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I am looking into alternatives to reduce the future fuel costs for my mobile home. It is currently powered with a petrol 7.5 litre EFI Ford V8. There seems to be two possible alternatives; Re-power with a Ford V8 diesel that is available or convert to a gas injection LPG system.
What do you recommend taking into consideration fitting cost, ongoing cost, and future predictions of fuel costs?
Ralph
From the "Ask Jack" archives - 14 December 2009
I'm not sure I can answer this question with any certainty or credibility as there are so many variables. You certainly need to be asking a number of people their opinions and just as importantly trying to find people who have done conversions to either diesel power or LPG.
Making contact with the Motorhome association (www.nzmca.org.nz/) may also be helpful.
I don't believe a diesel conversion will be as straightforward as you may think as there are always hidden surprises with any power unit change like this. You will also need some peace of mind the donor engine is going to be reliable so there could be some reconditioning required which will be an additional cost.
The costs can escalate very quickly if you are paying for the total conversion (parts and labour). Once these types of jobs are started there is no turning back and remember diesels are not the cheapest engines to maintain and you will have to pay Road User Charges (RUC) once you are up and running. The vehicle may need to have a hub meter fitted as well depending on its weight.
LPG has come a long way in recent times and I am told the introduction of gas injection has made a huge difference to the overall performance and enhances the compatibility of running a duel fuel system (both petrol and LPG). With the current engine being fuel injected then the change to LPG is much easier from both a time and performance perspective. I am told a LPG conversion like this may not be possible on a carburetted engine..
I believe a LPG conversion would be the cheaper option, even so, expect to pay upwards of around $7,000. A diesel conversion could easily double that figure by the time you purchase the engine and pay all the labour and parts costs.
A couple of important points to remember are; Diesel will give you better fuel consumption with LPG up to 20% less fuel efficient (litres per 100km). The cost of LPG is currently around 25 cents cheaper per litre but you do not pay any RUC.
Future petrol and diesel prices are very hard to predict so don't do the sums assuming everything will stay exactly the same as it is today. LPG is imported into NZ so the retail price is subject to exchange rate changes as well.
Lots to think about Ralph and I don't hold myself out to an expert on the subject. I recommend you find someone who is knowledgeable about LPG conversion to talk to.