EGT Probe

[GBurton]

I give up, pre-turbo or post-turbo, that is the question? What I was told is if you go pre-turbo you are only measuring the temperature on one side of the exhaust system. If a problem developed on the other side of the exhaust system from the probe, you would not know about it. If you go post-turbo the reading is lower by about 300 degrees but you are measuring both sides.
How constant is the temperature drop across the turbo? It would seem to me that at higher boost pressures the turbo is doing more work. That means that it takes more energy to spin the turbo. Since heat is energy there could be a larger temperature differential across the turbo at higher boost pressures.

Comments both pro/con of both methods? smile.gif

George

[hoot]

Pre turbo gives you real EGT's. If you want both sides, put in two gauges/probes. SOme guys put in one gauge, two probes and a switch to go between the two.

I watch my egt's for load reasons, not so much if something goes wrong. Watching one side in my opinion is enough for me.

Post turbo to me is too far from what you really are measuring. Kinda like measuring the heat in your fireplace with a thermometer on top of the chimney.

[mackin]

GBurton ,

I am for pre-turbo.For the Most part it is most accurate...... I would rather now what temp is going in to make the correction (let UP) as to know those temps are present outer side of turbo ....... How much of a factor is it really to only monitoring one bank.....? If you were to loose a cylinder for various reason you would know guage or no guage..... The measuring side would show a sudden temp spike or drop...... In addition one could or would feel a performance drop in the seat of the pants...... Go pre-turbo so there is no approx. math involved ......

Next........


MAC :D

[ 07-10-2002: Message edited by: mackin ]</p>

[Maverick]

Go with pre-turbo. Put it in the manifold. Easy job. Unless you plan to modify the engine with 20K, for what 90% of us do here one side is acceptable.

[tmg115]

wait wouldn't pre turbo show a problem on the post turbo since it would heat up the pre turbo side?

[mowser]

For the "POST TURBO" side;....BANKS exhaust & gauges for BOTH my old "93" 6.5TD and for the new "2002" D/A are or were both post turbo.
Banks has been fooling around with TURBO'S for a long time and has a good reputation, so.... if it's good enough for BANKS it's good enough for me.
Having said that, "IF" I was flogging the SNOT out of my truck, you're right, I'd go PRE-TURBO................

I checked the BANKS website and someone asked the question where is the best place to put the EGT probe on the Duramax and they said the passenger side exhaust manifold. http://www.bankspower.com/Ask_Banks_Ans.cfm MORE POWER did an article on this installation......

;)

[ 07-15-2002: Message edited by: mowser ]</p>

[Southard]

Post turbo lets you know when the turbo is cooled enough to shut down. Pre turbo does not.

[Lawnboy]

The whole reason for a pyrometer is to prevent piston meltdown. They are your weakest link! By mounting the sending unit in the exhaust manifold (pre-turbo) you are getting the MOST accurate reading on the internal cylinder temperatures.

Not only are you getting a skewed reading by placing the sending unit POST-turbo, you are also getting a slower reacting reading.

[hoot]

I don't believe post turbo is the way to go. To get a good turbo temp reading, you need a pyro mounted on the turbo housing, not in the exhaust stream. You are compromising all readings by going post turbo.

[Brad Pelot]

Does anyone know the actual difference in the temp readings from pre turbo to post turbo? 300 degrees sounds high to me. I would think it would be around 100, just guessing though.

[SoMnDMAX]

I am running two pyro probes in my truck, both running to ther same gauge. I have a DPST toggle switch selecting the probe I want.

I've seen anywhere from 0 degrees difference to 400 degrees difference between the pre turbo and post turbo locations. Typically, once throttle and fueling has stabilized (i.e. cruise control activated), the difference is 200-250 degrees.

I will tell you this- go pre turbo. The gauge shows more of a real time sample of what's going on in the engine. Post turbo is delayed, and not the most accurate way to measure EGT.

[GBurton]

Thanks to all of you who responded to my question.

SoMnDMAX, it appears that you are the one with the answer that I was looking for. The temperature differential across the turbo does vary a lot with the load. That is what I expected to hear but without both gauges there is no way to tell. It appears that most of the folks that have an EGT gauge select either a pre and post turbo probes and run with it.

Since you have both probes can you do a bit of a test for me? When you have time can you record and post the two different temperature reading at some different throttle settings? say idle, half throttle and wide open. If you have the time to do this both on flat ground and when climbing a grade I think some people would be interested to see the differences.

I am going to go pre turbo on my vehicle.

George

[ 07-11-2002: Message edited by: GBurton ]</p>

[SoMnDMAX]

George, I'll be driving my truck to work tonight, and I'll record some numbers for all.

[YZF1R]

I believe Hewitt makes a dual probe 2" gauge. Check www.hewittindustries.com for a look. It's two gauges in one. Put a probe in each exhaust manifold.

Steve

[GBurton]

SoMnDMAX

Did you have time to record some numbers? smile.gif

George

[SoMnDMAX]

Idling- the same, about 200-250 degrees, both pre and post.

Cruising @ 60 MPH, 450 degrees post, 600 degrees pre. No wind, flat ground. A head wind or hills will increase the EGT. I have cruised @ 60 MPH with an EGT of 800 degrees pre turbo, with a 30 MPH head wind.

WOT- max of about 1400, pre turbo hangs at about 1000 degrees. There's so much variance, it's hard to track and get good numbers. The numbers vary from 1000-1400 degrees when accelerating pre turbo. Post turbo, they are much slower reacting, and lower- about 700-1000 degrees. After a hard accelleration run, occasionally the post turbo EGT will be 150-200 degrees hotter than pre turbo. Depends how hard the truck is loaded, and the duration of my foot being stuck to the floor.

All numbers are with the Juice set on #4. Stock trucks should see lower EGT numbers. I can only assume the differential in temp will stay the same when comparing pre to post turbo probe locations.

I have not had time to pull a grade yet. Here in south central MN, we don't have many hills, except in and out of the river valleys.

[ 07-13-2002: Message edited by: SoMnDMAX ]</p>

[GBurton]

SoMnDMAX
Thanks for taking the time to record and post those numbers.

George