Natural Gas or Propane Dual-Fuel w/Diesel?

radmatty

New member
Joined
Feb 4, 2018
Location
Chicago. IL
TDI
2005 Passat
Anybody on the board had any experience with compressed natural gas or propane as a supplemental fuel for performance enhancement or as a dual-fuel scenario?

I saw a couple of YouTube videos created by people seeking to sell equipment to make it possible. They made it look like it was pretty easy to inject a metered stream of natural gas just upstream from the turbo and be running as much as 75% CNG. The benefits seem to be pretty substantial. A cleaner more complete burn of the diesel fuel, increased performance and the ability to use a less costly fuel, in the case of CNG. Of course, carrying any amount of CNG is a pain in the neck due to the high cost of the equipment and the bulky nature of the storage tanks.

Nevertheless, the idea appeals to me. And since I'm contemplating a TDI swap into my Toyota pickup I would have the room and a convenient location to keep a tank or tanks for CNG. With 19 gallons of diesel onboard and 12 gallons equivalent of CNG my truck would have roughly an 1100 mile range.
 
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turbobrick240

Top Post Dawg
Joined
Nov 18, 2014
Location
maine
TDI
2011 vw golf tdi(gone to greener pastures), 2001 ford f250 powerstroke
Running on 75% CNG or LPG would give significantly less performance than straight diesel. Unfortunately, both gasses have pretty poor combustion characteristics for compression ignition engines designed to run on diesel fuel.
 

TDIMeister

Phd of TDIClub Enthusiast, Moderator at Large
Joined
May 1, 1999
Location
Canada
TDI
TDI
Negative on running that high %age CNG/LPG, especially with the rudimentary controls to use it in a car and have it properly interact with the existing Diesel fuel injection system and ECU. 10-20% max as a performance enhancer, and I'm sure Bob Mann (CNGVW) will wax poetic about it so I need not say more about it here.

True dual-fuel (gas + pilot Diesel ignition) setups are far more complex and are seen more for truck and stationary engines, but even then are going more towards to mono-fuel natural gas / propane with spark ignition because recent advances have closed the torque and efficiency gaps but at far lower costs and much easier emission control.
 

CNGVW

Vendor , w/Business number
Joined
Sep 15, 2009
Location
Bob Mann Auto, 111 High St, Pembroke MA 02359
TDI
Many TDI Jettas and a Beetle Race car fitted with CNG dual fuel conversion.
Thank for the kind words TDI Master
Let's see one of my ALH street setup with a computer control system did for added HP and Torque red is with CNG first time on the dyno

This on the Ford truck 70% CNG 30% on one test
the cost of CNG at the time was $1.00 a GAL below is a3 pulls with 2 CNG/D one for max power and one forever day driving


I do not do any more system cost of CNG is too high got a bunch of systems and support stuff I will sell off
Negative on running that high %age CNG/LPG, especially with the rudimentary controls to use it in a car and have it properly interact with the existing Diesel fuel injection system and ECU. 10-20% max as a performance enhancer, and I'm sure Bob Mann (CNGVW) will wax poetic about it so I need not say more about it here.
True dual-fuel (gas + pilot Diesel ignition) setups are far more complex and are seen more for truck and stationary engines, but even then are going more towards to mono-fuel natural gas / propane with spark ignition because recent advances have closed the torque and efficiency gaps but at far lower costs and much easier emission control.
 
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wrenchtech

Member
Joined
Feb 1, 2018
Location
Lake Geneva, Wisconsin USA
TDI
2005 Golf TDI
I was seeing stuff on youtube that made it seem like a thing to look into. It looks like a number of individuals have tried to create businesses selling CNG dual fuel systems, but they seem not to last very long.

Glad to get the straight dope here on TDIclub.

So if anything, CNG or propane are best used as a performance enhancer at low concentration (10 -20%). Any benefits of one of those fuels, one over the other?
 

TDIMeister

Phd of TDIClub Enthusiast, Moderator at Large
Joined
May 1, 1999
Location
Canada
TDI
TDI
Propane stores as a liquid, so it has a much higher BTU per volume stored - a tank that fits in the spare tire hole holds more propane than a CNG tank that sits between the rear shock towers.

OTOH, CNG has a higher octane rating and autoignition temperature, making it more resistant to knocking and preignition when fumigating it into the intake of an engine and compressing it 19.5:1.
 

NewTdi

Top Post Dawg
Joined
Jan 15, 2004
Location
NorCal
TDI
2003 Bora, Reflex Silver
Bob Mann, do you have a kit that you are selling for the CNG?
I believe I came across one of your YouTube videos which caught my attention.
 

deckerfl

Well-known member
Joined
Jan 29, 2011
Location
Falls Church, VA
TDI
2004 Passat Wagon TDI W/ Geared BSM, DUK 5Spd.
I have a CNG setup in my Passat TDI (BHW engine) I run about 35% CNG, (my MPG readout shows ~65 MPG vs 40MPG on diesel alone) There is more power but I haven't really tuned it yet for the CNG, so I think overfuelling is limiting my power. Propane is denser, for sure but more expensive. Natural gas at home for me is around $1.00 for 1 GDE, gallon diesel equivalent. but that's ignoring the compressor I have to compress it and repairing that and keeping it running is a whole other expense / time consumer. In fact, in my mind it's the lack of quality home CNG compressors that prevent CNG from being more widely used. I'd do a search and see the cost of CNG at a local CNG pump nearby, and the price of Propane. that maybe the deciding factor.
 
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