EGT Observation. Lower on Dyno than on Street
12-20-04, 03:16 PM
#1
Eats, Sleeps, Dreams Rotary
Thread Starter
EGT Observation. Lower on Dyno than on Street
So I went on a killer 300 miler in the twisties in AK and noticed something. I redlined 4th at 16psi once and and my EGTs got up to almost 1500F. On my Dyno run at 16psi It barely saw 1200F...
What do you make of this and what do you consider an unsafe EGT?
What do you make of this and what do you consider an unsafe EGT?
12-20-04, 07:05 PM
#3
Eats, Sleeps, Dreams Rotary
Thread Starter
Originally Posted by Jason
Did you dyno on a Dynojet? Driving on the street puts more load on the engine than spinning the rollers on a dynojet. I suppose that could lead to higher EGT's.
Jason
Jason
12-21-04, 04:47 PM
#6
Eats, Sleeps, Dreams Rotary
Thread Starter
Originally Posted by jeff48
Apnea
Are your egts Post turbo and if so, where is it mounted.
Are your egts Post turbo and if so, where is it mounted.
Originally Posted by eViLRotor
Isn't it a given that you will run slightly leaner once you are out on the street after tuning on a DynoJet, rather than an eddy current dyno like the Mustang?
Leaner would mean slighly higher EGTs...
Leaner would mean slighly higher EGTs...
Last edited by apneablue; 12-21-04 at 04:50 PM.
12-21-04, 06:30 PM
#7
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Driving around elevates EGT's due to heat soak.
Remember, everything is more hot, especially if the engine went into closed-loop mode.
Closed-loop allows the hottest burning mixture.
Most likely on the dyno, you had the car sitting there for a while before you ran it.
Due to rest, you don't have the heat soak associated with normal driving, so you'll see anywhere up to 200F to 300F cooler EGT numbers on the dyno.
1200F is like 650C, and that's pretty damn cold, dyno or no dyno.
I used to regularly see a little over 700C post turbo, and this equate about 1300F.
Is your car tuned?
Absolute highest with a post turbo EGT should not exceed 900F or about 1650F.
At 1500F, you're still fine.
-Ted
Remember, everything is more hot, especially if the engine went into closed-loop mode.
Closed-loop allows the hottest burning mixture.
Most likely on the dyno, you had the car sitting there for a while before you ran it.
Due to rest, you don't have the heat soak associated with normal driving, so you'll see anywhere up to 200F to 300F cooler EGT numbers on the dyno.
1200F is like 650C, and that's pretty damn cold, dyno or no dyno.
I used to regularly see a little over 700C post turbo, and this equate about 1300F.
Is your car tuned?
Absolute highest with a post turbo EGT should not exceed 900F or about 1650F.
At 1500F, you're still fine.
-Ted
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12-21-04, 06:56 PM
#8
Eats, Sleeps, Dreams Rotary
Thread Starter
Originally Posted by RETed
Driving around elevates EGT's due to heat soak.
Remember, everything is more hot, especially if the engine went into closed-loop mode.
Closed-loop allows the hottest burning mixture.
Most likely on the dyno, you had the car sitting there for a while before you ran it.
Due to rest, you don't have the heat soak associated with normal driving, so you'll see anywhere up to 200F to 300F cooler EGT numbers on the dyno.
1200F is like 650C, and that's pretty damn cold, dyno or no dyno.
I used to regularly see a little over 700C post turbo, and this equate about 1300F.
Is your car tuned?
Absolute highest with a post turbo EGT should not exceed 900F or about 1650F.
At 1500F, you're still fine.
-Ted
Remember, everything is more hot, especially if the engine went into closed-loop mode.
Closed-loop allows the hottest burning mixture.
Most likely on the dyno, you had the car sitting there for a while before you ran it.
Due to rest, you don't have the heat soak associated with normal driving, so you'll see anywhere up to 200F to 300F cooler EGT numbers on the dyno.
1200F is like 650C, and that's pretty damn cold, dyno or no dyno.
I used to regularly see a little over 700C post turbo, and this equate about 1300F.
Is your car tuned?
Absolute highest with a post turbo EGT should not exceed 900F or about 1650F.
At 1500F, you're still fine.
-Ted
At least now I have an idea of what to look for on the street (and what to set my peak warning on my EGT.)
12-21-04, 10:20 PM
#9
Lives on the Forum
Originally Posted by apneablue
Yes, car was tuned...Runnig really rich at about 10.3 right now. Here's the video of the EGT run after the dyno
That is pretty darn rich.
At least now I have an idea of what to look for on the street (and what to set my peak warning on my EGT.)
If you want absolutely maximum EGT, 1600F to 1650F would be good.
If you set it to warn you of unsafe EGT's under WOT (like around 1550F) , it's going to be constantly triggering when you're in cruise with leaner EGT's.
-Ted
12-21-04, 10:33 PM
#10
Eats, Sleeps, Dreams Rotary
Thread Starter
Originally Posted by RETed
Man, your spark plugs must come out black!
That is pretty darn rich.
It depends...
If you want absolutely maximum EGT, 1600F to 1650F would be good.
If you set it to warn you of unsafe EGT's under WOT (like around 1550F) , it's going to be constantly triggering when you're in cruise with leaner EGT's.
-Ted
That is pretty darn rich.
It depends...
If you want absolutely maximum EGT, 1600F to 1650F would be good.
If you set it to warn you of unsafe EGT's under WOT (like around 1550F) , it's going to be constantly triggering when you're in cruise with leaner EGT's.
-Ted
See thread here for some photos of my plugs and the plug cleaner. I am running greddy race plugs in the leading because there was some ignition breakup during tuning (still stock ignition)
12-22-04, 03:24 AM
#12
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Top row...
1st left - normal, but it looks like you use a lot of additives in the gasoline?
middle and right - too rich
middle row, spark plug by itself - too rich
bottom row...
left - cannot tell, too much flash
right - normal
Your plugs should come out black with some ting of tan, like the "normal" plugs look like.
The plugs should come out flat black / sooty, and the black soot should rub off with your fingers.
-Ted
Last edited by RETed; 12-22-04 at 03:27 AM.
12-22-04, 07:19 AM
#13
Eats, Sleeps, Dreams Rotary
Thread Starter
Originally Posted by FD2Envy
and what, by chance, were those dyno numbers (hp/tq) if you don't mind me asking?
Originally Posted by RETed
Top row...
1st left - normal, but it looks like you use a lot of additives in the gasoline?
middle and right - too rich
middle row, spark plug by itself - too rich
bottom row...
left - cannot tell, too much flash
right - normal
Your plugs should come out black with some ting of tan, like the "normal" plugs look like.
The plugs should come out flat black / sooty, and the black soot should rub off with your fingers.
-Ted
12-24-04, 02:56 AM
#14
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We try and run around 1600-1700deg F measuring pre! turbo, a couple inches
away from the rotor housing. I found that the EGTs I used to measure by the
O2 or turbo exit was a lot lower temp and false. We run on the roads at
30psi and try to keep the egts @ 1600F.
away from the rotor housing. I found that the EGTs I used to measure by the
O2 or turbo exit was a lot lower temp and false. We run on the roads at
30psi and try to keep the egts @ 1600F.
Last edited by Xcessive; 12-24-04 at 02:58 AM.
12-27-04, 01:17 PM
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Originally Posted by Xcessive
We run on the roads at 30psi and try to keep the egts @ 1600F.
A couple of ?s for you.
What RPM range @ 30psi (like 3K-7K? etc)?
Street or Race Gas?
What AFR's at 30psi/rpm
What is the temp differential between your front and rear housings?
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