What is the highest compression ratio that is the best for todays gas. I am building a 454 with aluminum 119cc chamber heads and don't want to get to high of a ratio so it will still run on pump gas.

First you have to get your static ratio and then you can calculate your Dynamic Ratio after you have chosen what cam you are using.

Ditto!

Hunt up the late great Pat Kelley's DCR site and read it at least three times!

I did.

pdq67

Like these guys said^.your effective Cr will differ with valve timing events.I am not a big fan of across the board 9-1 iron and a point more for tin heads.To vague and to generic for my liking.Fwiw..my retired iron headed 427 puked up 11.25/1 static cr but never detonated on 93 with a 294 magnum and 3500 stall converter.The current 461 has a static 7.5/1 cr..but the timing events and positive manifold pressure mimics a static 13/1 n/a engine.

Consider the Speed Pro ZL2349F with a 29.40cc dome. It should give you approx 10:1 Static running a .039" Composite Gasket for Alu-Heads but the Quench would be like .064" - not so good for knocking. I would consider decking the Block .020" or .025" to get a 10.4:1 Static and .040" Quench.

As mentioned DL Patric Kelley's DCR Calculator and choose a Cam. With the Block Decked, a cam installed straight up with something like a 282 Advertised duration would give you around an 8.2:1 DCR which is about MAX for 93 Octane. A 286 duration would probably be more Octane friendly with around an 8:1 DCR.

Alu-Heads are somewhat more Octane friendly then Iron so I imagine you could get away with a higher DCR.

I'm running an 118 Iron Chamber with the Speed-Pro L2465F30’s with a 25.7 cc Dome and a .019" Shim Gasket which gives me a 10.2:1 Static and a .044" Quench. I run a SR with a 288 Advertised duration cam installed 6 degrees advance that gives me an 8:1 DCR. I can run 89 Pump Gas if necessary but prefer 91.

You don't necessarily have to buy Speed Pro Pistons but I think you get the idea.

10:5:1

Thanks for all the suggestions, I am not a big engine guy, I leave that up to my brother, I do the body work and paint,I will pass everythinigonto him. I will lookup the DL Patrice Kelley web site and read up on it.

Thanks again.

At least three (3) time's here, I did before it sunk in!

pdq67