EGT question?

djpast · 02-17-2005, 04:37 PM

ok, simple question. are the egts on a 100% stock exhaust the same as a 2.5" or 3" turboback exhaust??

lambertvr4 · 02-17-2005, 05:37 PM

I don't have first hand knowledge of that comparison.

I have seen that EGTs drop with a reduction of exhaust pressure (post turbo). If there is a great deal of exhaust pressure that can be reduced by a larger exhaust the EGTs will drop significantly. EGTs can be dropped even more with proper tuning on the "new" exhaust.

markgholland · 02-18-2005, 03:37 PM

Another easy question, why do you care?

EGT's(on turbo cars) are about as useless as an internet website blocker trying to stop a perverted 16-year-old.

~Mark

Spoolin98 · 02-18-2005, 03:41 PM

Quote:

Originally Posted by markgholland

Another easy question, why do you care?

EGT's(on turbo cars) are about as useless as an internet website blocker trying to stop a perverted 16-year-old.

~Mark

Since when are EGT's useless on turbo cars?

markgholland · 02-18-2005, 04:11 PM

Quote:

Originally Posted by Spoolin98

Since when are EGT's useless on turbo cars?

I used to care about them, but then I did some searching and found out exactly what "high" EGT's represent... pulled timing. Nothing a logger can't see. If I see more than 3 "counts" of knock on a logger, I know I have a problem. I don't need to look at a gauge that is telling me in a vauge way that I am knocking.

I mean, I guess they are fun to look at

Regards!
~Mark

TurboGraphX · 02-19-2005, 04:41 PM

.....I used to care about them, but then I did some searching and found out exactly what "high" EGT's represent... pulled timing. Nothing a logger can't see. If I see more than 3 "counts" of knock on a logger, I know I have a problem. I don't need to look at a gauge that is telling me in a vauge way that I am knocking.

I mean, I guess they are fun to look at.....

And if you think that "retarded timing" is the only thing that causes high EGTs, then do yourself a favor and....
1) park your car.
2) put a sign on it that says "free to good home".
3) throw away the tinker toy tools that you have.
4) get a cheap bike for your mode of transportation.
5) STOP POSTING INCORRECT INFORMATION ON THE WEB BOARDS!

Pulled timing "can" give you high EGTs, but it would have to be pulled WAY back!
High EGTs are usually (read that as 98% of the time) caused by too lean of an air/fuel mixture. Do you know any thing about the combustion process? I bet you are also thinking that the more fuel you give an engine, the faster it will run. WRONG!
You see, the fuel that you put into your car will only burn at a set temperature. This means, that so long as nothing else changes, you can add fuel and add fuel and it will not get any hotter. (gasoline burns at a set temperature. simple science) Now, when you add oxygen to that fuel, that in turn, makes the gasoline burn hotter. Oxygen also burns at a set temperature. BUT, if you play with the mixture of air to fuel ratio, you can raise the temp hella high or drop it hella low.
In short.... you need to see if you are burning too much air. (lean) Or if you are burning too much Fuel. (rich)
In a nut shell.... the gauge can be VERY important in tuning.
Ken

Spoolin98 · 02-19-2005, 05:50 PM

Its about time someone ripped this guy a new A$$ for his comment on EGT's being worthless. I agree with the above poster, stop posting wrong information, if you dont know what your talking about, dont post anything at all.

markgholland · 02-19-2005, 09:30 PM

Quote:

Originally Posted by TurboGraphX

.....I used to care about them, but then I did some searching and found out exactly what "high" EGT's represent... pulled timing. Nothing a logger can't see. If I see more than 3 "counts" of knock on a logger, I know I have a problem. I don't need to look at a gauge that is telling me in a vauge way that I am knocking.

I mean, I guess they are fun to look at.....

And if you think that "retarded timing" is the only thing that causes high EGTs, then do yourself a favor and....
1) park your car.
2) put a sign on it that says "free to good home".
3) throw away the tinker toy tools that you have.
4) get a cheap bike for your mode of transportation.
5) STOP POSTING INCORRECT INFORMATION ON THE WEB BOARDS!

