Temps
- Thread starter mike97760
- Start date
H&H Racing
Member
1200-1350 degrees depending on the location of the sensor.
alvin l nunley
Site Supporter
You want to run the EGT at the highest temperature you can get. That sounds crazy, but that's how EGT's work. The hotter the burn, the more the air expands, the more torque you get. It takes a little getting used to if you've only run a CHT. Exactly what temperature to look for, it depends on the position of your probe, so I can't give you an exact number.
Run the engine a little rich compared to where you normally run it. See what kind of readings you get. Then you want to lean the carburetor down a little and check again. If you go to lean, the EGT readings will be lower. When you get too lean, you get detonation, and that lowers the exhaust gas temperature. If you're out running and the EGT is reading fairly consistently, and after a few laps it starts to go down, that means the engine has leaned out. Engines will do that when they get hot. The EGT is not like the CHT, you can't get it too hot. If the mixture burns too hot, you get detonation, that lowers the EGT temp.
Caution; if in the first heat the temp was say 1100 and in the second heat it was only 1000, that could mean one of two things. It could mean the ambient conditions have changed enough to lean engine out, another reason for watching the air density. And just the opposite could be true, if the air density goes down, you could be rich. It's a little more complicated than a CHT, but after you get used to it, you're going to be faster.
I have a lot of experience with the EGT, and even if you don't think I know, at least try what I'm saying.
Run the engine a little rich compared to where you normally run it. See what kind of readings you get. Then you want to lean the carburetor down a little and check again. If you go to lean, the EGT readings will be lower. When you get too lean, you get detonation, and that lowers the exhaust gas temperature. If you're out running and the EGT is reading fairly consistently, and after a few laps it starts to go down, that means the engine has leaned out. Engines will do that when they get hot. The EGT is not like the CHT, you can't get it too hot. If the mixture burns too hot, you get detonation, that lowers the EGT temp.
Caution; if in the first heat the temp was say 1100 and in the second heat it was only 1000, that could mean one of two things. It could mean the ambient conditions have changed enough to lean engine out, another reason for watching the air density. And just the opposite could be true, if the air density goes down, you could be rich. It's a little more complicated than a CHT, but after you get used to it, you're going to be faster.
I have a lot of experience with the EGT, and even if you don't think I know, at least try what I'm saying.
Nobody uses EGT as far as I know with these engines, CHT is what most are using and it goes under the spark plug. That is what the temps I gave were based on, I couldn't tell you about EGT, I dont mess with it and have never needed to honestly, our predators are winning races everywhere we take them only using CHT to tune them.
alvin l nunley
Site Supporter
Nobody uses them so they must be bad, right? You've never used them and have won a lot of races, so they must be useless, right?
I won a lot of races and never used one.
I've crewed for a couple of young guys, taught them how to use the EGT, and they won a lot of races. Dare I say, they dominated in their respective classes.
I find it hard to believe that someone could say that something is not necessary, even though they've never tried it.
I saw a TV show about building the top racing karts in Europe. Interestingly, every kart that left the factory had an EGT on it. I have to believe they know what they're doing and wouldn't incur that expense unless they felt it necessary.
I've been preaching this stuff, air density, EGT, compression pressure and other stuff for years and have made no inroads that I know of. I will not give up!
H&H Racing
Member
Like Al said. Tune it for the highest reading you get with out it dropping of after it peeks. Low exhaust temp=rich. Exhaust temp that climbs then peeks and then starts to drop =lean Now all of this is with the motor under load and not on the stand. I like looking at exhaust temps but many of the 4cycle racers don't use it as I don't think most understand it.
EGT gives immediate accurate data on the state of combustion, CHT is an indication of how hot the external metal is at and around the spark plug. The area under the plug is slow to heat up, slow to cool down does not accurately indicate combustion, it simply shows how well the engine is dissipating the heat. If you have it and can use it EGT and even better a lambda(o2) sensor will give you usable information.
That and most stock class rules do not allow exhaust pipes to have tap for egt probe.
Great explanation of how to use it though.
Egt is not allowed to be used on the track under the rules most tracks use Al, that is why we usually don't see them. I never said one was better then the other, but Cht is allowed, which is why we use it. Egt can be used on the dyno or at practice days or whatever just not in a race, and would require changing pipes to use it also
silverback
Member
My Egt sensor only requires an 1/8 inch hole in the header. The hole can be covered with a hose clamp when not being used.
Jim
alvin l nunley
Site Supporter
That's got me wondering, why would they make an EGT illegal? What could be the reasoning behind that decision? Any guesses?
I have a guess, could it be that, with an EGT, you have an unfair advantage? I've been in karting for a long time, and I've seen many totally illogical decisions and rules, is this just another one of those?
The rule came about at a time when guys were working with venturi effects in the exhaust. At one time, air was allowed in pipe to speed flow.
alvin l nunley
Site Supporter
Thank you for that. I don't get the connection. But there's a lot of things I don't get.
I'm curious, what is this venture effect?
Never got to see it. Heard stories about curious pipes at non sanctioned events. I'm sure someone on here can explain it better than me.