One of the recent podcast puzzlers got me to thinking what motivated the Toyota engineers to decide to put 16 valves in my Corolla’s 4 cylinder engine? What are the advantages and disadvantages of 16 vs 8? I can think of these possibilities 16 is better than 8 b/c more engine power 8 is bett…

Probably better efficiency and pollution control with the 16v engine.

More valves equal more power since Puegeot did that in a 3 liter 4 cylinder in 1913.

Conceivably you could get the same power from 8 as 16, just make the 8 valves bigger. Or isn’t that feasible b/c of space conflicts? Or if the big- 8 idea remains feasible, does it cause other problems?

Nope, see what the total circumference of four circles vs two are that fit inside a single circle. If 2 valves were just as good, don’t you think they’d use them?

[image] texases: total circumference of four circles vs two are that fit inside a single circle Ok, that’ll be my Christmas puzzle. Do you mean “area” rather than “circumference”?

He means area and circumference… curtain area. Valve lift times the circumference. Much greater with 4 valves than 2. Also, the lighter 4 valves can be revved higher making more hp.

Nope. The area for air flow is approximately the valve circumference times valve lift. @Mustangman beat me to it. Harry Miller made huge advances with DOHC 4 valve supercharged engines in the 1920s, evolved into the Offy engine that won dozens of major races.

[image] texases: Offy engine that won dozens of major races 39 times in 57 tries at the Indy 500! Harry Miller was sent the Peugeot for repairs in 1915. He liked what he saw… as did everyone else! DOHC 4 valve engines exploded in racing from that point on. Sunbeam built a 24 valve 6 in 1923…

Is the 4 valve per cylinder design what allows Toyota gasoline engines to be non interference?

A Corolla w/ 8 valves vs 16?

Maintenance/Repairs

Mustangman December 25, 2023, 1:48pm 11

No, 4 valve engines could be either interference or not. It depends on the valve lift, valve angle from vertical, compression ratio and the reliefs in the piston tops.

High compression engines generally have trouble being non-interference.

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A Corolla w/ 8 valves vs 16?

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