LPG Chimaera (Follow My Conversion)
Discussion
Oh no... we're about to start fiddling with 'Ol Gasbag' again 
Next up???
Some mild brain surgery
With the support of David Hampshire of Canems Engine Management Systems and the eternally patient & very talented guys at Lloyd Specialist Developments the duel fuel ECU is recieving another sensor input.
What can it be
Next up???
Some mild brain surgery
With the support of David Hampshire of Canems Engine Management Systems and the eternally patient & very talented guys at Lloyd Specialist Developments the duel fuel ECU is recieving another sensor input.
What can it be
NZ fan said:
Intake air temp?
Nope mate, got that one already 
The plan is to measure LPG volume, then build a correction table.
Gaseous fuels exhibit far greater volume changes over a much narrower window of temperature fluctuations when compared with a liquid fuel like petrol.
Clearly these fuel volume changes will have a direct impact on AFRs, and nailing AFRs is everything when getting LPG to work well. We've dealt with this by implementing a wide band closed loop strategy which proved immensely successful.
So why even bother with volume correction?
We'll there is a small chance we can use it help out the closed loop strategy which while very effective is clearly working a lot harder to nail the AFRs on gas than it has to on petrol.
But to be honest, its as much an interesting experiment as anything as the system continues to deliver beyond my expectations:
- Vehicle weight: 1103kg wet
- Power: 251 hp on LPG & 249 hp on petrol
- Torque: 268 ft/lbs on LPG & 261 ft/lbs on petrol
- LPG top speed: 152mph (Sat Nav confirmed)
- LPG 0-60: 4.9 seconds (Dynolicious confirmed)
- Best petrol economy: 27.8 mpg (steady 72mph cruise)
- Average petrol economy: 23.1 mpg
- Best LPG economy: 23.2 mpg (steady 72mph cruise = cost equivalent 42.3 mpg*)
- Average LPG economy: 21.5 mpg (cost equivalent 39.20 mpg*)
- Max LPG fill: 65 litres
- LPG range (best): 332 miles
- LPG range (average): 307 miles
- Additional petrol range (average): 135 miles
- Cost equivalent figures based on buying LPG at 0.68p lt & the same service station selling 95 Ron petrol on the same day at £1.24 lt (Sainsburys Service Station, London Colney, AL2 1AB)
Best LPG economy: 1.24 / 0.68 = 1.823 x 23.2 = 42.3 mpg (cost equivalent)
Best LPG economy: 1.24 / 0.68 = 1.823 x 21.5 = 39.20 mpg (cost equivalent)
NZ fan said:
Part of me knew it wouldn't be something so simple. Sooo..
NZ fan said:
What sort of device will you be using to measure the gas volume?
I'm not sure yet mate, most modern dedicated LPG piggyback (slave) ECUs use some form of volume correction, so there are plenty of dedicated sensors out there.Do you have any mates into LPG & CNG Neville?
I know you Kiwi boys have a good knowledge base on the gas subject, after all it was when I was spannering for the NZ Forestry Corporation in Rotorua that I started to get into all this.
NZ fan said:
I probably won't understand your answer.
Nonsense, don't undersell yourself Neville!NZ fan said:
Is it like an air flow meter but for gas?
See, you totally get it, that's exactly what we're looking at. "An air flow meter but for gas" is the perfect way to describe it.TBH I've been calling it LPG volume, but as you've quite rightly point out what we actually need to measure is true fuel mass. To do this LPG ECUs look at fuel temp, fuel pressure, & fuel volume.... then use an algorithm to calculate the true fuel mass.
What we really need is one sensor that can do all this itself and deliver a reading to our new ECU input, once we know the true LPG mass we can build a correction table.
Truth is it'll be David Hampshire at Canems who chooses the sensor and works all this out, and the boys at Lloyds that build the correction table.
As always I'll just follow from the rear learning from the experts
Such an interesting fuel this 110Ron LPG stuff
ChimpOnGas said:
Nope mate, got that one already
The plan is to measure LPG volume, then build a correction table.
Gaseous fuels exhibit far greater volume changes over a much narrower window of temperature fluctuations when compared with a liquid fuel like petrol.
