[Diy_efi] Knock Detection using GM ESC Module

[Ken Richardson]

Melted tops and ring lands broke on one piston. It's clearly detonation. We
are limited to what we can do to the engine by our rules. We run a GM HEI
distributor with MSD coil, 9.2:1 compression, fairly stock cam. Premium fuel
only.

The engine ran A1 on the dyno for 20 to 30 pulls, everything looked fine. We
ran 1 heat race and a practice session before the race with no problems. The
plugs looked fine after the dyno pulls and heat race/practice. It almost
seems the carb picked up some dirt during the race, although we didn't find
anything. Regardless, a knock detection device "might" have saved us, that's
why we put one on the engine. Now I'm wondering how much we should trust it.

Ken



----- Original Message -----
From: "Programmer" <nwester at eidnet.org>
To: <Diy_efi at diy-efi.org>
Sent: Wednesday, May 29, 2002 12:13 PM
Subject: Re: [Diy_efi] Knock Detection using GM ESC Module


> "melted pistons" or broke off ring lands ? Detonation looks different than
> running lean. Which distributor are you running ? What compression, cam
and
> fuel choices ?
>
> Lyndon
>
> ----- Original Message -----
> From: "Ken Richardson" <krichar at ns.sympatico.ca>
> To: <diy_efi at diy-efi.org>
> Sent: Wednesday, May 29, 2002 4:57 AM
> Subject: [Diy_efi] Knock Detection using GM ESC Module
>
>
> > We recently had one of our race engines fail due to a lean condition. It
> > basically detonated itself to death, melted 4 pistons until one finally
> let
> > go. The engine ran fine on the dyno and in testing so we think it was a
> fuel
> > restriction that caused it. We couldn't find anything so we're going to
> > richen the carb up and add some octane boost to the fuel to be on the
safe
> > side.
> >
> > I picked up a GM ESC module from an early 90's GMC truck, 5.7L. Our race
> > engine is a 350cid GM smallblock bored 0.060 oversized. I'm going to use
> the
> > ESC module with a power transistor to drive a warning light on the dash
of
> > the car. I haven't experimented with this before, it looks like it
should
> > work. Lightly tapping on the block with a hammer flashes the light. Will
> the
> > ESC module/sensor consistently detect detonation at higher RPMs, in the
> > range of 3800 to 5800rpm? This is the RPM range we run the engine. Will
> the
> > larger cylinder diameter throw the sensor tuning off enough that it
won't
> be
> > reliable?
> >
> > We want to limit our chances of burning any more pistons. We got lucky
> this
> > time, no damage to the block, although the heads needed to be rebuilt
due
> to
> > the aluminum buildup. It gets expensive not to mention working our buts
> off
> > to get ready for the next race.
> >
> > Opinions??
> >
> > Thanks
> > Ken R.
> >
> >
> >
> > _______________________________________________
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> > Diy_efi at diy-efi.org
> > http://www.diy-efi.org/mailman/listinfo/diy_efi
> >
>
>
>
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