View Full Version : lpg powered motor

01-04-2007, 09:10 PM
Gday i don't know the first thing bout motors lets get that out of the way right now. But do you think this is possible to run motors on lpg?. Probably not with the current motors but could they develop uch an engine?.With the price of boats going north what if you could half your running costs of fuel.
Your thoughts. Or is this just a ridiculous thought?


01-04-2007, 11:38 PM
Hell yeah, motors do run on LPG, even Diesels get more power from mixing the gas in with it's normal fuel. Very few boats though, rumour has it Sydney water taxi's run on LPG gas, but last time I asked one of the skippers he daid they don't.

To get the best use out of LPG, the compression has to be bumped up to near 20:1 as LPG has a octane rating of around 120. That be why it's great for the Diesel.

But to run a boat on LPG, think the motor runs to cold and the gas could be prone to freezing up, then you go no where.

Running out of fuel could be a problem too, unless you hook your barbie bottle up as a spare fuel tank.

02-04-2007, 01:54 PM
Fuel leaks with LPG,,,,,Boooommmm
Very dangerous.

02-04-2007, 06:08 PM
gas on a twostroke hmm dont know
but applied to a 4 stroke cant see why not
inboard cant see a prob
there is issues of explosive nature
no worse than petrol
there is a issue of lubrication as petrol does act as a lubricant gas doesnt do the same job why the reason gas cars have hardend valves and seats
could be worth looking into if rebuilding personaally wouldnt fit to standard motor
then there the economy issue as you would use a lot more gas and have a power reduction but pay less for gas plus sest up costs ?????
but cant see that manufactors couldnt build a motor if they wanted all depends on consumer demand

02-04-2007, 06:10 PM
G'day Dave

I wouldn't be surprised if it's been on the drawing board before, or is currently being looked at. There's endless possibilities with marine propulsion, look what their doing with light weight high speed diesels now. There are international regs concerning diesel producing air pollution from ships, LNG carriers are able to use the boil off of their own cargo to fuel the turbines. As the supply of hydrocarbon fuel diminishes, more efficient methods of using hydro fuels will be developed.
A sealed, pressurised tank will even add to reserve buoyancy.

02-04-2007, 06:35 PM
Found this bit of info which may be of interest:

02-04-2007, 06:42 PM
I don't know about LPG boat motors but having had an LPG car for two years and about to replace it next week with exactly the same, I love LPG vehicles.

Smoother running. No smell. Cheap to run.....BUT .... when the gas runs out, you have to be towed home. Not even the RACQ can help you on the road if you have an all LPG vehicle. (They on't have gas fitter licences.)

Having said that, autogas is available everywhere now. I drove to Charleville last week and filled up in Dalby, Roma and Charleville with no problems at all. Set the cruise control and you'll soon forget the slightly lower power.

Give them time - surely LPG boat motors will come when petrol prices skyrocket as oil starts to run out.

02-04-2007, 08:10 PM
Well i guess there would be a few issues. Running out of fuel perhaps a dual fuel set up could be done.
With the tecnology thats in outboards these days surely it could be possible.
the only thing that could put a damper on things is the amout of units they sell.


02-04-2007, 09:09 PM
I am told there is no loss in power with LPG, they detune the LPG so it will run on petrol. My old Datsun 1600 rally car I converted to LPG only and worked the motor to suit LPG and it flew. It was only a street car when in LPG.

as for running out of gas I did have an emergency fitting to hook up to a BBQ bottle (sick bird) but never used it

the thought of my 4st on LPG Mmmmmm, nah I only put between $5 and $15 a trip in her so the it would not be cost effective for me

Cheers Murf

02-04-2007, 09:27 PM
a turbo'd LPG inboard would be the only combo that I would think would be worthwhile. Due to the high detonation resistance already mentioned, turbo LPG motors are a great sucess. psssssssssssssh

02-04-2007, 09:58 PM
Not sure there Hamish 73, my old AB Cordia Turbo had pretty low compression.
But don't really know how LPG would effect it my guess only, it wouldn't work that well on a low comp motor, but boosted got me thinking NOS works well maybe LPG could have some merit, if it's blended with the petrol.

03-04-2007, 06:40 AM
the only one I had anything to do with was a Ford Ghia wagon with a decompressed 250 crossflow, big truck turbo on LPG, ran up to 18PSI, low 11's on the 1/4, his previous engine was dead stock with a head spacer and lower boost, and that was still good for high 12's. EGT monitoring is essentiol tho.

Getting back on track, not sure I'd want to be on the water with a LPG cylinder.
I would like to take my 3 way fridge out for day trips and run it on gas, but have never liked the idea of having a gas bottle in the boat with me.

03-04-2007, 05:02 PM
Mecury marine outboards can be run on lpg all u have to do is get a conversion kit,as i was going to do it 4 my last outboard, i don't know if other brands also do this. One problem is most steel gas containers rust and are expensive to maintane, as far as being dangerous on a boat most larger commercial vessles have large gas cylinders for there freezers

03-04-2007, 10:39 PM
Well the old water taxi that ran to coochie from readland bay ran on lpg and was outboard powered. The problems with lpg for boats is the tank being steel the shape and size of the tank and where are you going to mount it in you boat.
I install, service and repair lpg systems to all makes and models of cars and light commericals i run my boat on petrol. MARK.

03-04-2007, 11:20 PM
Yes copie the tank would be a bit of a problem.

You would be nice and busy with the rebate scheme how long is the wait?


04-04-2007, 05:53 PM
did some ringing around about lpg motors and it is true that a motor built and tuned for gas only can produce as good or better horse power
due in cars i might add the cam timeing adjustment and ignition timeing are greatly different so that is one reason why duel fuel vechiles are a happy medium so lesss power with gas
sole gas motor willnot run on petrol but personally if you could countor the effects of corrosion on gas tanks or use a alternitive storage the oputunties for gas power boats is endless
which would be great since i been told some dams now prohibit 2 strokes for pollution

05-04-2007, 02:38 PM
Hey dave yes lpg is laways busy but kits and tanks for most vehicles are now readily available.