Propane injection

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bacho
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Location: Greenville South Carolina

Propane injection

#1

Post by bacho » 12 years ago

I searched and didnt find another thread just about this so I figured it would be good to start one. I am wanting to start spraying stuff into the motor to try getting some more power from it. I have decided that I am just gonna see what the diesel is capable of at this point.

I found this kit for $85, seems aweful cheap but this may be just a vapor system. I am under the impression that you want to spray liquid.

http://www.importpoweronline.com/propanecontent.html
1992 nissan pathfinder 4x4
1985 KC 720 4x4
1982 KC 720

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asavage
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#2

Post by asavage » 12 years ago

I am not an expert. I am not a chemist. But I do have considerable knowledge of how hydrocarbon fuels work in theory and practice (tooting my horn: I built a methane digester before I was twelve, and wrote papers in high school about alcohol and LPG as alternate fuels -- in the 70's -- and wore a patch on my jacket, "LPG - Performance Fuel" -- I kid you not), and without Googling on the subject again, I'm just going to type some stuff from memory on the topic of propane fumigation for diesels.

Propane fumigation has been around for a long time, at least since the 1950's, and possibly much earlier. It is not a new idea.

Adding propane (LPG, a mixture of propane, butane, methane, etc.) doesn't make diesel fuel burn more efficiently or more completely -- diesel already burns very, very clean in terms of unburned fuel (HC) and partly burned fuel (CO), as compared to gasoline. There just isn't much improvement to be had, and adding propane doesn't improve the burn.

Adding propane to the intake air stream of a diesel does make more power. In some setups, a lot more power. So does adding more diesel fuel in a similar setup. The power you get is from the same source in both cases: you have added more fuel. In some setups, the addition of propane instead of more diesel is cost-effective for everyday operation, when you are not demanding more power -- it can be slightly cheaper in terms of dollars per mile to dribble a bit of propane in semi-continuously, rather than burning the same BTUs via more diesel -- this is economics of BTUs rather than efficiency.

There are downsides. EGT can skyrocket (but can also remain safe) depending on the flow rate and control system used. Propane displaces valuable oxygen in the intake stream, so the net volumetric efficiency goes down when adding propane: you do not have as much excess oxygen as you did before, so the IP may overfuel: smoke and high EGT.

As I understand the process, the optimum propane-to-air ratio is one that is too lean to spontaneously ignite at diesel compression pressures. It gets hot but cannot quite oxidize rapidly. When the diesel is injected, the temperature gets hot enough to light it off, and it provides higher cylinder pressure than normal. Somehow this isn't detonation -- I admit I don't understand why it isn't.

So you've added more fuel -- without turning up the IP or swapping in higher-flow injectors, but rather by dribbling the fuel in the intake.

I think I'd rather buy one of those adjustable ECM patch setups and just put more fuel in via the IP. Whaddayamean, you don't have an ECM on your diesel? You've got a smokescrew, don't you?

Again, a pyrometer is absolutely essential for this kind of modification. Adding more fuel -- any kind of fuel -- requires monitoring of the one variable that will determine whether you've crossed the line or not -- or are merely pushing it.

I hope this helps. I am not trying to start a war over this, but from my point of view there is a whole lot of hype being pushed on this topic (and about WVO, IMO) and not a lot of facts. I may have some of the above wrong, but most of it I think I have right.
Regards,
Al S.

1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.

bacho
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Location: Greenville South Carolina

#3

Post by bacho » 12 years ago

What what I read, the propane helps burn more diesel. As it is I can get a little black smoke on accel and I was under the impression that LPG could help burn that when I needed it. I dont think turning up the smokescrew anymore will help my case. I am already at a little smoke and 10psi boost.
1992 nissan pathfinder 4x4
1985 KC 720 4x4
1982 KC 720

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asavage
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#4

Post by asavage » 12 years ago

Black smoke is:
  • Timing
  • Injector(s)
  • Low compression
  • Too little oxygen for available fuel (too much fuel)
If you have black smoke and can eliminate the first three, then the engine already has as much fuel as it can oxidize. Burning = oxidation, which requires oxygen which the propane will displace. Adding propane will reduce the available oxygen -- there is no way adding it can make the diesel burn more!

