Larry has come up with a new way to
actuate Teflon slide throttles for P-port engines.
Slide throttles cut the internal aerodynamic drag
of intake manifolds to a minimum... minimizing the fuel
burn and maximizing the horse power. Butterfly throttles
plates have undesirable aerodynamic drag.

This design cuts down the overall length of the slide at some
additional cost. Also the throttle cable travel and force can
be changed by changing the length of the lever.

Looks cool and incorporates the new skinny injectors
holders such as the RX8 (Denso) and Siemens, pico or
Bosch (Ford).

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Here is some interesting background info on Teflon.
http://whitetrout.net/Chuck/Teflon/teflon.htm

One of the most expensive parts of this slide throttle
is the solid Teflon slide itself. I had an idea of looking into
what it would take to coat an aluminum slide. A Teflon
coated aluminum slide could be thinner saving some weight
and cost. Just like a Teflon coated frying pan but with
Teflon on both sides and the edges. Mikuni slide throttle
carbs use Teflon coated slides.

Perhaps a Teflon coated housings for an even lower coefficient
of friction. Teflon on Teflon.

One needs a low coefficient of friction in this
application as when you close the throttle and the engine
is driven by the prop the manifold pressure can be pumped down
to minus 15 psi. With about 13 square inches of total area on the slide
the clamping force could be as much as 13 x 15 or 195 pounds jamming
the slide closed. Here is where Teflon's low coefficient of friction
(.06) comes into play. 0.06 times 195 pounds is 11 pounds. That means
the force on the throttle cable under prop wind milling conditions would
be a max of only 11 pounds. I suspect Teflon on Teflon would
be lower still.

This is easy to check. Buy a frying pan, saw it up and put the Teflon
sides back to back. Apply a known load and see how much force it takes
to move one part laterally relative to another.
Any volunteers to do this project?

Coating metal with Teflon appears to be easier than it looks.


 http://www2.dupont.com/Teflon_Industrial/en_US/products/product_by_name/teflon_ptfe/aqueous.html

Paul Lamar

Larry wrote:
 Paul,
 We can do some testing... but I am still going to make the slides out of
 teflon. I am using .25 thick teflon and by getting enough for 10 slides
 at a time, the price is acceptable.
 The body it rides in can be hard anodize with teflon impregnated into
 the ano. That will give a near teflon on teflon frictin at only a few
 bucks above the standard anodizing.
 Larry

OK we need to build one with 1/4 inch to get a feel for the forces
involved. We started with 1/8 inch thick and worked our way up to 3/8th
through 1/4 inch when we felt 1/8th inch thick was not strong enough.
The problem was the joint between throttle cable and Teflon slide.
I was not comfortable with the 1/8th inch.
Knock one out with 1/4 inch and lets see what happens.

Paul Lamar