Drilled wrong place for pyrometer!

[raxley]

I drilled exactly in the middle of the exhaust manifold and hit that segmented part. I can see where it is open on one side, but I will never get a pyrometer into it. I plan to tap the hole, put a plug in and eventually get another manifold. Maybe if I drill in the correct spot (and get it working), I will leave it for now (where is the best place to drill?). I plan to upgrade with another turbo and exhaust manifold soon (altho maybe a little sooner than I had expected)
I guess the discussion on aftermarket manifolds is 'lively'? I had a BD (think 3 piece) manifold and was happy with it (in my 3rd gen). I thought the idea of keeping the pieces independent, so they can expand and contract independently was a good idea. I hear some people have had leaks, though.
What is the 'deal' with the stainless steel manifolds? Are they any good, or is it too new to tell?
I'd appreciate any advice with your exhaust manifold choice, and why.

 

[Missouri Mule]

I take you drilled in the middle of the manifold going toward the turbo.
I will to look at my manifolds and see if it is off center or in the center of the manifold that heads toward the turbo.
If you drilled closer to the engine or down a little way you should be able to weld it and drill a whole in the correct place. But it seems you drilled the manifold close to engine. It seems a friend and I centered in the middle it about 4 to 6 inches from where the manifold started to head for the turbo.

 

[raxley]

I take you drilled in the middle of the manifold going toward the turbo.
I will to look at my manifolds and see if it is off center or in the center of the manifold that heads toward the turbo.
If you drilled closer to the engine or down a little way you should be able to weld it and drill a whole in the correct place. But it seems you drilled the manifold close to engine. It seems a friend and I centered in the middle it about 4 to 6 inches from where the manifold started to head for the turbo.

I drilled it in the exact center a little past where all the cylinders join together. I thought I would want an 'overall' temperature reading. Now that it's done, seems I remember something about drilling at the point that would 'cover' two cylinders.

I'm kind of doing my upgrades slightly on the 'economy' style, for right now. I'd like to get to the point where I've maxed out the turbo and need a upgraded turbo before I get another manifold too. I'm not too worried about what it looks like right now, but I'm a little chagrined that I drilled in wrong place. It's not apparent on top so much that it's segmented, but if you put your fingers underneath the manifold you can feel that it's split. I was drilling, drilling and drilling. I didn't understand why I hadn't gotten 'through' yet. I didn't 'feel' anything and I was almost an inch down. I didn't feel it going through (where the drill bit drops after penetrating one side) because it was solid where I was drilling (or 3/4 solid-about 1/4 of the 360 degrees was exposed into manifold.

It seems that the plug is working, when I started it I couldn't feel any air blowing when I put my hand around the plug. It didn't sound any differently either.

 

[cerberusiam]

As you found out the manifolds are divided, front 3 and rear 3 cylinders. You want to monitor the rear 3 cylinders as they run the hottest due to coolant, air flow, and stuffed under the cowling. You would drill in the middle of the back half or the manifold about 2" back of the flange for placement.

 

[GAmes]

What is the 'deal' with the stainless steel manifolds? Are they any good, or is it too new to tell?
I'd appreciate any advice with your exhaust manifold choice, and why.

I have a three piece, but if I were to buy a manifold now it would be a one piece stainless.

 

[raxley]

Thanks everybody for the information!

 

[Ken Bultman]

What do you think is wrong with the three piece manifold?

 

[GAmes]

It's a good, better, best deal to me. Good being stock, better being the 3 piece and stainless being the best. I might be wrong but I believe the stainless has smoother runners for air flow, plus I think they look better. It isn't a big enough deal to me to change now that stainless are available.

 

[Matt42]

I drilled exactly in the middle of the exhaust manifold and hit that segmented part. I can see where it is open on one side, but I will never get a pyrometer into it. I plan to tap the hole, put a plug in and eventually get another manifold. Maybe if I drill in the correct spot (and get it working), I will leave it for now (where is the best place to drill?). I plan to upgrade with another turbo and exhaust manifold soon (altho maybe a little sooner than I had expected)
I guess the discussion on aftermarket manifolds is 'lively'? I had a BD (think 3 piece) manifold and was happy with it (in my 3rd gen). I thought the idea of keeping the pieces independent, so they can expand and contract independently was a good idea. I hear some people have had leaks, though.
What is the 'deal' with the stainless steel manifolds? Are they any good, or is it too new to tell?
I'd appreciate any advice with your exhaust manifold choice, and why.

Where are you located? I have a low mileage 1996 manifold in the garage. I changed it out to a 3 piece when I thought the original had shrunk. It hadn't.

 

[Shadrach]

I had a stainless AFE on my 03 and liked it. Never had any issues with it.

