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View Full Version : EGT temps-how high is too high?



turbovanman²
12-29-2005, 06:07 PM
Just came back from a 10 hour trip, 5 there, 5 back, never done hills, long steep hills before. My egts reached 17-1750 deg going up the very long hills, lol, part throttle, 0-5psi of boost, spurts of 10 psi, going 100-120 km/h very easily. The power was there, didn't seem to drop off, I got scared even though I have forged pistons and a TU cal. I backed off a few times, was I ok leaving it there or was I right backing off?

moparzrule
12-29-2005, 06:19 PM
I've hit 1650 before, but 1750 seems excessive. Maybe it's just because of it being a van and the extra load of wind resistance.

looneytuner
12-29-2005, 06:20 PM
I would have freaked out. You were right backing off. I think you need to contact Paul on the cal. That's just my humble opinion. I AM crrazy though after 19 years with these cars.

BadAssPerformance
12-29-2005, 06:31 PM
I've seen 1700F+ regularly on the highway at part throttle on my old setup that only ran 1400F at WOT at 20 psi. I think it has something to do with part throttle stagnation of the exhaust in the manifold and causes a heat soaking effect.

turbovanman²
12-29-2005, 06:32 PM
Hmmm, I am calling him tomorrow so I will ask. I was loaded but only 400 lbs-big deal, lol!

Sorry JT, it has a tubular exhaust header, :thumb:

GLHNSLHT2
12-30-2005, 08:36 PM
we want pics of this tubular exhaust header!

turbovanman²
12-30-2005, 10:24 PM
I mean its a log header, sheesh, was thinking tubular when I wrote the addition. Its made by Typert.

looneytuner
12-30-2005, 11:09 PM
I have to ask this dumb question. What is your exhaust system?

turbovanman²
12-31-2005, 04:03 AM
I have to ask this dumb question. What is your exhaust system?


2.5 inch dp, then 4 inches later, 3 inch mandrel bent system, walker 3 inch super cat and Magnaflow muffler exiting behind the right rear wheel.

BadAssPerformance
12-31-2005, 10:43 AM
Sorry JT, it has a tubular exhaust header, :thumb:

coolio! :thumb:

Una
12-31-2005, 01:30 PM
One thing that always drove me nuts with the stock cals is the part throttle tables. I don't know what Paul does with his, since I never ran his cal on a properly running engine. But if you have an AF gauge, you might notice that the stupid computer is still bouncing stoich if your at about half throttle or less and about 5psi or less.. That's because the part throttle tables, under boost are TWENTY FIVE PERCENT leaner! than the full throttle tables in that same area.. When I do cals for my own cars, I bring the part throttle under boost tables up to the exact same spot as the WOT tables.. Until I get a wideband or get the car on the dyno, I have to assume it needs 25% more fuel at part throttle, rather than say, 15% more, and 10% less at WOT which I'm betting is more like it.. Anyways, running stoich under load and under boost would definitely give you those kind of EGT's..

turbovanman²
12-31-2005, 02:19 PM
Hmmmm, I knew he jacks them up, when I finally get around to calling him, I will ask.
My dawes went between red and yellow, and off when it was doing this.

moparzrule
12-31-2005, 11:41 PM
The dawes is a WOT only gauge...not lighting up in anything other than WOT is completely normal.

Una
01-01-2006, 01:43 AM
The dawes is a WOT only gauge...not lighting up in anything other than WOT is completely normal.
In my cal, it lights up any time your under boost.

moparzrule
01-01-2006, 10:04 AM
The gauge lighting up at part throttle has to do with the throttle position not how much boost you have. At 3/4 throttle A/F ratio is supposed to be something like .7-.8ish, which might light up the red light because that one starts at .78V. Less throttle results in less voltage, therefore shouldn't light up the dawes at all.

Una
01-01-2006, 12:56 PM
The gauge lighting up at part throttle has to do with the throttle position not how much boost you have. At 3/4 throttle A/F ratio is supposed to be something like .7-.8ish, which might light up the red light because that one starts at .78V. Less throttle results in less voltage, therefore shouldn't light up the dawes at all.
Boost is boost, doesn't matter what the throttle position is. When your under boost,you need to be running 11.5:1 or richer. .7-.8 is far from 11.5:1 (who knows how far, since it's a NARROW BAND sensor), but it's not the .975 or whatever the dawes is targetting to tell you you're at 11.5:1.. It's not normally a big deal, but as Simon noticed.. Go try to climb a mountain pass at a steady speed. That means 1/4 throttle and 5psi for 30 minutes at a time.. I'll take my slightly less fuel efficient but FAR SAFER fuel curves.. :)

turbovanman²
01-01-2006, 05:00 PM
The dawes is a WOT only gauge...not lighting up in anything other than WOT is completely normal.


