Diesel fumigation in the air intake

[CAJUN 93]

diesel combustion is a function of temperature and pressure. anything you inject has to remain atomized and be able to withstand combustion at the cylinder pressures generated by this engine (compounded by 40 lbs of boost). thats were octane and cetane differ. octane is the measure of how resistant fuel is to auto ignition(hence the use of higher octane fuels in higher compression race engines).problem is high octane fuels burn really slow. cetane is the opposite, the higher the number the faster the burn.

we've all heard the stories about the guys old lady who fills his diesel with gas and the motor explodes. it doesn't work that way. gas wont burn in that environment. the octane slows the burn down too much to generate any power and the motor won't run.

i guess my ? is will diesel fumigation increase the burn dwell time and increase hp enough to justify it's cost and complexity, especially compared to h20 meth and/or propane. my thinking is no.

the other thought i have is were does the extra air come from to support the added fuel. most of us are on the ragged edge with temps now. without additional air, exhaust temps would soar just the same as larger injectors.

it is good to step outside the box from time to time.

daryl

[meby]

the other thought i have is were does the extra air come from to support the added fuel. most of us are on the ragged edge with temps now. without additional air, exhaust temps would soar just the same as larger injectors.



daryl

keeping this in mind could someone explain to me again why water/meth lower egt's?

matt

[wannadiesel]

the other thought i have is were does the extra air come from to support the added fuel. most of us are on the ragged edge with temps now. without additional air, exhaust temps would soar just the same as larger injectors.



daryl

keeping this in mind could someone explain to me again why water/meth lower egt's?

matt

The water vaporizes and absorbs heat, cooling the air. The meth also vaporizes and removes heat, but the main benefit of the meth is that it lets you spray more volume of liquid into the engine without putting out the fire. Cooler, denser air in = more air in the cylinder to burn the fuel = lower EGT.

[CAJUN 93]

yep, what wanna said. kinda like setting the nozzle on your garden hose to fine mist, shooting it up in the air and walking through it.

brings up an intersesting question. water has a cooling effect upon expansion and atomization. propanes qualities for cooling upon going from liquid to gas is well known. what if any cooling effect does diesel fuel have upon atomization?

daryl

[meby]

the other thought i have is were does the extra air come from to support the added fuel. most of us are on the ragged edge with temps now. without additional air, exhaust temps would soar just the same as larger injectors.



daryl

keeping this in mind could someone explain to me again why water/meth lower egt's?

matt

The water vaporizes and absorbs heat, cooling the air. The meth also vaporizes and removes heat, but the main benefit of the meth is that it lets you spray more volume of liquid into the engine without putting out the fire. Cooler, denser air in = more air in the cylinder to burn the fuel = lower EGT.

Oh duh....I think once explained it to me before. I'm to young to be forgetting things like that.

[Begle1]

gas wont burn in that environment. the octane slows the burn down too much to generate any power and the motor won't run.

How does octane "slow the burn down"? Provided that enough air is present, shouldn't the octane light off as soon as the Diesel is injected, and then serve to aid combustion of the Diesel by increasing combustion temperature? Since the gasoline would be better mixed with the air in the cylinder, it would burn first.

i guess my ? is will diesel fumigation increase the burn dwell time and increase hp enough to justify it's cost and complexity, especially compared to h20 meth and/or propane. my thinking is no.

I don't even see how Diesel injection is capable of working; why doesn't the Diesel preignite and knock like crazy? I can see how it'd work for starting, where you're at such a low load and RPM that the fuel isn't expected to fully burn anyways... But under full throttle I'd think that it'd blow headgaskets in a jiffy, if not just stall the engine or melt cylinders. And it should be way inefficient igniting fuel that far before TDC anyways.
Although, that logic contradicts Loch's first-hand experience, unless he was just running on borrowed time.

the other thought i have is were does the extra air come from to support the added fuel. most of us are on the ragged edge with temps now. without additional air, exhaust temps would soar just the same as larger injectors.

Well, the traditional limitation of the VE pump (or just about any Diesel injection pump) is the inability to move fuel fast enough to keep up with the cylinders at high RPM, at which point turbo boost should have well out-stripped injected fuel.
And, also, you can always use nitrous or alcohol. Or nitrous and alcohol.
Or use a wet-nitrous system, like a gasser, that'd pre-mix the correct mixture of nitrous and alcohol.


I think that a P7100 pump injecting directly at TDC, coupled with a 500HP shot of wet nitrous/ alcohol, would be crazy powerful.

[Begle1]

I think that a P7100 pump injecting directly at TDC, coupled with a 500HP shot of wet nitrous/ alcohol, would be crazy powerful.

Ya'll hear that silence? That's the mark of a good idea.

[dpuckett]

Ok, I thought the VE's fuelling problems at higher RPM were supply related, and not limited to the capability of a hot-rodded/ modified pump. Or are we talking 5000+ as high RPM? I consider anything over about 3500 to be "high" RPM in our applications, as I would consider 2800RPM in a N14 to be "high" RPM. (I've driven stock 290s that turned 2400RPM).

And as far as octane and cetane ratings, they are just that, ratings. There is little to no cetane or octane in either fuel- it is just expressed as a RELATIONSHIP between the ignitability of the fuel vs the cetane/ octane.

If you inject at TDC, you will ALWAYS have some time delay between injection and ignition. That is why you inject before TDC- to fill the gap and make sure the fuel lights off around TDC, if not a degree or two before. There is also a short time (I'm talking milliseconds or less) between initial combustion and actual power production. Again, more reason for advance. Then you have the time from when the pump pressurizes the "system" (in this case, the injector line and injector) to when the injector pops open.

