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.

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On Jul 7, 2013, at 2:17 PM, Scott Emery <shipchief@aol.com> wrote:

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.

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On Jul 6, 2013, at 12:36 PM, David Leonard <wdleonard@gmail.com> wrote:

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.

On Sat, Jul 6, 2013 at 11:57 AM, Patrick Panzera <editor@contactmagazine.com> wrote:

I'm editing an article about a bone stock, turbocharged direct injection car engine that boasts 20 lbs of boost.

I want to convert that to MP so us airplane junkies can wrap our heads around it.

Thanks!

Pat 

On Sat, Jul 6, 2013 at 11:44 AM, David Leonard <wdleonard@gmail.com> wrote:

Simply convert 20 psi to Inches of Hg (its about 2 to 1 but not exactly) and add it to 29.9.  So the MP should be about 69 inches, give or take depending on losses and where in the system you measure.

I keep my plane less that 45 inches MP.  You have to be more rich and skilled than me to go higher without detonation.

On Sat, Jul 6, 2013 at 11:14 AM, Patrick Panzera <editor@contactmagazine.com> wrote:

Friends,

Hypothetical question. 

Let's say it's a standard day and I'm at sea level.

I've installed a turbocharger and have also connected the stock automobile turbo boost gauge, along with my traditional manifold pressure gauge.

I ground-run the engine to full throttle (where the MP would normally be reading 29.92- minus some efficiency loss) and the boost gauge is reading 20 psi.

What should the MP indicator be reading?

Thanks!

Pat

--
David Leonard

Turbo Rotary RV-6 N4VY
http://N4VY.RotaryRoster.net
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--
David Leonard

Turbo Rotary RV-6 N4VY
http://N4VY.RotaryRoster.net
http://RotaryRoster.net