i was a jet engine mechanic in the air force in the 1960's, we used pyrometers to moniter egt. also in diesel truck and industrial engines. why not moniter egt for gasoline engines ?
There are plenty of examples of monitoring EGT in gasoline engines, but I think the problem for tuning with it is that it isn't completely reliable on its own. Changing the ignition advance can make a huge change to the EGT. Is the EGT too high because your ignition is off, or because the carb needs adjusting? I would think that monitoring EGT is more useful as a warning system, you have a fully tuned high performance engine and know that some specific temperature is the normal max temp, if the EGT starts going up above that you know there's an issue to handle before it goes all the way into meltdown mode - i.e. get off the throttle and check why it's suddenly running (probably) lean.
Before the days of O2 sensors and digital air fuel meters, our dyno had 8 EGT's to monitor mixtures and fuel distribution. Unless you have an individual A/F meter for each cylinder, you don't know much about distribution. When the first A/F meters were $1300, we got one. And still used the EGT's for checking individual cylinders.
My turbines have EGT on all of them, warning at 870F, shutdown at 950F. With a continuous source of combustion there's no timing and all sources of increase in EGT are known: load and airflow restriction/fuel increase. Fuel should only increase with load. You expect the EGT to rise with load, but if it's due to airflow restriction that'll be bad and the numbers go out of sight quickly. My turbines don't have concerns with thinning air due to al***ude - these will never leave the ground. I've got a whole bunch of Solar Saturn's and three NATCo's. Fun machines to work on!
In-situ egt monitoring for the hot rod to what benefit...it will take away from time to watch and text on your phone I do know of a Bonneville record holder that monitors all eight to help determine why everything came undone because a momentary excursion in the wrong direction is usually very unforgiving He monitors and trends many data points....once you have the data, you need to ****yze it and apply in a meaningful manner a sanity check with an infrared camera is what I use when doing my tuning...but then again, I don't have a bizillion dollars in my engine and am not going after any records.......besides, I don't want to take away from my phone time
Crewed on a 1/4 mile drag car that used them for a short while. The issue that we ran into was the raw data wasn't easily relatable to tuning. I don't know if it was a steep learning curve we didn't hurdle, the temps changing over the run or other issues. This was not a high dollar top of the line deal, so that may have been part of it too. Pulling the plugs showed one thing, the temps something different. Lots of times, the temps were high enough to be scary. You could get the car to run well and color the plugs evenly, but the temps were uneven. So after getting what seemed to be alarming, garbage data, it was ignored. The probes made some servicing more difficult, so the system was removed. Overall, the owner fell back on other experience and felt it had been a failed experiment. This is not an indictment of EGTs just one experience data point.
My dyno had one for each cylinder, we knew what was a normal range to be in and looked at cylinder to cylinder for consistency but used brake specific fuel consumption and plug reading for tuning. It was just another tool in the bag of tricks. It made locating a skip easier.
I'm always looking for more gauges to add to me engine test stand. I think I'll get one one these and weld in a bung on the exhaust stub on each side.
EGT gauges were not unusual to install on 2-stroke motorcycles. The piston is fuel cooled, so modified engines are often run excessively rich to avoid seizing. EGT monitoring allows finding the ragged edge of best power vs seizure.
Its complicated. O2 sensors measure thermal conductivity not absolute temperature. Exhaust temperature in a gasoline engine can vary because of a number of different factors, including throttle plate position and ignition timing, neither apply to a gas turbine or diesel. Its a different combustion process
Commonly used on general aviation air-cooled piston engines. Pilots like to run them "lean of peak" to save money on fuel and then wonder why they have to shell out so much for a cylinder change due to burnt valves...
In the early 2000s when I was the president of the University of Delaware Formula SAE team, we put thermocouples in each header tube to do fuel mapping. That was on a 610 cc Yamaha R6 with a custom intake fed through a 20mm restrictor, clearly off-topic here. It's certainly not a bad idea as it pertains here, but practically, when using "traditional" equipment, it's tough to address a single cylinder that might be lean with a carburetor and single plenum intake. In the aforementioned application I had the ability to add fuel to a single cylinder by adjusting the parameters on that individual injector from tuning on a laptop. No such luxury with a carb, though it might work better with a multi-carb application.
In our modern foxbody turbo EFI drag cars we use a pyrometer in each primary header tube for EGT monitoring and EFI tuning. In a normal street car a single EGT probe is sufficient if you need that data.
What are those who have used them successfully seeing for temps? Gasoline, Diesel and other? Idle, WOT, cruise? Willing to learn but as I posted, the numbers we saw were not helpful.
In my aforementioned application, the engine was running on 100 octane gas. In our mapping, which was nowhere near as advanced as it is today, we had to set ignition and fuel parameters for all parts of the rpm band and throttle. So we would make dozens of dyno pulls at 10-20-30-40... percent throttle, monitoring horsepower, ignition timing, and fuel. If we saw exhaust temps spike, we knew we needed to add fuel, back off timing, or both. Interestingly, at WOT, the redline on that engine was so high that it would take just about any amount of timing we threw at it. Something like 56 degrees of total timing at 14,500 rpm, though peak power was around 12,500 and with 48ish degrees of timing.
To answer Rods question @wot on race gas in the 1200's was good at idle no load a few hundred at part throttle with some load as in braking in you can manipulate it up and down with throttle and load we were taking readings at the exhaust flange of the head. My opinion is to use an air fuel meter with an oxygen sensor to adjust mixture but it will be only marginally useful on a run in stand no load.
The Jalopy Journal
