MarineGas for MPI (multi pont injection) engines

[Whitelighter]

I know a lot of people that have converted older engines (Volvo 5.7 etc) over to Marine Gas, and on the whole they are all pleased. I have a newer MPI engine (mercruiser 350 MAG) and would like to follow suit, but I am getting conflicting information from suppliers and fitters of kits on the south coast.

I would love to hear from anybody who has had a conversion done on this type of engine, or any reccommendations as to where I might go for reliable info.

 

[ontheplane]

In my (limited) experience, the MPI engines (in cars) respond MUCH better to an LPG conversion than a single point or carb engine.

HOWEVER - I would suggest the following:-

Shop around.
If the boat is trailable, look into getting a good car conversion (£1500) rather than a boat one (£3000) and fill up at the thousands of filling stations around at £0.29 - £0.40 ppl and then get an adapter to fit the marine filling points (at last count only 6 of them and dropping fast).

Also if you are getting the conversion done by Calor, then get something in writing from them to confirm they will not be reducing the filling points any further - if they refuse ask yourself if there is going to be the ongoing support for gas (if Red gets the duty added then I suspect there will be, if not it may die altogether).

I love LPG, we have 3 cars running on it, and I will be considering getting the boat converted - however this will be by a local company and it will cost £800, it will also have an Autogas not marine gas fill point and I will look for an adaptor.

Also remember that LPG conversions are still back in the 1980's really, and with all the conversions I have had done there have been significant teething problems - make sure you get a 3 year warranty (MAKE them give you that in the price) and make sure the company will still BE there in 3 years or get the warranty from an independant insurance company.


Have fun.

 

[Whitelighter]

Thanks for that.

Fortunately my current Marina, Sparkes on Hayling Island, has a good supply of Marine Gas. Also, my preffered cruising area has a good 5 or 6 listed (hamble, lymington and poole included), but I take your point.

Just seems that red diesel is on the way out (bloody europe), which is why I didnt spend the extra £15k the diesel boat would have cost me.

 

[Xenopus]

Hi Jez,

We've run two LPG boats over the last 6 years and have had quite literally no gas related problems whatsoever - I know that the MPIs are perfectly do-able and I'm almost certain that the person who did our boat has done them. PM me and I can give you their details - one thing to check is that you can take enough LPG to make it worth the while, we reduced the petrol tanks so that we can take 600L.

have good fun with the boat!

Matt

 

[MadMat]

There are a few issues on a boat. All can be worked around, if you are prepared to make some compromises:
a) Storage. The tanks are big, heavy, and usually steel. You can only fill the tank something like 2/3 full. Is the existing/proposed tank space big enough to give you adequate range?
b) Higher fuel consumption - because they are all gas injection systems, it displaces air, hence you tend to lose a little bit of power.
c) On a boat you run flat out for extended periods of time, the vaporiser can struggle to keep up on bigger motors and fitting multiple vaporisers adds to cost and complexity, plus coolant flow through the vaporisers to keep them hot can be limited.
d) The vaporiser needs to have a closed cooling system. A large proportion of mercruiser inboards have a raw water system and retrofitting closed cooling on an older motor is not always recommended.

 

[corncob]

Is your engine still under warranty? I have heard that Mercruiser will void your warranty.

 

[BrendanS]

I don't know anyone personally that has trouble free conversion. I've known several boats/owners who have converted to LPG. Without exception, they have all had problems, either with the conversion per se, or with icing on longer cruises, which meant swapping over to the petrol tank when they were usually in the middle of races or rough weather, or starting problems when they really didn't want to turn the engine off for any reason.

One of the LPG convertors, Solitaire, posts here quite frequently, and has now gone diesel, so he can probably comment more thoroughly.

This personal experience of the problems it's caused, along with Calor reducing the number of marine supplies which means few places to refuel, I'd never even consider it. A rather negative opinion, but based on real life boating.

 

[Solitaire]

Let's put it this way - I'd not do it again! As to the price of red changing, well, having run a petrol boat for so long when red does go I'll be back to square one. The only difference is I'll get nearly twice the range for the same money plus the reliability.

Hind site is a very rich man! /forums/images/graemlins/crazy.gif


PS: Xenapus runs twin 7.4's in a Hunton, he has had great succes with his conversion, there was/is a boat called "Causation" in the Solent that was used as the bench mark for LPG converted boat, that ran twin 7.4's as well. He upgraded his engines to 8.4 but as far as I know did not have the gas "reconnected".

