928 LPG Consumption

[swordfish767]

I had many issues with the jetronic and decided to convert it to LPG.
Any experience?
What evaporator do you use and what is the average consumption of LPG?

[JK McDonald]

Hey Swordfish, If you could figure a way to buy LPG without the road tax, the conversion may be worth the effort. Where are you planning to put the storage tank ? They are normally installed in the trunk because of the hanging weight.

Just a comment - several years ago the Canadian Government initiated a nation wide campaign to convert thousands of both public and private cars, trucks and buses to run on LPG. To generate sufficient pork barrel enthusiasm amongst their members of Parliament and the voters, an assortment of federal subsidies and tax incentives were offered toward each vehicle conversion. To the individual on the street the project initially seemed economically feasible as long as their Gov helped pay for the equipment installation, vehicle upgrades (suspension, etc...) and subsidized LPG to keep it economically viable compared to gasoline. But in reality all the subsidies dried up, the price of LPG jumped significantly and the advertised mpg was much worse than expected. Add to this the - Increased Vehicle Weight, Lower LPG Combustion Efficiency, Canadian Cold Weather Reliability Issues, Maintenance Intervals and then the bottom fell out of the value of a converted vehicle.

Their program reminds me of the typical poorly thought out American government boon-doggle forced down the throats of Americans called Ethanol. The difference is that at least the Canadians had a choice whether to participate.

Good Luck, Michael

[Plexus928]

I have owned LPG (LPG in Australia,propane to all you people in the states) powered cars for over 25 years, love it, Done 4 conversions myself.
First thing to be aware of, DO NOT GO DUAL FUEL! You cannot tune so that both run at 100% efficiency.
Rip out the petrol tank and there will be heaps of room for a barrel LPG cylinder, I actually contemplated doing this myself, when I split my plastic petrol tank, (local thief wanted $600 for a replacement, but I found one for $200 so did not proceed with LPG)
LPG makes it a breeze to pass emission tests, near zero emissions. Octane rating for it in Australia is 105,(used to be 110) runs better with high compression engines 10, 12/1. might not be as good in a 928, which are 8.something /1
Keep it simple, don't go for a computer controlled system, you could end up with more problems than you are having with stone age jetronic. Check LPG carbs that give a variable jettable gas flow.
Gas research a company here in Australia make some A1 performance carbs google them.

[swordfish767]

Hi, yes I will keep it simple-without any computers,Will install the tank in the trunk or will remove the plastic petrol tank.....Just not sure what evaporator to use.Any suggestions?

[Plexus928]

The evaporator has to match your mixer/carburettor, first work out what system you want to run then pair them. starting with what will fit is a good start point.(Is there enough room at the plenum inlet to mount a carb there?)
different systems different requirements.

[JK McDonald]

Hey Swordfish - Of course anything can be accomplished with enough persistence and money. All I'm saying is to just do your homework before committing to the LPG system conversion and start buying parts. There are many long term factors to take into consideration. Two very good friends who I worked along side in Fort McMurray, Alberta sunk a lot of money into converting their pickups to run on LPG only to be disappointed in the overall economic returns on their efforts.

Hey Plexus, I spent a couple of years running the roads between the Goonyella, Moranbah and Peak Downs mines in Queensland. Put a lot of km's on a little diesel 4x4 Ute while I was over there.

Swordfish - Where are you located ? Perhaps there is a forum member close enough to lend a hand in sorting out your L-Jet problems.

Keep us posted, Michael

[swordfish767]

The main problem is that I am in Bulgaria, Europe.
Not many 928's. I have converted few cars to LPG, but dont have experience with such a big engine.
Here is impossible to find someone who understands Jetronics.Buying a new fuel distributor will be very expensive, sending the old to a service in Germany or UK will be a bit cheaper......
I decided to completely remove the fuel distributor and install the LPG system.

[Plexus928]

try here for information
Propane Forum - Alternative Fuels
Low performance in LPG vehicles is usually related to Compression too low, Car still tuned for petrol( for some stupid reason, a lot of people that convert and go dual fuel keep the tune for petrol-even though they converted to save money on fuel)
A camshaft with revised openings more suitable for LPG is adviseable.-then it definitely will run like **** on petrol. One or the other, don't go dual.
JK, you are talking the real wide open spaces with those places in Queensland-warmer than texas as well.(in the daytime)
I'm setting up on the Gold Coast, waiting to die, commuting between there and current house in Sydney at moment, up there permanently in a couple of months..

