using an Infrared TEMP gun to tune and test



using an Infrared TEMP gun to tune and test

Postby bob » March 3rd, 2009, 9:45 pm

grumpyvette turned me onto use of this tool, and now that Ive gooten used to using it I can,t believe I every tried to tune an engine without one.

I use the same tool that grumpyvette uses, (after seeing how well his works)

Image

http://www.professionalequipment.com/ex ... ermometer/

http://us.fluke.com/usen/Products/Fluke+568+566.htm

now if youve never used one let me give you an example

WHERE to point it

ok I usually point it at the top of the headers at the point just off the exhaust port about 1/2" from the cylinder heads

what to look for

basically temp differences between cylinders, but keep in mind the front two cylinders generally run a bit cooler due to the airflow from the radiator air cooling the front header tubes, and the rear two cylinders tend to run a bit hotter because of a lack of airflow while its sitting in your driveway or shop,naturally, how high the idle speed is set, the engines displacement, compression ratio, and how the injectors or carb is adjusted and how they are working and fuel pressure etc.and other factors will vary the temp, your not looking for a standard temp. on the headers as much as that tell tail variation between the cylinders temp indicating theres something different occurring.

BTW this info below and its sub links may help also

viewtopic.php?f=80&t=728&p=4775&hilit=+sensor#p4775

viewtopic.php?f=50&t=383&p=2301&hilit=+gauge+vacuum#p2301

Image
vacuum gauges must be connected to manifold vacuum

TAKE NOTES

the tool has a lazer pointer so you can be consistent at where you point the sensors on the tool, grumpys got a small sheet of 3/4" plywood about 12" long and 6" wide with four holes drilled on each of the two longer edges and the fronts marked FRONT, the rears marked REAR and the other two sides are marked drivers and pass , the holes are about 1/2" and spaced about 2" apart ,allowing you to drop in the upper porcelain spark plug where the wires normally connect so the threaded section that goes into the heads is held up easy to see, theres a 1-3-5-7 on the drivers side and a 2-4-6-8 written, neatly in majestic marker and a clip for holding a 3"x6" note pad on the center., there a large magnet on the back covered with a thin layer of old inner tube so the board will stick to most air cleaners easily without leaving marks.

ALWAYS HELPS TO HAVE A SHOP MANUAL
viewtopic.php?f=80&t=728&p=8392&hilit=sensor+location#p8392
process

my buddy comes by and says his 440 road runners just not running as well as it should, I use the infrared gun and a spark plug socket and a ratchet, etc to pull the plugs and look at the plugs after it cools but before that I had him run the car around the block and we popped the hood and I took temp measurements , they gave me a good idea as to why the engine was not running correctly, the whole drivers side was running in the 670F-720F range, the pass side ran from 380F on the front cylinder to 912F on the rear cylinder.
checking for vacuum leaks I located a loose rubber vacuum line and after adjusting the carb it was rather obvious that the fuel distribution needed work.
I called grumpyvette and he suggested I pull the plugs and inspect them after the engine cooled down.
the front pass cylinder looked rather wet/black, the rear pass looked clear almost white, most of the rest looked rather dry/tan in appearance, testing with a v.o.m. revealed a bad high resistance plug wire on the front pass cylinder, and the rear pass cylinder port had a connection to the open vacuum line mentioned earlier.
after correcting the problems most of the cylinders ran in the 800f range

knowing there was a huge difference in exhaust temps helps point you in the correct direction and saves a good deal of testing and random parts swapping that used to go on when I was basically guessing most of the time!
Last edited by bob on March 4th, 2009, 8:05 am, edited 1 time in total.
bob

 

Re: using an Infrared TEMP gun to tune and test

Postby grumpyvette » March 3rd, 2009, 10:26 pm

leon posted this bit of info
"Exhaust gas temperature (EGT) depends on combustion temperatures. The hotter the mixture burns inside the cylinder, the hotter it will be coming out. Theoretically, combustion temperatures are at a maximum at stoichiometric, but realistically the maximum occurs slightly rich from peak because of the dissociation of Oxygen from the combustion products (CO2, H2O). Why temperature drops when rich or lean is described by the energy released caused by the chemical reactions between the fuel and air. Too little fuel (lean) and there is less energy contained within and more heat is transferred to the cylinder walls (no fuel evaporation or boundary layer), thus the lower temperature when it burns. Too much fuel, and combustion efficiency drops thus generating less heat.

I know, this is not too detailed, but it gets the point across without involving too much technical jargon.

Of course, this all assumes MBT timing and stable combustion. You can also change exhaust temps by varying spark timing, arguably more so than by just varying AFR. EGT is increased when spark timing is retarded since you are giving the gasses in the cylinder less time to cool off before the exhaust valve opens. "


thanks for posting, that.

BTW these threads might be useful

viewtopic.php?f=50&t=1853&p=4848#p4848

viewtopic.php?f=62&t=953&p=1638&hilit=sparkplug#p1638

viewtopic.php?f=62&t=882&p=1390&hilit=propane#p1390

viewtopic.php?f=44&t=773

viewtopic.php?f=80&t=728&p=4775&hilit=+sensor#p4775
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

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