Subject: Re: 034 EFI

[Huw Powell]

> Regarding the pickup of any ignition system, .......the pickup of all the
> racing engines I can recall, or have built, or seen all have pickups on the
> crankshaft...not the cam or other (flywheel IS the crank); reasoning: lash at
> high RPM's on timing belts, chains or any other mass that might accelerate at
> slightly different speed from the crank and pistons may cause big timing
> issues.

I read Orin's comment on this with interest, of course what he says
makes complete sense.

sender on flywheel - huge diameter and heck, it's pretty much in touch
with where the pistons are
sender on camshaft gear - medium diamter, timing belt flex/play/lash
will let it deviate from exactitude
sender on distributor - tiny diameter, and one more gear to add lash and
variability to the signal.

why do I mention the diameters?  I forgot, but it seemed to make sense
that if you want a very accurate degree mark on something hat is
rotating, the larger the circumference you take it at the more precise
it will be.

And... since most of the EFIers are doing it to go well beyond 200 hp,
this could prove to be of very worthwhile consequence.

If you're simply going with EFI to make initial installation easier,
make the car simpler, etc. (I know I would), it might not matter as
much...

--
Huw Powell

http://www.humanspeakers.com/audi/

http://www.humanthoughts.org/