Come to think of it, propane fumigation might work as a crude work-around for the lack of a boost compensator on the IP when adding a turbo. But, since you have visible smoke already, you have enough fuel (leaving aside the other three smoke contributors).

Have you explored an intercooler -- make the air charge cooler and denser, and you can run more timing advance safely while lowering EGT. Or water injection triggered by boost state? Water injection can be done very cheaply, if you can fit a reservoir somewhere.

The reason propane injection is as effective a power boost as it is on modern hardware, is that the mfgrs do have their (American truck diesel) engines tuned to make it through warranty and Federal emissions without meltdown, and adding fuel (whether via an electronics/IP mod to overfuel, or by adding propane) is removing some of that emissions/durability margin. And my time hanging out in one of the forums at ford-trucks.com let me find plenty of people who "ride the smoke": lots of black smoke must mean I'm going faster (kind of like those who put exhaust megaphones on the furious weed-whackers).

Speaking of margin, I'm hearing noises again in the '82 Wagon -- I'm about to have to put in a third right rear wheel brg. First was making some noise by 95k, got bad enough that I had to replace it by 110k. Now it's starting up again.

It's the same rear end (basically) as the 720's. The LD28's torque is about, what, 25% more than the SD22's? These things Nissan built are not all that overbuilt (see transmission brgs thread).

There are downsides to more power, including reduced vehicle life.
Regards,
Al S.

1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.

pbknowles
Posts: 95
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Location: Illinois, USA

#5

Post by pbknowles » 12 years ago

Black smoke from a diesel may well be the result of a mechanical problem, as Al suggest in:
* Timing
* Injector(s)
* Low compression
* Too little oxygen for available fuel (too much fuel)
And, it is completely correct that when the exhaust begins to become opaque, the engine has reached the limit of it oxidizing capacity, and the mixture is stoichiometric, e.g. all the air and all the fuel are consumed with none left over. One wonders then, why diesel drag racers and truck pullers and etc. exhibit truly startling plumes of black smoke. Isn't this just wasted fuel? Why would they do it? The explanation is in the chemical makeup of diesel fuel, which is ~85% carbon 15% hydrogen. As the fuel air mixture is richened beyond stoichiometric, the hydrogen begins to preferentially consume the oxygen rather than consuming the carbon. Oxygen having a greater heat content than carbon, more power is generated (and heat) and the carbon is left over (black smoke). The "pulling" engines referenced above make lots more power than they would at a stoichiometric A/F ratio. But they won't do it for long! BTW, I am not smart enough to figure this out, it is a paraphrase of an explanation from a friend who is a combustion engineer. Now I will have to ask him how the propane figures in to all this, and when I get an answer will report back...
PK
SD22 powered '85 Chevy S-10

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Knucklehead
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#6

Post by Knucklehead » 12 years ago

pbknowles wrote:One wonders then, why diesel drag racers and truck pullers and etc. exhibit truly startling plumes of black smoke. Isn't this just wasted fuel? Why would they do it?
Aha! I have always wondered that!
'82 standard cab 3 axle SD22 turbo
'89 int'l 9700 Cummins 444 (855 ci)
'29 HD FD export model

davehoos
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#7

Post by davehoos » 12 years ago

LPG or other gasses used in with diesels in several forms.

assist.normally in small bottle for starting and short term extra power.aproaching a hill.some use this tech in combination with aftermarket turbo instalation to fix tuning troubles.

reduce pollution. this will become more common,in combitation with
catalists and scrubbers

fuel replacment, there are very good LPG systems around that will run an engine using a % of gas reducing costs.i dont know by how much but in australia LPG is less than half cost of diesel.