I actually dont think any oil (in the sense of it doesnt evaporate very quickly, if at all) would make a good heat dispersant, for the simple reason it doesnt evaporate, and thus, take the heat with it. Think of when you get oil sprayed on you from a hydraulic line split- it doesnt cool off in the breeze like water would. Yet, spray some alcohol on your arm, and you get almost instantaneous frostbite, or so it seems. These are two extremes of the scale, but they prove my point, I think. The faster it evaporates, the better it will dissipate heat, unless someone has real world prrof to prove me wrong (and by all means, post it here).

Gotta agree with cajun93- I like someone who comes up with new ideas and is willing to try them.

I missed Loch's setup on the other site, but then I am lucky to make it here once a week.

Daniel

[seeker1056]

A thought and one I will try,

Given that heat helps get our turbos spinnin I was thinkin in terms of injectin alky right at the exhaust manifold to the turbo mount to see if afterburn would speed up spool.

thoughts?

[oldestof11]

A thought and one I will try,

Given that heat helps get our turbos spinnin I was thinkin in terms of injectin alky right at the exhaust manifold to the turbo mount to see if afterburn would speed up spool.

thoughts?

You might see a UFO go through the hood Even though they spin 100,000+ (am I right?) rpm, they have a limit before they, ummm, whats the word? Explode? Something like that.

Jon

[Begle1]

Ok, I thought the VE's fuelling problems at higher RPM were supply related, and not limited to the capability of a hot-rodded/ modified pump. Or are we talking 5000+ as high RPM? I consider anything over about 3500 to be "high" RPM in our applications, as I would consider 2800RPM in a N14 to be "high" RPM. (I've driven stock 290s that turned 2400RPM).

The injection pump itself is a major reason why torque and horsepower drop off at RPM; plumbing dual 150 GPH feeds at 60 PSI can minimize the pump's limitations, but if more fuel could be provided at high RPM and high boost, then there'd be an instant increase in power. The pump can only flow so much.

I think that KTA de-fuel's around 3,000 RPM; any more than that, and fuel from a different source is required to increase power. And his pump seems to have capabilities well beyond what's typical.

It's proven how effective alcohol injection is at increasing power; but typically, people only fumigate it to the point that their timing gets in the way... I think that much more power could be had if timing was retarded in order to go with more alchohol. Or hydrogen or high octane.

If you inject at TDC, you will ALWAYS have some time delay between injection and ignition. That is why you inject before TDC- to fill the gap and make sure the fuel lights off around TDC, if not a degree or two before. There is also a short time (I'm talking milliseconds or less) between initial combustion and actual power production. Again, more reason for advance. Then you have the time from when the pump pressurizes the "system" (in this case, the injector line and injector) to when the injector pops open.

Maybe not inject at dead-on-balls-accurate TDC, but pretty close. As close as possible to not get timing knock; I don't know what would be required. But you'd never get timing knock at exact TDC.

The basic idea is that it's far eaisier to fumigate fuel instead of injecting fuel. Provided that you have control over the fuel that you're fumigating, then you wouldn't need a throttle body. And the VE has enough dynamic timing built in that things should work.

I think that different fumigated fuels would require different levels of timing advance; hydrogen probably burns faster than alcohol, so it wouldt knock worse under high advance. Of course, provided that the fuel has enough time to burn, you would want to retard it as much as possible to increase efficiency and reduce head gasket pressure. So you'd have to reduce the advance more for hydrogen, but it'd be more effective provided that enough hydrogen is injected.

So, provided that the fumigated fuel takes less time to burn than the Diesel, what's the matter with not burning all the Diesel? If at 3000 RPM it takes Diesel 20 degrees to burn and methanol 10 degrees to burn, just inject the Diesel at 10 degrees and fumigate enough methanol that it don't matter.

Unburned fuel in the exhaust manifold tends to afterburn provided that oxygen is present, which results in really high EGT's... To minimize that you could either ensure that the cylinders are always leaned out with alcohol, or do something like inject water or nitrous into the manifold.


Another thought; since our timing advance is controlled by case pressure, and I'd want to reduce it at high RPM's, install a variable pressure regulator in the shut-off solenoid port. Then I could relate the timing advance to the amount of fuel fumigated on the fly to ensure that I don't pre-ignite.



Not only do I want to use more drugs than #2, I want to turn my Cummins into what's essentially a gasoline engine. Does that mean that I'm kicked out of the club for good, or just until it works?

[dpuckett]

....I want to turn my Cummins into what's essentially a gasoline engine. Does that mean that I'm kicked out of the club for good, or just until it works?

I think he needs to be put on probation, anyway.

DP

[6BT Dakota]

Searching the forum and came across this one. I know it's an old post, but was just wondering if any of you guys ever did try a wet nitrous system using a high auto ignition fuel like methynol? Pretty interesting stuff for a race truck or puller.....

[fourwheelininajeep]

On this topic, I have dabbled with hydrogen in my gas engine, got a small conduit plastic box put 2 leads with 8 cells of stainless steal with plastic washer filled in with water and put 12 volts to it, my suzuki samurai will almost run just on the hydrogen it produces, I had a budy tell me that you can run hydrogen into a diesel and it will help improve mileage and power, but with a gas engine I can regulate how much hydrogen by opening or closing the butterfly for the throttle then the computer takes over and the fuel decreases and runs primarily on hydrogen. What would happen in a diesel since there is no real way to regulate it. Runaway Im sure is a option but does hydrogen have a low enough flash point or temperature befores it ignites to creat the deisel affect or does it have to have diesel to go up first then start the hydrogen up like propane injection. Hydrogen is free to create if this was a possiblility to run in diesel to add power that would be awesome Im afraid to try it though. Let me know if any one has heard or tried it.

[Begle1]

Hydrogen has a very high octane, higher than almost anything else. But it has little energy content per volume.