LPG

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Or888t

Original Poster:

1,686 posts

172 months

Wednesday 5th January 2011
quotequote all
After 2mins of wikipedia research. (After knowing next to nothing)

Turns out it has a octane rating of 108 RON!
So why doesnt all perforance cars in the Uk run on this stuff instead of the enormously expensive 'shell v-power'?
How do you 'convert' a car to run on lpg?
And yes i know it lowers MPG.
Is it simply because it's not very widely available??

Or888t

Original Poster:

1,686 posts

172 months

Wednesday 5th January 2011
quotequote all
doogz said:
Or888t said:
After 2mins of wikipedia research. (After knowing next to nothing)

Turns out it has a octane rating of 108 RON!
So why doesnt all perforance cars in the Uk run on this stuff instead of the enormously expensive 'shell v-power'?
How do you 'convert' a car to run on lpg?
And yes i know it lowers MPG.
Is it simply because it's not very widely available??
I know absolutely hee haw about it.

But when i was thinking about having a conversion done to a car i was looking at, i phoned a couple of companies that supply and fit kits, and the recurring info i got from them was that it would lower bhp and torque by anything between 10 and 30% depending on how the kit was managed.
Makes sence with such a race-fuel-like octane rating, but surely, in a mighty performance car, compression could be upped, mapping could be done to a very high stress level. ( Ok i know nothing about mapping, but still!)

DaveL86

868 posts

176 months

Wednesday 5th January 2011
quotequote all
Or888t said:
So why doesnt all perforance cars in the Uk run on this stuff instead of the enormously expensive 'shell v-power'?
The cost of installing/converting to LPG often out weight's the potential savings that can be had, the power gains are minimal although team AON in the BTCC are doing very well with their new LPG powered Focus.

Or888t said:
Is it simply because it's not very widely available??
LPG is widely available, I can think of a good three garages within a 5 min drive from my house and those are the ones I know about, probably more I just haven't seen.

Or888t

Original Poster:

1,686 posts

172 months

Wednesday 5th January 2011
quotequote all
I see, how much would a installation to convert to LPG be then? - on average.

Surley at 20p a mile on shell v power @ 30mpg; And 12p a mile on autogas@25mph Thats £1000 per 12,000 mile.

And then being a higher octane fuel...a high performance car would run better &more safe, with further possibilities for tuning.

Mr2Mike

20,143 posts

254 months

Wednesday 5th January 2011
quotequote all
Or888t said:
After 2mins of wikipedia research. (After knowing next to nothing)

Turns out it has a octane rating of 108 RON!
So why doesnt all perforance cars in the Uk run on this stuff instead of the enormously expensive 'shell v-power'?
How do you 'convert' a car to run on lpg?
And yes i know it lowers MPG.
Is it simply because it's not very widely available??
Really high octane ratings aren't much use unless the engine is designed (or modified) to make use of it e.g. higher compression ratio. You are then tied to using only LPG.

LPG holds less energy than petrol, and with the common (and significantly cheaper) vapour phase injection systems the gas displaces more air giving a double whammy on power capability. With liquid phase injection it can can make similar or even more power than petrol, and with an engine designed to run only LPG I'd suspect you could make some reasonable power gains, but the systems are complex and expensive.

Shaw Tarse

31,543 posts

202 months

Wednesday 5th January 2011
quotequote all
shoutJem0911
LPG your input is needed!

Or888t

Original Poster:

1,686 posts

172 months

Wednesday 5th January 2011
quotequote all
Mr2Mike said:
Or888t said:
After 2mins of wikipedia research. (After knowing next to nothing)

Turns out it has a octane rating of 108 RON!
So why doesnt all perforance cars in the Uk run on this stuff instead of the enormously expensive 'shell v-power'?
How do you 'convert' a car to run on lpg?
And yes i know it lowers MPG.
Is it simply because it's not very widely available??
Really high octane ratings aren't much use unless the engine is designed (or modified) to make use of it e.g. higher compression ratio. You are then tied to using only LPG.

LPG holds less energy than petrol, and with the common (and significantly cheaper) vapour phase injection systems the gas displaces more air giving a double whammy on power capability. With liquid phase injection it can can make similar or even more power than petrol, and with an engine designed to run only LPG I'd suspect you could make some reasonable power gains, but the systems are complex and expensive.
yes
So a case of expensive heavily moddified engine?

What about a 458 or similar current breed of supercars?
Wouldent they made use of the octane rating?
Do all cars have to 'converted' in some way?
Or by 'converted' does it simply mean changing the petrol tank, to a lpg tank/canister?

Willy Nilly

12,511 posts

166 months

Wednesday 5th January 2011
quotequote all
I use an LGP forklift at work. Been using it for nearly 10 years when it was just about new.

It is the fuel of Satan and I would not even consider it for use in a car. It's too bulky, too expensive and the cooling system needs to be in tip top condition or the regulator freezes up and you go nowhere. I am told that it costs double to fuel than the same forklift with the diesel running on red. So any saving one would make running one over a petrol car is down to taxation and taxation can change at any time. The only reason this machine is LPG is for local soot emissions in the shed it works in.

I think LPG has a lower specific weight than petrol which is lighter than diesel so you will get less mpg.

littleredrooster

5,523 posts

195 months

Wednesday 5th January 2011
quotequote all
Octane rating doesn't tell you anything about the power a fuel will produce, only that it resists detonation or pinking.

The important bit is the calorific value, (how many calories per litre) of which LPG has much less compared to diesel or petrol.

In order to get equivalent power from an engine running LPG, you would (as you started to say) have to apply general tune-up principles; gas-flowed ports, raised compression ratio (the bit that you like!), wilder cams, different ignition mapping etc. This would mean that it would probably no longer run on petrol, and therefore could not be started in cold weather because LPG doesn't work particularly well from a cold start.

Or888t

Original Poster:

1,686 posts

172 months

Wednesday 5th January 2011
quotequote all
littleredrooster said:
Octane rating doesn't tell you anything about the power a fuel will produce, only that it resists detonation or pinking.

The important bit is the calorific value, (how many calories per litre) of which LPG has much less compared to diesel or petrol.

In order to get equivalent power from an engine running LPG, you would (as you started to say) have to apply general tune-up principles; gas-flowed ports, raised compression ratio (the bit that you like!), wilder cams, different ignition mapping etc. This would mean that it would probably no longer run on petrol, and therefore could not be started in cold weather because LPG doesn't work particularly well from a cold start.
So because of its lower calorific value, doing all you mension above, would only make LPG produce the same(!) as a petrol engine.
And then of course it will not longer work on petrol.

yes?
thumbup Thanks PH.

Well if thats the case, when it's cold, you could always run it on race fuel, and get the benefits of the highly strung modififed engine boxedin

Edited by Or888t on Wednesday 5th January 17:51