Exhaust temp. How hot?

I am looking to install a exhaust temp reader onto my motor. This is a drag only car and it sees NO street time! I just have a few questions:
Is anyone out there using this device?
How hot should exhaust temp be?
Which cylinder is usually the hottest?
I am just looking for some feedback to see if it is worth the time and money to use this device.o No:
Thanks,
Tony

 

I have not used one, although it's on my "wish list".

You have to install a thermocouple into the airstream- this means that you'll be drilling a hole in the exhaust tube(s) to install it. I think it's usually about 2-3 inches away from the head.

I am a little confused on exhaust temps, but my understanding is that for an NA motor you will targer 1300 - 1400, but I think for turbo motors and such (these are popular in the GN world) they get temps more like 1700 degrees. Maybe someone else can confirm.

I believe there are also thermocouples that you can clamp to the outside of the exhaust pipe/header, but I've heard these are slow to react and read a lower temperature.

A hot temperature can either indicate running lean or having the timing retarded (so that you actually get some flame coming out the exhaust valve because combustion hadn't completed yet).

As for the leanest cylinders, depends on your motor- different intakes, heads, and exhaust combinations can move that around. You'll see some setups where they monitor one cylinder, and others that monitor every single cylinder (nice but costly).

-Bob Cunningham

 

Tony
I started using one on my car.
I've only read the #5 cylinder so far and EGT's have been in the mid 1300's.
From what I understand the temps will change with ambient temp as well,so don't rely on them too much for tuning.
Seems like they help you get the jetting closer though.
I've been able to decrease jet size w/o gaining much EGT and the ca seems more consistent.

 

I would recomend one for any bracket car. I got to the point that I could predict the weather with the egt gage before looking at the weather station. Very useful to read the air in the staging lanes after you learn to use it. I would put a bung into each header tube and move your probe to different tubes to read what the engine is doing. Most engines can perform better with a little jet stagger and this is the best way to find what your engine wants. An engine with good balanced porting will run with less ( or no) stagger compared to poorly ported or unported heads and intake. Once you figure out how much stagger you keep the stagger the same and change all jets at the same time to keep the balance. This may not be the safest tune up but I used to set up on the lean side by one jet in the mid day sun and let it go even more lean as the air comes around at night, this will keep the car more consistant through the whole day. If the air changes a lot through the day this may put you into a very lean condition at night, I used ceramic coating on everything in the combustion chamber and would run EGT's from 1475 to 1575 through the day. The neat part of this is when every other car started to break out I would run the same number all day. I wouldn't suggest doing this without ceramic coating as 1575 deg. can cause damage. Another note is that thermocouples and gages will very from one to the next, I had all my notes up to date when I had a thermocouple go bad and had to buy a new one, the new one was almost 100 deg. different and the gage needed to be calibrated to get my info back. The location of the probe in the tube will make a big difference both height and distance from the head. When installing more then one bung meassure and machine the same on every tube or your readings will tell you nothing. You wont learn much in a weekend racing, you need to go on a test night and make multiple passes and keep good data to get the full benefit. If you plan to be serious about bracket racing I hope you have a lot of extra time, you will need it.

 

exhaust gas temp

Thanks for all of the info guys.:TU: I really appreciate it!! What brand of exhaust temp gauges are you using?
Hey Gary Kubisch! What kind of rpm do you turn with your car? What do you shift at and what is your rpm through the speed traps on the far end? 9.65 et is very impressive:eek2:
Thanks everyone,
Tony Rossini

 

Tony
Shift points are 6200 and the car runs through the top end at 67 to 6800.
Thanks....