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View Full Version : SR guys, what are your avg EGTs?



Brad
10-27-2004, 10:09 PM
tried searching, seems like an easy question but maybe i suck at searching

anyways, what are your guys' avg EGTs and idle, wot and highway cruising (lets say ~3000rpms and 70mph)?

mine are about 4-500 deg C after the car is warm and has been driving around at idle. freeway cruising it is about 690 deg C. used to be about 670 but the safc was advancing my timing and killing my engine so i had to retard it

im just wondering if im normal or what? no SRs around here have an EGT gauge so i cant really compare

knate
10-27-2004, 11:36 PM
If you're going to get any useful info you'll have to post where your probe is. The temperatures are super dependant on where you've put your probe. Just letting you know before people try to give you [censored]. http://forums.freshalloy.com/images/graemlins/smile.gif

a2low240
10-28-2004, 07:07 AM
highway cruising (lets say ~3000rpms and 70mph)?




Mine sits around 900deg F. in this situation. My probe is right behind the turbo outlet into the exhaust.

Enthalpy
10-28-2004, 07:39 AM
EGT's are a waste of time...

arkman0
10-28-2004, 08:01 AM
http://www.arkman.com/afregt.jpg


ALL RIGHT, EGT's are goin down!! i must be running rich!
after this, we can debate on why running pig rich is so much safer!!!

Kim_Jong_Il
10-28-2004, 08:03 AM
EGT's are a waste of time...



You what's funny, you've said that countless times but no one listens...

Enthalpy
10-28-2004, 08:11 AM
EGT's are a waste of time...



You what's funny, you've said that countless times but no one listens...



Some people just want to believe what they have heard even though it is wrong. not much ic an do except keep trying to educate people...

Nikeboy355
10-28-2004, 10:23 AM
I'm curious why... I always thought that when you start to run lean your EGT will go up... after 1000 degrees you need to stop driving the car hard or you will start to melt the internals... please advise...

NOSTALGIC_HERO
10-28-2004, 10:29 AM
after ONE THOUSAND DEGREES... of rotation?

Enthalpy
10-28-2004, 10:50 AM
I'm curious why... I always thought that when you start to run lean your EGT will go up... after 1000 degrees you need to stop driving the car hard or you will start to melt the internals... please advise...




Advice - Figure out who told you that...and from now on NEVER listen to ANYTHING they have to say about cars.

I dont know why EGT's are so mis-understood. there is nothign special or particularly helpful in knowing your EGT's.

THE FOLLOWING INFO IS FOR REFERENCE ONLY...DO NOT ATTEMPT TO TUNE YOUR CAR TO THESE VALUES

Typical EGT readings for a PROPERLY tuned car (air fuel and timing both tuned correctly) should be around 1350-1400F or 725-750C.

...but this is useless info if you do not have complete knowledge of the air fuel ratio AND the ignition advance.

blah blah blah..use the search it's been covered a thousand times.

too little timing = higher EGT
too much timing = Lower EGT
too lean = higher EGT AND lower EGT
too rich = lower EGT AND higher EGT

so go sell your EGT guage and buy a wideband and some dyno time....

Brad
10-28-2004, 11:44 AM
damn i got caught slippin like scott said, someone said "buy it when you get a bigger turbo" so i did. i guess it is a waste, to be honest ive never really used it. just another thing to look at instead of paying attention to the road i guess

i think it would be more work to try to take it out of my exhaust runner and plug the hole than it would be to sell it for the 50 bucks or whatever the used greddys go for. oh well i guess that answers my question on EGTs http://forums.freshalloy.com/images/graemlins/grin.gif

Gladius
10-28-2004, 12:51 PM
I just use my egt gauge to make sure im not melting anything. I have it tapped right where no.1 runner enters the manifold. I guess its good for this aspect.

Enthalpy
10-28-2004, 12:52 PM
why is that? EGT's and combustion temps are not always related!!

besides what are you worried about melting? the manifold? the turbine housing? the turbine wheel?

In reality the only thing that ever usually "melts" pistons is hot spots from detonation. they will not melt purely from the combustion process!

