EGT and 02 sensors

[Kevin Johnson]

How about the measured EGTs? Many sensors that we’ve tried have so much lag that they are really only informative in steady state constant rpm tests.

https://web.ornl.gov/sci/transportation ... h/engines/ Researchers at a national lab might be easier to approach for suggestions on rapid EGT sensors than a private company. They might repeat back what you have already discovered. That being said, be sure to contact AVL.

[ptuomov]

How about the measured EGTs? Many sensors that we’ve tried have so much lag that they are really only informative in steady state constant rpm tests.

https://web.ornl.gov/sci/transportation ... h/engines/ Researchers at a national lab might be easier to approach for suggestions on rapid EGT sensors than a private company. They might repeat back what you have already discovered. That being said, be sure to contact AVL.

I meant to ask how fast reacting EGT signal can you process from Bosch wideband sensor outputs?

[David Redszus]

How about the measured EGTs? Many sensors that we’ve tried have so much lag that they are really only informative in steady state constant rpm tests.

ALL EGTs that we have bought or built have significant time constants; they are slow to respond to large changes in temperature. Your observation regarding their use only in steady state conditions is correct.

I found the data file containing lambda, Lambda tip temp, EGT, and rpm.
The data confirm the slow response of the EGTs to changes in throttle.

However, the data was collected over CAN and sampled at 10 Hz which obscured the response time for temperature. In addition, the mixture cycled lean with throttle lift which altered EGT but not Lambda tip temp which was inversely coupled.

The more data we collect, the less we understand.

[Matt Cramer]

How about the measured EGTs? Many sensors that we’ve tried have so much lag that they are really only informative in steady state constant rpm tests.

The data logs I've looked over from drag passes and dyno pulls where EGT was logged - anywhere from 10 to 100 Hz depending on the setup - generally show you won't get the real, steady state temperature values in these conditions at all. But you do get enough data to use the EGT probes for checking cylinder to cylinder variations. If one cylinder's graph went slightly higher than the others during a run, chances are that cylinder needs more fuel. Cylinder abruptly has its temperature starting to drop? Dead cylinder, most likely not getting fuel or a valvetrain issue. A very abrupt rise can mean the fuel is burning in the exhaust rather than the cylinder. Just like with tuning in a steady state, the value is more in using the EGTs as a secondary tuning tool and comparing what one cylinder is doing relative to its neighbors.

Some ECUs also have the ability to shut down the engine or shut down a cylinder in the event of runaway temperature readings.

[David Redszus]

How about the measured EGTs? Many sensors that we’ve tried have so much lag that they are really only informative in steady state constant rpm tests.

The data logs I've looked over from drag passes and dyno pulls where EGT was logged - anywhere from 10 to 100 Hz depending on the setup - generally show you won't get the real, steady state temperature values in these conditions at all. But you do get enough data to use the EGT probes for checking cylinder to cylinder variations. If one cylinder's graph went slightly higher than the others during a run, chances are that cylinder needs more fuel. Cylinder abruptly has its temperature starting to drop? Dead cylinder, most likely not getting fuel or a valvetrain issue. A very abrupt rise can mean the fuel is burning in the exhaust rather than the cylinder. Just like with tuning in a steady state, the value is more in using the EGTs as a secondary tuning tool and comparing what one cylinder is doing relative to its neighbors.

Some ECUs also have the ability to shut down the engine or shut down a cylinder in the event of runaway temperature readings.

EGTs are not very responsive to changes in mixture; they should not be used for fuel tuning. They are much more responsive to changes in timing, either ignition timing or combustion timing. They can be used to determine cylinder to cylinder balance.

EGTs do not present actual exhaust gas temperatures. They present a time weighted average of pulsed temperatures.

As Matt indicated, combustion in the exhaust header is common and alters exhaust pipe tuning considerably.
But high EGTs are not normally detrimental to piston survival while low EGTs can indicate pre-ignition issues.

[ptuomov]

I understand that the sensor measurement is something like an exponentially weighted moving average of the actual temperatures that the sensor tip is exposed to. The sensor tip is going to have some thermal inertia.

