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vferrero14 t1_iuh6uop wrote

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 your statement about push rods vs overhead cams, while mostly accurate isn't completely true. Push rod engines were still used by a lot of American manufacturers throughout the 1990s and I'm pretty sure Ford still has engines using push rods. I do believe Ford was able to get variable valve lift with their modern pushrod engine but I'm not totally sure on that.

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DonaldTrumpTinyHands t1_iuhaq1a wrote

A lot of (mainly American) manufacturers maintain that pushrod can be superior due to lower centre of gravity. i.e. the main cam is deep inside the engine.

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vferrero14 t1_iuhdfjw wrote

It's also simpler and weighs less, especially a V8 with double overhead setup. The four cylinder overhead cam isn't as bad cause you just have two instead of any V config will have 4 cam shafts. Weight can effect fuel economy and simple (pushrods) always has its own benefits.

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series_hybrid t1_iuhr5tq wrote

The GM LS-family of engines is exceptional, and they use pushrods. It was an attempt to see how much modern design could keep pushrods relevant, and the results were good enough to continue pushrods for quite a while.

The main benefit is they cost less than OHC, especially if you are only using 2-valves per cylinder. They also allow a shorter engine, but that's only a benefit for something like a Corvette, while millions of SUV's from GM didn't care if a pushrod engine was an inch shorter.

I would go so far as to say that if you are adding a turbo or a supercharger, you only need 2-valves per cylinder. For naturally aspirated, OHC and four valves per cylinder seem to be dominant, so there must be a benefit to that.

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