[WolfPlayer]

AFRs are 12:1 tapering quickly to 11:1 @ 4000rpms and continuing at 11:1 until redline. Lots of people run a lot more aggressively than this.

Total Spark advance is fairly normal: ~14d at peak boost around 3000rpms, 20d @ 5000rpms, 25d @ 6400rpms, approaching 30d @ redline.

Boost is 18.5:1 with total boost coming on @ 3000rpms (sometimes 2800 ). Boost holds nice and strong similar to what jaygoesfast runs. Boost tapers to redline with ~15.5psi at redline.

Pretty run of the mill tune.

... In a 4th gear pull why the heck is my EGT so high? I am not staying in it long enough to really find out what the max EGT is. I can hit 1550d around 5000rpms with no sign of it steadying out. Maybe I should just be a little more relaxed and run 4th gear out a little more. But, I don't like rolling the dice. Everything seems sort of normal ... AFRs aren't lean, timing is ok. I have a feeling the first recommendation I will get is to turn the boost down. yea, I guess. But, this isn't any different than what most of the custom tunes are running.

Sitting here and thinking about this ... there has GOT to be tons of custom tunes out there running really high EGTs. I am lucky - I have an EGT gauge installed. However, if I didn't have one I would think that everything is 100% coolio. AND, IMHO, I don't think it is. I really don't want my EGTs climbing up to 1600+ on a WOT 4th gear pull. Then again, maybe I am just being a puss-e, lol. Maybe 1600-1650 isn't really that high? You tell me. EGT bung is on the button on the driver's side exhaust manifold (http://www.bescaredracing.com/sti/ga...t/DSC02278.JPG, http://www.bescaredracing.com/sti/ga...t/DSC02451.JPG)

t

[Neanderthal Racing]

1600? my egt's are running 1000c/1832f at the top of 5th. do what i do...just look away (isfh).

[MidlifeCrisis]

Wolf - is that a stock exhaust manifold? Is that bung hole there in all of them?

[MidlifeCrisis]

Originally Posted by nhluhr

The hole is not there, but that little cast-in button of thick iron is there. Just drill it, tap it, and thread in your probe adapter. Usually 1/8NPT.

Nice. Any recommendations for EGT guages. The only data collection device I presently have is an LM-1. I'd like to bring the EGT data into ST, too.

EDIT: Nevermind, looks like the LMA-3 is the obvious answer.

-Bruce

[R4ND0M_AX3]

I'm not tuned at all. Just running the V1.10 Stage 2 ST map. I see EGTs in the mid 900 DegC area. Scares the crap out of me. I've always thought it was the excessive boost I was seeing (1.4 bar).

Defi alarms going off almost every time I put my foot in it. (currently set to 1.3bar & 900DegC)

[WolfPlayer]

Originally Posted by R4ND0M_AX3

I'm not tuned at all. Just running the V1.10 Stage 2 ST map. I see EGTs in the mid 900 DegC area. Scares the crap out of me. I've always thought it was the excessive boost I was seeing (1.4 bar).

Defi alarms going off almost every time I put my foot in it. (currently set to 1.3bar & 900DegC)

Curious, if you are seeing 1.4 bar (20psi) then why don't you just turn down the WGDC high map? It is a very easy change and will get you to your target boost. Unless this is related to boost creep?

940 c is close to 1750d F. Holy cow. I definitely wouldn't feel safe running that. You have the means to run safer. Fix the boost issue and give it more fuel. My situation is somewhat different. I'm definitely not hitting that high .. and if I WAS hitting that high I would immediately add fuel because the life of my car is more important than running really fast.

t

[R4ND0M_AX3]

Originally Posted by WolfPlayer

Curious, if you are seeing 1.4 bar (20psi) then why don't you just turn down the WGDC high map? It is a very easy change and will get you to your target boost. Unless this is related to boost creep?

940 c is close to 1750d F. Holy cow. I definitely wouldn't feel safe running that. You have the means to run safer. Fix the boost issue and give it more fuel. My situation is somewhat different. I'm definitely not hitting that high .. and if I WAS hitting that high I would immediately add fuel because the life of my car is more important than running really fast.

t

Yep. I don't run the car that hard usually. But ya. Gonna drop the DC so boost is better. I've had the EBCS rolling around in my trunk for a few months now. I've been dabating installing it or just doing the helper spring route. But now that I see that you are running so much less EGT and still freeking out that I too should start freeking out and fix it before anything else.

[2fas4u]

If the magic number of 1600 Deg F is our max point you guys are dangerously close! I can pull hard in 4th, 5th and my max I've seen is 700-750 C. If I was 900 + C I would make sure you have a tow companies number handy because the motor is not going to take much of that abuse! I purposely detuned my new GT30R setup with the increased boost to make sure that the EGT's were in a "happy" range.. Interesting talk guys... Thanks!

[Siegel Racing]

Excellent stuff here guys. Excellent advice.

I would expect to see 850 to 875, tuned for power, with your EGT in that location. 890 is getting up near as high as you'll want to go. The WRX's with the EGT sensors throw the code at 890, but that's in the up-pipe, not RIGHT at the leanest cylinder.