DeatschWerks_Dave
10-29-2004, 06:11 AM
IMO, EGT's aren't useless, they are just "over used" by people. They are definately NOT a replacement for a WBO2. I will soon have both http://forums.freshalloy.com/images/graemlins/grin.gif

Hugh
10-29-2004, 07:47 AM
I don't think we need to be militant in hating on exhaust temp gauges. I use mine to tune my ignition timing because I street tuned without a dyno. I only used it for minor adjustments, as I wrote the initial map according to Enthalpy's instructions on here.

Tweaking the timing to raise or lower my EGT has shown a definite improvement in power and safety of the tune.

If you already have a wideband to tune fuel with, there's nothing wrong with using and EGT gauge for monitoring purposes. I have a great wideband, and I'm not giving up my EGT anytime soon.

cwdmark
10-29-2004, 07:52 AM
imo you need a wideband and egt to be properly tuned. wideband makes sure your air/fuel is safe and egt tells you your timing and is used as a prevention gauge (just like an oil pressure gauge).

lately though i've been hearing a lot of people say that egt gauges are completely useless and all you need is a wideband.

cwdmark
10-29-2004, 07:54 AM
Tweaking the timing to raise or lower my EGT has shown a definite improvement in power and safety of the tune.


what do you tweak the egt's too? 700C, 800C, 900C? right now at full throttle when i hit around 140mph egt's are about 860C and probe is in collector of manifold.

Enthalpy
10-29-2004, 08:24 AM
imo you need a wideband and egt to be properly tuned. wideband makes sure your air/fuel is safe and egt tells you your timing and is used as a prevention gauge (just like an oil pressure gauge).

lately though i've been hearing a lot of people say that egt gauges are completely useless and all you need is a wideband.




Arghhh... This topic kills me. i'm pulling my hair out. proper timing is not determined by EGT's!!! it is determined by analysis of dyno results. ever heard of Minimum timimg for maximum TQ? you set your basemap with conservative timing. tune your AFR's to the level you feel is acceptable for your application. THEN you slowly increse timing until only minimal gains are achieved. this is minimum timing for best TQ (MTBT). Now your car is tuned for WOT. there is no other tweaking of timing based on EGT's necessary. if you are adjustign timing without measuring the resultant change in engien performance you are not doing yourself any good. you see...nowher in this do i discuss EGT's at all. they are irrelivant to the tuning process. EGT's are a BYPRODUCT of combustion...not a detemining factor. why tune a BYPRODUCT...instead of a desired quantity? Your goal in tuning should be to maximise power and reilability not to point tune AFR's. A tuner that does that needs to take an EFI101 class by Ben Stradler.

When are EGT's useful?

if you do not have an onboard wideband then they can be useful for measuring engien changes. once you tune your engine on the dyno for MTBT take the car out on the street and beat the ever living hell out of it. watch what the EGT gauge does. if it ever does anything drastically different then you know you have an issue. however EGT gauges are a slow response devise due to the fact that they utilize a thermocouple that takes time to respond because the sesor has a thermal mass that has to react to the changes in exhasut gas temps before the gauge wil read anything different. plus the turbo manifold has a thermal mass which will absorb heat out of the exhast stream. the amount of heat absorbed depends on the delta T between manifold and Exhaust gas. So you can get varying results.

example...you fuel pump takes a crap on you adn isnt mainting fuel pressure. you don know this becasue the car is runnign fine off boost. you have just warmed the car upa nd decide to take it for a 18 psi pump gas blast down the skreet. you bury the throttle and your engien melts #2 before you know what happens. before the EGT gauge could respond and the manifold could heat up the engien was way lean and detonated the hell out of #2 and melted the piston.

Where were your prescious EGT's then?

We could go on forever...but any tuner worth his salt will agree that EGT's are secondary data that is eniterly unnecssary to tune a performace engien.

If you want to try and disprove me feel fre...i'm always willign to learn.

cwdmark
10-29-2004, 09:01 AM
thank you for the detailed information.. you are obviously a lot smarter than me http://forums.freshalloy.com/images/graemlins/grin.gif

i understood everything you said (i think thats a first, heh). you think that 860C at WOT in 4th is too high, and timing should be retarded? i've got a mines boost up ecu, im not sure how much that is effecting the timing maps. boost seems to come in a little late and the timing might need some adjustment.

scott to set timing, do you pull the valve cover or use a timing light? i pulled the cover before and lined up the dots, but im not sure completely how accurate that is, and it seems i can never find the right procedure to set the timing according to the timing light (the setup procedure-- engine revs, tps, etc.). boost doesn't come as quick as my older car, but im not sure if thats do to the timing or tubular manifold.