new car systems are required to meet exhauste emision standards so exhauste mixtures are checked and he deal is that the fitted system has been aproved.in older times home made conversion was common.

i had a old sd22 urvan camper at work for a/c repairs.it had a century convertor with a venturi in air intake.when you opened the throttle gas was drawn in and the diesel IP topped up what was needed.the idle circuit was blanked off.

a 3.9 liter isuzu [4BD1]with factory turbo added.it had a electronic controlled LPG mixture using a map sencor and simple spud into the air intake before the turbo no real venturi just a draft tube.it had a EGT censor.the landrover was fitted with the long torpedo look gas tank common in UK,i dont think its more than 30liter.

inlaws customer purchased a new kangaroo van with liquid injection,it ran up to 50%.he thought.
WCJR31 Skyline.3.0 manual.wagon
R31 SKYLINE/Passage GT/PINTARA
LPG Ford Falcon 99-06 93 Disco
Local Shire Southern Zone Mechanic.

bacho
Posts: 121
Joined: 13 years ago
Location: Greenville South Carolina

#8

Post by bacho » 12 years ago

Ok, I will start the water/meth deal this week becuase I have all the parts needed for it and I will try that out. In the mean time I will collect parts for the propane.
1992 nissan pathfinder 4x4
1985 KC 720 4x4
1982 KC 720

davehoos
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#9

Post by davehoos » 12 years ago

i found a few web forums and had a chat to local gas fitter.

on the forum they refer to 14% mixture.
when you do the maths--
nonturbo 12 L per 100KM on diesel.
changes to 10L/100km and 2.5 L of LPG.LPG is 45% cost of diesel.
at this mixture 0-60 times are improved and up hill speeds.

turbo--- 14 15.5L/100km is reduced to 10.5-12.5L/100Km of diesel
at 2-3L LPG.lots more power.

most commented not to bother with vapour induction as you loose too much oxygen unless it turboed and use electronic controled unit.
WCJR31 Skyline.3.0 manual.wagon
R31 SKYLINE/Passage GT/PINTARA
LPG Ford Falcon 99-06 93 Disco
Local Shire Southern Zone Mechanic.

greaseburner
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Location: southwest Manitoba, Canada

#10

Post by greaseburner » 12 years ago

I just checked out that link. The $85 piece is the EWS (empty tank warning system). The propane injection system is $300 US. Price is at the bottom. When you click on the 'to buy' button, it goes to the wrong link. Otherwise the system looks reasonable.
1987 Kingcab SD25
Dave

bacho
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Location: Greenville South Carolina

#11

Post by bacho » 12 years ago

davehoos wrote: turbo--- 14 15.5L/100km is reduced to 10.5-12.5L/100Km of diesel
at 2-3L LPG.
Not sure I completely understand the numbers you have there. Can you simplify that?
1992 nissan pathfinder 4x4
1985 KC 720 4x4
1982 KC 720

davehoos
Posts: 525
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Location: Karuah Valley,NSW Australia
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#12

Post by davehoos » 12 years ago

from a nissan patrol forum and a few 4X4 forums i combined comments to give aprox range of fuel use.talking to my works customers and a other mechanics I'm happy with these aproximates.patrol is much heavier than maxima,or 720-D21 but it give a basic guide to add up is it worth fitting.

australia we use liter per 100KM.L/100km
100KM is around 60MPH.
1 US gallon is 3.785L
LPG is not 90% propane as in USA and has a octane rating of 91.

aftermarket TURBO TD42 patrol will use between 12 and 16 liters to drive 100KM normal everyday driving.
3 to 4 US gallons per 60 miles.15 to 20 MPG.

gas assist units refer to 14 % lpg added.i dont know if this is a ratio of fuel or air. 2.5L is 16% of 15L.

the owners mostly claim that for 2.5 liters of LPG added you save 2 to 4 liters of diesel and have a cleaner exhaust and slight power increase.
they dont apear to claim a low end tourque increase.

