Can someone start me off in the right direction as to what causes high EGT's and what you can do to keep them low and also what temps are good and what are bad?
I have now got a EGT gauge but dont know what temps i should be looking for really and know there are some very knowledgeable people on here.
All feedback welcome.
Cheers.
EGT's
Scott put a lot of info in here:
http://www.bigpower.co.uk/forum/viewtopic.php?t=982
Hope that helps
http://www.bigpower.co.uk/forum/viewtopic.php?t=982
Hope that helps
It really does depend on the car, and the position of the sensor.
The Rover V8 I was doing some map calibration on was showing ~420degC at low and medium loads. jumping up instantly to ~650degC at Wide Open Throttle (WOT)
The Clio 16v seemed to sit in the 500-600 degree range.
I've talked to other developers who've seen ~1050degC with high boost and good AFR (max power ~0.85 lambda)
Assuming perfect AFR, EGTs rise with retarded ingnition and drop as they start towards MBT.
Assuming perfect Ignition EGTs will be lower below stoichometric (lambda 1.0 - 14.7:1 gasoline) rise to a peak above stoich, and fall off rapidly to the point of lean misfire.
All good in theory but how does this help you?
Well first off we need to know where you're starting from and what control you have over your setup - are you running an aftermarket system or are you using a boost controller or something else?
Can you put your control system close to standard so that you can establish a baseline EGT temperature?
The Rover V8 I was doing some map calibration on was showing ~420degC at low and medium loads. jumping up instantly to ~650degC at Wide Open Throttle (WOT)
The Clio 16v seemed to sit in the 500-600 degree range.
I've talked to other developers who've seen ~1050degC with high boost and good AFR (max power ~0.85 lambda)
Assuming perfect AFR, EGTs rise with retarded ingnition and drop as they start towards MBT.
Assuming perfect Ignition EGTs will be lower below stoichometric (lambda 1.0 - 14.7:1 gasoline) rise to a peak above stoich, and fall off rapidly to the point of lean misfire.
All good in theory but how does this help you?
Well first off we need to know where you're starting from and what control you have over your setup - are you running an aftermarket system or are you using a boost controller or something else?
Can you put your control system close to standard so that you can establish a baseline EGT temperature?
You wont be able to tune with or rely on the egt readings unless you can fully load up the engine ( to max the egts )
I am not sure of your engine parameters but i would be surprised to see 1000 deg C on anything short of a full blown race car.
Best place is to put the K type before the turbo but you need to be aware of the cylinder distribution in the manifold. ie you could get a toasty cylinder and not be aware of it. I would stay away from tuning to the edge using egts as they can rise very quickly.
You will need a good amount of exhaust temp to get a correct spool etc.
Usually i tune egts up to gear shift ( where i set my max )
They can do some odd things and i takes a bit of instinct and experiance to predict things. ie you can sometimes drop you egts by doing the opposite to what you would expect ( this is not exclusive )
Scott
I am not sure of your engine parameters but i would be surprised to see 1000 deg C on anything short of a full blown race car.
Best place is to put the K type before the turbo but you need to be aware of the cylinder distribution in the manifold. ie you could get a toasty cylinder and not be aware of it. I would stay away from tuning to the edge using egts as they can rise very quickly.
You will need a good amount of exhaust temp to get a correct spool etc.
Usually i tune egts up to gear shift ( where i set my max )
They can do some odd things and i takes a bit of instinct and experiance to predict things. ie you can sometimes drop you egts by doing the opposite to what you would expect ( this is not exclusive )
Scott
"You think you have a limit, As soon you touch this limit, something happens to you; suddenly you can go a little bit further. With your mind power, your determination, your instinct and your experience as well, you can fly very high."
It is a function of everything that is going on during the combustion process, including when and how it got started. It is used along with an oxygen sensor to quickly get into the "sweet spot" power wise, where the best performance for that time and day may be recovered.
Since it is the end result of a bunch of inputs it changes with air temp, density, pressure and ignition advance, split if any, RPM and of course mixture. If there is a turbo involved, then turbine inlet temp, or TIT. My favorite temperature.
So once you have such a gage, how do you tune with it?
Can you tune at all? You must have a carb or if injected, a method of controlling the mixture at points along the RPM range. I would limit this tuning to full throttle tuning only where you show off the equipment.
EGT equipment is of little value in the part throttle situation. There is just very little information to be recovered. The first thing you notice is that the gage goes up and down just like the tachometer. And just as fast. So, you need help with data recovery. A friend to watch the gage for you, and, or, a movie camera to record EGT and tach at the same time. In the race car .
You can run up the revs to whatever the test RPM is, say in third gear, and left foot brake to hold that RPM for a second at full throttle. It may be that this will upset the car so badly as to make it dangerous, so tune it on a dyno if at all possible, or with the camera idea.
I have been instructed by a world famous engine builder that NA readings above 1600 degrees are not usefull for long term reliabillity. So I don't do that. There are some who go well above that and the apex seals are fine, and then one day the engine goes soft with a warpped seal, and then who do you call?
Don't call me. I told you not to do that.
Here are some example numbers from a NA 12A with bridgeports and a free flowing exhaust. Note the relationship between EGT and mixture ratios.
6500 173.3 HP 1515 front 1491 rear A/F 12.3
7000 196.9 HP 1518 front 1489 rear A/F 12.0
7500 218.2 HP 1517 front 1494 rear A/F 12.1
8000 233.9 HP 1522 front 1511 rear A/F 12.6
8500 239.2 HP 1543 front 1540 rear A/F 13.0
9000 241.9 HP 1583 front 1578 rear A/F 13.2 BSFC .662 oil temp 167 oil pressure 105. Timing is 25 degrees.
