Fuel consumption problem!

I need help from some of the engine guru's out there in stunt land. I fired up my new PA65 RE on my new plane yesterday. I have a 6 oz TRW slip in tank in a Dave Midgley carnivore. The engine starts on the second flip and settles into a smooth 4 stroke run. The problem is my run time is only 4 minutes. Does this seem right to you. The needle is open approx 5 turns. Anyone out there have any ideas??
Thanks

Several possibilities:

Are you sure all the fuel is being consumed? i.e., Does it take 6 oz. to refill the tank?

Are you starting immediately after filling the tank? Is there any chance the tank is siphoning part of the load?

How much time on the engine? If new, economy will improve with running.

Also might want to check venturi size, a larger venturi will give more power at lower fuel economy. My .02 wort [photo not recovered: sipcof.gif]

>I need help from some of the engine guru's out there in stunt
>land. I fired up my new PA65 RE on my new plane yesterday. I
>have a 6 oz TRW slip in tank in a Dave Midgley carnivore. The
>engine starts on the second flip and settles into a smooth 4
>stroke run. The problem is my run time is only 4 minutes. Does
>this seem right to you. The needle is open approx 5 turns.
>Anyone out there have any ideas??
>Thanks

In addition to what Ralph (and maybe others) pointed out, a lot depends on your set-up. Matt was running around 6 ounces on his, while others reported using 8 ounces or more.

What is your head shim thickness? What venturi are you using? What prop? What pipe? Pipe length? What nitro content? And, lastly, how are you setting your engine up to run?

All of the above can affect not only the power/thrust output of your engine and the way that it will run, but also its fuel consumption. Matt runs his on 5% nitro even at Muncie. Others use as much as 15% or 20% nitro. And, yes, they will run more fuel.

You mentioned settling into a smooth 4-stroke. Does it stay in a 4-stroke throughout the patter, or does it break into a rich 2-stroke at the top of the loops or perhaps a bit earlier? If you set it so that it will get that break, it will use less fuel (run leaner). If you are setting it for that constant 4-stroke, you are throwing more out the pipe.

As to the needle setting, that depends on a lot of other factors, but it seems that you are running it farther open then needed and that can contribute to fuel consumption. A larger venturi will do the same thing (and need the needle to be opened further).

Where are you running this? (Altitude, temperature) That, also makes a difference.

"I need help from some of the engine guru's out there in stunt land. I fired up my new PA65 RE on my new plane yesterday. I have a 6 oz TRW slip in tank in a Dave Midgley carnivore. The engine starts on the second flip and settles into a smooth 4 stroke run. The problem is my run time is only 4 minutes. Does this seem right to you. The needle is open approx 5 turns. Anyone out there have any ideas??"
Thanks

Steve Everett

I think we need more specifics, as even if all of the factors mentioned by Len were additive you've got a real serious problem.

Or maybe not. You didn't mention actually flying the engine; are you quoting ground-run times? If so, not out of line with the use of a hard tank as the pick up can't reach all the fuel.

In any case a rough rule of thumb is that 60s and 65s will need around 1 ounce of fuel for 1 minute of flight. Many of us are using more fuel than that for a full pattern. Howard is getting marginally to substantially better mileage even without factoring in his new Toyota Pious.

So whether your new 6-ounce tank is working properly or not, you should probably begin looking for a 7- or 7 1/2-ounce tank...

Dan

Why don't you call Randy. He can give you all the information you need!!!!!!!
Gene

Try a tad leaner setting on the needle with a little less pitch on the prop, that should improve fuel economy a little anyway. Better solution is to get a bigger tank if you can get it into the plane?

Jim Pollock

I used around 6.5 ounces at Muncie with my PA .65 on a pipe .Swinging a 13-4 Eather 3blade @ 9,600rpm.