 

[MN12valve]

Simplify your life here. If you really think you need to monitor exhaust gas temperature, put the thermocouple within a couple of inches of the turbine outlet. You just need to learn how to read it (just like other engine operating parameters). Yes, it is true the gas temperature is higher on the turbine inlet than the turbine outlet (2nd law thermodynamics), some work is done across the turbine. A turbocharger is a gas turbine with the Diesel engine as the burner. Also, you eliminate the risk of the thermocouple ending up in the turbine housing.
Many years ago Cummins Engine Co. sold and California Air Resources Board approved what was called a “smoke kit” for naturally aspirated NH-250 engines. This kit was essentially a turbocharger with a maximum boost of about 10”Hg. Part of this kit was a pyrometer that the kit instructions recommended be installed at the turbine outlet.

 

[GAmes]

We learned long ago that outlet temps are not nearly as accurate or as immediate as pre-turbo thermocouples. Several members who had duel EGT gauges reported that although 300 degrees was a ballpark average difference there could be a 100 degree difference or a 500 degree difference, and those differences were not immediate. We got over the thermocouple in the turbo phobia years ago. My thermocouple has been installed for over 1.2 million miles.

 

[cerberusiam]

You just need to learn how to read it (just like other engine operating parameters).

While that may be true, until there is a baseline for the difference between pre and post turbo post turbo is useless. One would have to install a probe in each location to get the difference to begin with, so at that point there is no reason to install post turbo as it is already done pre turbo where it is more accurate.


Post turbo EGT's are much more useful in low drive pressure high flow turbos where the differences are consistent and predictable. It doesn't work that way with the VGT turbos and definitely not with the emissions challenged 5.9 engines with high drive pressure turbos, the difference is too broad and variable to be accurate if one is looking to actually drive by an EGT gauge.

As far as a tip breaking off, there is about as much chance of that happening as blowing a head gasket and less chance than having an issue with a 53 block. If it does happen it is operator induced.

 

[MN12valve]

We learned long ago that outlet temps are not nearly as accurate or as immediate as pre-turbo thermocouples. Several members who had duel EGT gauges reported that although 300 degrees was a ballpark average difference there could be a 100 degree difference or a 500 degree difference, and those differences were not immediate. We got over the thermocouple in the turbo phobia years ago. My thermocouple has been installed for over 1.2 million miles.

GAmes. I certainly like the idea of monitoring exhaust gas temperature. It’s a good way to say something about engine load and thermal stresses. However, I must disagree with your analysis. Exhaust gas temps are a relative measurement. If you read the exhaust temp from the same place all the time then you have the appropriate reference. Accuracy? Accuracy compared to what? The accuracy of the thermocouple has nothing to do with its installed location. If your concern is accuracy or response time why not put a thermocouple at every exhaust port? Not practical for this application but commonly done in engine development. The truck drivers who drove those trucks back “in the day” knew how to read their pyrometer, in fact, they would shift gears according to the pyrometer. Lastly as far as the thermocouple going though the turbine, I will admit that is a rare event. But a catastrophic one to say the least. Maybe it hasn’t happened to you yet, but it has happened and will happen again.

 

[Bob4x4]

I guess I’ll jump in here.I ran 2 pyros on my modified 12 valve to prove a point to the 300 degree rule group.My findings were the 300 degree difference only happened on a flat road in steady state conditions.On a grade I saw up tp 600 degree difference.Upon accell the diff would depend on the level of power/load.
If I drove anything that could climb past a safe Egt level I would only use a pre turbo installation.To disspell the broken t/couple myth I have been working in the diesel field since 1985 and have yet to see 1 instance of that happening.That scare may have come from the way they are used post turbo in airplane applications-but remember also they are gas engines.

 

[MN12valve]

Gentlemen, I am new to TDR and respect the experiences and opinions shared here. Yes, even if they differ from my own. Moreover, when presented with analytical evidence I have changed my opinion.
Please recall that this tread started out with raxley trying to drill his exhaust manifold to accept a thermocouple. He shared that he was having a somewhat difficult time doing so. In fact, his difficulty came when he tried to center the pre-turbine hole in the manifold so he would be measuring the gas flow from all cylinders. Apparently the manifold casting doesn’t allow that. So you have to drill the hole on one side or the other so the gas flow that is measured comes primarily from 3 cylinders. Thus, as I suggested earlier, the only so called “accurate” way is to put 6 thermocouples. One at each exhaust port. What I am suggesting is far simpler (post turbine) and has been demonstrated to be useful on quite literally millions of heavy-duty diesel powered on-highway trucks over more than 70 years. I seem to recall that Caterpillar engines (at least in Peterbilts) provided a post turbine fitting that would accommodate a thermocouple. I must admit that a T of 600 degrees across the turbine is hard believe. Let’ say my diesel engine testing experience pre-dates 1985 by just a few years. I have tested numerous Diesel engines on an engine dynamometer including Caterpillar, Detroit Diesel (both 2 and 4 stroke) and several model Cummins engines (NH, NTC, V-903, VT-555, L-10, ISB, ISL, ISM, KTA). This testing was done primarily for exhaust emissions purposes in compliance with CFR 40 Part 86. In order to ensure test repeatability these engines were equipped with several pressure and temperature sensors as well as fuel flow and carbon balance from the gas analyzers. I'm certain that the electric dyno we used could load the the engine greater and quicker than the engine in a truck. In all this this testing I never saw anything like 600 degree difference across the turbine. In accepting your statement of a 600 degree difference my comment is “so what”. This temperature is irrelevant to the problem at hand. My opinion continues to be once you have established what the pyrometer says at peak engine torque and peak engine power then you have the relevant reference points whether the thermocouple is pre or post turbine housing.
Respectfully,

