Hydrodiesel: Turning max fuel down for better economy?

[mappley]

I've just installed an on demand HHO/Hydroxy cell on my '90 1.6TD Jetta and I want to maximize the fuel economy while retaining some pep. I've looked around but everyone seems to want to turn the max fuel screw closckwise to increase the fuel and smoke, but I havn't found anyone yet that wants to turn the max fuel counterclockwise down. Is this a bad idea? I figure I may have to adjust the idle up instead of down afterwards. The addition of the Hydrogen I'm hoping will allow the diesel to be turned down a good bit.
Does the max fuel screw adjust fuel delivery over the full throttle range, or just the max?

I've been lurking your posts especially the pump rebuild and Mtdi rebuilds. Great stuff. I hope I can help along the knowledge sometime.

Thanks

[Bugsy_malone 666]

Having just read the quick 'home' page on hydroxy garage to understand what this system is, I would say you dont adjust anything. The whole purpose is to make the engine more efficient and in doing so will give you better MPG.

I think you have to see it as less about the fuel screw and more about efficiency. If I was going to do the same I'd probably do a just diesel tank and then a tank of diesel with the system running to see if there were any gains.

I'd then look at making a more effiecent intake mainfold, improving aerodynamics and general car condition before messing about with to much fueling. Just my opinion realy, but I too am on a quest to look at fuel economy but turning the fueling down is not something i'd do.

Is your Jetta intercooled? lower intake temps will make it more efficient.

[theman53]

You want the engine to make as much power/efficient as possible...then, this can't be stressed enough, STAY LIGHT ON THE GO PEDAL! The biggest difference maker is your right foot. So do not turn it down, if you do you will be needing more and constantly to the wood to get it. Using the same or usually more than if you had it set where it was. The only way it would work is if someone had turned it up and you were putting it back.

If I would change anything pump related is the timing of the IP. Bentley has specs for timing and fuel consumption.

[clarkrep]

By turning the full load screw counter-clockwise you move the entire fueling curve down(atleast the way I understand it) and it will affect your idle speed. I hope this helps to answer your question.
Aaron

[bootlegdsm]

Hi Map, while I'm new to the diesel world, I have some experience with the hho systems. I've built and installed them in a few vehicles to varying degrees of success. I too am considering this for my Jetta. Here's my 2 cents, and remember my diesel knowledge is limited:

If you are burning fairly clean now, no black smoke, I wouldn't touch the fuel screw. When you add the hho, you aren't going to make enough to replace fuel, only to increase combustion. (unless you have a multiple gallon unit, and that's a whole 'nother set of problems) With that better combustion you'll get more power which requires the engine to work less to do the same job. If you do decide to play with the fuel, just be careful, have gauges to tell you the info you need for the safety of the engine.

My last hho car was a 92 geo prism. I gained 10mpg on that. I've had varying success with different sized units. Also played with acetone in gasoline, and saw huge increases in older Ford engines.

Either way, good luck to you in your experimentation and please let us know how it turns out, I know I'm real curious. Have fun!

[R.O.R-2.0]

just use less throttle, thats just like turning the fuel down..

[mappley]

Thanks all for your answers. Sounds like I won't be playing with the max fuel screw but just dial time the pump back and keep my foot off the pedal.
I'm using what is called a dry cell with a reservoir and a bubbler for the incidental flashback catch. Presently it is pulling around 15 amps and should be putting out 1.2-1.5 litres of gas a minute, which is plumbed into the hose just before the intake manifold, after the turbo.
After installing the car ran fine still, and I did seem to notice that it required less pedal to maintain 65.
So I went to the parts store and got a cheap coolant reservior and some fuel hose, which I'll use to estimate my mileage with. Tried yesterday, but the wind and storm were outrageous.

It was getting 35 mpg before- so I'll dial time it for eco, make sure the tires are inflated properly, maybe switch the boost pin with an AAZ I got floating around here, go featherfooted, and choose the downhill circuit for my test.

I'll keep you posted-

[macka]

Please do some decent control testing.  After getting everything set the way you would like it, turn off HHO, do the test run, turn the HHO, do the same test run, turn it back off and do it again, turn it back on and do it again, etc.  Otherwise, any info you present will be worse than misleading.

x2 plus log where you buy your fuel from, how many gallons each fill up, idle time, and altitude.

