In reply to 1SlowVW :
Yes. A Hall effect sensor on the back side of the distributor rotor. Right up to 1993 when they switched to digital and used an actual crank sensor. The trouble is there are at best 3500 of those in the states. With normal attraction on 27 year old cars I'd be very surprised if there are 1000 left. Those engines command prices in the thousands rather than a few hundred.
Paul_VR6 (Forum Supporter) said:I will have to see what is still under NDA and what isn't and see what I can share. All of the injector stuff got paid for by others
which locks up the data in a few ways.
On the flame speed front I have the following numbers in my notes, no clue where they are from at this point as they are 20+ years old likely out of an old crusty book:
Gas .34ms
Ethanol .39ms
Methanol .43ms
All at stoichiometric from what I remember, likely in open air, and that obviously can change in an engine. There is also a difference between the front speed and how they build pressure, and how quickly they build to peak pressure. I can't see how ethanol has a faster burn rate/flame speed but then need more ignition lead. It's counter intuitive, and doesn't line up with my experience.
Edit - it's likely the @ AFR being the difference, that chart above is in equivalence ratio (1/lambda) so for most high power ethanol cars it would be all the way to the right (~1.33) and for methanol it would be off the chart to the right (~1.6). Just looking at the trends on that end of the chart, the order of results would change a bit.
You are right alcohol has a slower flame front which is why it helps a long stroke motor more than a shorter stroke motor. It does a better job of "Chasing the piston" I vaguely remember a formula for piston speed since technically it stops at both the top and bottom of each stroke. A longer stroke engine's piston "lingers" at the slower piston speeds longer building pressure and gains massive velocity at mid stroke relative to a short stroke engine. That velocity translates to increased power and torque when the rod is at 90 degrees to the crankshaft.
Offenhauser and Jaguar's both had very long strokes. Jaguar's was 4.27 and the 270 Offy was 4.50. Effectively limiting rpm to around 5500 rpm when piston speeds exceeded 3000 fpm
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