:::RHMT::: Real Home Made Turbo
General Category => Engine Management => Topic started by: d112crzy on August 30, 2009, 03:15:00 AM
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How many of you guys actually pay attention to EGT's and use it as another tool for tuning?
Say that you've tuned timing in on the dyno for best power over all. Will adding a few more degrees, especially after MBT help a lot with lowering EGT's, even if it doesn't make a difference in power?
How detrimental are high EGT's on engine life span? Does a drop, or raise of 50*F make a huge difference?(say, 800 to 850)
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i wouldnt worry about it so much with WOT. If you can read plugs and your not an idiot on the dyno, you dont need an EGT gauge. I would say its nice for tuning part throttle as you can really get a better idea of where you stand.
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I used to have a really cool chart that showed power, timing, afr, egts, and a bunch of other gases all overlaid over each other
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I used to have a really cool chart that showed power, timing, afr, egts, and a bunch of other gases all overlaid over each other
Pics or it didn't happen!
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i wouldnt worry about it so much with WOT. If you can read plugs and your not an idiot on the dyno, you dont need an EGT gauge. I would say its nice for tuning part throttle as you can really get a better idea of where you stand.
This is my view on it as well. I've just been thinking about it lately and thought I'd post up.
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1300 deg *f wot 4th gear pulls is what i use to net and around 800 cruising light load 1000f moderate.
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I used to have a really cool chart that showed power, timing, afr, egts, and a bunch of other gases all overlaid over each other
Pics or it didn't happen!
agreed, i've been trying to find them again for awhile, it really puts things in perspective.
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Exhaust valve temps are directly related to engine longevity. As long as the exhaust valves aren't getting thermally assraped by insufficient timing, those temps are pretty much carved in stone.
Temps go up, of course, at WOT. Everytime you hit the fun pedal you consume the engine a little bit.
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The flame that burns twice as bright lasts half as long
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The flame that burns twice as bright lasts half as long
nicely put...
Beaner.. i wonder if your posting this because of the 3page debate we had on cb7tuner...
i personally will always use EGT as a correlation to the tune (when possible... im not gonna install EGT probe in every car..) but if its someones daily.. and their real concerned for longevity.. and a nice lifespan.. then sure.. egt will be considered.. especially if the car is sporting a log manifold...
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EGTs are completely irrelevant unless it's individual cylinder EGTs.
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EGTs are completely irrelevant unless it's individual cylinder EGTs.
pretty much, 5 degrees of timing will leave you scratching your head if your reading ETG's
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Has anyone actually ran 4 egt probes..and if so..what difference..or should I ask..how big of a difference between cylinders..were there (in egt)
I can't forsee egt's being totally irrelevant..even if just running 1 probe.
Ignoring them will only decrease engine longevity..
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But if you're timing is right, then egt's will be right as well. Or close enough to where it 5-10* won't make a difference.
If you're timing is right, then you know how to read plugs and/or you're tuning on a dyno.
I don't know of any other tuner that ever pays attention to egt's.
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Has anyone actually ran 4 egt probes..and if so..what difference..or should I ask..how big of a difference between cylinders..were there (in egt)
I've run multiple CHT probes, EGTs are a waste of time.
There is always a flow difference between cylinders. One cyl reading higher than the others is indicative of this, and nothing else, and you can figure that out without an EGT probe. If one cyl suddenly takes on a lot of heat relative to where it's been, even if it's still not as hot as the other cylinders, then it is a warning there is something wrong with that cylinder. Since you probably aren't paying attention to delta temperatures across the last three pulls then it's without merit.
I can't forsee egt's being totally irrelevant..even if just running 1 probe.
Then explain how EGTs are remotely useful?
I'd rather monitor crankcase pressure, THAT is actually useful.
Ignoring them will only decrease engine longevity..
What longevity issues? These are performance engines we are discussing, they break oil pumps and drop valves and have reliability issues due to novice/enthusiast workmanship. Log exhaust guide temperatures if you want to monitor engine longevity, don't waste your time with EGTs.
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its really only going to tell you anything when you have a failure....
Unless your getting all scientific and measuring every thing like even cylinder pressure, intake pulses, and such as the OEMs do in development throw that shit out the window
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EGT’s are relevant to tuning but not an end all be all. Just like a wideband they don’t come with a brain so you still have to use your own.
Using an egt gauge can go like this you tune the car on a dyno or at the track watch what egt’s are at peak trap speed or peak torque on a dyno. You can kind of use the egt amount for reference to tune fuel or timing in when things like the weather changes.
Just like a wideband egt’s fucking lie to you or you can also be humble and admit there are things going on to complicated for you to understand or to many variables to draw one conclusion from the data in front of your face. LOL Dave Blundell told me this one time early on in my tuning days and it broke my false sense of security like and left me just lost. But I learned so much more after he told me that there is no tool that can do it for you if there was no one would pay anybody to tune a car.