Clearly these fuel volume changes will have a direct impact on AFRs, and nailing AFRs is everything when getting LPG to work well. We've dealt with this by implementing a wide band closed loop strategy which proved immensely successful.
So why even bother with volume correction?
We'll there is a small chance we can use it help out the closed loop strategy which while very effective is clearly working a lot harder to nail the AFRs on gas than it has to on petrol.
But to be honest, its as much an interesting experiment as anything as the system continues to deliver beyond my expectations:
Best LPG economy: 1.24 / 0.68 = 1.823 x 23.2 = 42.3 mpg (cost equivalent)
Best LPG economy: 1.24 / 0.68 = 1.823 x 21.5 = 39.20 mpg (cost equivalent)
I noticed LPG is still the same price but petrol is dropping like a brick .The plan is to measure LPG volume, then build a correction table.
Gaseous fuels exhibit far greater volume changes over a much narrower window of temperature fluctuations when compared with a liquid fuel like petrol.
Clearly these fuel volume changes will have a direct impact on AFRs, and nailing AFRs is everything when getting LPG to work well. We've dealt with this by implementing a wide band closed loop strategy which proved immensely successful.
So why even bother with volume correction?
We'll there is a small chance we can use it help out the closed loop strategy which while very effective is clearly working a lot harder to nail the AFRs on gas than it has to on petrol.
But to be honest, its as much an interesting experiment as anything as the system continues to deliver beyond my expectations:
- Vehicle weight: 1103kg wet
- Power: 251 hp on LPG & 249 hp on petrol
- Torque: 268 ft/lbs on LPG & 261 ft/lbs on petrol
- LPG top speed: 152mph (Sat Nav confirmed)
- LPG 0-60: 4.9 seconds (Dynolicious confirmed)
- Best petrol economy: 27.8 mpg (steady 72mph cruise)
- Average petrol economy: 23.1 mpg
- Best LPG economy: 23.2 mpg (steady 72mph cruise = cost equivalent 42.3 mpg*)
- Average LPG economy: 21.5 mpg (cost equivalent 39.20 mpg*)
- Max LPG fill: 65 litres
- LPG range (best): 332 miles
- LPG range (average): 307 miles
- Additional petrol range (average): 135 miles
- Cost equivalent figures based on buying LPG at 0.68p lt & the same service station selling 95 Ron petrol on the same day at £1.24 lt (Sainsburys Service Station, London Colney, AL2 1AB)
Best LPG economy: 1.24 / 0.68 = 1.823 x 23.2 = 42.3 mpg (cost equivalent)
Best LPG economy: 1.24 / 0.68 = 1.823 x 21.5 = 39.20 mpg (cost equivalent)
SILICONEKID345HP said:
I noticed LPG is still the same price but petrol is dropping like a brick .
And your point is 
Actually I think I know all too well where you're going with all this, so before you get too smug lets analyze it properly using maths with true & up to date figures taken from my proven real world experience
So I filled up this Monday brimming the tanks at the Sinsburys in London Colney where the 95 Ron petrol was £1.179 and the LPG was £0.679p.
Trust me although I still have a very practical 130+ mile petrol range and £1.179 is the cheapest we've seen 95 Ron for a long time I still wasn't at all tempted to fill with the expensive stuff.
Lets look at why this was
After brimming with gas I drove around Essex for three days and found myself back at Sinsburys in London Colney this afternoon brimming the tanks again after covering 268 miles (still over 50 miles of gas left but its good to fill up when I have spare time to do so).
The tanks took a 52.97 litre fill which is 11.65 gallons of LPG.
268 / 11.65 = 23mpg average, which is an excellent fuel consumption figure for an ancient 4.0 litre V8 sucking propane.
Now lets look at what 23mpg on gas would need to be on petrol given the difference in pence per litre between each fuel.
£1.179 / £0.679 = 1.736 X 23mpg on LPG = 39.928mpg petrol cost equivalent.
And remember that's an average of (as near as damn it) 40mpg over the 268 miles, much of which was spent cruising in the fast lane of the A12 & M25 at 85 leptons with the odd dip into the tonn plus.
I looked at my wife's petrol Nissan Micra trip computer today and it told me she's doing an average of 43mpg, now I know she doesn't drive fast but I've checked it before & that computer lies. Last time I did a brim to brim check on the Micra it was returning a genuine 40.3mpg.
