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Alternative Diesel Fuels (Biodiesel, WVO, SVO, BTL, GTL etc) Discussions about alternative fuels for use in our TDI's. This includes biodiesel WVO (Waste Vegetable Oil), SVO (Straight Vegetable Oil), BTL (Biomass to Liquid), GTL (Gas to Liquids) etc. Please note the Fuel Disclaimer.

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Old May 23rd, 2012, 10:41   #16
Join Date: May 2012
Location: Reno

I'm interested on this and I'm looking into this option, I'm already checking out some CNG conversion kits:


Silly question though... will the CNG blend work with Bio-d?
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Old May 23rd, 2012, 13:05   #17
Join Date: Sep 2009
Location: Bob Mann Auto, 111 High St, Pembroke MA 02359
Fuel Economy: Built a 2002 TDI Jetta that got 120 mpg of diesel using a CNG blend.

Hello on Bio-d I do not know.
Be careful on just jumping in to diesel/CNG. I have over 8 hard years on CNG conversion on turbo gasoline engines Bi-Fuel systems. I designed this kit for TDIs I spent a year on just planning it.
I worked on the car a bit today it started to slip the stock clutch when the CNG was engaged so www.IDPART.com sold a leftover old stock clutch to me.
Fixed an EX leak. Fixed a window and will clean it up.
The CNG system has 2 adjustments Idle/off idle and flow under load. The trick is to adjust the flow to get the max HP without a stumble off idle or under low load 2100 RPM. Now it pulls hard no more slipping the fun part of the kit is you can be driving it on just diesel and click the CNG switch and it feel like someone hit you from behind..
I have taking some pic and will add then over the week end.
Bob Mann
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Old May 23rd, 2012, 13:18   #18
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Join Date: Feb 2002
Location: Yukon, Oklahoma
Fuel Economy: 49/45/41

Good information, thanks, Bob. Could this mean others could have dial-in issues such as clutch slippage once it was installed and set, I assume, to your baseline specs?. I sent you a PM, but when you say "trick", does that mean it will be a situation of having to change the flow during different driving conditions, or will it be proportionate to throttle position, for example? A set-it-and-forget-it would be nice. I missed the part about performance increase, just thinking about fuel econ, lol. a CNOS system!
Unnamed green 2002 NB, Malone Stg 1, 2" suspension lift
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Old May 23rd, 2012, 13:57   #19
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Location: Valencia Ca.

It would seem that the biggest advantage of CNG is it costs less per BTU than diesel or Gasoline....
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Old May 23rd, 2012, 15:18   #20
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Location: Fail Command (Central Ohio)

Originally Posted by RWHP View Post
Why even say that....shouldn't you be supporting the alternative fuel being as you are the administrator of the alternative fuel board? I think its pretty amazing that you may only have to visit the pump for fuel once a month. I've looked into the conversion and every way I work it out, it pays for itself in a year..all of the above factors included. I might try it out over the next few months on my 2000.
I got this one as well .......

The thread title is not "wow, you can run your car on cng and diesel" or the like. The thread title is about getting 120 mpg. The sub-plot of this superlative claim is that the OP will be selling a kit so you too can do this. All of this strikes a similar cord to infomercials which throw the same type of pitch: "There is a secret", "it is easy once you know that secret" and of course "anyone can do it with this kit". I would expect, no I would insist that someone throwing that kindov stuff out there in such a dramatic fashion would be challenged.

I would also expect that the OP who threw it out there would be ready to back it up "with the math" rather then trying to offload a bunch of kits onto the the "true believers" that infomercials cater too on a regular basis.
The bottom line is that if it works, great --- you should be able to handle the tough questions. But wait, there's more ....... If you want too start a thread with a dramatic claim without being able to answer the questions then expect the members of this Board to call you on it. So before the OP starts with a few easy payments of x and just paying extra shipping and handling, lets deal with the math and the testing regiment.
When interviewed about why no diesel for the new F150, Ford responded to effect that diesel makes no sense in the 1/2 ton market. That brilliance should be repeated in every Ram 1500 eco-diesel commercial.

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Old May 23rd, 2012, 16:18   #21
Join Date: Sep 2009
Location: Bob Mann Auto, 111 High St, Pembroke MA 02359
Fuel Economy: Built a 2002 TDI Jetta that got 120 mpg of diesel using a CNG blend.

As I laded it out in the post the car was driving 60 mile round trip and used only .52 GAL of diesel. The math is very easy here 60 x 2 = 120 miles using .52 GAL x 2 make up one GAL.
Bio Diesel is not GOD sent and not the solution for everyone. Natural Gas is at the lowest it has ever been and it burns a lot cleaner then Diesel. I invent a lot of thing and sell a lot of stuff mostly around clean energy products. And listed as one of your Trusted TDI Mechanic I have not asked anyone to buy a kit.
I do build and sell VW and Audi,s converted to CNG BI-Fuel cars using a Auto Gaz kits from Poland I am a importer for the systems.
Once the TDI system is installed and adjusted after a few drive and tune sectioning you never have to adjust again. As I said you are more than welcome to drive it.
Bob Mann
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Old May 23rd, 2012, 16:19   #22
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Location: Sterling, Massachusetts. USA
Default VW diesel gets 12,000 miles per gallon of diesel on a biodiesel blend.

