Paul:

Dave's stock turbo was operating under the following temperature conditions at or near the time of failure.  The operating conditions are from memory and may not be exactly as Dave described....but
close.

Altitude:  14,000 feet density altitude
Underhood temperature:  100 deg F (under cowl heated air into the intake filter)
Turbo inlet pressure 7.5 psi (15" Hg)
Turbo outlet pressure 18 psi (36" Hg) Note: the MAP will be 2-4" less due to losses
MAP: 16.5 psi (33" Hg)
Compressor efficiency 70%  (This is probably higher than the compressor was providing)
Outlet temperature of the turbo:  431 deg F
Pressure ratio 3.4

With these input conditions to the intercooler...
Intercooler input temperature:  431
Intercooler efficiency:  80%
Intercooler pressure loss:  1 psi (2" Hg)
Ambient temperature:  32 deg F
Intake manifold temperature post intercooler:  112 deg F

112 deg F intake air instead of 431 deg F intake air!!  It isn't a matter of weighing the weight of the intercooler system against some weight bogey....it is realizing that at any decent altitude,
the intercooler is a necessity on a turbo system.

Calculated using the neat on-line calculator at: http://www.stealth316.com/2-turbotemp.htm

This is a good example of why an intercooler is an absolute necessity for aviation use.  The conclusion reached is that intake heat and detonation did not kill the Hummer which it might have without
the intercooler??  Dave was aware of this possibility and had integrated his intercooler into his system in what I consider a very "sanitary" manner utilizing his cowl inlet openings to feed the
intercooler and routing the intake tubing below the PSRU around to the opposite side to the throttle body.

Doug Dempsey

 
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