13B-T Pyro Temps

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boogie74

boogie74

10 Year 15 Year
Joined
Dec 10, 2008
Threads
29
Messages
434
Location
Benders, OZ.
Hello All,

I've been busy this week fixing up my BJ74. Just taking care of the little things that make the cruiser ride better.
I just got back from testing out my new Autometer Sport Comp Pyrometer. As you can see from my picture I went
post turbo on the install. Bag me out if you wish believers of pre turbo thermocouples.

Anyway after searching on mud and other places I need some clarification on exhaust temps.

After my drive this arvo I recorded the following stats:
Idling @ 95C (200F) before driving & 205C (400F) after driving.
Cruising at 70KMH @ 300C or 45MPH @ 600F
Gunning it from 70KMH to 90KMH @ 370C or 55MPH @ 700F
Up a steep hill 500m long got up to 800F or 426C going through 2nd, 3rd
& 4th gear. I was pushing it to see how high I could go.
Would have pulled out if it had got close to 1050F.
Seems like I still have 200F of headroom before I get into the red zone.

So how do these temps compare to other people's EGT temps? It would be good to see how mine compare to others findings.
I was worried about the depth of the probe but I have the standard 2.5" dump pipe with about 1.5-2" of probe going into it.
That much probe should give accurate readings shouldn't it? I pretty much screwed the themocouple in the dump pipe so the threads
on the thermocouple sat flush on the inside of the dump pipe. I thought if the threads were too deep inside they may burn up.
Don't know if I'm being too cautious here.

Cheers All:beer:
Time for a beer now or may be a turkey!!!!

PyroProbe.jpg
 
boogie74 said:
Hello All,

I've been busy this week fixing up my BJ74. Just taking care of the little things that make the cruiser ride better.
I just got back from testing out my new Autometer Sport Comp Pyrometer. As you can see from my picture I went
post turbo on the install. Bag me out if you wish believers of pre turbo thermocouples.

Anyway after searching on mud and other places I need some clarification on exhaust temps.

After my drive this arvo I recorded the following stats:
Idling @ 95C (200F) before driving & 205C (400F) after driving.
Cruising at 70KMH @ 300C or 45MPH @ 600F
Gunning it from 70KMH to 90KMH @ 370C or 55MPH @ 700F
Up a steep hill 500m long got up to 800F or 426C going through 2nd, 3rd
& 4th gear. I was pushing it to see how high I could go.
Would have pulled out if it had got close to 1050F.
Seems like I still have 200F of headroom before I get into the red zone.

So how do these temps compare to other people's EGT temps? It would be good to see how mine compare to others findings.
I was worried about the depth of the probe but I have the standard 2.5" dump pipe with about 1.5-2" of probe going into it.
That much probe should give accurate readings shouldn't it? I pretty much screwed the themocouple in the dump pipe so the threads
on the thermocouple sat flush on the inside of the dump pipe. I thought if the threads were too deep inside they may burn up.
Don't know if I'm being too cautious here.

Cheers All:beer:
Time for a beer now or may be a turkey!!!!

PyroProbe.jpg
Click to expand...

Since your probe is post turbo your readings are low compared to if you had installed it pre-turbo. From memory my pre-turbo readings are as follows:

idling = 350 F
around town = 500 to 800 F
highway = 600 to 1000 F
climbing = 900 to 1200F+

As for depth of the probe I installed mine in approximately in the center of of the exhaust collection manifold (in the center of the chamber) where temperatures should the highest. During sustained climbing with the truck loaded for a trip the pyro temps increase VERY RAPIDLY. I have found the EGTs are more related to the amount of fuel the engine is using, rather than RPM. EGT's rise under hard throttle.When EGTs temperatures are high (over 1,100-1,200F) I often have to back off on the throttle and sometimes shift down. Shifting down only has a small effect of reducing EFTs. When under maximum load that is when the pyro is most usefull. Often when I am climbing with other 74's I advise them over the CB that I am backing off on the throttle. I have an after-market water temperature gauge in my truck and even when EGT are high, the water tempertaure gauge only increases a few degrees. EGTs are very sensivtive to the amount of fuel burning in the engine. I think post turbo you should add 200 to 300 F to estimate your actual pre-turbo EGTs. In a way, this imprecision defeats the purpose of the location of a post turbo pyro.
 
Interesting figures there Glenn. Thanks for posting.

Gives a good correlation between pre and post turbo. Looks like
mine are around 100 to 200F lower than yours which is what I
expected after reading as much as I could find on the subject. Still
got to do more research before/if I start playing with the fuel screw.
Danhr has a good thread in the diesel section on adjusting the max
fuel screw and boost compensator.

I'll keep watching the pyro.

Anyone else want to post their EGT's? Pre or Post.......

