Exhaust gas temperatures 6/1

[vdubnut62]

Those flex sections are standard on just about  every front wheel drive car made to accommodate the engine movement where its connected to the exhaust system.  C'mon, Recycle!
Ron

[Jedon]

Those flex sections are standard on just about  every front wheel drive car made to accommodate the engine movement where its connected to the exhaust system.  C'mon, Recycle!

The junkyard wanted more for one than Ebay did...

[mobile_bob]

i picked up two of the stainless braided/accordian flexpipes, one new from a local surplus yard
that no longer is around and the other from a local pick apart as it was just laying on the ground
after someone had removed an engine  (i get most or my parts that way, fans, radiators, pumps
pipes and all sorts of nicely formed rubber hoses, mounts etc)  just laying about after someone
has worked his ass off removing another larger part.

call me lazy?  yup!



also of note, in my mount design (floating torque box) all motion is centered about the centerline of the
crankshaft and because the unit direct drives the  st head the generator shaft is also centered within this
rocking motion leaving a very stable point of egress for my exhaust system. i just made the exit inline
with the crank/genshaft so that there is no movement of the pipe other that a very very slight twist motion
that is measured in a few thousands of an inch.

perhaps a listeroid user could design an exit point for their exhaust pipe that would greatly limit the pipes movement
as well?

bob g

[Crofter]

If you dont restrain the pipe near the discharge the puffs puts quite a bit of jet reaction force into the exhaust system so it is not only engine movement that has to be dealt with.

[vdubnut62]

Go MobileBob! Pull-a-Part is really, really, your friend Guys! That's where my rubber U-joint is going to come from.
The parts store wants close to a C-note for ONE. I can get a complete driveshaft at Pull-a-Part for under $15.
As usual Bob is correct, a bunch of stuff is just laying on the ground, or thrown in a car or truckbed.
Ron

[veggie]

***UPDATE ***

Some Listeroid testing done at Columbia University incorporated an exhaust gas temperature thermocouple very close to the cylinder head.
The temperature readings are shown in the chart below.
Seems 250 C (482F) is typical for these engines.

Veggie

[veggie]

*** UPDATE ****  Dec/09

After installing my new exhaust system, I let the engine run loaded for 1/2 hour and then took some readings.
The reading were taken in 4 places.
1] At the exhaust manifold (2" from the head)
2] 3ft. away where the pipe turns horizontal to the base
3] At the muffler body
4] At the tail pipe where the metal connects to the rubber flex hose

Here are the results:


LOCATION        Deg.f     MAX. Recorded
==============================
   1                295             310

   2                157             186

   3                76               ----

   4                70               ----

As you can see my concerns about overheating the rubberized flexible muffler tubing turned out to be a non-issue.

veggie

[veggie]

<sigh> he FINALLY believes .... man that was painful ...

Dude...I never doubted you for a second 

[quinnf]

Veggie, well done.  It's great to see some hard numbers being generated.

However now that that's over, here's something else to keep you awake at night.  

Any time part of your exhaust system is below 100 C/212 F, you're likely to get water condensing out of the ehaust gasses.  Over time that water will saturate the soot deposits on the inside of your muffler and you'll end up with pinholes leaking brown rusty water on the ground.  In days of yore, when sulfur content in pump diesel was higher, the sulfur dioxide component of the exhaust gas would, when in contact with water, form sulfuric acid, making matters much worse.  For that reason, long exhaust runs are usually heavily insulated in order to keep the temperature high.  With today's mandated low sulfur diesel fuels, acid generation shouldn't be such a problem, but if you're contemplating burning any waste veggie oils, it's likely they have plenty of sulfur in them from cooked food.  And I suspect lube oils have plenty of sulfur in them, so if you're burning WMO, watch out.

That aside, don't worry, be happy.

Quinn

[veggie]

Thanks quinnf,

When the unit goes into full time duty, I will seriously consider insulating the pipe and muffler for the reasons you pointed out.

veggie

[quinnf]

I once thought so, and it nearly put my lights out permanently.  Long story, short version:  Boat auxilliary engine with a dry exhaust line condensed water from the exhaust gasses which pitted, and then holed, the exhaust line over a period of several years.  I happened to be down below, breathing said fumes without knowing it.  Splitting throbbing headache developed, red face and nausea drove me topside. 

I hear what you're saying, Jens.  However the Vegster is recording temps as low as 70 degrees F (not C) in his system.  That's much lower than the temps you're running.  And condensation of water vapor out of an exhaust stream is not as simple a phenomenon as reading the numbers off a psychrometric chart might make it appear.  I don't have any problem with running 70C exhaust temperature.  Nothing is going to condense out at that temperature.  70F, though, is another story.

Around the corner from my office is the building's 2000 HP backkup diesel generator.  I love it every time it starts up!  It's exhaust line is about 16" in diameter, and snakes around probably a total of 50' until it exits at roof level.  The entire length of the exhaust is wrapped with about 8" of fiberglass insulation which is covered by an outer layer of galvanized steel.  Dry marine exhausts are similarly constructed.

Simply put, it's good practice to keep exhaust component temperatures well above the condensation point of a saturated water vapor atmosphere, which can be in the lower 70F range.  Add any hygroscopic combustion byproducts from the burning of your wvo/wmo/whatever fuel to the layer of soot and odd things can happen.

Quinn

[veggie]

Jens, I just noticed the same thing.
When the engine was cold, there was water dripping from the outdoor exhaust pipe.
Once the engine warmed up a bit, the dripping stopped. After an hour of running, there was no additional water on the ground.
(outside temp is -22C).
There was water vapor in the exhaust gasses throughout the test. But the dripping stopped.
Having said that, I should point out that there is very little moisture in the air right now.
Very low dew point at -22C (Brrrrrr !)

veggie

[quinnf]

Yeah, no matter how careful I am to edit and re-edit what I write while I'm composing, as soon as I hit the POST button, I notice something that needs changing/clarifying/rewording.

q.

[quinnf]

I just worked out the percent of water produced by burning diesel fuel, and it ends up that about 7.5% by weight of the fuel you burn ends up as water vapor. 

Don't know what I'm doing here any more.  Everyone else has gone home.  Nothing needs doing.  Hmmm . . . I think I'll split.

Happy New Year,

Quinn

[mbryner]

I have a propane canister muffler about 18 inches from the exhaust outlet on my 6/1.   I've checked a few times for water condensation via the valve on the bottom of the tank, but there's never any water there.   Also, by the time the exhaust leaves the muffler tank it's only slightly hotter than warm.   In fact one of my joints just past the muffer is held together by a short piece of radiator hose (to give a hint of flexibility).   It's almost cool enough to grab with a bare hand while under 1/2 load.   There's just not that much heat in a 6/1 exhaust.  (or the muffler is like a little woodstove getting rid of all the heat first....)  I believe your numbers.