4 ms·
Modern direct injection diesels still use OHC, even though they run at really low RPM, so valve float can't be the only reason virtually all modern engines use
by _yb2s 4y ago
Modern direct injection diesels still use OHC, even though they run at really low RPM, so valve float can't be the only reason virtually all modern engines use it. I think this is because it allows for larger and better positioned valves, or even more valves (e.g. DOHC/4 valves per cylinder), making the engine breath better. I imagine the advantages of that would be even greater at altitude.
- jabl 4y agoI'm not saying OHC aren't better, they certainly are (in most respects). Just saying that I wouldn't consider pushrods a showstopper either. (As an aside, when aviation engines started going with 4V designs in the 30'ies, it wasn't only about breathing, but better cooling of the valves was an equally big motivation.)