Don't forget that EGT sensors are not always perfectly accurate, yours might read a touch high - that said it's likely in the leanest cylinder, and your O2 gets an average from all 4.

Trying to be near 30 degrees and 11.0:1 at 7k usually helps, but nhluhr is very correct that the gauges have a delay on them. He's also right about wanting to have your AFR's bottomed by peak torque, which is likely near 3400 rpm...

I also like my AFR's to look like a dish, I call it a smile, but you can call it a dish If you have EGT issues maybe try staying at 10.9 at 7k rpm...

It's funny, with the same Boost, AFR, and timing graphs I have seen WILDLY different EGTs. Some cars with almost IDENTICAL Boost, AFR, Timing, and POWER graphs will NEVER break 1450, while others are knocking on 1600 (until I add a little fuel to the top.)

Good stuff...

SS

[R4ND0M_AX3]

I also suspect that bumping up the timing would reduce some the EGTs by starting the burn earlier and therfore within the combustion chamber rather than right on top of the sensor 20cm after the exhaust valve. <-- is that a run on?

But the first order of bidness is getting the boost under control.

[jays05]

I see about 880-890c max on my Greddy EGT gauge (I tapped the drivers side manifold) at the top of 5th gear. 4th gear doesn't seem to be consistent enough to base any opinions on, but I usually see 850c there. I run approx 11.5:1 AFR at peak tq and 11.3 up top. I am running the timing values mentioned by Wolfplayer in his StreetTuner tuning FAQ. 17@4000, 22@5000, 24@6000, 28@6800 or somewhere around there.

I see similar EGT's with both my high octane(96) and low octane(93) maps. The only difference between the two is the boost curve. 19.5 tapering to 16.3 on the 96 map, and 18.5 tapering to about 15 on the 93 map.

I consider 900c+ high. As long as I'm below that the gauge is no cause for concern.

[Christian.]

WolfPlayer, try lowering your boost across the board...I would like to hear what that does to your EGT. Just curious.

Here is another perspective on tuning and using EGTs. Let me know what you guys think?

Rednecks, Bonfires, & EGTs
A technical article
by Christian Krahenbuhl

I am writing this to assist you with tuning your vehicle and I am simplifying the example to better assist those who do not have much tuning experience...just trying to help.

Think of your combustion chamber as a bonfire...a very technical bonfire in a sealed environment, in which the timing of the event is critical. With all other variables remaining constant, generally speaking, if you increase fuel (run richer) for a given RPM and Load point, you will increase EGTs because you are adding fuel to the fire (just like a redneck with a pallet fire, they pour gasoline on the fire and it burns hotter). The combustion chamber is given more fuel which will continue to burn as it exits the combustion chamber, past the exhaust valve, and continues to burn its way down the exhaust manifold and past your EGT probe. You have given your fire more fuel to burn, thus creating greater heat. Make sense?

With all other variables remaining constant, generally speaking, if you decrease fuel (run leaner) for a given RPM and Load point, you will decrease EGTs because you are removing fuel from the fire...you will have less combustion gases to burn, thus a more complete burn will occur for the given time in the combustion chamber, and less fuel will be present to burn as it exits the combustion chamber. This is taking into account that you are not running too lean already; this can also create excessive heat.

With all other variables remaining constant, generally speaking, if you use less ignition advance (retard ignition) for a given RPM and Load point, you will increase EGTs because you are igniting the combustion gases later in the combustion cycle allowing less time for a complete combustion in the chamber and more of the unburned bonfire (combustion gases) will exit the chamber and burn their way down the exhaust manifold and past your EGT probe. These gases were not ignited early enough for a complete burn in the combustion chamber.

With all other variables remaining constant, generally speaking, if you increase ignition advance for a given RPM and Load point, you will decrease EGTs because you are igniting the combustion gases earlier in the cycle...burning more of the fuel in the combustion chamber thus allowing less of the unburned combustion gases (bonfire) to exit the chamber and burn their way down the exhaust manifold and past your EGT probe.

If none of these modifications work, then lower boost pressure because you are most likely creating too much exhaust gas back pressure...more pressure = more heat. You could also be running the turbo beyond its efficiency point, then the turbo shaft speeds will go through the roof and the turbo becomes a flame thrower, increasing an engine's inlet air temperature, and increasing the ability to destabilize combustion gases and detonate = boom at the wrong time. Your flame front and combustion gases will be going down and the same time your piston is going up. This will usually pound the crap out of your rod bearing for that cylinder or crack the crown or ring land of the piston. Detonation 1, engine 0.

Again, the type of internal combustion engine, type of fuel, ambient temperature, oxygen content of the combustion gases, running the turbo in its efficiency range, intercooler efficiency, and exhaust gas back pressure, all must be taken into account as well. I hope this helps.
The author of the article is a fellow redneck and means no offense to his own people.

[R4ND0M_AX3]

I dropped the WGDC a little last night and things are much better. EGT just almost touching 900C (1650F). Boost is now in the 1.15 (16.7psi) to 1.25 (18.2psi) range.
Yay for non alarming Defis.