Pulled timing "can" give you high EGTs, but it would have to be pulled WAY back!
High EGTs are usually (read that as 98% of the time) caused by too lean of an air/fuel mixture. Do you know any thing about the combustion process? I bet you are also thinking that the more fuel you give an engine, the faster it will run. WRONG!
You see, the fuel that you put into your car will only burn at a set temperature. This means, that so long as nothing else changes, you can add fuel and add fuel and it will not get any hotter. (gasoline burns at a set temperature. simple science) Now, when you add oxygen to that fuel, that in turn, makes the gasoline burn hotter. Oxygen also burns at a set temperature. BUT, if you play with the mixture of air to fuel ratio, you can raise the temp hella high or drop it hella low.
In short.... you need to see if you are burning too much air. (lean) Or if you are burning too much Fuel. (rich)
In a nut shell.... the gauge can be VERY important in tuning.
Ken

You must be pretty clever, however, you forgot to quote where I said that it the only thing they are good for. I know damn well high EGT's can also represent a lean condition. Are you challenging my knowledge of the combustion process? I laugh at such a comment. PM me if you care to continue this conversation...

Do you have a knock sensor in your N/T? Last I knew, nope, sure don't. I stated that, in Laymen's Teams (that's for idiots), if you have the ability to see knock and timing retard, depending on the ECU, you DON'T NEED AN EGT GAUGE.

Like I said, PM me if you care to continue to argue with me.

Regards!
~Mark

TurboGraphX · 02-20-2005, 07:25 AM

And a knock sensor and a logger to see pulled timing tells you what about the mixture that you are running? answer: not as much as a good wideband and a EGT will.
The EGT gauge is still the best way to see how rich or lean you are running. (other than maybe a wideband o2 sensor.)
I understand your point... it is nice to be able to see if your timing is being pulled... but it is much better to see what kind of mixture you are running so you can tune it.
As for the knock sensor, actually yes... I DO have one on my N/T. Why you may ask, well.. because when running 13.5:1 compression, I have the same problem as you with the turbo.... The engine tends to detonate, so we use the knock sensor to see that as-well.
There is alot more to tunning than just watching your knock counts. Besides, you can run 1550 EGTs and have zero knock. What are you going to do then? (other than melt your engine)
Regards.
Ken

gsx951 · 02-20-2005, 08:01 AM

[quote=TurboGraphX Besides, you can run 1550 EGTs and have zero knock. What are you going to do then? (other than melt your engine)
Regards.
Ken[/QUOTE]

Man I hope I can run 1.550 with no knock.

djpast · 02-20-2005, 05:57 PM

[quote=gsx951]

Quote:

Originally Posted by TurboGraphX Besides, you can run 1550 EGTs and have zero knock. What are you going to do then? (other than melt your engine)
Regards.
Ken[/QUOTE

Man I hope I can run 1.550 with no knock.

uhh you can run alot hotter then that with no knock. a i have seen well tuned engines go past 1650 without a single count of knock.

sojmisa · 02-21-2005, 05:06 AM

Also to my understanding, egt's are used to monitor the turbo itself to make sure it doesn't get to hot & burn up.
as for the original question---with increased flow(exhaust) it is very feasible to see a lower egt as long as other varibles stay the same, however more exhaust flow means more spoolage, more spoolage means more heat, unless there is more fuel to cool it. So if you are looking for a yes or no answer, than NO.

sojmisa · 02-21-2005, 01:16 PM

I should say no, not nessacerily.

gsx951 · 02-21-2005, 02:22 PM

Quote:

Originally Posted by djpast

uhh you can run alot hotter then that with no knock. a i have seen well tuned engines go past 1650 without a single count of knock.

I was kidding. These EGT threads provide comic relief and I was playing along.

750_sport · 02-22-2005, 12:03 AM

Wow this was a crazy thread.

