LPG conversions in sporty cars

[Jim AK]

skyrover said:

lpg = total ballache

Twice the servicing, twice the complexity, twice the chance of something going wrong

And then then you either lose your spare tyre or a chunk of your loadspace.

Total BS as regard service, you only really need filter(s) changed every 15k or so.

Total BS as regard things going wrong too. If anything you have more chance of completing a journey with both fuels available, from a running out point of view the car will use a 'slave' ECU for the LPG Install that will mirror the existing petrol set up. Biggest thing is to fit a Flash Lube system to lubricate cylinders, I think all good systems come with this now anyway

Yes you may loose some boot space/spare wheel carrying ability but I ran my very unsporty Volvo V70 with some sort of gloom in the tyres that would seal a puncture.

As I say I ran a V70 for 5 years on LPG totally faultless gave me cheaper motoring for all that time & I would have considered it again but for 2 things. Diesels are so much better on economy & a Common rail petrol engine needs to run petrol all time to to cool the rail.


I now run a Merc 220 CDI & fuel costs are almost identical.

[Glyn84]

I've run a 6 litre Monaro on LPG for 50,000 miles and have no complaints. I've found the key is get a good garage with someone who really knows what they're talking about and has a rolling road to set it up with. I have a LPG Vs petrol comparison dyno graph and up to about 4k rpm it's pretty equal, beyond that it tails off to around a 10 BHP loss (runs 440 bhp on petrol). That's not the whole story though as the LPG throttle response is nowhere near as good as petrol, but you can switch fuels at the push of a button.

If you're that bothered some of the LPG installations can have the ECUs configured to automatically switch to petrol above a certain RPM.

[74merc]

There was an article on here recently about LPG E9X M3s track cars at Palmersport I think. Sporty enough?
There's nothing like a question on LPG to bring the naysayers out!

[p1tse]

How about the safety aspect? Say most tanks are in the boot or spare wheel well, what happens to a significant rear end shunt does this increase of flammable chances ?

Also what about the practical side of things, do you install a fuel gauge etc.?

This makes an interesting read.

Tbh I'm looking at b6 s4 audi 4.2 v8 but noticed a handful LPG on the used markets

[Ozzie Osmond]

If you want "sporty", buy a petrol.

If you want "economy" - buy a diesel.

To my mind LPG is in a bit of a no-man's-land these days with diesel continually improving.

[zcacogp]

Purity14 said:

zcacogp said:

TooMany2cvs said:

... since LPG is around 100-105RON, pinking is the least of your concerns. If you're setting it up as LPG-only, you can take advantage of that and regain the power lost to the lower calorific content.

And that's where my interest starts to kick in. Given the high RON (106), an LPG-only engine could be built with a very high compression ratio and better ignition advance which would give huge power, wonderful torque and decent economy - and it would run on cheap fuel. The only downside is that it would ONLY run on LPG, with no option of a reserve petrol tank.

Has anyone ever done this?

Someone on the micra.org.uk forums has indeed done this with a 1.3 Micra, even removed the stock petrol tank - 4-2-1 manifold with GA16 throttlebody etc - this was many years ago though.

Ooooh, interesting. Do you have linkage?


Oli.

[V8RX7]

Ozzie Osmond said:

If you want "sporty", buy a petrol.

If you want "economy" - buy a diesel.

To my mind LPG is in a bit of a no-man's-land these days with diesel continually improving.

What if you want Sporty WITH Economy ?

Or like to listen to a V8 ?

Or enjoy revs ?

Or don't want the risk of diesel injectors, pumps, turbos, DPFs ?

LPG has been a great option for many years.

Currently my wife runs a 165bhp 2.3 Mazda6 - giving the equivalent of 50mpg - she used to run an A6 1.9 TDi 130bhp giving 43mpg

I run a 225bhp 4.6 F150 giving the equivalent of 30mpg - I used to run an Isuzu 150bhp diesel that gave 25mpg.

So both have more power and more economy and sound / drive better.

[kambites]

V8RX7 said:

What if you want Sporty WITH Economy ?

Buy something light.

Personally, I rather like the idea of something like a 911 converted to LPG.

[mini1380cc]

Had an LPG'd FTO back when it was 30p per litre. It was great for long commutes and saved me a fair amount of money. It was slightly down on power compared to petrol though.

[RWD cossie wil]

I'd love an E39 M5 converted to LPG, think it would work out the same cost to run as a E39 530d that I'm currently using? Averaging 39.7 mpg in it at the moment.

