I run 1390 the EGT is 4 inches from the down pipe

 

i think the hottest my EGT gauge said was 1450deg. my probe is located in the little hole that was premade for it in the racingbeat 3" system.(it's ryte next to the 02 sensor) i also don't really have a EGT gauge. it's a pyrometer from auto meter.

 

For an N/A- 1850^o 6" from the exhaust port is optimal for power.
That's damn lean for a turbo though, and higher than most in-car EGT gauges read!

 

I've hit 1500 a couple times before letting off. it should be safe up to 1600 or so on turbos, but I'll leave the max limit testing for others

normaly around 1400 at wot.

memory recall kicks ***

 

Celsius owns you!

Highest I've hit is 760C in 4th after I added my current mods. Boosting about 11.5-12 pounds bleeding a couple of pounds towards redline with stock catback.

 

everyone says egt guages are better, so I bought one now, noone can tell me what the best egt I am tuning for at WOT is. I have a T2 and the egt probe is plumbed about 2" from the flange in a RB downpipe, just behind the O2. How do you guys tune with these? What should I tune for? Its an Autometer pyrometer(standard not Celcius). Please help cuz as of yet this 200$ guage is pretty much useless without FACTS!

 

thats EXACTLY the same situation I am in. I bought the EGT guage because well I understood it to be more accurate than a pretty light show a/f ratio guage. It is and it's badass but...all I have is numbers. Most of the EGT guages are plumbed in right next to the stock 02 sensor. From searching around for hours I've gathered that stoich is 760-800 at W0T. Anything over 820 is lean and you should let off immediately. I plan on going to a local dyno soon without a SAFC - I just want to have a wideband o2 sensor hooked up so I can correlate actual a/f ratio numbers with EGT temps.

 

well it's different for every car. I had mine wide band tuned and it was hitting around 800C. I richened it up a bit after though to be safe and I'm hitting around 760C now.

 

Hopefulyl you are aware of the fact that EGT readings are not neccesarly an indication of correct air fuel mixtures.. It is quite possible to have tons of fuel going through your system and still read high EGT #'s if your timing is too retarded...

Best plan of action is to utilize a dyno with a wide band to get an idea of your air/fuel mixtures and use the EGT readings to make sure your timing is also spot on..

 

I'm pretty sure they are higher with advanced timming, not retarded timming.

 

Exhaust temps increase the more timing is retarded.. when you retard the timeing you are basically igniting your mixture "late".. when this happens there is alot of heat that was generated from the combustion process which doesn't get a chance to be used up to make power and that excess heat is just passed out via the exhaust port.. hopefulyl that makes abit of sense

 

but retarding your ign = less change of detonation.

detonation is caused by heat.

2+2

I am missing something?

 

I am shooting for about 760 deg C, or 1450 deg F on my EGT gauge. That gives me plenty of room to be safe, and doesn't put me too far out on the edge. My EGT probe is mounted a half inch behind my O2 sensor.

 

Detonation occurs when the pressure and temp of the unburned portion of air/fuel mix in the rotor reaches the point when is will spontaneously combust..
Advancing timing increases pressure and heat.. this increase in pressure results in more power.. however, the greater pressures and heat also makes the air/fuel mix easier to ignite..

Retarding the timing will decrease the pressures in the rotor, which will result in less chance of pre-detonation .. however it will cause your EGT's to increase because more of the heat caused by combustion will be passed through the exhaust

To simplify things a bit more, the hgher the octane of gas you run, the more pressure and heat it takes to make the mixture combust (hence, you can run more advance with higher octane fuel)

The heat you are measuring with the EGT is exhaust gas temps.. which is the end result of the combustion process .. The "Heat" which contributes to detonation is not entirely related to the exhaust temp, but more so the temps in the rotor housing prior to combustion..

If you notice that your coolant/oil temps start to climb, however your EGT's are okay as well as your air/fuel , chances are you are starting to run a bit too much ignition advance .. If you notice that your EGT's are starting to shoot up, but you know you are putting enough fuel into your motor, and your coolant/oil temps are staying near normal (or a tad bit higher) then check for too much retard...

 

So at this point my egt guage is still useless! There seem to be no facts in relation to specific numbers. Does anyone have the awnser? Also the needle moves so slow on mine that by the time I let off the throttle it was still creeping up on 1500.

