Ok, so I've made up my mind now about 6 different times about which kind of pistons I'm going to put in my 390. Still not sure what I want to do so maybe some of you can help.

I figure I have really three choices:

1. Silvolite 1131 or 1131h pistons for a CR of around 9.5:1
2. TRW L2292 pistons for a CR of around 9.5:1
3. KB150 pistons for a CR of around 9.0:1

This will be going in a 1970 F250 4x4 that sees its share of pulling. I had decided to go with the KB150 pistons based on a lot of the recommendations on threads here, but there is a voice in the back of my head that keeps wanting to say I want a little higher CR.

What is the highest compression ratio I can safely run on pump gas (89 octane) and be able to pull a trailer through a mountain pass without any detonation? I'm thinking with an FE I should easily be able to run 9.5:1, am I wrong?

It seems to me that to get the most efficiency out of an engine I would want as high a compression ratio as possible, with the limit being mostly due to the quality of fuel I can run. Any thoughts??

By the way--I'm planning in the area of 4.080 bore, crane 343941 or 343901 cam depending on final CR, ported/polished D2TE-AA heads, adjustable valvetrain, etc. I also drive it a lot, so fuel economy is important, but I figure either piston/cam setup should be about the same in this area (right foot being the more dominant factor).

Thanks for your time,
Nick

 

Dynamic CR what's the problem not static CR.
Run your combination thru www.eDyno.com.
Those KB 150's would be my first choice provided
you ended up with a tight quench plus pulling loads
and 4 wheelin hence low rpm's with high throttle conditions.

 

Hot Damn thanks Carl, its about time someone set one of these up online "for free" lol really cool..