egt probe placement

[Darkapollo]

Ive been thinking of where to put the egt probe on my hybrid. I noticed the egr port on the side of the head and i can easily make a plate to mount the probe to.
only issue i see is it is only seeing heat from one cyl. but will that really make that much differance?

[puppet]

I'll get the ball rollin' ... put it in the swing valve close to the O2 sensor. If it burns off it can't go through the turbo. Temps are a little cooler here but not a bunch ... maybe 50-75*F. Easy to get at ... yadda yadda.

[cordes]

I'll get the ball rollin' ... put it in the swing valve close to the O2 sensor. If it burns off it can't go through the turbo. Temps are a little cooler here but not a bunch ... maybe 50-75*F. Easy to get at ... yadda yadda.

Depending on the car I would bet that there is a large pressure differential between the SV and turbine housing. Either way it would throw off the readings one would shoot for compared to 99% of the rest of us.

[puppet]

Depending on the car I would bet that there is a large pressure differential between the SV and turbine housing. Either way it would throw off the readings one would shoot for compared to 99% of the rest of us.

Maybe so ... but you really can't do a direct egt comparo between different engines anyway ... at least how I see it. The way I use an egt reading to fine tune my A/F, timing differs from some peoples way anyhow. A guy just needs a consistent reading .. low or hgh(er) doesn't really matter much.

Once the tune is set-up it is what it is (temp). Respect that and your good.

[cordes]

I just wouldn't want to go through the process of finding out what my max safe EGT would be with it in the SV. Hearing the engineers at SDAC 17 speak about EGTs at length has me very content with shooting for 15-1600* as long as the probe is anywhere in the manifold or turbine housing.

[turbovanman²]

I just wouldn't want to go through the process of finding out what my max safe EGT would be with it in the SV. Hearing the engineers at SDAC 17 speak about EGTs at length has me very content with shooting for 15-1600* as long as the probe is anywhere in the manifold or turbine housing.

Please elaborate.

[cordes]

Please elaborate.

All the main points are pretty much covered in the SDAC 17 tech session thread I started after we got home. However they said to shoot for 1600*F and that the temp shouldn't vary enough anywhere in the manifold or entrance to the turbine housing to get results which would be out of the normal margin of error of the probes. They also said that to tune for those EGTs one should load the car for up to a minute by dragging the brakes to keep the motor at a constant RPM at WOT and monitoring the gauges.

Having adopted much of their advice, I can say that it is a great way to tune if you have a nice stretch of straight road near you. I have all that I can handle so it works very well for me.

[puppet]

I just wouldn't want to go through the process of finding out what my max safe EGT would be with it in the SV. Hearing the engineers at SDAC 17 speak about EGTs at length has me very content with shooting for 15-1600* as long as the probe is anywhere in the manifold or turbine housing.

Not to try and talk you into anything put have you tried an egt placement in the SV? I've had them in the manifold ... several spots in fact and in the SV. Actual temperature difference isn't that great. 50-75*F normally ... maybe 100* under extreme conditions. I know what has been "folk lore" concerning placement and temperatures over the years but it seems to be a bit overstated.

[turbovanman²]

Not to try and talk you into anything put have you tried an egt placement in the SV? I've had them in the manifold ... several spots in fact and in the SV. Actual temperature difference isn't that great. 50-75*F normally ... maybe 100* under extreme conditions. I know what has been "folk lore" concerning placement and temperatures over the years but it seems to be a bit overstated.

Again, more great info, thanks.

[cordes]

Not to try and talk you into anything put have you tried an egt placement in the SV? I've had them in the manifold ... several spots in fact and in the SV. Actual temperature difference isn't that great. 50-75*F normally ... maybe 100* under extreme conditions. I know what has been "folk lore" concerning placement and temperatures over the years but it seems to be a bit overstated.

That is very interesting. I haven't put one there nor have I heard it recommended before. 50* is well within what the guys at the tech session suggested was normal for variation between probes...

[puppet]

I know ... and the minor difference surprised me too. At any rate, it works just fine there for me.

[moparloper]

From my understanding it's not so much the slightly lower temp readings it's the reaction time for the probe. When you see 1600* at the manifold it's time to shut it down, but by the time the SV (or elbow, IE diesels) gets to 1550* it can be too late.

[puppet]

... it's the reaction time for the probe. When you see 1600* at the manifold it's time to shut it down, but by the time the SV (or elbow, IE diesels) gets to 1550* it can be too late.

Good quality probes take literally tenths of a second to react to temperature changes. Remember though, you're only reading an average of four cylinders. If it had to be perfect, you'd be running four probes near the head.

[moparloper]

It's not the time it takes for the probe to react to temp variances, which is dependent on; percentage of the temp variance, velocity of the medium, controller, wire size and junction termination which can add up to a second or two. I was stating it's the differance in time between exhaust temps in the manifold to be 1600* and the exhaust temps in the SV to reach 1550*after they pass through a huge oil and possible water cooled heat sink. Yes, optimal placement would be a probe for each exhaust port, second best is placement in the manifold near the flange. The SV may be the easiest but least effective.

[contraption22]

I've gotten frustrated with EGT's just because everybody says that 15-1600 EGT's are the safe ceiling. I routinely peg my EGT guage past the 1600 mark and the plugs always look fine and the car runs strong. I just tune by the wideband and the knock sensor.

[cordes]

I've gotten frustrated with EGT's just because everybody says that 15-1600 EGT's are the safe ceiling. I routinely peg my EGT guage past the 1600 mark and the plugs always look fine and the car runs strong. I just tune by the wideband and the knock sensor.

How many seconds would you say you have the gauge pegged like that? Also, are you running forged pistons? Where do you have the bung placed, and is it welded in? I have experienced the same thing as you in my shadow, but I'm curious to hear of your experiences.

[contraption22]

The probe is threaded into my TU SS header just before the turbine inlet. I would say the guage is pegged any time I am at full boogie. Yes I am running forged pistons.

[cordes]

The probe is threaded into my TU SS header just before the turbine inlet. I would say the guage is pegged any time I am at full boogie. Yes I am running forged pistons.

Thanks. My shadow would run at 1500*+ in cruise with my gauge, but I wasn't sure if I was the only one or not. I don't know that I would want to try that for minutes at a time, but it stayed alive.

[contraption22]

Thanks. My shadow would run at 1500*+ in cruise with my gauge, but I wasn't sure if I was the only one or not. I don't know that I would want to try that for minutes at a time, but it stayed alive.

I think EGT's that hot under cruise are normal and are really not a concern because you're not under heavy load.

[cordes]

I think EGT's that hot under cruise are normal and are really not a concern because you're not under heavy load.

That's the conclusion I was forced to come to with the shadow when I had an EGT in there. My omni never sees those EGTs at cruise though. It is an entirely different animal EGT wise actually. I have two theories for this, one being 2.5 vs. 2.2, but more likely a cal with way too much timing causing it to be pulled all the time.