Egt’s read the highest at stoich 14.7:1 because that’s where gasoline burns most efficiently and completely and they cool down as you lean out even until you get misfires you know less fuel for the fire,They also cool down from going richer.
We all know motors make the best power between 12.1 and 13.1 so with an egt you can find stoich and then richen it up all its doing is indicating fuel. I’d rather just go for what I really want to know and use the wideband and common sense. I’m not saying an egt is a bad thing or a waste of time you could use it with the wideband and with a dyno and just be fucking on it have three points of reference to really nail in and get to the truth. But if you take away the wideband o2 or the dyno from the mix and an egt is just too vague to go by. IMO
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We should just give up and convert everything to carbs.
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We should just give up and convert everything to carbs.
Agreed
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Here's a 2200 whp small block with a Ron's Flying Toilet mechanical alcohol injection setup and a mechanical advance distributor. Sadly, this engine was only built to last a couple years of abuse because as you can see the tuner didn't use EGTs.
(https://realhomemadeturbo.com/forum/proxy.php?request=http%3A%2F%2Fi256.photobucket.com%2Falbums%2Fhh166%2Fjoeymisanthropy%2FCAMAROPOWER2.jpg&hash=4085dc27d9c4f58955f87f74970788c0b0e28833)
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What an incompetent fuck hole. They should have went with J.Davis :yes:
That is so cool. It'd feel so awesome to get to work on something like that.
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They also should have let Full-Rice make the manifolds. As you can plainly see, those are not merge collector manifolds. The fucking fools.
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They also should have let Full-Rice make the manifolds. As you can plainly see, those are not merge collector manifolds. The fucking fools.
And the runners are not even close to equal length >:( everyone knows how absolutely critical that is.
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I guess the alchohol is taking car of IATs.
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Yeah, but if you want to make real power you have to switch back to gas to keep from melting the engine down. Alky isn't safe when taken to the limit.
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agreed with all said above.. just been told several times that it is useful.. not the most important thing in the world.
but.. it can show u whats going on with the motor just as a wideband can..
and like jose said.. if ur timing is right then your egts should be within range right?
whose to say at 22* on X engine egt is at Y..
and on X2 engine at same timing egt is at Z..??
obviously you guys know not one engine is the same.. what im getting at is.. besides detonation doesnt excessive combustion temps kill rings?
sure watching your timing will mean no need to monitor.. but like you said JD these are performance engines.. not everyone wants to run their engine to the extreme side of the spectrum.. some people just want some power...and be SOMEWHAT reliable.(yeah yeah i know power/reliable/cheap... choose 2 etc etc..
in the end.. all im really trying to say is.. cant you use EGT to GUIDE you in what timing to run.. to allow for a "safer" tune..disregarding power goals
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reading spark plugs will guide you.
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valid point..
but couldnt this then be ANOTHER form of doing just that(no im not saying dont read plugs at all)
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Sure. But there's no need for it if you can read spark plugs. How often do you hook up an egt gauge on a customers car?
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agreed with all said above.. just been told several times that it is useful.. not the most important thing in the world.
but.. it can show u whats going on with the motor just as a wideband can..
Perhaps, but it's even less accurate than a wideband. Because it is also directly influenced by small ignition changes, heatsoak, and borderline cooling issues. It's hard to log all of that and make correct sense of it. I can see an EGT being a great tool on a problem vehicle where you can't have too much information, but I can't see it as being a backbone tuning tool.
and like jose said.. if ur timing is right then your egts should be within range right?
What if your AFRs are completely wrong, although your wideband (and any other wideband) reads "correctly"? AFRs are indicated and very much not actual, and the pitcher is spitting on the ball before he curves it to you.
whose to say at 22* on X engine egt is at Y..
and on X2 engine at same timing egt is at Z..??
obviously you guys know not one engine is the same.. what im getting at is.. besides detonation doesnt excessive combustion temps kill rings?
There is no difference between detonation and excessive combustion temps on the combustion level - temps get too hot for water and hydrogen to join together and form the water vapor (steam) that generates combustion pressure, and instead they consume aluminum in a rather explosive reaction. This is what creates detonation pitting. Although the situation you are alluding to involves a lot more heatsoak of the chamber and likely result in more impressive carnage, or distributes it across the chamber until one thing decides to go.
Too much heat:
- Nukes exhaust valves, sets you up for preignition
- Heats the piston, causing it to expand until it binds across the skirt. Since aluminum's strength is directly related to it's temperature, ring lands will pop off on stock units. If this is a rich or correct mix with significantly too little timing, creating an effective lean condition in the chamber, it is possible to melt the piston which will leave an aluminum residue at the top of the bore in some cases.
