From: emory!bangate.compaq.com!sravet
X-Source: The Hotrod Mailing list
Date: May 1994
Subject: Cylinder pressure sensors?
X-Sequence: 8635

Sorry if this is a repost, I can't remember if I asked this here before.

Does anyone make a pressure sensor rugged enough to live in the
combustion chamber?  I seem to remember someone mentioning that
there was one that went on the spark plug or something...

thanks

--steve


Steve Ravet	sravet@bangate.compaq.com
"Baby you're a genius when it comes to cooking up some chili sauce...."

[Yes.  Kistler, Valedyne, Piezo, Endevco all make piezoelectric
pressure transducers.  Kistler makes one built into a spark plug.
Better grab hold of that wallet and get ready for a ride though.
Several hundred bux a shot.  Then you need the external charge amp
which is more $$$.  Kistler advertises in most of the hotrod magazines
(Circle track and Stock Car Racing, for sure) and they all do in
"Sensors" and "Measurement & Controls" magazines, the latter being
the journal of the Instrument Society of America.

If you can sit tight for a couple of years, these things will be OEM
off-the-shelf items.  This is going to be the next big increment in
engine management sensor technology and several companies are on the
verge of rolling out production engines with combustion chamber
transducers.

Incidentally, there was an interesting article in one of the SAE
pubs within the last year or so about using the spark plug gap
resistance to measure cylinder pressure.  Might want to look that one
up.  JGD]

From: John De Armond
Subject: Re: Manifold Pressure sensor?
Date: Tue, 12 Oct 1999 18:37:29 EDT
Newsgroups: rec.aviation.homebuilt

Mark Doble wrote:
> 
> Anyone know where i can find a manifold pressure sensor for a lycoming
> 320/360?  I'm rolling my own engine monitoring system....
> 
> I have heard it referenced as a GM Map sensor?

That's it.  The MAP (Manifold Absolute Pressure) sensor.  A solid
state absolute pressure transducer.  There are two versions.  One
version is for normally aspirated engines (P/N 16017460) and a 1 bar
unit for turbocharged engines (P/N 16009886).  Rumor has it that GM
briefly made a 2 bar version for high performance engines but the
part number I was given (P/N 16036394) has never been acknowledged
by GM as valid.  Numbers given are GM part numbers.  The sensor
should cost in the range of $15 at a car parts place.

If you hold the sensor so the connections face you and the pressure
port is at the bottom, the three electrical connections are:  Top -
ground, Middle - signal, Bottom - V+ (12 volts, as I recall). 
Output signal is 0-5 volts across the rated pressure span.  

John