Hi,

Is there such a thing as a forged BBC piston that has a very small dome volume, say 5.0-7.0 cc's? Thanks.

My SRP's are 10 cc.

Hi Bill...I found the 10 cc ones, but when I used those to calc my engine compression it came out to be 10:1 ...with 5-7 cc's the compression came out to my target number of 9.6-9.7:1. Question...is 10:1 okay in a 460 with iron heads...on pump gas?

It depends on your cam, how much overlap, lift, etc. What matters more than your static compression is your dynamic compression. Do you have the dynamic compression calculator? Can you post your cam specs?

Depending on the cam used, I doubt you would have any driveability issues bewtween 9.7 and 10.0, especially with a slow ramp hyd flat tappet cam. You can also run the cam at 110 ICL to control cylinder pressure. Keep in mind, combustion chmabers are often all over the place and piston/deck heights need to be accurate.

Hopefully this will help. I guess I should have provided this earlier...


454 +030 (460)
virgin block (~.025 in the hole)
Voodoo 268 cam 268/276, 227/233, 110/106, seat to seat IO, IC, EO, EC data not known (however, I would think this is considered a fast ramp hydraulic cam)
'290 heads w/2.18 & 1.88 valves (~99.0 cc's)
stock rods & stroke
Stealth intake
HEI
Gasket .039 (really didn't want to go to a shim gasket)

I have requested the cam data from Lunati to try and calc my required static compression (Ed Staffel's book), but have not received the data yet. I thought I needed the same data to calc the dynamic compression ratios. Any help would be appreciated...I'm finally able to start working on the car so hopefully you won't mind my entry-level questions.

James,
I would think it should be fine. I just noticed you're in FL. Make sure the cooling system is sufficient.

You'd be better with the compression (ratio) a little lower. On the dyno we have trouble in the warmer weather (80 degrees and above) runnin' a true 9.8:1 with an iron head on "real" 93 octane. Also for most street only cars you're better off with a wider L/S. It'll tend to flatten the torque curve somewhat. The cam is a little bit short for the C.I.'s. It's almost one we use trying to chase a little gas mileage at the same time. That size engine with your compression about where you are would probably like something in the neighborhood of a 230/236 degree x 112/114 L/S for the street use. The smaller grind would better fit a 396/427 L.C. combo. Thanks, Gary
P.S. The second reason for knocking the C.R. down just a bit, is all it takes to ruin good pistons if you're runnin' on the edge, is one bad tank of gas. We've had fuel from the pumps in my neighborhood tested, and the results were horrible. So you never know! All new computer controlled cars have an edge as far as detonation. The computer watches it and compensates.

Thanks guys. I'll try to keep the compression in the 9.5 to 1 range.

Bill - You mean my old three core radiator that I'm using for my 307 now won't work?!? ...just kidding, I have a new radiator on my "parts still to buy" list (but at least the list is getting smaller!). Thanks for your help.

James

You can get any dome size you want. I have a 7.5cc dome in the new motor I am building. I told BRC the specs I wanted and they made me pistons.

Thanks for the info Jim. I'll call them to see what the going rate is for custom pistons.


Chevyrelic