DonaldTrumpTinyHands t1_iuhamu0 wrote on October 31, 2022 at 9:58 AM

Reply to comment by BlowjobPete in ELI5: How exactly do we get some much power from engine now, than we did 40, 50, 60 years ago? by Micromashington

I think the most significant is higher RPM. pushrod engines have a tendency to fly apart at higher RPMs, whereas DOHC do not.

Kahless01 t1_iuhtp7l wrote on October 31, 2022 at 1:22 PM

not at all true. the 289 in my 65 mercury would hit 9k no problem. and that car was from 1965. the biggest problem at that rpm is valve float. the biggest benefit ohc engines is better variable valve timing. its easier to independently control intake and exhaust timing with ohc engines. and it couldve been done with no cam if freevalve had taken off earlier. that couldve pushed ICE engines another decade if they got it out the door sooner.

DonaldTrumpTinyHands t1_iuiek61 wrote on October 31, 2022 at 3:51 PM

What variety of that engine did you have? Since I read the stock Ford 289 redlines at 5500.

Uncle_Father_Oscar t1_iuinz6u wrote on October 31, 2022 at 4:54 PM

Is valve float the fact that the valves can't close fast enough?