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Does HHO work differently in a diesel?
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Clipper Offline
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Post: #1
Does HHO work differently in a diesel?
I have noticed that, at least in larger diesels (such as Ford, Dodge and Chevy pickups and SUV's, as opposed to the Mercedes and VW's) the gains reported seem to be somewhat less than with a gasser.

Subjectively speaking, it seems like diesels reporting a baseline of 15-22 mpg are only reporting gains of about 3-5 mpg, or about 20-30 percent, with few exceptions. Gassers seem to be able to regularly realize 40 to 100% or better.

I have a theory as to why diesels don't realize as much gain.

Please don't jump all over me, guys, this is a THEORY based on totally SUBJECTIVE observations based on totally ANECDOTAL reporting...no scientific method involved, here, OK? Just throwing it out there for your perusal and amusal. Please scrutinize and criticize freely.

Gas engines ignite a mixture of fuel and air by a spark. The hydrogen and gasoline ignite at the same time.

Diesel engines compress air to well over the ignition temperature of the fuel, then inject the fuel to ignite it.

Except that when you introduce HHO into the intake airflow of a diesel, you are NOW compressing a MIXTURE of hydrogen AND air to well over the ignition temperature of the hydrogen. Theoretically, this would cause preignition, would it not?

So the question THEN is, what is the autoignition temperature of hydrogen, and when, during the compression stroke, is it reached?

According to
http://environmentalchemistry.com/yogi/p...l#Physical
932 degrees F (773K) is the autoignition temperature of hydrogen.

According to
http://www.engineering-4e.com/ (there is a Diesel Cycle calculator about halfway down the page)
773 degrees K is reached at a compression ratio of just under 11:1.

Now, granted, this is theoretical. This assumes ambient air at 1 atm and 70 degrees F, perfect adiabatic compression, and no fluid flow losses.

Ford Powerstroke and Dodge Cummins engines run at 18:1. Chevy 6.5's run at 21.5:1. Chevy Duramax at 16.8:1 to 17.5:1, depending on the year.

When do you reach 10.9:1? Depends on the maximum compression ratio.
In a 17:1 engine, 11:1 is reached at about 20 degrees BTDC.
(My calculations may be incorrect on this one...someone check me please)
In a 21.5:1 engine, 11:1 is reached at about 23 degrees BTDC.

This, of course, assumes perfect compression...that the entire length of the compression stroke is spent compressing the air (it is not, because of valve timing, which would cause the 11:1 number to be reached later in the stroke)

According to:
http://www.engineersedge.com/power_trans..._cycle.htm
The valves do not close until about 43 degrees ABDC
Injection timing starts at about 28 degrees BTDC

Depending on the engine of course...

Injection timing would have a mixed result on the preignition question. As the website above mentions, spraying the diesel fuel into the hot compressed air has the effect of cooling the air (as the fuel vaporizes and absorbs heat until IT reaches its' autoignition temperature) which obviously *delays* the ignition of the fuel.

But timing brings the fuel combustion event closer to the hydrogen combustion event. If the hydrogen combustion has already started, then spraying diesel fuel into it would make the diesel burn *somewhat* faster. How much? Who knows? I do not know how to calculate that.

And when you throw in fluid flow losses, turbocharging, etc. then none of the assumptions are correct, and frankly, I do not know how to calculate that, either.

But still, I would have to ask: are we experiencing preignition of the (tiny amounts of) hydrogen that we are putting into the cylinder, and thus, not burning it at the exact same time as the fuel?

And if we ARE, then could THAT explain why we do not seem to experience gains as dramatic as the gassers do?
(This post was last modified: 12-11-2008 03:48 AM by Clipper.)
12-11-2008 03:39 AM
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jriggs_18 Offline
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Post: #2
RE: Does HHO work differently in a diesel?
Clipper Wrote:I have noticed that, at least in larger diesels (such as Ford, Dodge and Chevy pickups and SUV's, as opposed to the Mercedes and VW's) the gains reported seem to be somewhat less than with a gasser.

Subjectively speaking, it seems like diesels reporting a baseline of 15-22 mpg are only reporting gains of about 3-5 mpg, or about 20-30 percent, with few exceptions. Gassers seem to be able to regularly realize 40 to 100% or better.

I have a theory as to why diesels don't realize as much gain.

Please don't jump all over me, guys, this is a THEORY based on totally SUBJECTIVE observations based on totally ANECDOTAL reporting...no scientific method involved, here, OK? Just throwing it out there for your perusal and amusal. Please scrutinize and criticize freely.

Gas engines ignite a mixture of fuel and air by a spark. The hydrogen and gasoline ignite at the same time.

Diesel engines compress air to well over the ignition temperature of the fuel, then inject the fuel to ignite it.

Except that when you introduce HHO into the intake airflow of a diesel, you are NOW compressing a MIXTURE of hydrogen AND air to well over the ignition temperature of the hydrogen. Theoretically, this would cause preignition, would it not?

So the question THEN is, what is the autoignition temperature of hydrogen, and when, during the compression stroke, is it reached?

According to
http://environmentalchemistry.com/yogi/p...l#Physical
932 degrees F (773K) is the autoignition temperature of hydrogen.

According to
http://www.engineering-4e.com/ (there is a Diesel Cycle calculator about halfway down the page)
773 degrees K is reached at a compression ratio of just under 11:1.

Now, granted, this is theoretical. This assumes ambient air at 1 atm and 70 degrees F, perfect adiabatic compression, and no fluid flow losses.