[ArmaghMan]

Ozzie Osmond said:

pjac67 said:

Very little difference in power and mpg

I'm not convinced. There's much less energy in a gallon of LPG - only about three quarters as much - so expect mpg to be down by about 25%

There's much less energy in a cubic meter of Nat. Gas than a cubic meter of LPG.
Does this mean that houses with Nat. Gas heating are colder than those with LPG, of course not.
It's a question of getting the map right for the car, and then how you drive it.
I had my M5 converted and then took the kit back out. Maybe slightly more kick from petrol.

[ArmaghMan]

kambites said:

Has anyone managed to solve the problems associated with using LPG on direct injection engines yet?

Not to my knowledge . Shame as a nice 335i on LPG has some appeal.

[edward1]

I hate people who make sweeping statements like "if you want sporty buy a petrol, if you want economy buy a diesel"

Personally I don't want a modern diesel which will inevitably cost me a small fortune in fixing when all the emission rubbish goes wrong. I could run 2 cars (and did for several years) one being a sports car and one a daily hack, but then I only really get to drive the sports car at weekend. Why shouldn't I drive a 400hp V8 every day get the pleasure out of the car but not pay through the nose in fuel costs. Hence I run a XKR on LPG. It costs about the same in fuel as running the other family car that the wife uses a 2.0l petrol mazda 6. In the case of the 2.0l the pay back time for the miles we do doesn't make it worth converting, however if a suitable LPG converted estate car happened to become available I'd swap tomorrow.

Converting to LPG also meant I could take advantage of the huge depreciation on big V8's. If I'd gone for an XJR I could have probably bought a car and paid for the conversion for less than say a 535d of similar age. Not that the BM is a bad car but I know which I'd rather have.

I would say I don't expect the LPG to add to the resale value of the car on this type of vehicle, if it were a rangerover it would be different as despite the same engine as some, peoples perceptions of LPG are that you shouldn't put it on a performance coupe.

There is no noticeable change in power when driving and in general the switch over is not noticeable. I have done over 30k on gas and the conversion has paid for itself at least 10k ago.

The biggest down side to gas is I find myself planning routes on long journeys to make sure I pass a LPG station. This doesn't normally mean going out of the way just being aware. The other being that it takes longer to fill than a petrol tank which can be annoying in winter.

[ArmaghMan]

Glyn84 said:

I've run a 6 litre Monaro on LPG for 50,000 miles and have no complaints. I've found the key is get a good garage with someone who really knows what they're talking about and has a rolling road to set it up with. I have a LPG Vs petrol comparison dyno graph and up to about 4k rpm it's pretty equal, beyond that it tails off to around a 10 BHP loss (runs 440 bhp on petrol). That's not the whole story though as the LPG throttle response is nowhere near as good as petrol, but you can switch fuels at the push of a button.

If you're that bothered some of the LPG installations can have the ECUs configured to automatically switch to petrol above a certain RPM.

This, this and this agin. Get on first name terms with the guys who install the kit. I know LPG is about saving cash but get a good installer.
LPG is a bit slow to fill so you can get talking to people as they fill. Get a reccomendation for an installer that way. I've done 70k plus miles in an M5 and a 528i and would heartily reccomend it.
By the by if you keep chickens or know someone who does they will have a giant LPG tank, and be buying their gas at 28p per litre. Obviously using such subsidised gas in a motor vehicle would be evading duty and thus illegal!

[TooMany2cvs]

zcacogp said:

And that's where my interest starts to kick in. Given the high RON (106), an LPG-only engine could be built with a very high compression ratio and better ignition advance which would give huge power, wonderful torque and decent economy - and it would run on cheap fuel. The only downside is that it would ONLY run on LPG, with no option of a reserve petrol tank.

Has anyone ever done this?

I remember talking to a bloke, years ago, who'd built a very SWB off-road special Landy, absolute bare minimum bodywork, smallblock Chevy v8 - and tuned to run on gas only.

Gawdaloneknows what power and torque it was chucking out, but it sounded like it was somewhere a chunk north of "adequate"... Looked like it might be mildly amusing. </understatement>

The biggest drawback has to be that it's not going to be straightforward to fill the tank, either when you first build it, or if/when you run out. Not beyond the wit of mankind... The built-in LPG cooker/fridge tank on our VW Westfalia camper has a port which you can either use as a take-off for connecting a BBQ etc to, or a gas bottle as an auxiliary supply - and there's a 1200 litre (at 45p/litre and 5% VAT) LPG tank in our back garden for the house heating... That'd be naughty, though, since LPG does have (some) duty on for road use, as well as 20% VAT...

[kambites]

ArmaghMan said:

kambites said:

Has anyone managed to solve the problems associated with using LPG on direct injection engines yet?