Australia did the same silly number with LPG, Instituted a program that subsidised conversions,
Prior, a conversion cost around $1500, Government set up a subsidy of $2000, instantly the conversion price jumped to $3500, , Government money became a bonus for the conversion industry.
Subsidy now nearly gone , last time I looked only $1000, and only for the first 1000 people that claimed per year.(Australia wide!)
LPG here used to be 1/3 price of petrol, now about 1/2, tax on it increasing, borderline not worth converting.
Coincidence, today Sold my wifes LPG car, too much trouble re-registering it in another state,and due to rising LPG price probably be the last LPG car we own.
Russ

[928s]

Originally Posted by Plexus928

try here for information
Propane Forum - Alternative Fuels
Low performance in LPG vehicles is usually related to Compression too low, Car still tuned for petrol( for some stupid reason, a lot of people that convert and go dual fuel keep the tune for petrol-even though they converted to save money on fuel)
A camshaft with revised openings more suitable for LPG is adviseable.-then it definitely will run like **** on petrol. One or the other, don't go dual.
JK, you are talking the real wide open spaces with those places in Queensland-warmer than texas as well.(in the daytime)
I'm setting up on the Gold Coast, waiting to die, commuting between there and current house in Sydney at moment, up there permanently in a couple of months..

Australia did the same silly number with LPG, Instituted a program that subsidised conversions,
Prior, a conversion cost around $1500, Government set up a subsidy of $2000, instantly the conversion price jumped to $3500, , Government money became a bonus for the conversion industry.
Subsidy now nearly gone , last time I looked only $1000, and only for the first 1000 people that claimed per year.(Australia wide!)
LPG here used to be 1/3 price of petrol, now about 1/2, tax on it increasing, borderline not worth converting.
Coincidence, today Sold my wifes LPG car, too much trouble re-registering it in another state,and due to rising LPG price probably be the last LPG car we own.
Russ

Agree on a number of points but here is my actual experience, we converted our Holden Caprice with 6.0 litre V8 and for other members this is a large car weighing around 1800 kgs. On the run and this car doesn't have cylinder deactivation it uses 12.5 to 13 litre per hundred kilometres. The injection is made by a Dutch firm JTG and it is a liquid injection system. It piggy backs the factory computer and it injects 1.3 times the fuel that it would if running on petrol. So it uses 30% more in terms of volume It cost $5,000 with a $1,750 subsidy. Lpg is a by product of the refining process so they need to sell this to get rid of it and the Govt is supposed to keep the lpg at at least half the price of petrol. Currently I pay $0.54.5c with discount verses about $1.30 for petrol. The car feels perkier on lpg and if tuned the car is supposed to have at least 5% more power than on petrol. More like a gain of 10% is likely. It certainly goes better on gas.

I have been considering a gas conversion for the 928 if I could get a custom carbon fibre tank made that would have enough capacity and this would allow enough range and I could run a really high comp which would help with the large camshafts I will have.

[Danglerb]

Doesn't the power drop like 30%?

[928s]

Originally Posted by Danglerb

Doesn't the power drop like 30%?

No as I said the power is up around 5% without a tune or other changes. Can be around 10% more with a tune and higher comp.

Australian LPG Warehouse - Systems

[JK McDonald]

Hey Swordfish, So you're located in Bulgaria ? Isn't that right down the road from Possum Trot Arkansas ?

Perhaps I misunderstood the fuel injection system we are all talking about. Does your car have the Bosch K-Jetronic (CIS) Constant Injection System or the electronic L-Jetronic system ? In either case with all the experienced Porsche owners around - surely we can help walk you through the troubleshooting process and chase some parts.

Let us know - Michael

[Plexus928]

Originally Posted by Danglerb

Doesn't the power drop like 30%?

It will if you just convert and leave everything in a petrol tune state.
bottom line it is a different fuel.
Set up properly- high compression plus cam. it will run close to 1 to 1 with petrol and as 928s says, much more oooph!
Direct injection is by far the best way to go, but at the price is it worth it?-Have to do a lot of mileage to justify it, and, Swordfish only wants to convert to get past an injection problem, Direct injection install would probably cost more than the car is worth.
I used Gas Research jetable carbs on several high compression rover V8s 11/1 comp on a 3.9L and 10/1 on a 4.6L both dedicated LPG engines with gas cams .(the beauty of primitive pushrod engines -only one cam to replace) No computers. simple flange welded onto a cut down throttle body, increasing fuel delivery from idle to WOT. Carbs at the time were only around $450. Rover engines NEVER went that good on petrol, and never ever got close to the economy.

http://www.gasresearch.com.au/epg.html

[Plexus928]

As well as the system that 928s describes I believe there is another computerised system that delivers BOTH petrol and LPG at the same time,
Not quite sure of the logic behind this one.

[JK McDonald]

Hey Swordfish, Seriously - if we can help with your 928 please let us know. Whether you decide to go with a LPG system or need help troubleshooting your original gasoline fuel injection there is plenty of experience and information available here. Please don't hesitate to ask.

Keep us posted, Michael