I need one of these. I'm running the stock programming for now, it works just fine except for one thing. When there is a heavy load on the motor, but it doesn't take a lot of power to get there, like going up a hill, I run into an extreme lean condition. It is remedied by shifting into third gear and applying throttle.

I would like to install an exhuast temperature guage to make sure I'm not melting any pistons.

Where do I install the sensor? Right behind the header? After the cat? Does it matter?

What kind of temperatures should I expect? My friend with a ZZ502 says that 600 degrees is acceptable, but higher than that I should start to worry. Sound right?

Thanks.

 

One sensor might not do you a lot of good if you only have a couple of problem cylinders - you'll need at least one per side and eight individual sensors would be a lot better. The problem is that if you only have one lean cylinder the others will mask the egt reading and you'll never see the problem on the gauge. You can buy egt's with a single readout and multiple sensors that let you switch between cylinders (I'm assuming you want to watch these things in "real-time," not use them for data acquisition to find out why the piston developed a hole after the fact...:) ). A wide-band O2 sensor in each side would probably be as good as a single EGT in each side for monitoring mixture, but the EGT will show other problems (like detonation) that the O2 sensor will not.

Where the sensor is placed makes a big difference in temperature reading and response, but as a general rule the closer to the exhaust port the better. The temp of the exhaust gas will not change much as long as the diameter of the exhaust header/manifold does not increase or decrease. Make sure that the tip of the probe is in the center of the header tube or manifold in order to get the best response.

Unfortunately I don't have any experience with engines like a small block running gasoline, but 600 F sounds a little low. The temp reading however depends entirely upon the placement of the probe so your friend's experience may not be the same as yours unless your probe is in the same location on the same-type header/manifold. FWIW, aluminum turns to jello at about 1100 F, so anything near that and you get a new engine....:).

Multi-probe EGT's don't cost that much, you can find them at most aircraft supply houses.

Bob Johnson
92 6spd coupe

 

Probing in exhaust just aft of manifold mounting flange, temperatures of 700-750
in strong motors under full load with appropriately rich mixtures are not uncommon.
There is a reason why dyno runs set exhaust manifolds aglow. I believe you want
EGT gauge for the wrong reason. Several variables affect EGT. You are best with
accurate measuring of A/F ratio. BTW, the temperatures stated are in Celsius!
Relevant info on EGTs can be obtained from http://www.sdsefi.com/
(go to their tech/FAQ link)


[Modified by arnold, 6:42 PM 12/25/2001]