Enthalpy
10-29-2004, 09:16 AM
Man,

without knowing what the AFR and timign values in the ECU are there is no way to tell what your EGT's mean. that's why they are of such little value.

you could be at any of these scenarios:

A) proper timing, way too much fuel (creating significant afterburn)

B) proper timing just lean of ideal

C) proper fuel, not enough advance (causing afterburn)

the real solution is to get the car on a dyno with wideband. adn adjust fuel...then timing. IF unknown...alwasy try retarding timing first..

I always set the CAS by the marks. ihave found it to be the best way to get the car within 1-2 deg of perfect with a minimum amount of hassle.

Kim_Jong_Il
10-29-2004, 09:17 AM
example...you fuel pump takes a crap on you adn isnt mainting fuel pressure. you don know this becasue the car is runnign fine off boost. you have just warmed the car upa nd decide to take it for a 18 psi pump gas blast down the skreet. you bury the throttle and your engien melts #2 before you know what happens. before the EGT gauge could respond and the manifold could heat up the engien was way lean and detonated the hell out of #2 and melted the piston.

Where were your prescious EGT's then?




Damn, done. I think that is all the explanation needed...

Hugh
10-29-2004, 09:20 AM
860C is a bit high, though.


Enthalpy, you know I had no dyno available for checking power while tuning, thats why I had to go with what was available to me. It would be nice if we all had dyno's to do run after run on... everytime we make a change to the engine. However, most of us don't have that luxury.

Now that I live in California, I will locate a place to do just that... and pay if I have to. I don't want to be blowing up any engines here. http://forums.freshalloy.com/images/graemlins/grin.gif

Hugh
10-29-2004, 09:22 AM
example...you fuel pump takes a crap on you adn isnt mainting fuel pressure. you don know this becasue the car is runnign fine off boost. you have just warmed the car upa nd decide to take it for a 18 psi pump gas blast down the skreet. you bury the throttle and your engien melts #2 before you know what happens. before the EGT gauge could respond and the manifold could heat up the engien was way lean and detonated the hell out of #2 and melted the piston.

Where were your prescious EGT's then?




Damn, done. I think that is all the explanation needed...



OK, I'll bite.

The engine wouldn't make it to 18psi. It would choke out.

Enthalpy
10-29-2004, 09:23 AM
Enthalpy, you know I had no dyno available for checking power while tuning, thats why I had to go with what was available to me. It would be nice if we all had dyno's to do run after run on... everytime we make a change to the engine. However, most of us don't have that luxury.

Now that I live in California, I will locate a place to do just that... and pay if I have to. I don't want to be blowing up any engines here. http://forums.freshalloy.com/images/graemlins/grin.gif



I know man, but that is why i preach to pick a setup, install it, tune it adn LEAVE IT ALONE!! having to street tune mods is a quick way to disaster...

MATT_BACK_VASS
10-29-2004, 09:33 AM
bull****, that's how rastas car blew up.

Enthalpy
10-29-2004, 09:45 AM
example...you fuel pump takes a crap on you adn isnt mainting fuel pressure. you don know this becasue the car is runnign fine off boost. you have just warmed the car upa nd decide to take it for a 18 psi pump gas blast down the skreet. you bury the throttle and your engien melts #2 before you know what happens. before the EGT gauge could respond and the manifold could heat up the engien was way lean and detonated the hell out of #2 and melted the piston.

Where were your prescious EGT's then?




Damn, done. I think that is all the explanation needed...



OK, I'll bite.

The engine wouldn't make it to 18psi. It would choke out.




Nope...I've seen atleast 3 SR's die this way. talk to "rasta" who used to be on thsi board, "91 240" on this board has also had the same failure, adn i know of another... if the fuel pump isnt maintianing pressure the car most definitely will make boost! you still make enough exhasut gas MW to drive the compressor at 15:1 afr.

