exhaust throttle idea-redneck

roddie Sun Mar 18, 2018 8:55 am

I'm curious if anyone has tried using an automotive fuel-line clamp as a throttle-sleeve? I think it could work on non-stepped cylinders.

Naturally; the spring-tension would need to be relieved to allow the clamp to rotate about the cylinder. Maybe if it were installed on a junk-cylinder and heated (annealed), would do the trick? A 9/16" (.562") ID clamp would be ideal.. if commonly available. The non-stepped Cox .049 cylinders measure .580" in diameter.

Slots (slits) could be cut into the clamp using a Dremel-tool and the clamp already has "ears" to connect a linkage.

A DRAWBACK would be the matter of port-indexing on alternate cylinders. Huh...

MiniatureAircraftFactory Sun Mar 18, 2018 9:03 am

I don't think it would be level enough inside to seal, for it to even work slightly you would need a good seal so at a minimum you would need to get it very close and then to ream/grind it to be smooth and match the cylinder.

NEW222 Sun Mar 18, 2018 10:49 am

I like your thinking. I will have to keep an eye out for one of these, and maybe play with the idea.

pkrankow Sun Mar 18, 2018 11:04 am

Pop it over some round stock steel to anneal. Heat to nonmagnet, about 1450F, and bury in fluffy wood ash...

Otoh, heating to dullest red in dim light will draw the temper pretty far, if not as far as it can be. The yield strength should be reduced, but it will still be very springy as the modulus of elasticity is not much affected by the carbon content, or temper of the steel.

I think it will work better if you require some mid speed run...

Phil

roddie Sun Mar 18, 2018 3:31 pm

.. OK.. so.. maybe I'll try to source some clamps.. and see if it's doable. If so; it would definitely be a lightweight alternative to the OEM Cox steel sleeve. The heat of combustion may also provide for some thermal-expansion of the clamp; allowing it to rotate, shortly after the engine warms up.

MauricioB Sun Mar 18, 2018 3:42 pm

roddie wrote: .. OK.. so.. maybe I'll try to source some clamps.. and see if it's doable. If so; it would definitely be a lightweight alternative to the OEM Cox steel sleeve. The heat of combustion may also provide for some thermal-expansion of the clamp; allowing it to rotate, shortly after the engine warms up.

Hello Roddie, at the beginning I had many illusions with various types of elements for staggered cylinders, after trying and learning, I definitely realized that the ring to work properly and can provide a range of revolutions in high, intermediate and low, should be perfectly twinned with the cylinder, otherwise it does not work properly.
For stepped cylinders the best thing is the supplements and then a ring that embraces the supplements, otherwise it does not work.

balogh Sun Mar 18, 2018 5:48 pm

roddie wrote: .. OK.. so.. maybe I'll try to source some clamps.. and see if it's doable. If so; it would definitely be a lightweight alternative to the OEM Cox steel sleeve. The heat of combustion may also provide for some thermal-expansion of the clamp; allowing it to rotate, shortly after the engine warms up.

Roddie the patented Proportional Exhaust Throttle aka PET for the 010 engines works on the principle of the throttle material i.e. bronze expanding more than steel thus when the engine warms up it gets lose and allows more exhaust blowby while when throttles it cools down and seals better.

If both components are steel they will expand with heat to the same extent

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exhaust throttle idea-redneck

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