Pyrometer

[philip]

Our resident member "Knucklehead" Galen gave and installed his experienced pyrometer into my truck's exhaust manifold ... some 375 miles away in Phoenix, AZ. My truck does -not- have a turbo.



I observed this data on I-10 between Tonopah to Quartzite, AZ For awhile, the meter -seemed- to get a stabled reading.

I set the "throttle knob" and just watched the pyro while cruising along over hills.

Set 64 mph: 700F
Slight downhill @ 67 mph: 500F
Slight uphill @ 60 mph: 800F
Greater uphill @ 57 mph: 950F

For awhile it -appeared- to be stable ... for the most time. But after passing back into Calif .... the meter went nutz. The most severe example was when running WFO at 65 mph climbing Whitewater grade (I-10)(5th gear). The meter seemed to be stabled as it registered 1250-1350F. There was only a barely visible exhaust smoke in headlamps of two vehicles behind me. Then .... after passing the crest and now passing by that Rest Stop (about 1mi) and before Hwy 111 jct, the pyro showed 350F - 450F ... waivering. Still at 65 mph.

First, I'm going to find out why this meter is erratic. I know this meter was not erratic on Galen's truck before installing it on my truck.

Next discovery. Before Galen installed the pyro sensor, he installed a hose fitting and pressure gauge to sample exhaust PRESSURE while driving. Keep in mind that my truck has the OEM exhaust system from the engine to the muffler ... which now has an aftermarket car resonate muffler ... and now a 1-3/4" diameter exit pipe (muffler to exit).

At 63 mph in 4th gear, throttle wide open, and with me driving while shotgun side Galen watched the gauge ... 1 psi .

[asavage]

At 63 mph in 4th gear, throttle wide open, and with me driving while shotgun side Galen watched the gauge ... 1 psi .

When I'd test for plugged cats on gassers, I'd screw a gauge in place of the O2 sensor. If I got more than 2 PSI sustained, we replaced the cat.

1 PSI is what I'd expect to see at WOT and rev'd up. This is consistent with what Galen & I said last year.

Adding a turbo now . . . what does Galen say about exhaust mods for an SD22 with more air? I'd guess that possibly some improvement might be in order. The OEM system clearly flows plenty for the stock setup, but with another 20% air (a ballpark guess), would the 1-3/8" need to go to 1-1/2" or 1-3/4"? Certainly 2" would be overkill for even a turbo SD22.

If Paul is reading: what diameter is the SD25 exhaust piping?

[philip]

SNIP- Adding a turbo now . . . what does Galen say about exhaust mods for an SD22 with more air?

Galen took me for a drive ... probably 15 miles. As you know, he's got a very quiet muffler with the rest of the pipe using the OEM ... mostly. Galen has a boost gauge and an exhaust gauge tied into the exhaust manifold (before turbo). He also had the pyro installed which he later reinstalled it in my truck.

While driving along with any exceleration ... I saw 10-12 psi from the exhaust manifold when boost psi was at 5-6 psi. I could hear faintly the turbo whine up.

Also, Galen let me take out alone his truck (well ... there was a petite young lady along ). Comparing to my KC, non-turbo truck, Galen's truck (non KingCab but has rear tandem axle), my "seat of the pants" torque improvement is maybe .... 25 ft/lbs. I didn't run the engine to max RPM because afterall ... this is not MY personal truck. I drove it like I would drive my truck ... which is relatively leisurely.

I'd guess that possibly some improvement might be in order. The OEM system clearly flows plenty for the stock setup, but with another 20% air (a ballpark guess), would the 1-3/8" need to go to 1-1/2" or 1-3/4"? Certainly 2" would be overkill for even a turbo SD22.

If Paul is reading: what diameter is the SD25 exhaust piping?

You'll have to ask him. The two gauges he had on the dash were for (1)for the intake manifold boost and (2)the exhaust manifold pressure before the turbo. I think Galen can answer about post-turbo exhaust pressure. I should have studied his truck's underside exhaust system but ... I was enjoying beer with apricot ale. I did observe a well exited soot exhaust (about 2-3 feet) in the rear mirror while I drove (tested) foot floored.

[philip]

I set the "throttle knob" and just watched the pyro while cruising along over hills.

Set 64 mph: 700F
Slight downhill @ 67 mph: 500F
Slight uphill @ 60 mph: 800F
Greater uphill @ 57 mph: 950F
-SNIP-

I hooked to the meter with my digital VOM. At 80mph (and to get there), the VOM showed 22.5 millivolt. The meter itself was very erratic and often low (600-1200F).

So I got in touch with the manufacture in Huntington Beach, CA (about 20 mi away). They tested and closely examined the meter's insides. They said it would cost more to fix this meter than to buy a new one. It's 7yrs old so ... I bought a new one.




On way home, I gave the new pyrometer another Italian tune-up. At 83mph (top end) the pyro indicated ... 1,350F.

I'll try a lower setscrew setting. There's no "black soot exhaust".

On a nearby steep hill (40 mph/4th gear WFO), what little exhaust that can be seen then, is like faint dirt dust.

[philip]

-snip-
On a nearby steep hill (40 mph/4th gear WFO), what little exhaust that can be seen then, is like faint dirt dust.