And this is with a carb! Note the A/F for each EGT. Note that the carb is going lean at the top, where injection should be dead on the tune all through the range around 12.7 or so, or whatever your builder wants you to run. Remember if you premix, leaning is removing top oil as well. Note also how low the EGTs for best power are.
Changing timing, mixture, RPM, air temp and whats in the glove box will change EGT. Just so you know, best power is just rich of peak EGT. And that can be real hot maybe 1800 degrees. It can also melt an apex seal and or detonate a turbo engine. I am always shooting for less than 1600 just before the driver shifts.
Peak power is 245 HP at 9,400 RPM.
Since it is the end result of a bunch of inputs it changes with air temp, density, pressure and ignition advance, split if any, RPM and of course mixture. If there is a turbo involved, then turbine inlet temp, or TIT. My favorite temperature.
So once you have such a gage, how do you tune with it?
Can you tune at all? You must have a carb or if injected, a method of controlling the mixture at points along the RPM range. I would limit this tuning to full throttle tuning only where you show off the equipment.
EGT equipment is of little value in the part throttle situation. There is just very little information to be recovered. The first thing you notice is that the gage goes up and down just like the tachometer. And just as fast. So, you need help with data recovery. A friend to watch the gage for you, and, or, a movie camera to record EGT and tach at the same time. In the race car .
You can run up the revs to whatever the test RPM is, say in third gear, and left foot brake to hold that RPM for a second at full throttle. It may be that this will upset the car so badly as to make it dangerous, so tune it on a dyno if at all possible, or with the camera idea.
I have been instructed by a world famous engine builder that NA readings above 1600 degrees are not usefull for long term reliabillity. So I don't do that. There are some who go well above that and the apex seals are fine, and then one day the engine goes soft with a warpped seal, and then who do you call?
Don't call me. I told you not to do that.
Here are some example numbers from a NA 12A with bridgeports and a free flowing exhaust. Note the relationship between EGT and mixture ratios.
6500 173.3 HP 1515 front 1491 rear A/F 12.3
7000 196.9 HP 1518 front 1489 rear A/F 12.0
7500 218.2 HP 1517 front 1494 rear A/F 12.1
8000 233.9 HP 1522 front 1511 rear A/F 12.6
8500 239.2 HP 1543 front 1540 rear A/F 13.0
9000 241.9 HP 1583 front 1578 rear A/F 13.2 BSFC .662 oil temp 167 oil pressure 105. Timing is 25 degrees.
And this is with a carb! Note the A/F for each EGT. Note that the carb is going lean at the top, where injection should be dead on the tune all through the range around 12.7 or so, or whatever your builder wants you to run. Remember if you premix, leaning is removing top oil as well. Note also how low the EGTs for best power are.
Changing timing, mixture, RPM, air temp and whats in the glove box will change EGT. Just so you know, best power is just rich of peak EGT. And that can be real hot maybe 1800 degrees. It can also melt an apex seal and or detonate a turbo engine. I am always shooting for less than 1600 just before the driver shifts.
Peak power is 245 HP at 9,400 RPM.
"You think you have a limit, As soon you touch this limit, something happens to you; suddenly you can go a little bit further. With your mind power, your determination, your instinct and your experience as well, you can fly very high."
Posted here with the kind permission of it original Author:
The graph shows the drop in efficiency and rise in EGT through retarding the ingition from MBT (Minimum best torque) timing assuming that the other factors in your engine (AFR, RPM, Load) remain constant. There are no values shown because these change across different installations.
BLD is Border Line Detonation.
The graph shows the drop in efficiency and rise in EGT through retarding the ingition from MBT (Minimum best torque) timing assuming that the other factors in your engine (AFR, RPM, Load) remain constant. There are no values shown because these change across different installations.
BLD is Border Line Detonation.
Thats a nice representation of egt and how it realtes to spark advance.
What i think you will now find is doors will start to close in front of you. You need to decide how this realtes to your specific set up. That is something the main tuners will have a good idea of. But the people at the top wont want to share this info. I found that timing advance to be a very close gaurded secret and is seldom discussed.
e.g.The exact in's and out's of my map's remain my secret. How the fuel map helps the timing map and vice versea is not something i talk about.
You will just need to preceed as cautiously as you can but at the same time always have a goal for each session i can howeva add my egts in the hope that others will follow to give you some guidance
Idle 200-300 deg C
Idle after a hard run 400 deg C
Cruise 722 deg C
WOT at shift point 7500 rpm ish 805 deg C
These are all post turbo so add 200-300 deg for port temps.
AS said before egt is only a useful tool under load.
Scott
What i think you will now find is doors will start to close in front of you. You need to decide how this realtes to your specific set up. That is something the main tuners will have a good idea of. But the people at the top wont want to share this info. I found that timing advance to be a very close gaurded secret and is seldom discussed.
e.g.The exact in's and out's of my map's remain my secret. How the fuel map helps the timing map and vice versea is not something i talk about.
You will just need to preceed as cautiously as you can but at the same time always have a goal for each session i can howeva add my egts in the hope that others will follow to give you some guidance
Idle 200-300 deg C
Idle after a hard run 400 deg C
Cruise 722 deg C
WOT at shift point 7500 rpm ish 805 deg C
These are all post turbo so add 200-300 deg for port temps.
AS said before egt is only a useful tool under load.
Scott
"You think you have a limit, As soon you touch this limit, something happens to you; suddenly you can go a little bit further. With your mind power, your determination, your instinct and your experience as well, you can fly very high."