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Message
Still have the old turbo bug but haven't run it in 8 years as I have
an airplane to fly now.
Ken Welter
Are we going
to have to call you Herbie now :-)
Thanks for
the real world (if you can call 100" MAP real world) failure modes.
Hopefully, I'll be a little safer at half that.
And now, for
more turbo math. With all the talk of intake temps, I was wondering
just how hot the mixture gets when the engine compresses it before
ignition. My thought was that a 100 degrees could be small
potatoes by comparison. Calling on all of my vast memory from Physics
about an eon ago, I searched internet until someone handed me the formula on a
silver platter :-)
The formula
is: (intake temp in Kelvin) * (compression ratio) ^ (gamma
-1)
gamma is
listed as 1.4 for gas engines.
For a 90F
day, and 9.7 cr, we have 305 * 9.7 ^.4 = 757 K or 903 degrees
F (ouch)
At first, I
though this was good news, until I found out that raising intake temp 100
degrees, raises the compression temp much more than 100.
At my 5 psi
intake temp of 214, the compression temp is 1210 F.
This is all
interesting, but doesn't tell me diddly. First, the actual intake temp is
probably a good bit lower, since fuel atomization will lower the charge temp
from what we measure before the throttle body. Second, octane, timing,
mixture and engine cooling have a large part to play in where detonation will
occur.
The lesson to
be learned here is that you should just delete my posts when you see them
:-)
Cheers,
Turbo
Rusty
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