Quote:
Originally Posted by 70RAlll
I agree..12.25:1 compression seems to be pushing it. Definitely race fuel vs the HO @ 9.9:1 compression could still run on readily available fuel... to me,and disclosure..just my opinion, not trying to start a fight here, I think that is a bit of a stretch. I get the 1.5 increase in compression on all engines from advertised , but when you take an engine from running on pump gas to racing fuel, well I just think you have lost the spirit of STOCK racing.. would love to see numbers of cars with original stock compression engines. Bet the difference ,especially with the RAlll would be glaring... I have always wondered how stock racing produces such numbers vs what these cars did in period tests..And RAlll getting 12.25:1 vs RAIV getting 12:1?? again, seems like the RAlll got a little benefit that makes its performance look better than it ever did against the RAIV,HO or SD's....
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70RAIII, '69 RAIV's also can go up to 12.25:1 compression since their advertised compression ratrio is 10.75:1 vs the '70's 10.5:1. When I rebuilt my RAIV motor the heads had been shaved by the previous owner down to 66 cc's. and without decking the block and the pistons .003" in the hole, the compression came out to 10.95:1 with .039" head gaskets. My goal was to keep the compression as low as possible and this is what I got with flat top pistons. I could have used a small dish, but I didn't. I'm sure this was the third time this engine was rebuilt. On the dyno it did 445 hp and 475 tq. In my '70 Judge it turns 12.80's @ 109 mph weighing in at 4050 lbs, original 3.90 rear and Turbo 400 trans and its 13" factory convertor. I'm sure with some 4.33's and some minor suspension work it could run in the mid 12's fairly easily.
Dennis