LPG- V8 Conversion

[dammer s]

I had my car (a 411s3) converted to LPG years ago and drove it for 3 years ( 30.000 km/year) without any problems due to this conversion.

[GREG]

I know a good place with experience in V8's -- maybe you could see if a doughnut tank will go in the spare wheel bay to keep all the boot for the 412 roof bits.

I couldn't believe it when I went to get a gallon fuel tank filled with Diesel on Saturday £9.72 !!! - all the prices in litres makes us old farts unaware of how much a gallon prices have gone up ! It was 50p / gallon when I worked at the local petrol station as a teenager , and I filled your car for you and washed your screen !!

It made me laugh the last time I was in Florida listening to a couple of American guys moaning about the high cost of fuel. They wouldn't complain after paying UK prices for a while.

Bristol did a fantastic job on the Blenheim 4 with the LPG. When we did the maths after travelling from London to Leeds , it worked out at just short of 40 mpg petrol equivalent cost. So more economical than my Merc diesel and no noticeable difference in performance from petrol.

I guess it depends on how much mileage you intend to do and how long you intend to keep the car - a lot of sums to do :-)

[lansdownplace]

Originally Posted by GREG

I guess it depends on how much mileage you intend to do and how long you intend to keep the car - a lot of sums to do :-)

It seems that you get 20% less MPG from Gas and 10% less BHP (don't know about low end torque) which whittles away the saving a little. On 12,000 miles a year it has to save at least £1,500 quid. What would it cost to install?

The tanks are a bit of an issue for the 412 as taking the roof off is a key benefit. Is there enough space left to slip the roof on top of the tanks?

P

[GREG]

About £800 to £2500 depending on the kit and who fits it.

You can always find all the bits and bobs on ebay very cheap to do it but most professional installers will send you away with a flea in your ear so you would need to find a competent mechanic to fit it all together and then get it tested. It would be the cheapest route and maybe the new Bristol company could help ?

I believe that the engine compression needs to be ramped up a bit and the cooling needs improving, along with going up to 10mm HT leads

Get some proper advise :-) The installer I talked to is near Tadcaster so a long way from you ! He reckoned around £800 for my 408 a couple of years ago.

[alistair]

If you have a carburettor car I would live with the fuel costs. My experience was that the car ran badly on gas and worse on petrol. The surge of power which is such a feature of the V8s disappeared altogether. Talking with Toby last year confirmed that their recent policy was to fit gas only to FI cars.
Alistair

[GREG]

I probably overall agree with Alistair because with a carburettor it will always be a compromise for the best set up for gas or petrol, whereas on the Blenheim 4 the ECU does the necessary fuel air mixture adjustments through the injection system.

I know that some people are happy with the set up on a carb but it always ends up as running better on one fuel than the other and usually starting on petrol and finishing on petrol -- needs to be monitored.

Saying that, Pauls car is such a special example, that it probably justifies the expense of converting to fuel injection and the box of tricks to make it all work properly.

Maybe it would be worth finding out if the wing bays could both take doughnut LPG tanks and the weight of the fuel safely, then doing away with the the spare wheel and moving the battery and electrics to the boot.

That would still leave ample room in the boot for the convertible roof components.

Hell of a lot of work and expense though and if you are going to go that far away from standard, maybe a nice modern common rail diesel would be the thing to give lots of power and torque with great economy !

Best leave it alone :-)

[Thor]

If you really want to run a Bristol with Chrysler V8 on LPG I would recommend the following :

1) Rebuild the engine with a high compression ratio, this gets back some of the torque and fuel economy otherwise lost. LPG is a very 'high octane' fuel, so it stands a lot more compression, and high compression improves thermodynamic effeciency.

2) Run the gas as a stand-alone injection system, using a wide-band lambda sensor in the exhaust, investing a reasonable time on calibration. The gas injector pipe design can improve combustion considerably (but this is proprietory knowledge, sorry).

3) Use two gas regulators (gas evaporation/pressure regulation) to achieve enough fuel flow capacity.

4) Either learn how to do the switch over to and from petrol manually, or remove the petrol system altogether, keeping the carburettor only as a throttling device (Alternatively buy a 4-barrel replacement throttle body of the fuel injection type.). Don't worry about cold start except in the deepest depths of winter, I can tell you how to deal with this down to about -15°C.

5) Plan long journeys to allow for the need to re-fuel at known LPG outlets.

6) Carefully think through the tank options, such as under-wing tanks, etc. to optimise the car for your personal requirements. If the petrrol system is removed, a good size LPG tank can go where the petrol tank used to be.

"Simples."

Total cost including the engine re-build : about £9,000 + VAT. SO probably not actually worth it in pure economic terms, but delightful when you get that feeling of enjoying all that performance without thinking of all the £s being ejected from your exhaust pipe.

As a complete alternative, I know somwhere which could fit a Land-Rover/Jaguar V6 turbo-charged diesel engine with about 400 lbf.ft and over 200 bhp.