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Build your own WMI

a little heat theory..

..look out...:eek:

Just started reading this thread. I think I'm going this route after the ATT install in order to just take the edge off the IAT when I'm pulling the trailer.

Warning. Engineer/licensed gadget nut is on line. :conehead: This might make your head hurt but give it a try.

I deal a lot with things called desuperheaters on industrial steam piping. They are basically the same idea as what you're trying to do. They spray water into a steam line that is running a few hundred degrees of superheat in order to get the steam temperature down to saturation before you use it. Enough of that, now how it might apply to our engines.

You want to spray just enough water to lower the temperature to where you want it. That amount of water (cooling) is based on the mass flow of compressed air coming out of the turbo and the temperature of that flow. This is going to tell you how much water or water+methanol it will take to drop the temperature back to where you want it. The cooling comes from evaporating water or water+methanol. If the water isn't evaporated by the time it gets to your cylinder you are pumping more water than will do you any good.

You will want your spray nozzle as far upstream as you can possibly get it. If I was willing to cut into my turbo's compressor scroll it would be a nozzle running in just as the turbo scroll straightened out pointing down stream. You've only got about two and a half feet of intake tract to evaporate that spray water to get the cooling, but we're only talking about 20-50 degrees.

So, to run through it-
Mass flow of the intake air at 150 degrees target temp and what, 15 psi boost? I'll use two atmospheres or 14.7 psi to keep the calcs simple. Heat load of dropping that mass of air from say 200 degrees. (Need the heat capacity of air.) Convert that to BTUs per second and that gives you how much mass of water per second it will take to drop the temp 50 degrees at 1 BTU per pound per degree F. Again, can we do that in 3 feet at 2500 rpm?

:sleep: :yawn: ... yeah, yeah...

As I type this I haven't run the numbers ( I don't have my tables at home) so I don't yet know how this will work out and it might take a couple of days to get it all done. If y'all will be so good as to not let my work get in the way of furthering the knowledge base of DTR (keep reminding me) I'll have this calculation done Monday evening.

(..which reminds me, I owe TD a schematic on glow plug RTDs for measuring cylinder balance... :oops: )

Mike
 
Got an idea of where I am getting the lines....now I need to get nozzles and hit the track in May....looking for low 16's....I'll see if I can find them....
 
I never did get the nozzle out of the truck yet Chris. Now that it is warm out and I have a bunch of time here at home I could pop it out and take a look. I remember it was the middle sized one in the Snow kit, I think. Let me know if I should take a look, it is in a fairly easy spot to get at.
 
Take your time....I'm not buying nozzles until I know what you were running...

Gonna be busy with seeding pretty quick anyways....
 
chris, I just tuned into this thread. My nozzles are a 5gph and 10gph. I have the devils own. also i'd suggest a boost activated unit is a waste of money. there is no consistency with boost. i think if anything is going to work you'd be better off doing it with egt based activation, after all do we not want cooler egt's unless you're gonna race it. then a simple toggle switch would work, full on or not at all. I re jigged mine so i have a toggle switch in line for the signal wire off the MAF for the hills. I also have my controller still hooked up on the lowest setting so it is full on if I hit the toggle switch. i'm still considering buying the devils own egt box for 75.00 so may yet change things, but for now it works great. and heath advises no more than 10% meth and when i tried that i noticed no appreciable difference except a lighter wallet. Ed
 
With my mystery size nozzle and 25% ethanol there is a pretty substantial push that you can feel. I really do not think I am stretching the statment when I say it feels like 50-75 ftlbs of added torque. 50% ethanol made audible knocking noises, and ALOT of power.

Ethanol is more resistant to pre-ignition than methanol (and propane for that matter), and it is less corrosive than methanol which is why I am using it. I do not really know if the corrosive properties are an issue or not in this application, I simply build and tune enough methanol burning engines to know what the stuff does to parts. Most companies are rating ethanol around the 115-116 octane, propane is in at a religious 110 octane rating and methanol can widely vary from 110 to 113 octane rating. According to those numbers ethanol should be a little more resistant to pre-ignition in our high compression engines. Plus if you get thirsty it won't make you go blind. :drunk1:
 
pre-igntion goes out the window when you talk about having IDI precombustion chamber. When you already have fire in the chamber is differnet than resistance to detonation from the heat of the compression. Thats why direct injection is so much better for this stuff.
 
Isn't compression ignition the factor that makes adding another fuel less simple than with a gasoline/electric ignition engine. The timing of ignition is (normal circumstances) controlled by the ignition system (given no detonation, etc.)

Diesel auto-ignites at a certain pressure/temp. Methanol, ethanol, propane - most any different fuel will auto-ignite at a different pressure/temp than diesel.

Haven't studied this a bunch but is it 2 flame fronts (diesel & alcohol) running into one another that causes the noises/damage?

Don't know if there is any significant pressure/temp difference btwn the IDI pre-cup & in the cylinder at the time of ignition. If there is, no doubt it's a very dynamic situation. I'd think any alcohol from the water inj system would be fairly distributed in the air charge by the time it's been squished/swirled into the IDI pre-cup.
 
