Ceramic Coating and EGT

[contraption22]

I have my EGT probe in the "collector" area, just before the turbine inlet on my TU Hybrid header. It is ceramic coated. What effect do you think this would have on EGT readings?

[johnl]

Don't know about the ceramic part but I got higher than typical readings, often 1600*F, with the probe in the same place - centered just before the flange. With appropriate fuel, played with ignition and cam timing to try to bring it down, never could.

[contraption22]

I am having the same issue. Didn't think so much about the placement of the probe, but I guess that is a pretty hot spot!

A quick google search netted this article by a DSM guy:

http://www.stevetek.com/R-EGTprobeLocation.html

[johnl]

I don't think ahead of the flange is wrong, just different from the "follow the crowd" idea that it should be in #4 or #3. Heck, ahead of the flange is almost #3 and close to #4.

So, you can do the 4 egt probes thing or you can send your injectors out to RC Engineering (or similar) for balancing, or you can measure their output yourself - all four at once - while hooked to your rail to ensure equal fuel.

Then you can explore the limits of "blended egt" - probably 1700ish* - that's where my last engine got tight. Regularly saw 1650. Got tight when I advanced timing to try to push the egt down. cause everyone said 1600+ was too high

[contraption22]

Actually on the TU header, the Turbine inlet is after 4. So it would be as close to sampling the average of all 4 cylinders. MY EGT only reads up to 1600... sure the needle goes past that, I THINK it's reading under 1700. My base timing is only at 10 degrees, so maybe I could advance it some.

[Austrian Dodge]

try advancing the timing a bit.
i'm running 13 degrees base timing, and very progressive timing curves and the needle goes up to 1550° at WOT (at only 12PSI of boost)

[cordes]

I have noticed that on my stock manifold with the probe between 2 and 3 in the boss that is there, my EGTs are consistently higher than what an engine should live at.

I really don't know what effect the coating would have on EGTs. I think that over a long enough time line (engine warmed up properly) there would not be significant reflection of heat enough to cause a difference.

[Stratman]

I've run thermal coatings since 2004 on ported exhaust manifolds and seen it run from 1600 to 1750 with a manifold coated inside and out.
My terribly built slow spooling hybrid turbo in 2004 would cause EGT's to shoot to 1700 and up withing seconds of WOT at 15 psi boost.
With the Super 70/stock turbine turbo it called down a bit to 1550 or so until I installed the race ported head which caused the EGT's to go up by about 100 degrees with the .63 housing. Cruising on the highway at 3500 RPM/65 MPH I would be at 1375-1425 depending on how much throttle I give it.
When I started advancing the timing in areas to find more power with the new head my EGT's came back down around 100-150 degrees when about 3-6 degrees of timing were added in areas of the RPM band.
Now with the 112 gas, 26-30 psi boost, and far more agressive timing I believe it continues to stay around 1600 or a little more and has always seem to like it there with no problems from the heat.

I have also seen the EGT needle fly quickly past the last mark of 1600 and probably ended up hitting around 1800 when I wasn't feeding it enough fuel and the ecu was retarding the hell out of the ignition timing.

Sensor located very close to the flage driver's side of manifold near #4.

[johnl]

Hey Mike, not sayin anything you don't know but be careful in advancing that timing. I mean the high EGTs haven't hurt anything yet, right?

[Stratman]

I found a good log. I remember having to add around 50 degrees to the log temp to be close to the guage reading. This is a log from my jacked up turbo. I can remember having to run pretty rich to keep detonation away at 18 psi of boost.

[Speedeuphoria]

Love that logworks Good question about the ceramic coating, I know I've hit 1700 when trying to get the knock sensor to work, it pulled timing because of false knock. Also I'm kinda leary of 1600 deg gauges, not sure how acurate they are when there maxed out

[contraption22]

Hey Mike, not sayin anything you don't know but be careful in advancing that timing. I mean the high EGTs haven't hurt anything yet, right?

You're right. They have not hurt anything yet. The A/F is safely rich and the plugs show no sign of trouble. But I'm wondering if the high EGT's could be a sign that more initial timing could be worth some more power.

[Stratman]

You're right. They have not hurt anything yet. The A/F is safely rich and the plugs show no sign of trouble. But I'm wondering if the high EGT's could be a sign that more initial timing could be worth some more power.

In my case it was worth more power, but I had to start running the race fuel to really get into the power I wanted to get out of this engine without the detonation. Unfortunately I don't have the EGT's hooked up to the Aux Box anymore so I can't show you what it's doing after tuning in close to 16 deg adv timing over stock in some areas using 112 leaded fuel to get the power up among the RPM band.

[Stratman]

Love that logworks Good question about the ceramic coating, I know I've hit 1700 when trying to get the knock sensor to work, it pulled timing because of false knock. Also I'm kinda leary of 1600 deg gauges, not sure how acurate they are when there maxed out

I seriously don't think it matters. I've had a 1500 deg guage and a my 1600 deg guage in just for the reason of not trusting one and both guages would still end up at around 1600-1650.

[contraption22]

In my case it was worth more power, but I had to start running the race fuel to really get into the power I wanted to get out of this engine without the detonation. Unfortunately I don't have the EGT's hooked up to the Aux Box anymore so I can't show you what it's doing after tuning in close to 16 deg adv timing over stock in some areas using 112 leaded fuel to get the power up among the RPM band.

I was using a fuel I don't normally use. They were outta c16 at the track, so I was using Q16... which is oxygenated. Maybe that's making a difference.

[Dusty_Duster]

Let's see if I remember any physics from college...

I don't think ceramic coating would affect your EGTs much. It will keep the rest of your engine from getting as hot, though. I suppose if anything, it might actually make your EGTs read a tiny bit higher since more heat is trapped inside the actual manifold.

[contraption22]

Well, I just read a tech bulliten about Q16 fuel. Looks to be some badass stuff. However when compared to C16, it requires 4-6% more fuel flow. So, perhaps thats where my high EGT's come in. It does say that the more efficient combustion should result in lower EGT's. So maybe I just need to add in some fuel when using this stuff. It also has a much higher resistance to detonation than C16, so I could get away with more timing.

Just sucks that I have to wait till spring to experiment with it.

Here is the tech info if anybody is interested. http://www.vpracingfuels.com/spec/Te...letin--Q16.doc

[Stratman]

Thanks for posting that Mike.

[contraption22]

No, thank YOU and all for repyling to my question.

[turbovanman²]

I am having the same issue. Didn't think so much about the placement of the probe, but I guess that is a pretty hot spot!

A quick google search netted this article by a DSM guy:

http://www.stevetek.com/R-EGTprobeLocation.html

Thats a good read. I am going to move my EGT probe.