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Meter pipe pressure - Propane vs MAPP

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Meter pipe pressure - Propane vs MAPP

Unread postAuthor: NewMexicoJoe » Tue May 18, 2010 6:09 pm

I'm switching to MAPP fro Propane. Typically, I run about 75 PSI through my 3/8" 6" meter pipe with propane. Any pointers on what PSI I might run MAPP gas?

Thanks. Sorry if this has been asked before - I didn't see much in the search.
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Unread postAuthor: Gun Freak » Tue May 18, 2010 6:23 pm

I think you would use the same pressure in the meter, unless you want to keep the power the same as it was with propane, then you would probably put a little less MAPP in the meter.
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Unread postAuthor: Hubb » Tue May 18, 2010 7:01 pm

Propane operates at 4.2% and MAPP operates at 4.6%. Since you already have a meter, I can assume that you already know the math to do the rest, right?
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Unread postAuthor: Moonbogg » Tue May 18, 2010 8:10 pm

I just use the same pressure. Actually, every fill is sort of a "close enough" eyeballed fill anyway and I can never tell the difference in power. MAPP, propane, 4%, 4.8%, 4.2%, 5%...blah...close enough!
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Unread postAuthor: starman » Tue May 18, 2010 9:31 pm

If you use 75 psi for propane, shift up to 80-85 psi for MAPP. This is actually a rather high meter psi especially for use in colder weather. Perhaps you should increase your meter volume some. I shoot for a 50-65 psi meter...still a number usually usable in Winter.

MAPP is also fairly liberal on its mix requirement...I have on occasion just injected a manual unmetered "squirt" in the chamber and it fire just fine.
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Unread postAuthor: NewMexicoJoe » Wed May 19, 2010 8:38 pm

Hubb wrote:Propane operates at 4.2% and MAPP operates at 4.6%. Since you already have a meter, I can assume that you already know the math to do the rest, right?


Thanks. Maybe!

3200cc x .046 = 147 = ??? psi?

I got a D in Physics and switched to Communications. I need help. :?

The thought was to get a little more power out of it.
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Unread postAuthor: Moonbogg » Wed May 19, 2010 8:56 pm

You won't notice much difference between MAPP and propane. I read somewhere that it was more powerful, but I can't seem to detect this elusive quality of the special gas. I am going back to propane because its only 3 bucks per bottle. MAPP is like 8 or something. Propane is effectively FREE. The only thing that costs money is batteries and limes.
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Unread postAuthor: mark.f » Wed May 19, 2010 9:28 pm

Or...

If you used 4.2% in your calculations for propane, use 4.6-5% for your MAPP calculations.

Actually, MAPP has been all by replaced where I live with MAP/Pro, which is propylene, which will work at 4.6% IIRC.
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Unread postAuthor: Hubb » Thu May 20, 2010 7:14 am

The thought was to get a little more power out of it.
If you can do the math correctly, you will manage to get just a little bit more power, but it will hardly be anything that you are going to notice.

If I were you, I would just stick with propane, if nothing else, then for the cost between the two.
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Unread postAuthor: NewMexicoJoe » Fri May 21, 2010 8:01 pm

Well, I went with 80 PSI - and it worked just fine. I had just assumed MAPP was a bit more intense - that's why I changed over. It's good to know ole' propane works just as well. Thanks for the help.

Here's a link to my finished cannon, in case you didn't see it.

http://www.spudfiles.com/forums/latest- ... 21040.html
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