I was just at the "Engine Expo 2000" in Hamburg and learned a little more
about knock detection, so I need to clarify some miss-information I
previously supplied.
The problem with knock detection on racing engines apparently is not
primarily due to the less than optimum selection and calibration of
accelerometers as I previously reported. Even ideal accelerometers are
problematic at high RPM as the normal mechanical noise in the engine starts
to fall into the same frequency spectrum as the knock, so the system cannot
differentiate between the two. If the system mistakes normal high rpm engine
noise for knock it will unnecessarily retard the spark and steal HP.
Most engines tend to knock more around the peak in the torque curve than at
max RPM though, so the things should work OK through the "normal" RPM range
as long as they are suppressed at high speed.
If the knock detection does not work at typical engine speeds (even with
nitro or nitrous) than there is a problem with the accelerometer or
software.
There is an ignition system available that can sense the changes in
ionization across the gap of the spark plug during detonation. In this way
it can detect knock even at high rpm. The system even looks at each plug
independently and automatically maps the optimal timing for each cylinder .
Unfortunately the system is $30,000 per engine. Their only customers have
been F1, not even the CART or NASCAR crews can afford them.
If anyone has 30 grand burning a hole in their pocket I can forward the
source of the system to you !
Greg
----- Original Message -----
From: "John Beckett" <landspeedracer@email.msn.com>
To: <ARDUNDOUG@aol.com>; <land-speed@autox.team.net>
Sent: Thursday, June 01, 2000 8:21 PM
Subject: Re: MSD Detonation Detector and Cockpit Display Meter
> Doug
>
> >From what little I know about these things they work great on street
> cars...are marginal on race cars...and I would guess about useless with
> nitro.
>
> John Beckett, LSR #79
>
> ----- Original Message -----
> From: <ARDUNDOUG@aol.com>
> To: <land-speed@autox.team.net>
> Sent: Thursday, June 01, 2000 3:55 PM
> Subject: MSD Detonation Detector and Cockpit Display Meter
>
>
> > Group,
> > Has any body out there used the MSD detonation sensor on nitro that
> has a
> > readout in the cockpit for the driver to see. Chuck Salmen has one on
his
> > $um-Fun gas roadster and he likes it. What I don't know is how they
would
> > react to nitro which is on the verge of detonating at all times.
> > Anybody had any experience?...............................Doug King
>
>
>
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