Engine/Transmission (1994 - 1998) Put infrared thermometer on exhaust ports on head & have diff. readings?

[JBlackwell]

I was letting my turbo cool down when I got to work this morning and killed a second and popped the hood and took some readings. I shot the beam on the exhaust ports on the head right in front of the manifold and got all kinds of different readings. #1 & #6 said 240*, #2 said 220* and #3 & #5 said 200*. Is that right or does it even matter?





Justin

 

[JFaughn]

I've been using one for a few yrs. on gasers and haven't got it out yet for the truck but at an idle I wouldn't think that those temps are out of line , thickness of manifold, valve timing ,age of injectors, also check powerbraking maybe 1200-1300 rpm but still not enough diff. to be an issue unless you were doing some high end mods. and compition then a little more tunning.

 

[JGK]

I did the same thing several times a few years ago while chasing a "lope" in the engine. I'd run it up a long hill to get it really hot and check it at the top. I'd see temps in the upper 400* to upper 500* range on the head exhaust port.



Seems like the middle ones were a bit hotter, then #6 just a bit cooler. #1 was usually the coolest due to being near the thermostat as well as the intial blast of air from the rad. fan. 6 would be hot due to being in the back. 3 and 4 where the hottest since they had heat on both sides.



#3 was usually a bit cooler than 4 and the one I thought was the source of the lope. But I was never able to nail it down. It has since cleared itself up. I hope to do an o-ring job this month and maybe a look inside will reveal something.



In any case, the difference you're seeing is well within acceptable variance, at least from my experience.



-Jay

 

[JBlackwell]

Thanks guys, I mind is now at ease...





Justin

 

[HEMI®Dart]

Justin,



This is from an older thread when we were discussing the Banks Twin Ram:



In TDR issue # 25 Scott Dalgleish mounted an EGT probe in each cylinder head exhaust port on his '98 12 valve truck. He was comparing the OE intake to the Banks TwinRam. He says that the engine was run at a constant RPM. What RPM is not stated. It must be up there. Here were his findings in degrees F:



Banks TwinRam:



Cylinder # 1-1264°

# 2-1248°

# 3-1216°

# 4-1216°

# 5-1248°

# 6-1216°



Stock:



Cylinder # 1-1296°

# 2-1272°

# 3-1216°

# 4-1248°

# 5-1264°

# 6-1232°



... ... The test results indicate that the stock setup has an 80° difference between the high & low cylinder temperatures. The TwinRam shows only 48° between the high and low, a decrease of roughly 60% in temperature differential. Morever, note that three of the cylinders are operating at 1216°, two at 1248°. Cylinder number one continues to slightly hotter (1264°) due to an accessory casting in the port of the head which causes a restriction of air flow to that cylinder... ... .....

__________________

 

[HBrunton]

look ok to me. if you had a bad injector or cylinder that was not firing completley or not at all, you would see a much more drastic difference in readings. also when trying to trace down which cylinder it is better to shoot the exhaust manifold as close to the cylinder head as possible rather than the cylinder head itself. Does your heat gun have the laser pointer on it, This feature can be of a great benifit in some confined spaces, not really a necessity but a handy feature to have. typically the middle cylinders tend to show a little warmer when shooting them with a heat gun. again, it is when you can see upwards of 75-100 degrees difference when you should start to be alarmed. try and shoot each port in the same spot if at all possible. play around with it, loosen a injector line and then shoot it and you will see. have fun .....

 

[Gary - K7GLD]

look ok to me. if you had a bad injector or cylinder that was not firing completley or not at all, you would see a much more drastic difference in readings. also when trying to trace down which cylinder it is better to shoot the exhaust manifold as close to the cylinder head as possible rather than the cylinder head itself. Does your heat gun have the laser pointer on it, This feature can be of a great benifit in some confined spaces, not really a necessity but a handy feature to have. typically the middle cylinders tend to show a little warmer when shooting them with a heat gun. again, it is when you can see upwards of 75-100 degrees difference when you should start to be alarmed. try and shoot each port in the same spot if at all possible. play around with it, loosen a injector line and then shoot it and you will see. have fun .....

YUP - I just got a temp gun yesterday, and did the same temp test down the head/exhaust manifold. As long as I shot the temp right on the exhaust manifold flanges at the head, temps ran +- 210 degrees all down the line - but varied more if I went further out the exhaust runners - and yeah, the center runners in that scenario were hotter...