Yeah, you want the other fuel to auto-ignite at a higher temp than the diesel fuel, but as soon as the diesel fuel ignites, its going to "burn" or explode differently than diesel.

Diesel fuel will start combustion in the precombustion chamber, but the atomized meth or eth, or especially propane will just explode when it hits burning diesel, even though it hasnt reached its auto-ignition temp in the compression stroke to fire at TDC when the diesel auto-ignites. Thats what causes the big problem, and why it has to be a low enough percentage in the air to not be combustable by the flaming diesel droplets out of the precombustion. Thats why direct injection is better for this, because there is no flaming droplets, the meth or propane would just ignite when the diesel fuel auto-ignites at TDC from compression.
 
Pre ignition leaves an audible valve slap. Piston going up to compress, cumbustion happens before full compression, Piston being forced down, and up and valve slap too.
 
Matt Bachand said:
Pre ignition leaves an audible valve slap. Piston going up to compress, cumbustion happens before full compression, Piston being forced down, and up and valve slap too.
Click to expand...

If your valves are being slapped by a spike in cylinder pressure, than there is something wrong with your valve springs or valve train. Most likely what your hearing is piston to pin wrap or piston to bore wrap.

For some interesting reading on the auto-ignition temps of various fuels, you can look here.

This bit of information seems to contradict what Jasonsmack is concluding from his experience regarding the pre-ignition characteristics of methanol versus ethanol, so maybe something else is in play. I would say that for the most pre-ignition resistance, one would be using isopropyl alcohol.

The other thing to consider is the latent heat of vaporization of the various alcohols. This will give a good idea of how much of a temperature drop you will experience through injecting X amount of each. The rub lies in the fact that you may be able to inject less of one (with a higher latent heat) than another and get the same cooling effect. The lower rate of injection would also lower the chances of having enough alcohol in the chamber to actually ignite, causing the pre-ignition. For latent heat, methanol wins hands down (that's why drag racers use it even though its really corrosive).

Regards,
 
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What in play is what I explained above, the fuels are not auto igniting from temperature. they are prematurely exploding from the flaming droplets coming from the diesel fuel precombustion area, because the 6.5TD is an Indirect Injection engine. So the Eth, Meth, or other is exploding too early because of actual fire already in the cylinder before even the diesel fuel autoignites from compression temperature.
 
buddy said:
What in play is what I explained above, the fuels are not auto igniting from temperature. they are prematurely exploding from the flaming droplets coming from the diesel fuel precombustion area, because the 6.5TD is an Indirect Injection engine. So the Eth, Meth, or other is exploding too early because of actual fire already in the cylinder before even the diesel fuel autoignites from compression temperature.
Click to expand...

This is pre-ignition!!!! Just because it occurs at a lower temp than diesel auto-ignition doesn't mean that it's not pre-ignition. The fact is that there is a (somewhere) near stoichiometric mixture of alcohol for the pre-ignition of such alcohol to occur.

Where does the "fire" in your analogy come from?

Regards,
 
The precombustion is supposed to happen with the diesel in the precombustion area of IDI, which is where the glo-plug and injector go to. Then you have flaming droplets (if you read) coming out of the precombustion area into the cylinder. Then you mix in just air in the cylinder and complete combustion of the diesel happens near TDC.

BUT add another volatile fuel to the air and boom! it explodes when it hits the flaming diesel droplets during the expansion stroke when air and fuel enter the cylinder. Thats what I tried explaining before.

That is the premature detonation you are trying to avoid and why direct injection is better suited. For direct injection there is no precombustion area and no flaming droplets of diesel before TDC, it just ignites when it reaches auto-ignition which in turns would ignite the alternative fuel mixed in the air, because it would have a higher auto-ignition temp as to not cause premature detonation.
 
buddy said:
The precombustion is supposed to happen with the diesel in the precombustion area of IDI, which is where the glo-plug and injector go to. Then you have flaming droplets (if you read) coming out of the precombustion area into the cylinder. Then you mix in just air in the cylinder and complete combustion of the diesel happens near TDC.

BUT add another volatile fuel to the air and boom! it explodes when it hits the flaming diesel droplets during the expansion stroke when air and fuel enter the cylinder. Thats what I tried explaining before.

That is the premature detonation you are trying to avoid and why direct injection is better suited. For direct injection there is no precombustion area and no flaming droplets of diesel before TDC, it just ignites when it reaches auto-ignition which in turns would ignite the alternative fuel mixed in the air, because it would have a higher auto-ignition temp as to not cause premature detonation.
Click to expand...

So what is your proposed solution? Change to Direct Injection?

Mind you, I am not agreeing with you. Because what you have explained also happens when injecting flammable liquids (alcohol, CNG, LP, etc) into any diesel. That process is called fumigation and has been done for decades. The burning diesel fuel is augmented by whatever fuel you have introduced through the intake charge.

In addition, there is also the "flame kernel" effect from injecting water and the resulting steam. This assists in creating a more complete combustion.

Regards,
 
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