Where to install the thermocouple? Before or after the turbo?

[HerbW]

Hello wealth of knowledge friends, I'm ordering the gauges this week and am trying to decide where to put the thermocouple. On the elbow after the turbo is a casting that looks like it was made just for tapping. Before I saw that I was going for the exaust manifold. It looks like a great location and it should last longer due to it being cooler there. Any ideas? Thanks, Herb

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'96 4x4 Dodge Cummins Truck,Smitty built running boards,AT,CD plr,Gemtop steel canopy basically stock and Polar white in color. Only 50 k miles and my cat now hangs in the barn while I "test" my exaust! Next "bomb" item is gauges and plates!!

 

[LSMITH]

I would recommend putting it in the manifold. After the turbo the readings you get are not very precise. I would like to have one in both places, pre-turbo for driving and towing and post turbo for shutdown temps, but have not put the post probe in yet.
Edit: I see in your signature that you are going to get a pump plate, the only way to go will be in the exhuast manifold. Don't take any chances.

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99 2500 QC 4X4 AUTO SB 24V LARAMIE SLT 3. 5 LSD 285-75-16'S SPA Boost/EGT Everything but leather NRA Member Great Lakes TDR Member

[This message has been edited by LSMITH (edited 04-15-2001). ]

 

[Bob Wagner]

Pre turbo and it will last for years...

 

[SlyBones]

Originally posted by LSMITH:
I would like to have one in both places, pre-turbo for driving and towing and post turbo for shutdown temps

Anybody,
How come post turbo for the shutdown temps? Are post turbo readings always lower than pre turbo? And finally, what about the ole post turbo rule of 10 degrees per pound of boost. -- Meaning if you are at idle and there is no boost, then there should be no difference, pre and post turbo are the same or very close?

 

[Missouri Mule]

If your going to be lugging things up long hills pre turbo is the best place.

 

[Champane Flight]

You guys can,t convince me to put anything pre turbo. I just can't think of a advantage of a probe going through a turbo. I use the old method of 100'per inch. Had a old diesel mech tell me this many,many,years ago. If you really think pre turbo temps are correct,remember that you are getting a hotter temp than at the turbo. Either way is not accurate to a point.

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95 Dodge 2500 Luverne grill guard,headache rack,running boards and Amzoiled. Soon to be mildly bombed. 84 Dodge d-150, 318 Hooker headers,Edelbrok intake,mallory ignition,Carter Afb,Accel coil,and Custom dual exhaust. Boat,fifthwheel,motorcycles,and shop. 72000 as of 3/1/01,not even broke in yet. Old Dodge 126000 miles and running better than new.

 

[Ted Jannetty]

Champagne, I totally disagree, the hotter temps are before the turbo, and you can't possibly predict pre turbo temps, by measuring post turbo temps.
The whole reason you want to know EGT is to stay out of PISTON MELTING situations.
The only accurate mehtod of measuring EGT is Pre Turbo.


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Ted Jannetty, Owner President, Jannetty Racing Enterprises, Inc.
97 3500 4x4 club cab 5spd. RED, JRE custom power kit, JRE 4" exhaust
JRE 1/2 inch fuel system, Bosch 300 hp injectors, Prime loc,
Cummins chrome kit, US Gear 20% over drive, 3. 54 posi, Autometer
Ultralite 50lb. boost, and Pyrometer, BD exhaust brake.
Horton fan clutch

99 Ski-Doo 800 Formula III Pipes, reeds, studs and clutching 172 hp
99 Honda Forman 450 ES jet kit, pipe, lift kit, 27" Mud Runners
2001 Ski-Doo MXZ 800 X stock for now 140 hp
2000 TransAm Ram Air WS6 Flowmaster, K&N, Granatelli Mass air meter, LS1 Lid 370 hp
1973 Camaro Rally Sport Street Strip 850+ HP

 

[gchas]

Pre-turbo is the way to go. No need to disconnedt the turbo for this procedure. It's a fairly straightforward installation process if the directions are carefully followed. I used grease on a magnatized drill bit to minimize metal shavings falling into the manifold while tapping, then probed the interior afterward with a magnet before installing the thermocouple, but got very few metal particles. Good luck.

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'97 Ext. Cab 2WD 35K mi,5 Sp Man 3. 54, ISSPRO Pyrometer & Boost

 

[Champane Flight]

I always was of the idea that the idea of having a pryometer was to protect from turbo damage,not piston meltdown. Most people are not fueling to a point of internal engine damage. The reason I run a pyrometer is to prevent coking of turbo bearing by not shutting down before cool off and of course keeping a eye on engine performance. If I am fueling to the point of piston meltdown,I would mount at each cylinders exhaust port. I just don't think you gain anything by putting a probe pre turbo to burn and go through the turbo. Especially when you can estimate and figure preturbo temps within 200' with post turbo readings. If I was to want to be exact you could mount pre and post and after baseline readings pull the pre and plug it.

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95 Dodge 2500 Luverne grill guard,headache rack,running boards and Amzoiled. Soon to be mildly bombed. 84 Dodge d-150, 318 Hooker headers,Edelbrok intake,mallory ignition,Carter Afb,Accel coil,and Custom dual exhaust. Boat,fifthwheel,motorcycles,and shop. 72000 as of 3/1/01,not even broke in yet. Old Dodge 126000 miles and running better than new.

 

[Steve M]

I have my pyro in the elbow where the dimple is made for it. My truck's not bombed so I'm not concerned with pre-turbo temps. 850 is the highest I've seen post turbo while towing up a grade. Shutdown is important and the turbo retains some heat that's measured post turbo and goes un-noticed pre-turbo while idling for cooldown. Probably not much but the turbo is what I'm wanting to monitor.

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98 2500 CC SB 4X2 12v 5spd 4. 10, -silencer, AFC+20, Edelbrock IAS, VDO gauges, Reese 15k Classic
97 Dodge Stratus 150HP
92 Harley Fatboy, Dynojet fuel management, Supertrapp 2-1
00 Jayco 25' 5th wheel, single slide

 

[Champane Flight]

Thats exactly what I am talking about. If you add three inches of space between the dimple or probe to the center of the turbo,you will have a high temp(stock machine)of 1150'at the turbo and another inch to the manifold 1250' . That is close to what a stock machine runs. I do agree if you are bombing to a 300-400+hp range you should have both pre and post.

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95 Dodge 2500 Luverne grill guard,headache rack,running boards and Amzoiled. Soon to be mildly bombed. 84 Dodge d-150, 318 Hooker headers,Edelbrok intake,mallory ignition,Carter Afb,Accel coil,and Custom dual exhaust. Boat,fifthwheel,motorcycles,and shop. 72000 as of 3/1/01,not even broke in yet. Old Dodge 126000 miles and running better than new.