Cheers:beer:
 
Hi Boogie74

Cant remember all now, but will advise accordingly, but regarding this .............
Would have pulled out if it had got close to 1050F.
Click to expand...
I think post turbo, you should not let it go higher than 800deg C, seeing that you cool about 200deg C with the turbo.

Mine is running on 33" with intercooler, pre turbo @ ± 5bar boost:
Pre-pump calibration was ±790degC at cruising speeds going uphill in 5th or 4th, not much load.
After calibration it is below 760degC at same conditions as above.

Can't seem to get my boost higher, had the actuator rod modified so that I can adjust it, can't get anything more now. Cruzer pulls well, no need for more feul now while I can't get more air into it.
 
Hi Benniebez,

I'd be interested to see your temps. How much boost are you
running? I dont know how bar pressure relates to psi.

I used 1050F as the limit cause this is what I understand to be
the upper limit for post turbo temps. 1250F was written to be the
max temp you would want to go pre turbo. That seems to be the
general consensus.

Do you have water/air or air/air intercooler? I've been looking at water/air
intercooler or meth injection to improve intake temps and performance.
 
chet said:
Glenn have you added more boost to your rig? If not it may help your EGT problem. It will use more of the fuel and lower your temps (or stop them from rising so fast!)
Click to expand...

Hi Chet,

Stock boost on the 13BT is about 5-6 psi. I put a 3/8" shim in which gives me about 12 psi boost. Those EGT readings are when climbing steep grades (Coquihalla) when I fully loaded about 5,850 lbs, which is about 600 lbs over the vehicles GVW of 5,250 lbs.
 
Hi Glenn,

I have a boost controller on mine. Mounts on the wastgate actuator
vacuum hose. Got mine to 12/13 psi. What are the advantages to shimming
the wastgate? Does boost come on quicker? ie spools up at lower RPM?
 
With a shim you have no controll over boost other than to limit it maximum. If you have a controller that is better, but now I don't give it any more thought. I increased the boost to compensate for power loss with the armour I have added and my Truxus 12.5 X33s on the truck.
 
The turbosmart boost controller does seem to have a very smooth arc on the boost guage.
I've been keeping an eye on the pyro:steer: Took it out on some farming back roads and could only
get the pryo to @ 825F. That was at about 120 - 30 kmh but once at that cruising speed the
temps dropped off to about 750F.

I will have to hook up the half cab and head down to the bay!!! There are a few
big long hills on the way which should take it to the extreme.

Anyone else want to chime in?
 
Hey Mate,

You would have read all the debates about pre or post but I dont think it matters to much where you put the Pyro. Having said that I have only ever had one and the sensor is mounted on the dump pipe. I ease off the accelerator when the temp starts to get around 1000F although it can probably go a bit higher. I have only seen the temp rise that high on long steep hills on the highway. The temps may have risen quite high when 4wdriving but when I'm thrashing it up hill or through the tough stuff I'm generally looking at the track and not at my gauges. I put in a pyro so I could play with the fuel but havent got around to doing that yet.

Cheers.
 
So basically it doesnt really matter which one you just have to have a max temp rate according to which one you go for. Im picking up a vdo pyro tonight for real cheap only thing it comes with the clamp style probe not the weld in one. Once it is up and running I will post my temps for comparison. Not really sure if im going pre or post turbo just yet.
 
The probe you have might be not be designed for being mounted on the exhaust manifold. Maybe check it out before you start the install. I think you really need to drill and tap to set up the probe for the manifold and dump pipe. The fitting you have sounds like its designed for the exhaust pipe. Is the fitting you have like a hose clamp with a ceramic washer?
 
I wouldn't go pre turbo unless you were doing extreme mods to the engine like turning up the fuel to get more power. I put mine in so I could tune the fuel to economy vs power without getting to hot. I'm not sure if my fuel has been turned up by a PO but I would assume so cause everything else has been f@cked with. Also for me it would be a big job the pull off the turbo and manifold but drilling the dump pipe still took a while cause I had never done any tapping before.

I drove my car hard on occasions before I had the pyro and now I look at the pyro and ease up a bit.
 
Re: Pre or Post turbo.

We don't need to re-iterate the pros and cons here, they have been beat to death on other threads. But the perhaps the best solution is to mount bungs both pre and post turbo, and do some comparison runs. Run the probe pre-turbo, do some tests, repeat the same tests post-turbo. And block the pre-turbo bung:o.

Then you will know how much temperature drop you have in your installation.. And you are not guessing by the seat of your pants, based on what others results. Have a look at Ishobie's dyno run on his HZJ79 The middle gauge is his EGT, and it rises much faster than the boost gauge. The challenge is, the more work your turbo is doing the greater the temperature drop across the turbo. Your temperature drop may only be 100F at 800F, but might be more like 200 or 250 when you are up close to 1200

So the worst case happens right when you need it the most, or when you push it into new territory. Then when you change something like cranking the fuel or adding an inter-cooler, you can re-test yet have the safety of the post turbo install 99% of the time.
 
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