It may also be the case that the true (cycle average) exhaust gas temperature only reaches its steady state slowly after, say, a load change. In fact, I'd be surprised if this weren't the case, as the exhaust port, etc. have thermal inertia.

The question is how to get handle on the magnitudes?

[David Redszus]

I understand that the sensor measurement is something like an exponentially weighted moving average of the actual temperatures that the sensor tip is exposed to. The sensor tip is going to have some thermal inertia.

It may also be the case that the true (cycle average) exhaust gas temperature only reaches its steady state slowly after, say, a load change. In fact, I'd be surprised if this weren't the case, as the exhaust port, etc. have thermal inertia.

The question is how to get handle on the magnitudes?

To which parameter magnitudes do you refer?
We have tons of EGT data. Is the engine NA or boosted?

I have written a piece on TC response time. Let me know if you would like to read it.

One of Blairs students did a paper on using measured EGT values to determine actual pipe temperatures.

[ptuomov]

I understand that the sensor measurement is something like an exponentially weighted moving average of the actual temperatures that the sensor tip is exposed to. The sensor tip is going to have some thermal inertia.

It may also be the case that the true (cycle average) exhaust gas temperature only reaches its steady state slowly after, say, a load change. In fact, I'd be surprised if this weren't the case, as the exhaust port, etc. have thermal inertia.

The question is how to get handle on the magnitudes?

To which parameter magnitudes do you refer?
We have tons of EGT data. Is the engine NA or boosted?

I have written a piece on TC response time. Let me know if you would like to read it.

One of Blairs students did a paper on using measured EGT values to determine actual pipe temperatures.

Turbo V8 with cast iron exhaust manifolds.

Yes, please!

[David Redszus]

I understand that the sensor measurement is something like an exponentially weighted moving average of the actual temperatures that the sensor tip is exposed to. The sensor tip is going to have some thermal inertia.

It may also be the case that the true (cycle average) exhaust gas temperature only reaches its steady state slowly after, say, a load change. In fact, I'd be surprised if this weren't the case, as the exhaust port, etc. have thermal inertia.

The question is how to get handle on the magnitudes?

To which parameter magnitudes do you refer?
We have tons of EGT data. Is the engine NA or boosted?

I have written a piece on TC response time. Let me know if you would like to read it.

One of Blairs students did a paper on using measured EGT values to determine actual pipe temperatures.

Turbo V8 with cast iron exhaust manifolds.

Yes, please!

Please PM your email address.

[Firedome8]

To which parameter magnitudes do you refer?
We have tons of EGT data. Is the engine NA or boosted?

I have written a piece on TC response time. Let me know if you would like to read it.

One of Blairs students did a paper on using measured EGT values to determine actual pipe temperatures.

Turbo V8 with cast iron exhaust manifolds.

Yes, please!

Please PM your email address.

Has infrared ever been utilized to record exh. temp ?

[David Redszus]

Turbo V8 with cast iron exhaust manifolds.

Yes, please!

Please PM your email address.

Has infrared ever been utilized to record exh. temp ?

We have used infrared to measure the outside wall temperature of pipes but not exhaust gases.

[jake197000]

i found egt very helpful when running highly modified big bore two strokes in quarte mile drags on ice.always read my plugs and bore scoped my pistons.wasnt trying to get air fuel readings from them but it got too hot there was a fine line from burning one down or not.having my pistons heads and pipes coated was one of the best things i did.keep that heat in the chamber so you can use that expansion to push that piston down.not to mention the improved scavaging.spelling sorry.

[David Redszus]

i found egt very helpful when running highly modified big bore two strokes in quarte mile drags on ice.always read my plugs and bore scoped my pistons.wasnt trying to get air fuel readings from them but it got too hot there was a fine line from burning one down or not.having my pistons heads and pipes coated was one of the best things i did.keep that heat in the chamber so you can use that expansion to push that piston down.not to mention the improved scavaging.spelling sorry.

Can you please explain how you used EGTs to be useful to you?

[jake197000]

because at least on 2 stokes,if the egt jumped up you could burn her down before you could get off the throttle.i had a data logging system and melted enough pistons to know.you didnt have time to look at it going 150

[jake197000]

lean is fast.until it melts.