Just came across this video figured some might find interesting.
This part 3 of the series of low buck 305 VS 302, part 1 they put similar cam carb intake headers cr etc.. On both and made similar hp and torque curves, part two they upgraded to better factory heads for each but the cr went from basically 9:1 each to 8.56:1 Chev and 9.56:1 Ford, so even though the Chev head had more flow it's gains were less than the 302's because of CR difference.
Which leads to video 3 they upped and equaled the CR to 10.9:1 for both about a 1.3 increase for the 302 and 2.3 for 305 which basically equaled out the power curves again. The interesting thing was the effects at lower rpms, for the 302 going from 9.56 to 10.9 had little effect down low especially for hp but did give a decent hp bump on top end. As for the 305 a 2.3:1 cr gain obviously added a decent gain of torque right across the entire powerband but again didn't do too much for the low rpm hp, mainly because hp is lesser than torque under 5252 rpm eg. Hp is 50% of torque at 2626 rpm so the 305 only gained around 15 hp down low which is decent but not life changing as some make it out that a cammed (218 duration) small displacement with low cr (V/P) that low speed power will fall of the map especially given our small engine (318) is about 4-5% bigger than these engines which is about equal to a point or two of cr aka a low cr 318 should be able to make similar curves as a higher cr 302/305.
This part 3 of the series of low buck 305 VS 302, part 1 they put similar cam carb intake headers cr etc.. On both and made similar hp and torque curves, part two they upgraded to better factory heads for each but the cr went from basically 9:1 each to 8.56:1 Chev and 9.56:1 Ford, so even though the Chev head had more flow it's gains were less than the 302's because of CR difference.
Which leads to video 3 they upped and equaled the CR to 10.9:1 for both about a 1.3 increase for the 302 and 2.3 for 305 which basically equaled out the power curves again. The interesting thing was the effects at lower rpms, for the 302 going from 9.56 to 10.9 had little effect down low especially for hp but did give a decent hp bump on top end. As for the 305 a 2.3:1 cr gain obviously added a decent gain of torque right across the entire powerband but again didn't do too much for the low rpm hp, mainly because hp is lesser than torque under 5252 rpm eg. Hp is 50% of torque at 2626 rpm so the 305 only gained around 15 hp down low which is decent but not life changing as some make it out that a cammed (218 duration) small displacement with low cr (V/P) that low speed power will fall of the map especially given our small engine (318) is about 4-5% bigger than these engines which is about equal to a point or two of cr aka a low cr 318 should be able to make similar curves as a higher cr 302/305.
