DBRoadster Posted February 13, 2014 Author Report Share Posted February 13, 2014 Nicely put Lumpy! Quote Link to comment Share on other sites More sharing options...
Plymouthy Adams Posted February 13, 2014 Report Share Posted February 13, 2014 modern engines are a bit different over the older technology..CR is still up there....I am running stock engine at 10.5 compression, recommended mid grade fuel....can run regular if so desired as there are knock sensors that immediately retard the timing to prevent detonation....of course those cars that are running higher "rated" CR pistons etc..as stated above is for overlap with very wild cams and that is only to ensure that the engine with the expected CR loss of this overlap will still be in the 10.5 area at TDC.. as the old cars and stuff is I would say fun to play with..they cannot come close to the very performance of the modern computer controlled engine in both power, economy and just flat out smooth running with no hesitation through the entire RPM band and variable loads we put on these vehicles with passenger, cargo etc..I have elected to take a few of old Mopars to this level of performance with the newer computer controlled upgrades.. 1 Quote Link to comment Share on other sites More sharing options...
knuckleharley Posted February 14, 2014 Report Share Posted February 14, 2014 I guess I really dont understand compression ratio to drive ability to performance issues. I bought an unmolested car once that had a 11 to 1 cr from the factory and it was just fine to drive. Another guy says you get over 9 to 1 or even 10 to 1 and it doesnt work well Now we hear if we get over about 8 to 1 its diminishing returns Seems I is all corn fused You were running the high compression in a OHV engine designed for high compression,and were also getting a lot hotter spark. New cars get away with running 10 to 1 on regular gas because of computer controlled timing and engine design. It also helps them get really good gas mileage. I'm thinking a conversion to electronic ignition would be the first good step to make to get the most out of a higher CR. Quote Link to comment Share on other sites More sharing options...
Lumpy Posted February 14, 2014 Report Share Posted February 14, 2014 Another idea might be to reverse the water flow, or pump, so that the cooled water runs into the head first, and then to the block, and then into the radiator. The auto industry did that quite a few years ago, (I think GM did it first...do'h!) for the specific purpose of cooler heads, which "resists" detonation, so that they could up CR. Well I don't know if "resist" is the right word, but you know what I mean. !!! It wasn't so long ago that our "modern" OHV engines, 225's, 273's, 318's, 360's, 383's, 400's, 440's, were only running around 8.5:1 in stock form. Now 10.0:1 is indeed the norm. k. Quote Link to comment Share on other sites More sharing options...
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