Extreme Speed Prop Planes Discuss the need for speed with fast prop planes (Screamin Demon, Diamond Dust, Shrikes or any REAL sound breakin'''' plane)

Car engine with a propeller

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Old 08-02-2004, 11:43 AM
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jlindqui
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Default Car engine with a propeller

I am wondering about the possibility of putting a .15-sized car engine on a speed plane. I finally cooked my OS .15-FP and need to replace it, an am thinking of switching to the OS .15-CV. Theoretically this will take me from 18,000 RPM to ~28,000 which would be a 150% increase in speed, but I'm not sure if I could maintain the same size prop, etc? Anyone have experience with this or ideas about it?

Thanks,
-Joe

Here's the plane it's going in:
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Old 08-02-2004, 12:03 PM
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Default RE: Car engine with a propeller

A car engine's timing and torque values are a lot different. Those engines run at that high RPM because they are using a gearbox to reduce the final shaft speed.

Even a large bore (.25) car engine will choke on an easy pitch prop. The only feasible way a car engine would work is to gear it down. I don't see any advantage to doing so, and in fact, since most gear drives are only 90% efficient, it most likely be a lot slower.

DP
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Old 08-02-2004, 04:09 PM
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Default RE: Car engine with a propeller

Thanks for the info. It may have saved me ~$100 and some headaches.

-Joe
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Old 08-02-2004, 06:57 PM
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Default RE: Car engine with a propeller

You could use a car engine... but there are buts:
Like the Pig stated: an engine timed for 30K rpm or higher will not swing the same prop as your .15 FP. It will need a VERY small prop to get there... probably too small compared to what you are running now. So you would need a different plane too... (smaller, lighter, sleeker)

When using a car engine in a plane, do not use the same low oil content fuel as the car guys! They can get away with it because they rarely run full throttle for any length of time... after a second or two you have to slow down to turn with a car... not so with a plane.

The large cooling head will have to go. Your engine will not get up to temperature with the mega head hanging out in a 150 mph breeze. Plus it will create a lot of drag.

A proper pipe would also help. But it has to be set correctly. Too short will cost you money (on plugs, and eventually engines)

The plane you have there would probably be a good candidate for an MVVS .15 on a venturi, running a 6.5x5 to 6.5x6 APC prop.
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Old 08-03-2004, 09:36 AM
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Default RE: Car engine with a propeller

ORIGINAL: jlindqui

I am wondering about the possibility of putting a .15-sized car engine on a speed plane. I finally cooked my OS .15-FP and need to replace it, an am thinking of switching to the OS .15-CV. Theoretically this will take me from 18,000 RPM to ~28,000 which would be a 150% increase in speed, but I'm not sure if I could maintain the same size prop, etc? Anyone have experience with this or ideas about it?

Thanks,
-Joe

Here's the plane it's going in:
I have modified 8 different car engines from 12, 15, and 18 size for props and found that the os 18cv is the best for power to weight. The 18 cv with open exhaust and 15% fuel turned an apc 6.5x6.5 at close to 21000 rpm. Its weight was a tad under 6 oz. It will probably tear the wings off your GLH. You will have to change the carb and modify the head and make a special prop nut.
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Old 08-03-2004, 10:02 AM
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Default RE: Car engine with a propeller

Thanks for all the info. I'm planning on ordering the MVVS .15 today. I've read some excellent things about the MVVS line and for less than the cost of a car motor, I can't complain.

-Joe
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Old 08-03-2004, 10:11 AM
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Default RE: Car engine with a propeller

The mvvs 15 is a strong engine but it is also weighs as much as some 25 size engines. Just a heads up. You will also need to get a tuned pipe for your engine to make it run strong.
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