EGT response times

[Bush65]

the 3mm-6mm are both rated to 1100degrees Celcius so I expect them to be as strong enough

the one Ian supplies doesn't get into the gas stream though and sits in the EGT pocket, try removing it and have a look/feel inside the manifold, it is approx 55mm from the EGT plate to get into the flow from number 1-4 cylinders.

the temp difference on min when I modded the T/C was approx 50degrees C

so when I saw a 735 max I would have only seen high 600's and not eased up.

Turbo failure is lower on the expected failure list than a cracked exhaust manifold which has occurred twice pre EGT gauge on a friends 300TDI, same Turbo reused with no damage.

My manifolds are different (no egr provision) and the t/couple is in the gas stream.

Temperature rating does not prevent mechanical failure.

I do a lot of work for a large chemical plant, with many t/couples, but all are installed in thermowells. I don't get too involved with instrumentation details (as John B. does), because they have process and electrical/instumentation people for that.

[white90]

here are some real world figures for the 3mm/6mm T/C's

climbing the same hill reaching 640 degress then pulling over and waiting for the T/C to reach 200 degrees

3mm-1min 40sec

6mm-2min 6 secs

driving off on a level road from 200degrees to an indicated 520 degrees

3mm 22secs

6mm 35 secs

Mark(AKA Scrumps) made me a far better fitting for the T/C's

ignore the washers as these were in place till I cut the bolts down

OLD set up:

New improved design

no need for the T/C to be bent and so easily replaced/checked etc.

Edited December 14, 2005 by white90

[Turbocharger]

Ooh - now that I do like The response times look better to me too, gives more confidence in the readings you're getting. Is your peak temp any higher now? With a 6mm t/c I find I run out of road/hill/bottle before the readings level out, but I'm not sure if that shows the t/c hasn't reached the gas temp, or the gas temp hasn't stabilised (intercooler heatsoaking or similar).

[white90]

to get absoloute max I need to get a heavy trailer on the back then drive the steepest hill around here that is over 1mile long.

so far max on a fairly steep hill was 620 (3mm)which was an indicated 602 with the 6mm T/C fitted

PS I have a UK supplier for 3mm K type T/C inc fittings for very reasonable money(postage was steep mind)

I guess cheaper posting could be asked for.

the plate makes a world of difference though for ease of fitting plus the T/C is inserted to the rear of the maniold then drawn back 10mm so is dead centre of the gas flow for no1-4 cylinders directly above the turbo itself.

[white90]

Further testing results:

Flat road driven in 5th gear till gauge displayed 600 degrees then lift off throttle and let vehicle coast in gear till display showed 200 degrees still in 5th gear no throttle/clutch/brakes applied

the display took 20secs dead to drop the 400degrees

these results using the 3mm T/C

6mm T/C same test procedure as above

the diplay took 53 secs to drop the 400 degrees

max temp has hasn't changed and peak temp reached was 640 with the 3mm and 617 with the 6mm

this was the longest hill I could find, driven in 3rd/4th gear foot to the floor.

Edited December 14, 2005 by white90

[isuzurover]

A type K thermocouple will always give the same reading. They do not need to be calibrated. For a presise measurement you need a cold junction reference, but this is not a laboratory setting.

Although a K-type thermocouple will always give the same reading at a given temperature, it is not necessarily an accurate/correct reading and not necessarily the same reading that a diferent thermocouple would give. I was once involved in calibrating K-type hermocouples for high temperature applications. Most thermocouples are only calibrated at 0oC and 100oC. And when these are then used at 700oC or so they are often out by a few degrees (and this is for high precision thermocouples).

That said, for an EGT application, a thermocouple that is accurate to +/- 10oC at 600oC would be fine.

Edited December 14, 2005 by isuzurover

[will_warne]

Further testing results:

Flat road driven in 5th gear till gauge displayed 600 degrees then lift off throttle and let vehicle coast in gear till display showed 200 degrees still in 5th gear no throttle/clutch/brakes applied

the display took 20secs dead to drop the 400degrees

these results using the 3mm T/C

6mm T/C same test procedure as above

the diplay took 53 secs to drop the 400 degrees

max temp has han't changed and peak temp reached was 640 with the 3mm and 617 with the 6mm

this was the longest hill I could find, driven in 3rd/4th gear foot to the floor.

Very interesting results Tony, What suprises me is how low your max reading are. Were they done on Simex? I'm not running mud terrains at the moment (need to find a suitable size) but the max I've reached is about 680 (locked in third, foot welded to floor on overboost) on a long steepish hill starting from rest. However, the last 1/2" of travel on the pedal is overboost (max goes up to an indicated 1.2 bar from one bar, exhaust not changes, EGT rockets) and if you don't use that it maxes out at arround 540.

[white90]

Very interesting results Tony, What suprises me is how low your max reading are. Were they done on Simex? I'm not running mud terrains at the moment (need to find a suitable size) but the max I've reached is about 680 (locked in third, foot welded to floor on overboost) on a long steepish hill starting from rest. However, the last 1/2" of travel on the pedal is overboost (max goes up to an indicated 1.2 bar from one bar, exhaust not changes, EGT rockets) and if you don't use that it maxes out at arround 540.

Will all done on M/Ts I've seen 735 as a max previouslyI subsequently turned the fueling back a bit, boost is back at 1.25 bar from the previous setting of 1.5 (boost measured at the inlet manifold)