 

[Dave_Snelson]

Hi Jez - I run two V6's in my Windy on LPG. By and large I would agree with the comments made by others here. The storage capacity is in fact 80% of the tank volume, so make sure you get enough capacity. I cannot comment on MPI as my engines are carbs, but I will say that there is no discernable loss of power and the engines run quieter. Also, at the end of the season, the oil, when removed, comes out near the same honey colour as when it went in on the last change. So it obviously burns much cleaner. I haven't had vapouriser icing problems, but then again, flat out for me is 46 kts, so I don't do that too often! A proper installation will have adequately heated vapurisers (one for each engine) and at each service just make sure that your engine thermostats are checked or replaced. This ensures the correct running temp, which in turn ensures that hot water (raw or closed) is circulated through the vapouriser(s).

I was lucky in that I bought my boat already converted - but I would echo the sentiments of others on here that suggest getting an automotive company to do this work as it is bound to be much cheaper than the usual "marine thievery".

The real downsides are weight and loss of storage / stowage capacity (not a real problem for me).

Just as a matter of interest for you, I did an 85 mile run the other week (heavily loaded) when the weather was nice (remember that?). It took me 3 and a half hours hours almost non-stop. Having filled up at the start and at the end, I had used up 240 lt which is 53 gallons. So the maths looks like:-

15 gallons per hour consumption (fully loaded)
1.6 miles per gallon (which it does consistantly)
Cost £86.40
Cost if it had been petrol £182.40 (including a 20% loss for LPG)

I am now in my third season, and although my Windy has given me more than my fair share of problems, the gas installation hasn't (touch wood!).

And as for Calor - well my opinion based on what I have found, is that they are a bunch of self-serving arrogant liars that may well make an expeditious comeback if red diesel goes...subject of many other debates on this forum!

Good luck
Dave

 

[KevB]

Can't comment on the MPI issue but can on LPG in genereal. I had my previous boat converted (twin 5.0 ltr) to LPG and had no problems at all. Run much smoother on LPG and no dramatic performance loss. The only down side was we could only carry 300 ltrs of gas. The gas tanks are cylindrical so not always easy to find enough space for more Gas.

Would I do it again.... Even though we had zero problems Proberbly not. when compared to diesel the running costs are still high due to the vast efficiancy gap between the two. I would say gas is at least 40% less efficiant than diesel
so although they may be comparable on price you get a lot more running with diesel.

Sorry petrol heads but in a 30' plus boat there is no substitute for the torque of a deisel lump.

 

[mercman]

Problems we found on LPG conversions are bodged installs. Normally by companies that fit it to cars and dont use marine grade hardware to install.
The carbs run better with LPG the boats with EFI/MPI have had loads of problems.
What it is was the o-rings on the injectors going brittle and breaking down. It was something to due with the lower temperature of the LPG flowing thru. They were freezing.

 

[Solitaire]

Solid sence again! I recall the problems on the MPI's. In fact at one stage Darren would not touch them with an LPG conversion. Even with marine grade fittings it would play up. I had endless problems with the sensors - bloody things would react to the damp and go off! Nothing wrong with the system as such, but the alarm drove you mad. Had to unplug the sensor to stop it! Defeated the object of having them.

 

[mercman]

Had a Four Winns in with conversion and over sensitive sensors.
This sensor cut the fuel off if it sensed LPG or petrol fumes. Even exhaust fumes cut the bloody thing out.....as we found out as the Lymington ferry was fastly approaching. We dont touch converted boats now tooooo much hassle

 

[BrendanS]

[ QUOTE ]
We dont touch converted boats now tooooo much hassle

[/ QUOTE ]

So that's a no then?

 

[Solitaire]

Yup - I had that on Solitaire a number of times. I put a plastic shield over the top of the sensors in the end to try and prevent water ingress into the unit itself as the salt would also corrode the inside of the sensor and knock it out - bloody nightmare frankly! I suffered for 2 years before finally throwing in the towel and converting to diesel. After all the trials and tribulations of breakdowns over that period my daughter will still not come on the boat, even though she's (the boat that is) now done over 300 hours of trouble free boating!

 

[mercman]

Are we agreed its a waste of time....

 

[Solitaire]

It would appear we do! /forums/images/graemlins/grin.gif