I would pick a gauge over a stand alone anytime. When I am playing. I like to glance over something with good info.I like to spend my thoughts on driving.....

I dont have time to plug in and drive at the same time. sounds like you drive a green eclipes from F&F.....

I had my twincharged car run to 950*c before it burned up. I didnt read the fine print on the guage, It was 950*C not 950*F ........ Never knocked before it tossed a melted piston. A EGT and a Wideband will out tune a stand alone with a laptop computer. I dont remember seening a Stand Alone and a Laptop only at the dyno the last time I was there... Oh wait that was today and the day before....and the day before that.....

gsx951 · 02-22-2005, 03:40 AM

Quote:

Originally Posted by 750_sport

Wow this was a crazy thread.

I would pick a gauge over a stand alone anytime. When I am playing. I like to glance over something with good info.I like to spend my thoughts on driving.....

I dont have time to plug in and drive at the same time. sounds like you drive a green eclipes from F&F.....

I had my twincharged car run to 950*c before it burned up. I didnt read the fine print on the guage, It was 950*C not 950*F ........ Never knocked before it tossed a melted piston. A EGT and a Wideband will out tune a stand alone with a laptop computer. I dont remember seening a Stand Alone and a Laptop only at the dyno the last time I was there... Oh wait that was today and the day before....and the day before that.....

It knocked like hell. You're lost and it cost you a motor.

750_sport · 02-22-2005, 10:15 AM

The learning curve of a twincharged aw11.

Thats supercharged and turbocharged. I have no lag on the bigger turbo. As the Supercharger is boosting in the lag time. That whole car is a nightmare. We toasted a motor on the way to the dyno as well. Car has 68k miles for a 1987. Been though 6 motors. In that time. I am now underway in building my last motor(#7).

But when the car runs, It hooks up and gets out of town like bat out of hell...

The fine line of the tuning curve, S/C runs out at 14 psi at 3950 rpm. The turbo has spooled up by then and a bypass valve opens up and reroutes air past the S/C to the I.C.
The turbo then goes on to 21psi.
Then the magnatic clutch on the stock S/C turns off and freewheels the S/C

Tuning can get out of hand quick........

I am new to the DSM but have 15 years of building and tuning. This should be fun playing with my new car!
Oh well enough of me ...... Back To work.. I have a few bikes to build!

bjones18 · 05-19-2005, 09:38 PM

[/quote]Pulled timing "can" give you high EGTs, .........(gasoline burns at a set temperature. simple science)...... Oxygen also burns at a set temperature.
Ken[/quote]

Simple science, Fuel does not burn, nor does oxygen. Combustion is a chemical reaction between hydrocarbons (gasoline ) and oxygen. Heat is the result of Chemical bonds being "released." The molecules break apart into tiny-tiny-tiny cabon, oxygen, and hydrogen atoms which collect into smaller molecules (CO2 & H2O) which "own" a lower chemical-energy-state as they exit your exhaust valve.

Gas, Nitro glycerine and gun powder have LOTS of Chemical energy waiting to be released.

Byproducts of this chemical reaction are water and carbon dioxide (perfect -Stoichiometric - combustion). Stoichiometric means the A/F ratio is perfect, and 100% of those little molecules find reaction partners. This is statistically impossible, and is the primary focus of combustion chamber research (improving combustion chamber efficiency...swirl, flame-front propigation, etc)

LEAN or Fuel-starved combustion means almost every little vaporized hydrocarbon EXPELS energy as it is converted to CO2 + H2O. HOT HOT HOT.

RICH or O2-starved combustion has extra mass (fuel) in the combustion chamber. As the other hydrocarbons EXPLODE (or release energy) the un-reacted fuel-mass soaks up this heat-energy thus reducing the combustion temperature. The unburned fuel (with it's soaked up energy) floats out the exhaust.

As combustion efficiency increases, so do temperatures. At very high combustion temperatures, other chemical reactions start taking place....Nitrogen and others.... This is the reason for catalytic converters, which catalyze reaction these un-wanted combustion byproducts to less harmfull emissions.