 

[Bob4x4]

The point I think you may be missing is that most of these ctds adding gauges are pushing the limit.They are not 11-12 liter engines designed to stay with in factory safe specs at full load.These are in many cases overfueled to the point they will melt pistons if not accurately monitored.The truck I used for an example could peg an 1800 degree pyro.
If we were talking about stock trucks the pyro would just be their to occupy space.

 

[leedonald5489]

Gentlemen, I am new to TDR and respect the experiences and opinions shared here. Yes, even if they differ from my own. Moreover, when presented with analytical evidence I have changed my opinion.
Please recall that this tread started out with raxley trying to drill his exhaust manifold to accept a thermocouple. He shared that he was having a somewhat difficult time doing so. In fact, his difficulty came when he tried to center the pre-turbine hole in the manifold so he would be measuring the gas flow from all cylinders. Apparently the manifold casting doesn’t allow that. So you have to drill the hole on one side or the other so the gas flow that is measured comes primarily from 3 cylinders. Thus, as I suggested earlier, the only so called “accurate” way is to put 6 thermocouples. One at each exhaust port. What I am suggesting is far simpler (post turbine) and has been demonstrated to be useful on quite literally millions of heavy-duty diesel powered on-highway trucks over more than 70 years. I seem to recall that Caterpillar engines (at least in Peterbilts) provided a post turbine fitting that would accommodate a thermocouple. I must admit that a [emoji667]T of 600 degrees across the turbine is hard believe. Let’ say my diesel engine testing experience pre-dates 1985 by just a few years. I have tested numerous Diesel engines on an engine dynamometer including Caterpillar, Detroit Diesel (both 2 and 4 stroke) and several model Cummins engines (NH, NTC, V-903, VT-555, L-10, ISB, ISL, ISM, KTA). This testing was done primarily for exhaust emissions purposes in compliance with CFR 40 Part 86. In order to ensure test repeatability these engines were equipped with several pressure and temperature sensors as well as fuel flow and carbon balance from the gas analyzers. I'm certain that the electric dyno we used could load the the engine greater and quicker than the engine in a truck. In all this this testing I never saw anything like 600 degree difference across the turbine. In accepting your statement of a 600 degree difference my comment is “so what”. This temperature is irrelevant to the problem at hand. My opinion continues to be once you have established what the pyrometer says at peak engine torque and peak engine power then you have the relevant reference points whether the thermocouple is pre or post turbine housing.
Respectfully,

I had a 1974 Cummings small cam 350 ,earlier ,and it had been turned up , I did not know it when I bought it , It would put 400 HP to the ground, there was ,one thing was to watch my PR . I never let it go over a set setting . There was one problem I had was it would eat linings , I had it re build in Bakersfield ,Ca. and the mania ice , sorry on speeding , I don't think he did a good job , I had to retro my JAKES my self , and less than a year in SEA World I had three liners gone again. I rebuild it my self , there , it was funny ,there was person help me get me the liners, a 400 pound York wrench , oil , antifreeze , and Cummings white antifreeze and other parts, I could not believe it , I be leave in Angles now , but back to the PR , there was place on the back spot of turbine you could put the PR , it was about 2" from back and you would get a great place to get the temperature , if think a bout it , it give you a reading of all 6 at once and if you think , it is better than 1 on each piston , off ecauste mana fold . And I watched my PR constantly , when I pulled a hill , I hope this helps ,I will be putting two on , 1 before & 1 be hind about 2" out from exhaust and on a 5.9 Cummings 12 valve .

 

[Joseph Donnelly]

Yes, the 300 deg. difference is just a rough estimate, and not to be relied upon with heavily fueled engines. I have experienced one broken thermocouple. It was post-turbo and the exiting turbine wheel and back half of the shaft tore it up as they roto-rootered their way through the downpipe, when the turbo blew up.