A four cylinder mag on a three rotor?? Vance

Good question. How does that work Paul?

Paul Lamar.

Paul Carey wrote:

Paul and Vance

The magneto is a 6 cylinder Bendix - a four pole mag geared 2/3 inside

for

six cylinders.
My gilmer drive is 2/3 to get the right rpm, and I run two leads to each
plug.
I have charts etc on how I worked it out if you want.

I have installed lots more dowells in the engine, but Ibarra and

Signorelli

and other hard
hitting rotor drag cars still have the twisting problem - I believe it
cracks the rear housing.

PC

I would be interested in the charts.

OK a big box on the bottom will do the job. You should use carbon fiber
however as it has a higher shear modules of elasticity to weight ratio
than either aluminum or steel. Both of which are the same BTW.

Giving it a little more thought you kind of have limited room under the
engine for a big box.

How about a large properly triangulated space frame using steel tubing
surrounding the entire engine? Front and rear motor plates. That would
give you a front chassis structure to hang the front suspension off and
give you service access to the the engine.

I'll do a 3D of what I am talking about.

Paul Lamar

Paul Carey wrote:

Hi Paul

I gave thought to a space frame originally, but opted against for a couple
of reasons.
1 - in my car the chassis is the original RX-7 Series 1 - which twists on
launch. I originally had a rear engine plate bolted to the engine and upper
blower plates - but my drag racing experts soon had me change that. To
assume that the whole engine will not turn on launch was a mistake. So all
engine hardware was transferred to the engine only - as then the
engine/gearbox has flexibility to turn under torque.
2 - the room around the engine is very tight, and must allow for access to
exhausts, quick plug changing etc. A space frame design would be compromised
in this particular installation.

If I build a full frame chassis, I will defenitely do the space frame for
the engine - makes perfect sense.

To Lynn - my engine builder John Otter has upped the oil px to 110 psi - but
we run larger main bearing clearances, and have drilled out the eccentric
shaft oil galleries.

20B/Magneto timing sequence attached.

My choice of ignition system is biased towards "blown alcohol" drag racing
applications, where all but none use magnetos. My original engine combo was
a copy of Bill Burnham's blown 20B dragster in Portland Oregon. Speaking
with him for hours over his setup, which he ran for years with over a
hundred passes, he advised to go magneto. He could not find a CD electronic
system that could provide a consistent run. The "miss" at 3/4 track that
bangs the blower was all too common. Note the quote from legend Don Zig
below:

Comments from Don Zig
"It's funny... evolution keeps coming back to the good old standard... the
magneto ignition system. Look at the most extreme, highest horsepowered
vehicles in the world... the Top Fuel Dragsters of the NHRA. No other
ignition system, not one, produces the spark required to make it down 1320
feet of asphalt without loosing cylinders. Only the magneto-type ignition
can do it. No matter what kind of racing... from circle track to pleasure
marine, top fuel, top alcohol, tractor pull... it does not matter there's
horsepower to be made here!"

Regards PC

Thanks for the chart.
There are magnetos and then there are magnetos. An aircraft mag is a far cry
from a MSD Pro Mag. Apples and oranges.

Paul Lamar
 
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