to 1 with cast iron heads and the ford f303 cam. i was concerend if i could get a way with the crapy 91oct. gas in california. Well it runs aswome on it. the guy who dyno tuned the motor said thay my heads didnt flow enough air to alow the dynamic compression to be to much for our gas. I suspect your alum heads will flow more so thats a different story. so i guess that it really doesnt mater what i have so ill just stop typing now.
LSx engines get away with 11.4:1 That is with knock sensors and the timing under computer control. If you set your timing well, and with the right cam, you should be able to do 11:1. Like mentioned, the cam matters... as well as the shape of the chamber. 11:1 with an open chamber will handle less than 11:1 with a quench chamber, which will handle less than 11:1 with a swirl chamber. Also gotta deburr everything and anything that is in contact with the combustion process. All sharp edges need taken off... Pistons especially.
I want to build 429-460 street/strip w/ cobra jet aluminum heads, weihand stealth intake, eagle h beam rods, stock crank, what piston and cam would you recomend on pump gas. thanx
Do some research for info on the 2003 Engine Masters Challenge. Jon Kaase won with a 460 pump gas Ford. Those engines were hanging on the edge of detonation.
I Would bet that 10:1 would be the highest.. it depends on a few factors. If you are pinging, you need to increase the octane. i had 9.5:1 in my car.. i used 91 octane.. and even ran a mix of 91 and 104 (purple) at the track.. i noticed a big power difference when i ran 104 in it. the heads, cam, and power band all play a part in what octane you can run with what compression..
EDIT: The guys at 460ford.com can probably help you specing out your cam. Just include the following info. What RPM do you plan to shift at? What kind of rear gear are you running? What kind of transmission will you run?