Not to my knowledge . Shame as a nice 335i on LPG has some appeal.

Shame.

As more and more engines go DI, I'd imagine that's going to kill the technology off eventually.

[Stick Legs]

If you plan to keep the car then why not!
I will admit that the anti lpg brigade will not be impressed with a sports car converted but any loss in value will be amortised by the saving in fuel costs.

I can think of many performance cars I would think lpg would be an inoffensive conversion to, anything GT or auto would be my choice. Big Jags, XK8, XJS. BMW 850i. Porsche 928.

For comparison a mate of mine runs a leggy 540i E39 on gas and his fuel costs, performance & driver enjoyment are the same as my F10 530d but he has no depreciation to contend with and did not shell out £20k for his car!

If you want to, go for it but be aware you limit your market for resale.

[zcacogp]

TooMany2cvs said:

I remember talking to a bloke, years ago, who'd built a very SWB off-road special Landy, absolute bare minimum bodywork, smallblock Chevy v8 - and tuned to run on gas only.

Gawdaloneknows what power and torque it was chucking out, but it sounded like it was somewhere a chunk north of "adequate"... Looked like it might be mildly amusing. </understatement>

Yup, that's the sort of thing I'm thinking about! And if it was an off-road special then he would be legal to use the low-tax LPG you talk about next ...

TooMany2cvs said:

The biggest drawback has to be that it's not going to be straightforward to fill the tank, either when you first build it, or if/when you run out. Not beyond the wit of mankind... The built-in LPG cooker/fridge tank on our VW Westfalia camper has a port which you can either use as a take-off for connecting a BBQ etc to, or a gas bottle as an auxiliary supply - and there's a 1200 litre (at 45p/litre and 5% VAT) LPG tank in our back garden for the house heating... That'd be naughty, though, since LPG does have (some) duty on for road use, as well as 20% VAT...

Filling the tank would be a hassle, not least because you can't (readily) take a 'spare gallon' in a jerry-can to the car to fill it up (particularly relevant for Mr Off-Road-Landie mentioned above, as he won't be driving it on-road to any LPG stations.)

I've heard that domestic heating LPG equipment is made with different pipe fittings to transport LPG equipment and that it's illegal to make a pipe that connects from one type of fitting to another (I can't vouch for the veracity of that statement tho'.) But I'm sure that a trip to your local Pirtek on a quiet Friday afternoon with a spare £20 note or two would yield a reasonable amount of off-the-record help IYSWIM.


Oli.

[p1tse]

V8RX7 said:

Ozzie Osmond said:

If you want "sporty", buy a petrol.

If you want "economy" - buy a diesel.

To my mind LPG is in a bit of a no-man's-land these days with diesel continually improving.

What if you want Sporty WITH Economy ?

Or like to listen to a V8 ?

Or enjoy revs ?

Or don't want the risk of diesel injectors, pumps, turbos, DPFs ?

LPG has been a great option for many years.

Currently my wife runs a 165bhp 2.3 Mazda6 - giving the equivalent of 50mpg - she used to run an A6 1.9 TDi 130bhp giving 43mpg

I run a 225bhp 4.6 F150 giving the equivalent of 30mpg - I used to run an Isuzu 150bhp diesel that gave 25mpg.

So both have more power and more economy and sound / drive better.

How are you working out equivalent mpg?
Mpg is miles per gallon?

Unless you mean £x.xx/mile is less

[V8RX7]

p1tse said:

V8RX7 said:

Ozzie Osmond said:

If you want "sporty", buy a petrol.

If you want "economy" - buy a diesel.

To my mind LPG is in a bit of a no-man's-land these days with diesel continually improving.

What if you want Sporty WITH Economy ?

Or like to listen to a V8 ?

Or enjoy revs ?

Or don't want the risk of diesel injectors, pumps, turbos, DPFs ?

LPG has been a great option for many years.

Currently my wife runs a 165bhp 2.3 Mazda6 - giving the equivalent of 50mpg - she used to run an A6 1.9 TDi 130bhp giving 43mpg

I run a 225bhp 4.6 F150 giving the equivalent of 30mpg - I used to run an Isuzu 150bhp diesel that gave 25mpg.

So both have more power and more economy and sound / drive better.

How are you working out equivalent mpg?
Mpg is miles per gallon?

Unless you mean £x.xx/mile is less

Equivalent in cost terms - it's what everyone running lpg uses.

If I said £/mile no one would have any idea how that compared to their car.

Hence in a simplified version if I get 10 mpg on LPG that costs half the price of petrol (or diesel depending what you are comparing to) the equivalent is 20mpg.