EGT and 02 sensors

[ptuomov]

Can you get an EGT estimate from the new lambda sensors? Not a rhetorical question.

Bosch lambda sensors can provide a digital output to the ECU, an analog output to the data logger as well as measured sensor tip temperature. We use them all the time.

One less sensor bung in each primary then!

[Newold1]

Less bungs and devices but as I recall the Bosch O2 lambda sensors with temperature output are a tad more expensive than EGT sensors and require seperate data logging equipment. Most all current dyno programs are set up to read EGT and report from the pull. Still obviously need an O2 wide band sensor or two but not 8-Bosch Lambda data sensors and related recording equipment or programs. Obviously there are testing setups and facilities where this type of system and equipment is available and in use but for most of the masses it does not seem apparent. Maybe Superflow and DTS have their systems set up to take this O2 tip temp data input and data log it, I just have not been on a dyno setup like that yet.

[emsvitil]

From an aircraft viewpoint:

http://www.gami.com/articles/egt_myths.pdf

[hoodeng]

Aircraft are steady state engines and the article is very informative for pilots, it demystifies what the EGT in an aircraft is telling them.

With drag racing we are in a very short state situation, that is, our data samples are over a very short time, so what we are looking for in our data for arguments sake is steady O2 over the cylinders,if we have that and an even EGT at the end of the pass the engine is pretty sound in its tune ,if we have even O2 and quite a variance in the EGT start looking ,there will be a reason for it.

Cheers.

[Warp Speed]

Aircraft are steady state engines and the article is very informative for pilots, it demystifies what the EGT in an aircraft is telling them.

With drag racing we are in a very short state situation, that is, our data samples are over a very short time, so what we are looking for in our data for arguments sake is steady O2 over the cylinders,if we have that and an even EGT at the end of the pass the engine is pretty sound in its tune ,if we have even O2 and quite a variance in the EGT start looking ,there will be a reason for it.

Cheers.

The problem with EGTs, is that both the cylinder to cylinder AFR, and burn rate in each cylinder (timing) can be optimum, and the EGTs can still vary greatly!

[RCJ]

I want ask about a different subject.
WARP if you are trying defeat a restrictor plate, you want to add plates above and below to create a ventuir from the plate holes.As high a c/r as you can get?

[Newold1]

RCJ

Warp loves his job and I am sure he cannot divulge certain Nascar secrets, not if he wan'ts to stay live and keep working!

Warp, what is your reasoning or findings of why there will be such variation sensor to sensor in a calibrated set of 8 EGT's on a V-8 engine on the dyno??

[Warp Speed]

I want ask about a different subject.
WARP if you are trying defeat a restrictor plate, you want to add plates above and below to create a ventuir from the plate holes.As high a c/r as you can get?

Yes and yes to both with a flat plate type restrictor.

[Warp Speed]

RCJ

Warp loves his job and I am sure he cannot divulge certain Nascar secrets, not if he wan'ts to stay live and keep working!

Warp, what is your reasoning or findings of why there will be such variation sensor to sensor in a calibrated set of 8 EGT's on a V-8 engine on the dyno??

I really don't know. It kind of is what it is, and we really don't worry about it much.
I'm sure many here might be able to come up with some theories or studies related. In our deal, a common plenum and firing order can have an effect. Also, slight cooling/temperature variations from cylinder to cylinder probably have an effect also. Power production varies cylinder to cylinder, but EGTs don't seem to follow this either.......

[David Redszus]

Aircraft are steady state engines and the article is very informative for pilots, it demystifies what the EGT in an aircraft is telling them.

With drag racing we are in a very short state situation, that is, our data samples are over a very short time, so what we are looking for in our data for arguments sake is steady O2 over the cylinders,if we have that and an even EGT at the end of the pass the engine is pretty sound in its tune ,if we have even O2 and quite a variance in the EGT start looking ,there will be a reason for it.

Cheers.

EGT and O2 are not related. Or, more correctly, very loosly coupled.

A quick check for EGT sensor (and wiring or gauge) problems is to check pipe temperatures of a cold engine.

Drag racing poses some additional problems. All EGTs have a substantial delayed response, often as much as two or three seconds. For steady state testing this is not a problem. But for dyno sweeps or track passes, they are virtually useless.

As the linked article points out, gas temperatures are pulsed flows with variances in high temperature mass flows followed by longer periods at much lower ambient pipe temperature. They are not actual temperatures but merely time weighted averages; they should be mass weighted but are not. They are steady state devices.

[hoodeng]

My attempt at being succinct was not well worded. My shot at differentiating between steady state and a short burst of data was missing the point of how the information gathered was extrapolated to an engines running condition.
The article on aircraft EGT was more about not jumping to ill informed conclusions with what the gauges were reading. [The design of one gauge to not read numerically but on a scale was clever for its day as this was new territory] .

The data collected over a 6-7 second pass will not necessarily display the actual EGT due to data collection delay,,,but,,, if that data has a definitive effect on the time card, we will use the numbers that caused that effect, after a while we will see a trend in an engine that makes it a very happy camper in its category. The one we ran liked the numbers on two cylinders pretty much in line.

Dave, i understand the two are not related, and we need a lot of other parameters in line and confirmed before a link between the two streams of information is usable, but if our et is on track and the data even and repeatable we can make changes and see where they go [Down on the et hopefully!!] and not loose the tune of the vehicle.

Even the time of engine run before a pass can muddy the water, its the guy that can see through the mud that seems to kick goals..

Cheers.

[ptuomov]

Can you get an EGT estimate from the new lambda sensors? Not a rhetorical question.

Bosch lambda sensors can provide a digital output to the ECU, an analog output to the data logger as well as measured sensor tip temperature. We use them all the time.

How fast does that EGT signal from the WBO2 sensor react to the changes in the actual EGT?

[RednGold86Z]

Widebands (that I use) have sensor element temperature readings but are heated to a specific temperature by the controller, so I doubt it's very good at reading EGT.

I've only used EGT *tuning* to ensure exhaust valve longevity. When fuel economy or emissions matter, stoich may need to be used at conditions that will burn stuff up if held there long enough.

Otherwise, EGT just indicates whether or not the cylinder is firing or an injector is out of whack or something. It's too indirect for much else. Colder can mean too much fuel or too much timing - which is it? One way is safe, the other is not. Pulling fuel could lead to meltdown.

[David Redszus]

How fast does that EGT signal from the WBO2 sensor react to the changes in the actual EGT?

The EGT types that we use are fine wire open tip, which are the fastest of all thermocouples. But they are still very slow with a time constant of about 2.5 to 3.0 secs.

The thermocouples contained within the lambda sensor are buried and much slower to respond. In addition, the sensor tip is heated which can raise temperature but does not assist during the cooling period with closed throttle.

Somewhere I have actual collected data of EGT, rpm, Lambda, and Lambda tip temperature. Still looking.
What I do remember is EGT continued to increase while the engine was at full throttle, constant 10,000 rpm.
EGTs have a time parameter to consider as well as throttle position and engine rpm. But mostly, EGTs react synchronously with combustion timing, i.e. ignition timing, combustion peak pressure angle.

[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.