Like the title implies I had the chance to test a 440 RB @ 9.4 static compression ratio and then again (due to an oil leak) @ 10.4 static compression.

This is a 446 I recently built for a customer using '915 heads and flat top Wiseco forged pistons. It ran all right during the initial dyno session but the rear main was leaking a little and that was not acceptable so I took it off the dyno and couldn't leave it alone.

When I was assembling the engine the pistons measured .055" in the hole. Also understand the customer really wanted to save these pistons so I cleaned them up and CNC machined them with a slight conical dish netting a little more volume. Basically I knew there was plenty of room to play with here so I decked the block exactly .045" per side which put it @ 10.4 comp. I had the chance to re-dyno with NO other changes. The power increase is somewhat expected but the timing requirements changed dramatically. Previous timing for max power was 35-36 total--Now 30-31 total is all that it likes. Interesting to say the least. So +30 HP +38 ft/lbs at the peaks was observed--the graph tells a much better story. J.Rob