No conversion kit, no cargo space loss, a cost of 8 cents per mile (because I buy retail with road use fuel tax included) or 2.5 cents per mile (for home brew).

p.s.: It's spelled conversion
If the quantity of carbonic acid increases in geometric progression,
the augmentation of the temperature will increase nearly in arithmetic progression.

Svante Arrhenius 1896

Cogito ergo soy (I think, therefore: Biodiesel)
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Old May 23rd, 2012, 16:57   #23
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Join Date: May 2012
Location: Northern IN
Fuel Economy: Malone Tune 51.2MPG

Sounds interesting... Doesn't some of the big diesel trucks use propane injection for power?
I'm sure CNG would be similar...
Heck.. I'd like to see pictures and more info!
Good going if it works as stated...
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Old May 23rd, 2012, 17:38   #24
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Originally Posted by T.J.K. View Post
And here we go.....
I said that when I read the title of the thread....
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Old May 23rd, 2012, 18:26   #25
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Join Date: Mar 2010
Location: Southern Tier NY

My uneducated opinion only...

From what I understand either propane or NG mixed into the diesel system result in a more complete burn for fuel oil. In other words more complete use of the available energy. Thus increased economy in fuel used for miles traveled.

Propane injection is an old standby and it works from what I can tell. The same being true (I assume) for CNG. The problem I see is that the propane system I noted is used more for diesel trucks. My Dodge Cummins has lots of room for an extra tank or pressure vessel. My Jetta doesn't!

For me it comes down to a matter of room and numbers. My Jetta costs just under ten cents a mile for fuel which I feel is very reasonable. The question then becomes whether the cost of a conversion and the loss of room makes economic sense. Further, I'm not too sure that I'd want a bottle of CNG riding inside the cabin with me.

So... To each his or her own. The idea has merit without question. Test donkeys bear out this fact. I'd just be more comfortable with a somewhat more refined storage and delivery system.
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Old May 23rd, 2012, 18:29   #26
Join Date: Sep 2009
Location: Bob Mann Auto, 111 High St, Pembroke MA 02359
Fuel Economy: Built a 2002 TDI Jetta that got 120 mpg of diesel using a CNG blend.

I got some emails on how it was installed I posted some pics and infomation here.

Bob Mann
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Old May 23rd, 2012, 18:57   #27
Join Date: Feb 2006
Location: Kansas City area, MO
Fuel Economy: TBD, new data forthcoming


or just google: Bob Mann inventor

If you omit pertinent info from your question, you cannot reasonably expect a good answer.//Not affiliated with any vendors except as a customer.// Wise people lurk more.// I'm not a guru.// 'I got actual real friends in the real world'-T'sTDI/ If you were the only entry, there wasn't a race.// Grammar and spelling really are important, but I don't claim to be good at it.// Typical drivers can't.
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Old May 23rd, 2012, 20:15   #28
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Join Date: Aug 2004
Location: Arizona
Fuel Economy: No data yet.

Originally Posted by nord View Post
My uneducated opinion only...

From what I understand either propane or NG mixed into the diesel system result in a more complete burn for fuel oil. In other words more complete use of the available energy.

How can the fuel be burnt more than 100%?

A regular diesel engine, even a non-turbo IDI from the 1980's, burns 100% of the fuel, effectively.

I'm not arguing against NG. If it's a cheaper fuel per btu, and it can be made to function with the engine safely and reliably, then clearly it is a valid alternative fuel.

I just don't think it can 'burn more efficiently'. Maybe 'burn more cheaply' for a given heat value.
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Old May 23rd, 2012, 20:35   #29
Join Date: Sep 2009
Location: Bob Mann Auto, 111 High St, Pembroke MA 02359
Fuel Economy: Built a 2002 TDI Jetta that got 120 mpg of diesel using a CNG blend.

Here is the article all 7 pages.

This is the cover story in the April 23 edition of The Christian Sicience MonitorWeekly
The thing to look at is the front page it show over 621 gave it a thumbs up to 165 thumbs down.
And 145 comments .4x4 I see your site got 3 comments??
Bob Mann
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Old May 24th, 2012, 19:30   #30
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Join Date: Aug 2008
Location: Ann Arbor MI
Fuel Economy: 64/56/45mpg

I know practically nothing about alternate fuel systems. It seems surprising that you can just feed in CNG to a diesel engine and have everything work well. Combustion conditions much change, emissions, etc.

The OP mentioned .51 gallons of diesel and 1.2 GGE CNG. This works out to 38.5 mpg if it was all diesel. If the car got 45 mpg on diesel alone, it looks like the overall efficiency has been reduced by introducing the CNG, which would not be surprising at all.

This is not to say it is not cheaper to run that way - surely it is given the current low price of natural gas. 1.2 GGE is 127 cu ft, 1.27 therms, which would cost (at my house) just about $1. So the 0.51 gallons diesel + 1.2 GGE CNG is about $3, around $.05/mile. That's about 30% lower cost per mile than I pay right now...

One thing I don't quite get, the OP mentioned home fueling cost at $0.40/gal, that doesn't add up to me. At the station, 1.2 GGE (1.27 therms, compressed) is $1, which is just right for $0.80/therm natural gas, and I don't think it's any cheaper in MA than it is in MI. So even if you are fueling at home, how do you get down below $1/GGE CNG?
'03 GLS TDI Wagon, 403K miles, .658 5th gear, RC2, ventectomy, T4 nozzles, Stant 195F Thermostat
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