To continue. I drove out the San Bernardino mountains. Yucaipa for apples. The final 4 miles is steep ... spending 4th and then 3rd with the pedal floored. 3,500' .

I've readjusted down the smokescrew so that when the engine rpm is in the upper side of torque peak (2,500)(4th gear) and WFO, the pyrometer indicates 1100F degrees.

Having that set, it's interesting how much higher the pyro increases as the rpm reaches much higher... like 1300F degrees.

Rather than turning further the smokescrew, I reset throttle butterfly limit screw to reduce air flow.

Hmmm.

[philip]

"Turning down" the "smoke screw" has resulted the obvious. Less power. Sure 950°F at WideOpenThrottle is safe but ... I barely passed a man on a bicycle. That's no go.

So I googled to find some specified EGTemperature. The older non-turbo Dodge Cummins listed 1250°F.

Hmmm.

Then I found this information.... Steve Auto


770°C = 1418°F
720°C = 1328°F

[asavage]

OK. You found one person who recommends a max EGT of 1400°F. Is this a consensus opinion? No.

[philip]

"...one person..." says he is "more comfortable" with 1300°F.

On internet, I happened across several Dodge Cummins non-turbo manuals listing 1250°F. Their temperature limit is at the maximum torque RPM ... not at max horsepower, which isn't listed.

I've readjusted (again) the smoke screw to achieve 1150-1200°F @ 2500-2700 rpm, WideOpenThrottle. Good torque returned. Remember, our forum lists the SD22 power chart showing max torque peak 1900-2400 rpm.

But ... I've discovered increasing RPM toward maximum horsepower (4,000) while WOT means more heat. So ... the prudent driver should back off the throttle per the pyrometer °F if prolonging high RPM / WOT is expected.

Diesels are all about torque ... not horsepower.

[philip]

Diesels are all about torque ... not horsepower.

Tanked full of B20 fuel.

Let's see what differences may happen.

[TruckA]

I'll try to chime in with some results now that I switched over my pyrometer from my other truck. Its an Autometer Pro-Comp 2 1/16" gauge and I put the thermocouple in the same location as Philip.

Coming to a stop and waiting 2-3 minutes: 375-400 F
Climbing hills trying to keep speed in 3rd/4th: 1300 F
Getting on the freeway going down hill in 4th WOT @ 65mph: 1400

I filled up with B50 today, so I'll keep an eye on the gauge to see how it changes. It was the first biodiesel this SD22 has seen, and I think it liked it. Flanges and other exhaust parts should be coming this week so hopefully I'll have the turbo installed over the holiday weekend.

David

[philip]

Filled to the brim with D2 fuel in San Bernardino. Drove west on I-10 and south I-605 to Santa Fe Springs.

Refilled to the brim: 53 miles, 1.2 gallons.

This is the first time I've driven keeping the pyrometer down to 600°F for as long as possible (ain't easy driving like there's an egg on the throttle pedal in 50-58 mph range !)

44.1 MPG

[moose60]

I knew that these trucks can produce interesting economy numbers if driven like the proverbial grandma. I have seen numbers in that range when driving all back HWYs at 45-55MPH. This kind of driving is not always practical or possible, but when I have plenty of time it doesn't bother me a bit.

[asavage]

I'm very skeptical of fuel mileage numbers derived from that small a sample. It's too easy for a very slight variation in fuel volume (ambient temp, for example) to skew your result significantly.

Anyone know the thermal expansion rate of diesel? If I heat a gallon of diesel from 40°F (underground tank) to 100°F (ambient, after an hour of recirculation via the IP plus ambient air temp), is it now 1.25 gallons? 1.125? Hmmm?

And the fuel tank changes volume, too. How many of you have had the experience of removing the fuel cap and hearing air rush in? The tank's sides can bow.

(See the last half of this post for my VW Rabbit diesel tank story.)

Run two tankfuls through and see 44 MPG and I'll be a believer. Until then . . .

[philip]

I'm very skeptical...-snip-... Run two tankfuls through and see 44 MPG and I'll be a believer. Until then . . .

Let's see; two tanks is about 24 gallons ... at $3.40 per gallon ... is $81.60. Ok, you send me $81.60 and I'll drive from home to Benson, AZ and back ... trying as hard as I can to limit the exhaust to 600°F. That would be about 1100 miles round trip. And, add $50 for one night at a motel. (that ain't happenin').

Back the real world. Of course the freak MPG I achieved is just that. What the pyro indicated to me is just how heavy footed my foot is without realizing it ... until now.

[Evildiesels]

So I got in touch with the manufacture in Huntington Beach, CA (about 20 mi away). They tested and closely examined the meter's insides. They said it would cost more to fix this meter than to buy a new one. It's 7yrs old so ... I bought a new one. Hewitt pyrometers shown

Yo dude, what a coincedence, I am importing 2 of these Pyros and 2 boost (0-30psi) gauges from Hewitts, I am dealing with a guy called Bruce Dankmyer, did you get the new LED back lit model??. Sort of sucks with the exchange rate over here in NZ, the lot is costing me $NZ 313.61 about $US245.80, cost more in freight than for gauges