Rasta was the perfect example. had a perfectly runnign SR one day...adn no compression in #2 the next day. When i pulled it apart to do the reduild #2 was melted to all holy hell. #1 was pretty bad too! I looked at it and i told him it looked as if he had a massive lean condition all of a sudden. I had not seen this phenomenon before... so i do the rebuild and he does the break in. we get together for tunign adn everything is fine at 10 psi..we up the boost to 14 psi and the car goes dead lean on a ROM tune program that should ahve been 12:1. i tell him fuel pump...we change it...BAM 12:1. this relates becasue hsi car was definitely making 18 psi when it let go originally. he was watching the gauge!! it was 16:1 lean and 18 psi!!

cwdmark
10-29-2004, 09:48 AM
scott, lets say i use the stock ecu, stock turbo/injectors/maf (the whole stock setup) with fmic/intake/downpipe/exhaust at 12psi. stock timing. what should the proper egt be in a 3rd gear or 4th gear run?

i just made a quick sprint in 3rd gear and egt at redline is 790C. in 4th gear it rises to around 850C. i popped it in 4th gear from 1500rpms and stepped on it, and got 12psi @ 3200rpm (a lot quicker than i thought it was). im getting roughly 290miles/tank (rich rich rich?).

i still have the stock ecu, i may plug that back in and see what it does. the mines ecu is programmed for 1 bar boost and stock everything with fmic and basic bolt ons, but unfortunately i really don't know what the exact ignition and fuel maps are, thats why i am most likely going to pop it back on ebay, sell my stock one and get one of your ecus.

Hugh
10-29-2004, 09:55 AM
Holy crap! Thats scary.

Oh well, thats why I have EGT and Fuel Pressure gauges with warning lights, and a wideband running full time with display of my A/F on the dash.

When you say "dead fuel pump" you mean one thats gradually dying? I didn't think the car would do much on one thats not making any pressure.


cwdmark, if your EGT's are going over 850, then you need to do something. If you're only boosting 12psi, you should probably see 750-800C. I only saw 850's while running 20psi in 4th & 5th gear on a big turbo.

cwdmark
10-29-2004, 10:01 AM
cwdmark, if your EGT's are going over 850, then you need to do something. If you're only boosting 12psi, you should probably see 750-800C. I only saw 850's while running 20psi in 4th & 5th gear on a big turbo.


i love the guages with warning lights too (greddy here). word of advice: wire a buzzer to them. i just wired some 108db siren to them so now i never have to watch the gauges again, and if you can't hear them, you're deaf.

3rd gear i see 800C tops, and 850C during a 4th gear pull right at redline... this is all at 1 bar. going down the track i normally seen about 820-830C with my peak hold.

the car runs just fine.. but im wondering if im a tad lean or a tad rich, and what the hell it is. i went to the dyno last night to watch my friend and i was going to pull... but it was getting too late so we left. i might go back up there this week just so i can get this out of my head.

Hugh
10-29-2004, 10:04 AM
A nice wideband would tell you exactly how lean or rich you are.

Chance are you're a tad lean, or your timing map is not advanced enough.

You can't be sure without having your A/F measured at that exhaust temp.

cwdmark
10-29-2004, 10:08 AM
yea, instead of spending $100-150 on the dyno i might just spend $300 and get the convertor for the greddy gauge so i can see what it ACTUALLY is, not some gay 4 wire narrowband.

MATT_BACK_VASS
10-29-2004, 10:41 AM
dead, dying, sucks at life, the three can be used interchangeably.

Vapor
10-29-2004, 01:00 PM
I found this link to be very informative when explaining the usefulness in EGT's. The DSM people didn't like it (ha ha) but its all very accurate.

http://www.sdsefi.com/techegt.htm

Hugh
10-29-2004, 10:46 PM
dead, dying, sucks at life, the three can be used interchangeably.



Well I see a difference between dead and dying. If he had said the fuel pump was partially working then I could see that... I was thinking dad fuel pump, is the motor siphoning the gas? Heh hehe

Enthalpy
10-30-2004, 09:04 PM
nah hugh...it would run fine at low boost but jus would flow at high boost....really weird..prolly bad motor in the pump.

Dave562
10-31-2004, 04:20 PM
Now that I live in California, I will locate a place to do just that... and pay if I have to. I don't want to be blowing up any engines here. http://forums.freshalloy.com/images/graemlins/grin.gif



There is a dyno day on November 7th in Stanton. It's $35 for two pulls and slightly more with a wide-band. If you want the details, PM me and I'll let you know.

