Temp range for an exhaust valve?
Temp range for an exhaust valve?
(OP)
I'm hot-rodding a Toyota 4AGZE, which is a 1600cc 4-valve supercharged motor. I would like to test the exhaust sealing ability of the valves by heating a closed valve with a propane torch (and then pressurizing the valve from the back side). Can someone give me a ball-park figure for the normal operating temperature range for an exhaust valve in such a motor? Probably the operating range of an exhaust valve for a generic IC gasoline engine would be close enough for what I am doing. Thank you.





RE: Temp range for an exhaust valve?
RE: Temp range for an exhaust valve?
RE: Temp range for an exhaust valve?
Rod
RE: Temp range for an exhaust valve?
You could figure this out on the run of course, the old way with a spanner and a screwdriver...
What are you hoping to do, Im intrigued
RE: Temp range for an exhaust valve?
RE: Temp range for an exhaust valve?
The normal method if you need them really tight is to close them down under various full load conditions then when power suddenly drops off, open them up a bit so they end up slightly wider than the widest setting that never lost power under any circumstances.
Unless for some reason they need to be really tight, the tight end of the manufacturers recommendation is OK.
Regards
Pat
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RE: Temp range for an exhaust valve?
Rod, thanks for the tip. I never considered a vacuum cleaner and stethoscope.
RE: Temp range for an exhaust valve?
The primary path for heat transfer in an exhaust valve is through its contact with the valve seat. And since your exhaust valve is an axisymmetric part with a relatively uniform input of heat flux, it should not experience much distortion with temperature. The heat input into the valve varies during an engine cycle, due to things like exhaust gas pressure and temperature, intake/exhaust flow overlap, A/F ratios, and engine load.
The leakage rate of your seated exhaust valve will be more affected by the heat transfer rate between the seat and head than anything else. With a small valve head diameter, overheating should not be a problem. Your exhaust valves should not see temps higher than about 1300degF, even with high levels of supercharge. But if you want to check exhaust valve leakage at operating temps, you will need to make sure that the valve, seat, head, etc. are all at the correct temperature, not just the exhaust valve.
Additionally, pressure leakage past the piston rings is likely much more detrimental than any leakage past the exhaust valve seats. So maybe you're efforts might be misplaced.
Regards,
Terry
RE: Temp range for an exhaust valve?
MS
RE: Temp range for an exhaust valve?
Old school stuff. It even works with a fully assembled engine to ck if you have a valve seal problem, ring blowby problem or blown head gasket. A shop towel and vacuum, a stethoscope (even a piece of fuel line hose stuck in you ear) can do all sort of diagnostics. A stethoscope can also aid in tune up jobs, e.g., balancing a set of Webers or SU's.
Sometimes the old way is still the best way, at least for some of us.
Rod
RE: Temp range for an exhaust valve?
Sometimes the old way is the only way, at least for some of us.
Regards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
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