K_knock sensor

Todd Knighton knighton at net-quest.com
Tue Sep 3 21:02:44 GMT 1996


Tom,
	For low compression or even mild compression that's okay.  But, with
high compression engines or turbocharged mild compression stuff your
rattling will knock the rings right out of it.
	Sounds like you're doing this at partial loads, what does this method
tell you about full throttle stuff.  Is your vacuum advance, or computer
chip for that matter, set up with the proper amount of retard so that
your condition is correct at all other rpms and throttle positions, or
only the one you happen to be at at that speed and throttle position.
	When I was 15, I used to set up my D-Jet 914 that way, and it seemed to
work pretty good.  Make a run, if it pings, retard it, if it doesn't
advance it.  You could get pretty good results.  But then again that was
a 2.0 liter 4 cylinder that made about 125 hp on a good day.  Now I'm
working with 3.6 to 3.8 liter 700 horsepower turbocharged engines that
won't tolerate that kind of stuff.  You'd grenade a high output engine
if it pinged just once!  Just ask Ford, when they were developing their
2.0 liter 4 cylinder turbo engine for GTP, they had a ignition glitch
that only hit at high rpm and load and made the engine "rattle a
little".  Actually, they destroyed about 20 engines before they found
the RF interference that was getting into the crank sensors and messing
up the timing.
	But then again, I've heard a lot of Ford, Chrysler, and GM products
running around the streets rattling like mad, and they seem to keep
going.  Low cylinder pressures I guess.
	The reason I told you about the J&S knock sensor is you can do exactly
like your saying, but the knock sensor won't let it "rattle" it will
just tell you how much it had to retart the timing to make it not
"rattle".  Then you can go retard the ignition by that amount.  No
damage done!

Todd Knighton
Protomotive Engineering


tom cloud wrote:
> 
> I don't do the race circuit, only want to go fast some times
> and just drive the others.  The way I tune my toy is to set the
> advance until I get a little rattling on long hills on hot days
> (we have some of both of those) and back it off a little.
> 
> So, Todd, or anyone else who cares to chip in, what's wrong
> widdat?
> 
> tom cloud



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