Ford Powerstroke and Dodge Cummins engines run at 18:1. Chevy 6.5's run at 21.5:1. Chevy Duramax at 16.8:1 to 17.5:1, depending on the year.

When do you reach 10.9:1? Depends on the maximum compression ratio.
In a 17:1 engine, 11:1 is reached at about 20 degrees BTDC.
(My calculations may be incorrect on this one...someone check me please)
In a 21.5:1 engine, 11:1 is reached at about 23 degrees BTDC.

This, of course, assumes perfect compression...that the entire length of the compression stroke is spent compressing the air (it is not, because of valve timing, which would cause the 11:1 number to be reached later in the stroke)

According to:
http://www.engineersedge.com/power_trans..._cycle.htm
The valves do not close until about 43 degrees ABDC
Injection timing starts at about 28 degrees BTDC

Depending on the engine of course...

Injection timing would have a mixed result on the preignition question. As the website above mentions, spraying the diesel fuel into the hot compressed air has the effect of cooling the air (as the fuel vaporizes and absorbs heat until IT reaches its' autoignition temperature) which obviously *delays* the ignition of the fuel.

But timing brings the fuel combustion event closer to the hydrogen combustion event. If the hydrogen combustion has already started, then spraying diesel fuel into it would make the diesel burn *somewhat* faster. How much? Who knows? I do not know how to calculate that.

And when you throw in fluid flow losses, turbocharging, etc. then none of the assumptions are correct, and frankly, I do not know how to calculate that, either.

But still, I would have to ask: are we experiencing preignition of the (tiny amounts of) hydrogen that we are putting into the cylinder, and thus, not burning it at the exact same time as the fuel?

And if we ARE, then could THAT explain why we do not seem to experience gains as dramatic as the gassers do?


Well I would love to see a 20-30% gain on the vehicle im working on, currently Im only seeing a 7-11% gain, using 2LPM on a 15 liter diesel. Im do not have as well of developed theory as you but I believe it has something to do with the combustion reaction being more efficent than spark-ignition. My theory is that how it affects the reaction depends upon how much H youre using, at 2lpm on a big diesel is hardly a drop in the bucket in terms of airflow. But Ive found that high lpm will kill mpgs due to alternator drag, i think that ultimately timing must be retarded if you intend on using more lpms. Ive also read contrary theories that the timing must be advanced to realize full HHO gains. Who knows?? Ive sat around and thought an awful lot about what happens when that piston is coming up and what might need to be changed to fully utilize and hho and diesel in the cylinder. I have a 24V cummins with and edge that will advance timing, so maybe I should install a cell on it and work with that....
12-11-2008 04:14 AM
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hydrotinkerer Offline
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Post: #3
RE: Does HHO work differently in a diesel?
Clipper have you taken in account of the octane and cetane ratings for gas, diesel, and hydrogen? Hydrogen has a octane rating of 130. If I understand it correctly making it harder to light than gasoline.

hexadecane < -30
n-octane -10
n-heptane 0
diesel fuel 15–25
2-methylheptane 23
n-hexane 25
2-methylhexane 44
hydrogen* RON > 130; MON very low[4]
1-heptene 60
n-pentane 62
1-pentene 84
n-butanol 87
E10 gasoline 87–90
n-butane 91
t-butanol 97
cyclohexane 97
iso-octane 100
benzene 101
propane 103
E85 gasoline 105
methane 107
ethane 108
methanol 113
toluene 114
ethanol 116
xylene 117

Another reason diesels don't get the returns gas burners get is the diesel is already more efficient. My cummins turbo diesel gets a 21% boost with hho. I don't think that is to bad for a 6700lbs truck.
(This post was last modified: 12-11-2008 06:13 AM by hydrotinkerer.)
12-11-2008 06:12 AM
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jriggs_18 Offline
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Post: #4
RE: Does HHO work differently in a diesel?
hydrotinkerer Wrote:Another reason diesels don't get the returns gas burners get is the diesel is already more efficient. My cummins turbo diesel gets a 21% boost with hho. I don't think that is to bad for a 6700lbs truck.

what kind of setup do you have on your truck, I am trying to network with diesel hho guys like yourself to figure out what working and what not. What LPM are you running? Amp draw? Do you have truck mods, i have a juice and injectors but stock turbo, and of course lots of tranny work to get it to the ground. I wonder what running a juice (which advances timing and can increases injection pulse time under load) will do, good or bad....

I think you are on target with diesel naturally being more efficent than gas... you can only improve the combustion so much and after that its waste...
12-11-2008 08:59 AM
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hydrotinkerer Offline
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Post: #5
RE: Does HHO work differently in a diesel?
Right now my setup is a 7 plate dry cell that only puts out 1lpm@14amps. My truck is stock except for a timing change and front cover tsb. My base mpg is 19 w/hho it gets 23. I have a new cell that will put out 2lpm+ and I'll install after the first of the year. I'm hoping to gain another 2mpg.
12-11-2008 09:25 AM
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AlexR Offline
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Post: #6
RE: Does HHO work differently in a diesel?
I think the reason for less mileage gain on a diesel can be attributed to the fact that they take in a lot more air that a comparable gas engine. They are turbocharged and this alone can have the engine gulp in twice as much air than if it were normally aspirated.

More intake air volume means more Brown's Gas added to get the desired mileage gain.

Alex

Cool Flame, LLC
http://www.cool-flame.com
12-11-2008 12:51 PM
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hydrotinkerer Offline
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Post: #7
RE: Does HHO work differently in a diesel?
I would say more gas the better.
12-11-2008 01:37 PM
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