Any air/fuel guage is a WOT guage but it also shows when the computer goes into open loop. Some programs do this at part throttle, like Una's. The stock cal would go into open loop at 1 psi of boost. I had Paul make mine 3 psi of boost as it used to hover around 1psi on the highway and my gas guage would start moving but with my new engine, I now have vacuum on the highway, :thumb:
If my dawes light goes on and stays on, the computer is seeing boost and going to open loop, :thumb:

Dave
01-09-2006, 02:06 PM
Simon you gotta remember, our fuel curves are only at something like 25% during part throttle. So if you slam it to 20psi somehow on part throttle, the A/F ratio is gonna plummet as is your EGT's. The fuel just isn't there at part throttle.

omnivore
01-09-2006, 09:54 PM
You mean the AF ratio will plummet, and the EGT's will do the opposite...right? LOL

Dave
01-12-2006, 09:09 PM
You mean the AF ratio will plummet, and the EGT's will do the opposite...right? LOL

I thought A/F and EGT's both kind of tell you how well the mixture is performing? :confused: The less fuel and more boost the higher the EGT's as in the higher the A/F's, right??

turbovanman²
01-12-2006, 10:47 PM
I thought A/F and EGT's both kind of tell you how well the mixture is performing? :confused: The less fuel and more boost the higher the EGT's as in the higher the A/F's, right??

Richer usually means lower EGT's as the flame is snuffed out with too much fuel.

John B
01-13-2006, 06:27 AM
Yes and no. The AFR gauge does that. The EGT gauge does too BUT it's readings are affected by other things besides the AFR: If the ignition timing is reduced EGT goes up. If the cam is retarded EGT goes up. I firmly believe you need both and should read the plugs religiously at the same time! Once you get your ignition and cam timing where you want them then your EGTs will tell you if you go richer or leaner. I tend to trust my EGT reading more than my AFR reading.

Dave
01-13-2006, 10:37 AM
So how do you feel about a Dawes Device A/F Lights? Is that good enough for propper tuning? I'm only looking for around 300hp out of the van, so should I invest in an EGT gauge? They are quite expensive.

Sorry to jack your thread Simon. :nod:

TrrboJeep
01-13-2006, 12:04 PM
I would definately invest in an EGT gage. :nod:

turbovanman²
01-13-2006, 01:00 PM
So how do you feel about a Dawes Device A/F Lights? Is that good enough for propper tuning? I'm only looking for around 300hp out of the van, so should I invest in an EGT gauge? They are quite expensive.

Sorry to jack your thread Simon. :nod:

Only 300hp, :yuck:

Anyhow, when I had my van on the dyno, the lights are bang on, the yellow is at the proper mixture, can't remember what reading specificilly but its good, :amen:

omnivore
01-13-2006, 03:48 PM
What I don't think you are getting is that the A/F ratio can be good enough for the A/F gauge to read rich, but still not rich enough to keep the EGT's low enough so as not to melt pistons etc. This condition is something that the A/F gauge cannot keep you informed about. A rich fuel misture burns cooler than a lean one-so a rich condition is a safegurad against piston damage.

As a testament to this, Lyle Reid (turbonation.com) was racing his minivan. 27 psi, dual stock intercoolers,ET was a 14.6 on stock Mits turbo, full green on the A/F gauge- results were 4 melted/broken pistons in one 1/4 mile pass.

My car makes a max of 230-240 hp, and even at this point, an EGT gauge is essential. Shooting for 300 hp, I say it is an absolute must-unless you own stock in a piston company. You are looking at more than double the stock power output, and you think a $120 EGT gauge is too much $$ to monitor the mess? That'd be like whining that you might need expensive gauges in a 750 hp Corvette,LOL

Dave
01-14-2006, 12:44 AM
Hmm well did Lyle Reid have a common A/F gauge? We use a narrowband O2 sensor so the reading stays usually 1 volt less which results in an incorrect reading.

But I will definately try to invest in an EGT gauge.

SpoolinGLH
01-14-2006, 10:53 PM
Bryan,

I use both a dawes device and a digital egt gauge from FM and the dawes device is really nice, because its so easy to read. Like simon said yellow is proper fuel mixture. But i would also recommend the egt because its really nice to know whats REALLY going on in there...plus the egt will let you fine tune easier as well.....

John B
01-15-2006, 04:14 AM
You don't have to spend a huge amount either. Look at the WSK2C2 EGT gauge and sender for $57.00 from airstuff.com in clamp on or threaded.;)

SpoolinGLH
01-15-2006, 04:37 AM
yeh but the digital guauge is nice because its easier to read,faster response,and you can have it hold on your max temp......