She runs!!!!!
https://youtu.be/yqRx-hH8xsk
https://youtu.be/PGN509s67oU
Is anybody running the slide throttle? I'm finding it hard to slide with
engine running due to the suction. Now mind you, I don't have any
mechanical advantage or throttle cable setup yet. I'm using a threaded
bolt to test with. Can someone share their setup with the slide
throttle / lever quadrant used?
With the engine on the test bench, what safe rpm would be good without
any load on the crank? I'm aiming between 2000-3000 right now. Not sure
if it matters without a load on engine?
- Matt Boiteau
You will have to put a 2 to 1 lever on it. That will reduce the force
by half.
The travel will be 4 inches at the top of lever. The lever can be six
inches long.
With the 5 square inch area throttle nearly closed and 15 psi
(atmospheric pressure at sea level ) across it the force is 76 pounds.
Assuming you did the Teflon liner properly and used the right kind of
Teflon the coef. of friction for Teflon is below 0.1 so that is 7.6
pounds of force on the cable.
As you open the throttle the pressure drop across the throttle becomes
less and that number will drop.
Historically slide throttles have used linear ball bearings but they are
very expensive and subject to jamming with just a little bit of dirt.
They usually cost over a thousand dollars US. The Teflon liner will
tolerate dirt and embed it in the soft Teflon. Many small slide carbs
have the slide coated with Teflon.
The SU is a well known example.
The e-shaft is absolutely the last thing you need to worry about since
we are using a stock e shaft and we are getting 650 HP. The part of the
e-shaft next to the flywheel is the most highly stressed part and that
has held up with over a 1000 HP on a turbo 4 rotor. Stock e-shaft and
stock diameter. The stock e-shaft is atomic bomb proof :-) After all It
was built in Hiroshima. Sorry! politically incorrect joke.
IT MATTERS!
BE VERY VERY CAREFUL. The engine will run up to very HIGH RPM's with no
load and then seize. I don't know how high WITH oil pressure but WITH
OUT oil pressure
it seizes around 10,000 RPM very roughly speaking. It has been done
so don't try it again :-)
Of course there is a rev limiter in the stock RX8.
Paul Lamar
Hi Paul,
I didn't realize that SU came out with a slide throttle carby, the
only ones I
have ever seen were butterfly ones that needed re-tuning weekly.
Cheers Chris.
Yes they had a butterfly throttle but there was also a plunger
with a needle attached that would go up and down depending
the vacuum in the intake manifold.
Talking to Max in Narsarsuaq Greenland today on the phone had an affect
on me.
Reminded of the days when I decided to sail singled handed a 1000 miles
down to the tip of Baja.
Sheer TERROR :-) It was in his voice "What the f@#$% am I doing here???" :-)
Imagine what it was like for Charles Lindberg? You don't trifle with the
sea.
Paul Lamar
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