Last night (from epay) I bought a manifold pressure gauge for a twin Cessna. The two needles are labelled Front & Rear. It's marked 10 to 50 inches of mercury absolute. I intend to use it to read turbo boost before the throttle body, and manifold pressure after the throttle body. I'm having a hard time finding an intercooler that fits the available space plus has a usable configuration of inlet/outlet tubes. The stock rx7 intercooler I have in hand seems the best so far, but it's a bit small compared to aftermarket offerings.
Sent from my iPhone I'm thinking my "Blown Engine" experience might be avoidable in the future if I add a large manifold pressure gauge in plain sight, install a 1.30 A/R exhaust housing, retard the timing, run 100 LL blue gas, and add an intercooler. In that order. I got an engine hoist yesterday so now I can put the repaired engine back on. Getting it off didn't require as much precision... After I get some experience, I'll try different grades of mogas @ defined manifold pressure limits.
Sent from my iPhone OK, so the more accurate conversion is 20psi=40.7 in Hg so in your example 20psi boost = 70.6 in MAP (Manifold Absolute Pressure)
It help in your article, turbos work as a boost ratio. So this turbo it then making a boost ratio of:
70.6 / 29.9 = 2.36
So as you go up in altitude you multiply the ambient pressure by 2.36
So at 17,500 ft the pressure is half, and so is the MAP, or, 35.3 " MAP
Losses are not porportunately reduced, and the turbo may be less efficient in that range so actual MAP may be less.
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