- Is really an irrelevant topic in a thread about EGTs
sure watching your timing will mean no need to monitor.. but like you said JD these are performance engines.. not everyone wants to run their engine to the extreme side of the spectrum.. some people just want some power...and be SOMEWHAT reliable.(yeah yeah i know power/reliable/cheap... choose 2 etc etc..
See, this is the breakdown in your understanding. Hondas, and most all inline 4's, are not knock limited engines due to having poor headflow and their cams advanced 5-10 degrees too far to create torque off of idle aka V8s. The Honda that continues to make power under detonation is rare (I owned one), unlike the lower revving big displacement motors. With a forced induction Honda you will always have 3-5 degrees of safety between best power and detonation, until you make enough power to run out of octane. Some high CR pumpgas NA builds that are all dome with no quench and a poor cam selection will mimick a V8 in the sub-2500 rpm range so that you have to pull timing to prevent detonation while also losing power to do so.
There is no difference on a peak power tune and a safe reliable tune for a Honda, Miata, SR20/KA-T, 2JZ (not fair comparo) or 3S-GTE, and a large number of other engines. The reason why these motors come apart is poor assembly, or Honda-Tech assclowns thinking a 2.0/VTEC can make 450+ whp on pump gas. When the timing requirement to make the power starts falling off hard it's because you're running out of octane and the shit is becoming volatile and unrepeatable; one tank of bad gas at the 400 whp level will do mild damage. The same gas at 450+ causes more damage. Over a long enough time, or bad enough gas, and your shit comes completely apart. I tune on a dyno that reads somewhat high if the corrections aren't turned off, recently had a local kid making 320 on it that couldn't get better than 290 on a Dynojet and was flipping out about it. I have yet to see a pumpgas Honda I would trust past 400-410 whp - power looks fine, plugs look fine, but timing is falling off and the carbon trail on the piston (FUCK plug reading, carbon trail is a much better indicator) shows signs of high frequency detonation.
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do you use a borescope Joseph?
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I have to on Subarus and SBF. The inline 4's and mod motors are nice, you can peer right down on the piston crowns with a flashlight. D-series are a bit of a whore with how the plug comes in at an angle so you have to manually turn the engine over to look at crown vs outside.
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Carbon trails, I understand what it means but I'm unsure of what exactly to look for. care to explain a little?
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Carbon trails, I understand what it means but I'm unsure of what exactly to look for. care to explain a little?
It's just like reading a plug, only simpler. A healthy engine forms a healthy carbon trail. Too rich, soot. Too lean or ignition too retarded (or sometimes nothing's wrong it just blew all the crap on the piston off and hasn't formed a healthy coat yet), bare. Blowby problems due to too much ignition timing or lack of crankcase ventilation or in the case of D-series over 7.x:1 CR, wet with oil. Pre-detonation forms tiny tiny pinholes in the carbon coat where you can see fresh shiny aluminum when you start running out of octane but are still making good power, or you are within your octane limits but feeding the engine too much timing.
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What the fuck are you talking about? I love D-series, it's purpose built high CR turbo D-series ignorance that I hate.
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(https://realhomemadeturbo.com/forum/proxy.php?request=http%3A%2F%2Fi23.photobucket.com%2Falbums%2Fb376%2F98vtec%2FIMG00011.jpg&hash=15aa3b9ea52c4f9821dd2ff393de7e74cee00462)
are you able to form any analysis on that?
Personally, i think it looks like i am getting great flame coverage but i know less about reading piston tops than i do reading plugs.
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I believe Joseph is referring to Carbon Trails in a fresh engine, you have some hard carbon buildup. Its far more difficult to read like that vs. a fresh clean piston
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Theres only so much crap that can stick to a piston, it's all valid.
Can I get a higher resolution picture?
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I've always had egts, and frankly they have always been hot. In my WRX they were hitting 1500F during long wot runs. My probe was prolly what, 4-6" from the ports. In my 4agte same shit, i hit at the most prolly 1500 but im pretty sure its cooler now than it was originally. Honestly I don't remember, my fuckin defi probe died and im to cheap to fix it.
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I use an egt gauge, but I would rather use a wide band, the problem being that I can't get a wide band to last more then one pull before it is so clogged with soot that it doesn't read any more... :'(
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I use an egt gauge, but I would rather use a wide band, the problem being that I can't get a wide band to last more then one pull before it is so clogged with soot that it doesn't read any more... :'(
What engine and fuel are you using? Does the heater in the O2 sensor work? What kind of wideband?
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LOL, Cummins 5.9L Diesel. :P
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Theres only so much crap that can stick to a piston, it's all valid.
Can I get a higher resolution picture?
nah, i sure dont. Next time i pull the head, i will take some better shots.