Your other option is to go mythbuster, and measure out the fuel and burn it completely for each test. Doing the hho on and off for 3 or more tests to get a semi viable data base to work with.

[R.O.R-2.0]

Thanks all for your answers. Sounds like I won't be playing with the max fuel screw but just dial time the pump back and keep my foot off the pedal.
I'm using what is called a dry cell with a reservoir and a bubbler for the incidental flashback catch. Presently it is pulling around 15 amps and should be putting out 1.2-1.5 litres of gas a minute, which is plumbed into the hose just before the intake manifold, after the turbo.
After installing the car ran fine still, and I did seem to notice that it required less pedal to maintain 65.
So I went to the parts store and got a cheap coolant reservior and some fuel hose, which I'll use to estimate my mileage with. Tried yesterday, but the wind and storm were outrageous.

It was getting 35 mpg before- so I'll dial time it for eco, make sure the tires are inflated properly, maybe switch the boost pin with an AAZ I got floating around here, go featherfooted, and choose the downhill circuit for my test.

I'll keep you posted-

retarding your timing is not going to give you better economy, advancing it slightly, WILL tho..

or, if im wrong, someone will correct me..

[rabbitman]

I'm using what is called a dry cell with a reservoir and a bubbler for the incidental flashback catch. Presently it is pulling around 15 amps and should be putting out 1.2-1.5 litres of gas a minute, which is plumbed into the hose just before the intake manifold, after the turbo.

How's the HHO supposed to get into the engine with the turbo blowing it back out? Seems to me like it would work better feeding in before the turbo.

[macka]

How's the HHO supposed to get into the engine with the turbo blowing it back out? Seems to me like it would work better feeding in before the turbo.

so it's pulling it through?

[bugnut]

When I read he is putting it in after the turbo I see no gains at all.  His hho maker is not above atmosphear. The engine is making atleast 1 bar.   So if he did see a gain it was all with how he uses the skinny pedal right now.   Introduce it before the turbo then I might think this works!

[bootlegdsm]

Why are you post-turbo with the hose? Just curious what your thoughts are with that.

The hho will probably have a steam cleaning effect on the combustion chamber, which should equate to higher mpg the longer you use it.

[R.O.R-2.0]

I'm using what is called a dry cell with a reservoir and a bubbler for the incidental flashback catch. Presently it is pulling around 15 amps and should be putting out 1.2-1.5 litres of gas a minute, which is plumbed into the hose just before the intake manifold, after the turbo.

How's the HHO supposed to get into the engine with the turbo blowing it back out? Seems to me like it would work better feeding in before the turbo.

i dont see how it could be working.. the turbo makes boost, then the HHO system is just a boost leak..

it needs to be injected between the air filter and compressor wheel.. where there is constant vacuum, however little it may be.

[mappley]

Hi All-
Lot's of comments and I appreciate them all.

When i say dial back the pump I mean setting TDC on the tranny bellhousing mark, setting up the dial meter on the back of the pump, rotating the engine backwards until the needle on the dial stops moving, zeroing the meter and rotating the engine forward back to TDC and reading the gauge. It was at 36, because I have an inches meter. I rotated the pump to 33 which I thought was retarding the timing, but am sure that's the direction you go for better economy.

The reason I'm putting it in after the turbo is because that's what was recommended by the guy I got the unit from, who said some other guy in Greece did it that way with his 1.6TD and got 60% increase in mileage. Seemed counter intuitive to me but I figured it would be a good place to start. I expected that if the Hydro-Boost was working well, it might cause the car to actually lag comparitively when the turbo kicked in.

I've set up a small metered tank for the tests, and I'll do several both with the Hydo-Boost on and with it off, using the same can of fuel I get from the local Biodiesel store. I might not ordinarily use biodiesel because of some of the pics I've seen of the insides of pumps, but it came as a biodiesel car, and there's a station here in town that sells professionally made BD99.

I'll be doing some tests next week after I work out a few things. If it doesn't work this way, I'll try it pre turbo, if that doesn't work then I'll try it on my 1.6 na caddy, if that doesn't work, well, I guess I'll know it doesn't work.

Thanks again for all your input.