Who can machine a new test head for me?

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gsjames
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Who can machine a new test head for me?

Post by gsjames »

I'm looking into modifying a FI-RE Schnuerle ported .28 car engine for use in Open B at the LSN next spring. The existing engine will need a new aircraft type head and probably an aircraft type carb. The carb is no problem but I don't have a lathe to turn a new head. Anybody out there do custom engine work?
sgilkey
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Post by sgilkey »

Gary, I have been pondering a similar project. An r/c car engine screaming at 35k should be interesting! For the head, I was just thinking of cutting off the "cooling tower" and leaving the combustion chamber and first few fins intact. For the carb I would open up the hi speed needle and use an RNV. THe part that I haven't been able to figure out is the prop driver and prop attachment. All the car engines I have looked at have a short threaded portion that looks totally unsuitable for prop attachement. Also some engines have a tapered split lock collet, but I have no idea what prop driver they would fit, and it any threads would be exposed after fitting a prop driver. How were you planning on mounting the prop? Finally, the RE header- most car engines have some type of wrap-around header sealed to the case with an o-ring, we'd need a straight header. I figured we could just use a stock car pipe, but the header has me stupmed. Curious how you plan to run your exhaust!
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boiler
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Post by boiler »

While pondering using a car engine for aircraft it occurred to me the load of a prop is far different than the load of a car wheel(s). After all the work to get it on a plane with a prop, you might wind up with a total dog. Let me know how it works out. You all have the youth and energy to experiment (not to mention the money).[;)]
crash_out
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Post by crash_out »

I've heard of converting boat engines, and them being pretty hot, but I wonder if it's all worth the effort?
sgilkey
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Post by sgilkey »

The load of a .28 sized car, between friction and air, is much higher than an airplane. Plus a car is constantly having to accelerate, while a plane does not. So a car engine has to have some pretty decent torque and a fairly wide powerband. As long as we pick the right prop, I think it has potential. The car pipes are just the right length to meet combat rules, too, so it should work out fine in that regard. We just need to find a prop that spins in the 30k range. That should not be too hard. Once we get there, we'll have 3+ (rated) horsepower to play with, We just need to be sure the engine can lift the load and get it up on the pipe. That might not happen till after launch, but once it gets there, HOLD ON. It'll be kinda like launching a Q40 race plane. Still don't have a clue how to bolt that prop on....oh one other nice feature, now our combat planes can have pull starts!!!
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boiler
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Post by boiler »

If it works, make one for me Daddy.[;)]
gsjames
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Post by gsjames »

From my point of view, this is nothing more than a "thought experiment" so far. Scott's points are all valid. I "think" the shaft is long enough to put a thrust washer on it, but until I get one to measure, I won't know. My LHS didn't carry it, and I'm not going to buy one at $135 to check it out. I'll keep looking around.

I "assume" that the shaft diameter is fairly standard among Asian engine manufacturers. It's probably 5mm or 6mm and thus parts from another engine in their lineup or parts from another manufacturer "might' fit. The exhaust header is similar in that it's probably a standard diameter, but I won't know until I get ahold of one. The one that I was looking at (TT Pro .28B-R) doesn't have a pull starter. They make both versions, one with, one without.

I've got a couple of OS 25FX's so I'll be good for Limited/Open B next year, but I'd like to have some more powerful engines for Open if possible. This will be a winter project along with setting up my homemade feathercut, etc.
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o1moregil
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Post by o1moregil »

Gary heres what me and Bruce are trying to have done, the price for cnc these heads are way to much in this area

http://s24.photobucket.com/albums/c37/o ... OMHEAD.flv
Rabbit Leader
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Post by Rabbit Leader »

Friend of mine used to race glow dirt oval, we messed around with an OSCZ12 a number of years ago..it was a runner, that was sure, but down on torque compared to an aircraft glow engine of comparable size, plus it was pretty finicky on the needle. I would think that you'll need to settle on a bit less prop load, and about 25-30 percent nitro to make it work to it's potential..but it should be a screamer..
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TheKid
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Post by TheKid »

APC 6x4 sport props are routinely ran at 33+k rpm in some circles. I think that would be an ideal prop for an engine this size and power. Now someone just has to pony up and get one...
Lee Liddle
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Post by Lee Liddle »

I`ve run 7/5 APC sport props at approx 30k with no probs on my crazy fast Stryker.

Scott, maybe this will help. I haven`t seen the engine, but if it has a collet type drive attachment, maybe an electric collet prop adapter would work. they make all sizes. 5mm, 6mm, 8mm.

And here`s my electric pitch. Here`s an IC engine that Scott says may produce as much as 3hp, and is legal for Open B if someone wants to do the leg work to make it work.

3hp = 2250 watts of electric power. Why is the so much concern about electric motors when engines like this are available? Why are people wanting to limit electric motors to 800-900 watts?

Bob, please remember this thread the next time the subject of limiting electric motors in Open B pops up.
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