I've also been following the fuel economy on my company car which is a 4 year old Toyota Prius Hybrid, again the computer lies telling me its doing an average of 45mpg, but a brim to brim check reveals the true figure to be 41.3mpg.
In summary my Chimaera is as cheap to run as a Nissan Micra or a Toyota Prius.
Is this what you wanted to know? or were you hoping to feast on a disastrous tale of how LPG is now pointless?
If so I'm sorry to disappoint you, the properly driven 40mpg TVR exists and it's running like a dream
Thanks for your concern though Daz
Quinny said:
I paid £0.577 for LPG last week
That's an amazing price Quinny, us "Soft Southerners" get ripped off compared with you "Northern Monkeys" Clearly LPG prices are following the decline in petrol prices nicely, it's just takes a little longer down here.
I can't help myself running my TVR figures again using your cheap as chips gas price, so here goes...
I'll use the same £1.179 petrol figure as that seems fair.
£1.179 / £0.577 = 2.043 X 23mpg on LPG = 46.989mpg petrol cost equivalent.
In a way Daz is correct, the equation changes with the differential between the two fuel prices.
The good news is even here in the south I am averaging the cost equivalent of 40mpg in my TVR which I think everyone will agree is none too shabby
And if I choose to venture "Oooop North" the car will just get cheaper & cheaper to fuel.
47 mpg petrol cost equivalent in a TVR, I'll have some of that
I agree with Dave.
Filled my 5.4l Griff up with LPG (65litres) at 57p/l acouple of weeks ago and have had a hoon to West Wales @ 220m (see TVR spotted- I wasn't trying to conserve fuel) and been driving nearly another 100 miles on the same tank. Sorry can't calc. MPG as I haven't needed to fill up yet....
Daz - stop whining and get converted.
ETA - I usually refer to LPG as half price which it usually is but at the moment is < half ie 57p v 117p...
Filled my 5.4l Griff up with LPG (65litres) at 57p/l acouple of weeks ago and have had a hoon to West Wales @ 220m (see TVR spotted- I wasn't trying to conserve fuel) and been driving nearly another 100 miles on the same tank. Sorry can't calc. MPG as I haven't needed to fill up yet....
Daz - stop whining and get converted.
ETA - I usually refer to LPG as half price which it usually is but at the moment is < half ie 57p v 117p...
Edited by pjac67 on Wednesday 10th December 21:47
SILICONEKID345HP said:
My main concern is why fuel has not followed the price of crude oil . 120 dollars to 70 dollars is a big difference .
Someone or a corporation is keeping the difference in there pocket .
That's rubbish Daz, if you really wanted to discuss that you wouldn't have chosen an LPG post to do it.Someone or a corporation is keeping the difference in there pocket .
Your point was as clear as was your intention.
What happened after that was you got shot down in flames by three experienced LPG users.
As said above, get on the gas Daz.
We all know you want to
Quinny said:
I topped up as I was passing, but the last time it was this price was 2010...
Cheeky buggers locally though are still at £0.699 (shell) and £0.769 (BP)
That receipt is a thing of beauty Quinny Cheeky buggers locally though are still at £0.699 (shell) and £0.769 (BP)
Are you aware how brilliantly the excellent Chevrolet LS engine takes to a diet of LPG?
Food for thought mate
ChimpOnGas said:
That receipt is a thing of beauty Quinny
Are you aware how brilliantly the excellent Chevrolet LS engine takes to a diet of LPG?
Food for thought mate
The TVR already benefits from the use of LPG ... the savings I make running 2 lpg jeeps, pays for the petrol for the tvrAre you aware how brilliantly the excellent Chevrolet LS engine takes to a diet of LPG?
Food for thought mate
Quinny said:
The TVR already benefits from the use of LPG ... the savings I make running 2 lpg jeeps, pays for the petrol for the tvr
Good way of looking at it or have an occupation where you can walk to work I stick less than 20 squids on average in my daily driver and thats 2.5 petrol so the TVR can do its best in the warmer weather LPG would be wasted on me and would take forever to recoup the cost not really relevant but my cents worth 
I feel I can say this crap now being an ex high mileage to work Veteran 
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