Paul,

Slide-throttle update: I received the 1/32" teflon from McMaster and
made a
piece to fit between the teflon slide and the inner aluminum plate.
While I
had it apart, I milled about .040" off the height of the slide to
allow for
expansion. I'm happy to report that the actuation forces are now very
acceptable, even after a good heat soak. This is one powerful engine.
During tuning at about 3/4 throttle, the brakes could no longer hold
it. I
guess I need to find a big tree. I've been told that the exhaust
tone isn't
louder, just throatier. Cooling system appears to be up to the task.
Stay
tuned...

Mark S.

If the brakes do not hold it you probably have static thrust about
equal
to the gross weight.

Some where between 1500 and 2500 pounds. What is the weight?

Paul Lamar



2080 lbs empty.

Mark in Texas

Wow! Here is a physics question for everybody. How much
net out of the prop HP is Mark's engine generating? Assume
the coefficient of friction between tire and pavement is one.

Paul Lamar

Are the wheels turning or are the tires sliding?  I got the impression
that the wheels are turning in which case the force is unknown.


Matt-

If you are pushing as hard as you can and the brake pedal
or master cylinder is bottoming out then your brake lines
are too flexible. Your caliber could also be deflecting
excessively.

The brake lines can be fixed with steel lines and
double braided -3 Teflon flexible brake lines.
If the  caliber is deflecting excessively then you have
more serious problems. You should be able to lock the wheels.
You may need to go to a larger diameter master cylinder.

Paul Lamar

Actually, to increase the hydraulic pressure, you need to DECREASE the master cylinder piston area for a given amount of applied pressure on the piston.   Pressure (psi)  equals force (lbs) divided by area/

Joel

True. But I am assuming Mark can apply more pressure on the brake pedal
and the system needs more volume to compensate for system deflection.
If the master cylinder bottoms out no more pressure or fluid are possible and
there may not be enough fluid to expand all the things that need
expanding such as brake lines and calibers.

We identified this problem years ago and started designing calibers
based on deflection. Rubber brake lines were changed to double braided
Teflon lined -3 AN to reduce expansion.

BTW I helped write a book on Racing Braking systems published by  Steve Smith
Autosports wherein all this was discussed.

Race Car Braking Systems book
by Paul Lamar and Steve Smith
Steve Smith Autosports
1975

Paul Lamar