 

If you are running the stock ECU, you don't really have to worry about messing around with your timing (Since you really don't have that much control over it anyways) .. You can then use your EGT to monitor your air/fuel levels.. Shoot for 800-850 degress C, anything higher then that is getting too lean..
These figures depend on the location of your probe as well.. I am assuming that the probe is in your downpipe by the stock o2 sensor location..

 

I have 900 F at idle, 1300 F wot/boost and 1400 - 1450 F Highway cruise around 3500 to 4000 rpm. I am getting over 22 MPG on the highway. 16 - 18 MPG average.

 

I'm running around 760 C.
Still running a bit rich for safety...

 

bumping up an old post....

If you're still on the stock ecu and you have the a/f ratio's under control at what point do you need to worry about timing?
Obviously I can't modify at specific rpm or boost points, but I could retard overall timing a couple of degrees. Running 12 pounds (.85 bar) with a front mount do I need to retard the timing at all? I don't mind losing a few horses for safety, this is only temporary as I hope to be stand alone of some sort by Christmas. Any help is appreciated.

 

at 12psi with an FCD you might wana drop the CAS back a couple degrees.

 

can anyone suggest what the best egt temp would be to tune for a single turbo 3rd gen. w/

low comp rotors
3mm seal.
street port
720 prim
1600 sec
tso4 turbo
HKS intercooler front mount

right now im running like at 650c to 675c and car is very slugish untill about 5000 rpm then it picks up but i can tell its still rich. Haltech measures about 820 to 875 on the O2 sensor.

thanks in advance
Rob

 

EGT gauges will read slightly differently for different cars EVEN WITH THE SAME MODEL AND BRAND OF EGT GAUGE.  That's so important, you need to read it several times.

Chris Ng is right - if you want to make absolute sure what YOUR safe temps should be, get the car on a dyno with a wide-band.  This will verify what is safe and what is not.

The EGT gauge is one of the most misunderstoog tuning tools, as intrepreting it's output is not very straight-forward.  Wide-bands have always been popular, because you shoot for a target number and reaction time is quicker (versus EGT).

EGT probe placement is also paramount in how the EGT gauge reacts and what kinda temps it displays.  Funky exhaust gas resonances can mess up readings off the EGT gauge!  I've got a big turbo FC running a divided turbine set-up that has a GReddy EGT installed with the probe in the downpipe; EGT's have always read low.  Leaning cruise fuel mixture to the verge of lean surging will only show 700C; I could do this to my car, and my exact same EGT model would easily show 800C+!  That's a different of over 100C!  This is why you should "calibrate" the EGT readings on a dyno.

Now, once you know what your safe EGT number is, we need to explain the relationship between lean and rich.  The engine has a narrow window to which the EGT is pretty stable.  We are primarily concerned with WOT (i.e. best power) EGT numbers, so we'll concentrate on that.  At "best power", the EGT number should be pretty stable.  Going leaner than best power will raise EGT - the dyno should also show the engine LOSING POWER.  This is due to inauaidble detonation.  If we go leaner, EGT will start to skyrocket and detonation is pretty evident.  From best power, if with richen it up, the EGT will actually go DOWN for slightly richer conditions.  You still get almost complete combustion, but the extra fuel cools everything down.  If we richen it up substantially, it'll come to a point where all the extra fuel will start to ignite out the exhaust port, and this will cause the EGT to rise (this looks exactly like lean!) and sound like detonation, because the excess fuel is igniting in the exhaust system; this is what Chris Ng is talking about when rich will raise EGT.

Now, on top of everything, there is a delay in the response of the EGT.  REMEMBER THAT!  O2 sensors (narrow and wide) will react pretty quickly, but the EGT reacts significantly slower...and you need to keep that in mind, especially when tuning fuel controllers and stand-alones.

With that in mind, these are the SAFE numbers I target until I can verify (with a dyno) that you cna go hotter...

In downpipe, 700C or about 1300F.
In turbo exhaust manifold, 740C or about 1350F.

I have an F to C chart here.
http://fc3spro.com/TECH/MODS/EL/egt.htm


-Ted

 

Ted, explain a bit about timing and it's relation to EGT. I have my GReddy EGT probe in the manifold before the turbo. With an indicated 11.1:1 a/f ratio and running 1.1kg, 15 degrees leading advance, 7 degree split, I am seeing about 1000 degrees Celcius at the top of 4th WOT on the dyno. A bit under on the road I believe ( I no longer do pulls in 4th to redline on the road). The intake/exhaust is ported. Whatcha think? No detonation recorded with the stock sensors on the Datalogit (PFC).