M112 Air Temperatures and intercooler

clintonvillian

Famous Member
We have discussed this a few times in other threads, I wanted to try to "nail" down some numbers and what I would really be looking at.

In multiple forums 8psi seems to be the magic number for when an intercooler needs to be added. My question is why 8 psi? What is the compressor doing at 8psi t cause the need? At what temperatures is it required? Is pressure the determining factor, or is it temperature?


Here are the charts for the M112:

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Again:

Pulleys:
Crank: 8"
M112: 3.2 (will have to order)
Ratio: 2.5:1

Bottom RPM 750 (Blower Speed 1875 rpm)
Top RPM 5000 (Blower Speed 12500 rpm)

Base on those charts it looks like Delta T is 180F. Assuming intake temps of 100 degrees thats only 280F. That doesn't seem that hot???
 
clintonvillian":1ywm61f1 said:
Base on those charts it looks like Delta T is 180F. Assuming intake temps of 100 degrees tha'ts only 280F. That doesn't seem that hot???

To start with gasoline has an auto-ignition temp of 475 to 536 degree F.
At an air temp of 280 degrees F before the charge enters the cylinder doesn't leave much for a pressure increase in the cylinder before detonation occurs.

If you can remove even 100 degrees with an intercooler and bring the air temps down to 180 degrees it's worth another 50 ft lbs of torque at 5000 rpm because of the increase in air density and the engine becomes less prone to detonation.

With a drive ratio of 2.5 the actual boost will be closer to 12 psi.
 
It is not just the hot air fuel you have to deal with, you also have raised the effective compression ''about '' one third ? So now you have higher compression and the heat and problems of that to deal with.
 
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