HIGHMILEHATCH
10-31-2004, 06:12 PM
I would agree an EGT gauge is a good thing to have as a reference. Tune the engine to a safe desirable a/f, tune timing to MTBT, make a note of the EGT at wot and all other conditions. After your ready to drive the car, if the EGT is not the same as it was when you tuned, then you know something is up. Like I said, reference only. I would never tune a car for maximum safe power with just an egt gauge. That's what widebands and dynos are for.

Dave562
10-31-2004, 06:19 PM
I would agree an EGT gauge is a good thing to have as a reference. Tune the engine to a safe desirable a/f, tune timing to MTBT, make a note of the EGT at wot and all other conditions. After your ready to drive the car, if the EGT is not the same as it was when you tuned, then you know something is up. Like I said, reference only. I would never tune a car for maximum safe power with just an egt gauge. That's what widebands and dynos are for.



This is the reason I have an EGT, in addition to a narrow band O2. Sure I can't use them as tuning tools, but they work great as idiot lights. If I'm flying down the freeway at WOT and the A/F gauge suddenly goes red, I know that something is wrong and I need to back off of the throttle. Without the gauge, I would have no idea what my A/F ratio is like.

Its always better to have a partial clue, than no clue what so ever.

With regards to this thread, I get about 850F at idle and 1450F cruising at 85mph. If I let the car idle for long enough, it will creep down to 650F.

HIGHMILEHATCH
10-31-2004, 07:11 PM
I've been searching all over and still have not come to a conclusion about which runner to tap my probe. I know the most accurate way is using an infared heat gun to measure the runner temp, but I don't have access to one of those. Some say 4, others say 1, others say 2 or 3. Wouldn't tapping the probe based on the firing order work just as well?

asad
10-31-2004, 07:16 PM
Wouldn't tapping the probe based on the firing order work just as well?



What does the firing order have to do with anything? It's a cycle.

Asad

HIGHMILEHATCH
10-31-2004, 07:25 PM
Wouldn't tapping the probe based on the firing order work just as well?



What does the firing order have to do with anything? It's a cycle.

Asad



If the firing order is 1342 on an inline 4 engine, cylinder 3 will retain the most heat. What do you mean by cycle?

asad
10-31-2004, 07:42 PM
If the firing order is 1342 on an inline 4 engine, cylinder 3 will retain the most heat.



Uh, why? Those seem like completely unrelated statements that you have there separated by the comma.



What do you mean by cycle?



I mean it doesn't just go 1342. It goes 134213421342134213421342134213421342... from the second you start the car from the second you turn it off. Not only that, depending on which cylinder fires first when you start the car, it could be

3421342134213421342134213421342134213421...

or

4213421342134213421342134213421342134213...

or

2134213421342134213421342134213421342134...

And do you really think that, after hundreds or thousands of revolutions (i.e. after about a minute of driving) that it actually matters which cylinder started first?

Asad

HIGHMILEHATCH
10-31-2004, 08:08 PM
How is that unrelated? 1342. Of those four cylinders, number 3 fires, then 4, then 2. 3 is located between 4 and 2. What other cylinder has two neighboring cylinders that fire consecutively, directly on opposite sides? None. You can type 13421342 as many times as you want. There is still no other cylinder, other than 3, that has two neighboring cylinders completing the combustion process, no matter how many times the cycle continues.

Enthalpy
11-01-2004, 07:25 AM
How is that unrelated? 1342. Of those four cylinders, number 3 fires, then 4, then 2. 3 is located between 4 and 2. What other cylinder has two neighboring cylinders that fire consecutively, directly on opposite sides? None. You can type 13421342 as many times as you want. There is still no other cylinder, other than 3, that has two neighboring cylinders completing the combustion process, no matter how many times the cycle continues.




how about #2??

if by you logic 3 is surrounded by 4 and 2 in the following order 3, 4, 2.

then by the same logic #2 must be surrounded by 1 and 3 in the standard order 2, 1, 3!!

which happens in the standard firing sequence 1,3,4,2,1,3,4,2....

go away rookie...

HIGHMILEHATCH
11-02-2004, 11:56 PM
I now see what your saying about the number 2 cylinder. I was wrong. No need to be a [censored] with the rookie comment.