from my LPG installers course manual a figor of 23:1 AIR:FUEL in liters
[15.5:1 KG] is needed to ignite LPG.i thought it was 230 :1 from my fire training.

http://www.gore-research.com.au/
sprint gas is in my local area with lots of one offs.
i was looking at the nissan fuel gauge switch.

http://www.lovatogas.com/
this is one brand sold near my work.ive seen these fitted using LPG..they are advertising a system in europe that runs 20% diesel 80% CNG.
WCJR31 Skyline.3.0 manual.wagon
R31 SKYLINE/Passage GT/PINTARA
LPG Ford Falcon 99-06 93 Disco
Local Shire Southern Zone Mechanic.

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philip
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Location: Southern California, USA

#13

Post by philip » 12 years ago

davehoos wrote:-SNIP-
australia we use liter per 100KM.L/100km
100KM is around 60MPH.
1 US gallon is 3.785L
LPG is not 90% propane as in USA and has a octane rating of 91.

aftermarket TURBO TD42 patrol will use between 12 and 16 liters to drive 100KM normal everyday driving.
3 to 4 US gallons per 60 miles.15 to 20 MPG.

gas assist units refer to 14 % lpg added.i dont know if this is a ratio of fuel or air. 2.5L is 16% of 15L. -SNIP-
"davehoo": How much for AU$$ per liter (x 3.78 for a USA gallon. $1AU = USD $0.84 http://www.xe.com/ ) for aussie propane? And, how much AUD$$ for D2?
-Philip
Passed 08May2008
My friend, you are missed . . .

1982 Datsun 720KC SD-22

"Im slow and I'm ahead of you"

zen
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Location: london uk

#14

Post by zen » 12 years ago

Here's a typical British add-on LPG diesel system...abit too expensive though.

"Turbo Diesel Lpg Autogas Conversion Kit for all engines"
Boosts the Performance, Power & Economy of the vehicle

Item number: 220001757251 (on that auction site)

Claims ...

"D-BES200 systems work by injecting small variable amount of LPG gas vapour fuel directly in to the engines manifold intake as required by engine under load, etc. increasing the diesel fuel combustion resulting in a noticeable increases in performance & engine torc up to 25% more power increase on some turbo charged engines, with far lower exhaust emissions, lower engine & exhaust temperatures have also been reported, etc. Diesel fuel savings can be achieved when used under the same driving conditions as before up to 30% more diesel fuel economy has been reported by customers. Savings made from normally un-burnt diesel fuel wasted in poor combustion & expelled through the exhaust system in pollution is now used to power the engine correctly, not only does un-burnt fuel cause pollution to our environment but is a direct cost to us in wasted fuel & money.
"
turbo it

(sd33t home turbo set up if anyone is interested..)

davehoos
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#15

Post by davehoos » 12 years ago

In hunter valley autogas is AU$0.45-0.59 per liter. road side bowser. comes from bass straight victoria. propane is often sold as autogas. comes from northern australia. it is used for home cooking gas and is delivered often by the same trucks.

Diesel is AU$1.33 per liter today.same as unleaded. this is urban prices and includes taxes etc etc. US$4.28 gallon.

There are discounts and tax rebates for fuel. fuel used by trucks to transport essential services [food] have a rebate to remote areas. diesel used for agriculture and mining have no road tax.

LPG conversion of motor vehicle has a AU$2000 fedral rebate and some states also have rebate schemes. a high tech conversion may cost AU$4000. it cost me for basic unit AU$1000-1500 +labour.

Factory backed LPG new vehicles amount to 25 cars per month in this state-26000 per month total.

In UK there are bonus systems and rebates, I'm certain that prices there are inflated. some of the conversion costs I've seen from UK you could ship a car to this end of the world for the conversion and use the same parts and have change.
WCJR31 Skyline.3.0 manual.wagon
R31 SKYLINE/Passage GT/PINTARA
LPG Ford Falcon 99-06 93 Disco
Local Shire Southern Zone Mechanic.

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