Originally Posted By: yonyon
Originally Posted By: dailydriver
What
is the (water injested quantity) 'tipping point' for hydrolock??
If the amount of water in one cylinder is equal to or greater than the combustion chamber volume you have a full hydrolock condition. If, for example you have a combustion chamber volume of 60 ccs, then with a V8 you're feeding four cylinders per revolution and need to feed 4 * 60 ccs or 240cc or 8 fl.oz. per crankshaft revolution to guarantee a hydrolock. At 2,000 RPM that means a volume of 480,000 cc/minute or 480L/mi. That's a rate of about 17 cfm. Considering that most common run-of-the-mill aftermarket 4bbl carburetors are rated in the neighborhood of 600cfm to 1400 of air (which is much less viscous of course) that's really not a lot of water needed.
However, to stall or damage an engine it isn't necessary to have that much water. At half that volume (30 cc or about 1 ounce) effectively doubles your compression ratio. This means an engine with a compression ratio of 11 to 1 would act like it had a compression ratio of 22 to 1, which is crazy high. This makes for huge pressures which can stall the engine or cause physical damage without reaching a true hydrolock. Once the engine is stalled and the starter can't overcome the high compression it seems like it's hydrolocked. Once physical damage occurs it probably doesn't much matter if it's fully locked or not. The tipping point for damage depends on the strength of the engine. If you have spark plugs that turn brown where the porcelain meets the metal part, you may be lucky enough that it will act as a fuse. Yay Bosch!
I think that's how it works anyway. Never really thought about it before. If someone who does engine work is reading, please correct the bits that I got wrong. Also, any corrections to math or more realistic chamber sized would be welcome.
Well thought-out answer
I would add that steam of course can be compressed, and as the water is ingested, the heat of the engine will in fact turn some (or most, or even all, depending on the volume) of it to steam. This is how people can dump a water bottle down a running engine and not hydro-lock it, even though the volume they are supplying the engine with exceeds what the capacity of the engine SHOULD be based on what you've described above.
