TVR Chimaera 4.0 litre V8
LPG System: Canems Duel Fuel engine management system
Tuning: Unique fuel & ignition open loop maps built for each fuel type
Additional strategy: Enters closed loop to follow AFR targets when certain rules are met
Notable exclusions: No LPG fuel temp or pressure sensing (proven not required for perfect LPG operation)
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
How far on £10 (best): 75.08 miles
How far on £10 (average): 69.55 miles
Drivability: Indistinguishable between petrol & LPG (its just faster on gas )

* 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)

EXAMPLES:
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)

Can't agree with 'proven not required'... If X amount of gas will flow through an injector with Y square mm nozzle size and Z pressure, then 2X of gas will flow with 2Z pressure... For the statement to be true regards pressure you would need an entirely pressure stable reducer or entirely predictable reducer pressure drop under load. Though the latter might be true, in the real world reducer pressure can change with temperature changes in both the gas supply to the reducer and it's body temperature (effected by water temperature, outside temperature, gas supply temperature and how much has it has recently been flowing). The statement can't be true regards gas temperature, this would be breaking Boyle's law. When gas pressure and temp are not accounted for, fuel mixture can fluctuate uncontrollably.

I like the idea of the Canems system, useful as a standalone ECU but it has the above limitation / it couldn't be used to replace the ECU on modern vehicles with Canbus systems... Maybe good for your car or a boat but not something you could stick on, say, a BMW X6.

Simon

_________________
Full time LPG installer
Servicing / Diagnostics / Repairs to all systems / DIY conversion kits supplied with thorough tech support
Mid Yorkshire
2 miles A1, 8 miles M62,
http://www.Lpgc.co.uk
Twitter https://twitter.com/AutogasSimon
07816237240

The statement is: "proven not required for perfect LPG operation"

I say this quite simply because we proved time & time gain we could achieve perfect LPG operation without the need for volume/temp correction.

That's not to say volume change isn't taking place, in fact there is absolutely no doubt LPG suffers quite dramatic fluctuations in volume over quite a narrow window of temperature changes, I've never disputed this fact and obviously these changes will have a direct impact on the AFRs unless some form of direct or indirect compensation can be built in.

However, logging the AFRs using the Canems system and observing them for thousands of real world miles using my AEM X-WiFi system at ambient temperatures ranging from 93 degrees in the South of France, to sub zero frosty February mornings here in the UK, has proved the AFRs remain firmly nailed to our targets using nothing more than our a closed loop strategy.

Obviously there's nothing groundbreaking about wide band closed loop, but we believe its delivering the results all on its own because the Canems dual fuel ECU takes the lambda figure direct from the sensor, then looks at our unique LPG targets and then makes direct LPG injector duration changes.

This is a far less protracted process you see on most LPG systems where the petrol ECU looks at lambda, then looks at the petrol targets, then makes petrol injector duration changes..... only then does the LPG piggyback take over twisting all the essentially wrong petrol information in a bid to make it right for gas. Talk about going around the houses!

But even after all our evidenced proof we can deliver perfect LPG operation without volume correction I'm still keen to put this one to bed, so in few weeks we'll be adding an LPG pressure input to the ECU, adding a suitable sensor, and building a correction table. TBH I really can't see it making much difference as its hard to imagine the AFRs being any more nailed than they are already.

But hey, I'm open minded to it as the temperature related variations in volume are well understood, perhaps the volume correction will help the closed loop strategy work less hard, perhaps this will result in the car becoming even nicer to drive, perhaps I'll find a fraction more economy?

I doubt it, but lets try anyway, in truth the Canems system was never designed for boring everyday street cars, it's not really for the plug & play LPG installers either, it's a solution for those that drive, develop & enjoy the type of vehicles that get converted to after market engine management systems.

Its a system for Classics going from carb to injection, for enthusiast cars that came with compromised injection/distributor setups like the TVR Chimaera, and for people that enjoy having complete direct control over injector duration & ignition mapping.

One of the great pleasures has been building separate, unique and completely different ignition maps that match the specific and very different characteristics of each fuel type. Using a rolling road, EGT & wide band data you soon see where the average LPG piggyback ECU misses the biggest trick in tuning on 110Ron LPG, IGNITION!

I'll let you all know if compensating for LPG volume delivers any real world benefits, I can definitely see why you need it on a piggyback, after all the poor things are already trying their hardest to twist the completely wrong petrol injector duration signals to work on gas, but with the Canems you build the right map first time using first hand sensor inputs not secondhand ones.

This and the ability to properly control ignition to match the chemistry of the fuel being burnt already puts the system at a significant advantage, lets see what happens over the next month or so as we play with volume correction.

I can understand how the system having much wider fuel trims than a standard petrol system would allow the system to compensate for temp and pressure without much of a problem (if I were to name one problem I would say shifting throttle position / rpms won't allow a respective fuel trim to shift fast enough for fast enough mixture correction).
The reason why, perhaps, I mentioned anything was because you said the system runs open loop much of the time and closed loop under certain conditions. How, then, when running open loop, can it compensate for pressure / temp?
I didn't realise you were a supplier... thought you were a guy who had fitted / had had fitted this system.. I'm not out to cause you a problem, I like what you've done!
I think the ability to read pressure and temps and compensate will only improve this system.
Most LPG ECU's don't look at lambda at all - the petrol system provides all the closed loop functionality, it is impossible to disable the petrol ECU because it also runs the ignition (yes I know your system runs the ignition), it might talk to the gearbox, aircon, notably the dashboard, etc, etc. Most LPG ECUs work as a slave to the petrol system, there outputs are based on petrol injection timing and (to a much lesser extent) rpm gathered from the petrol ECU.
Many petrol engines also have variable cam timing, forced idle air, turbo boost control, etc... It would be very difficult to make a standalone aftermarket ECU which could control the wide range of marque specific devices, and talk on cam busses to marque and model specific other devices (e.g gearbox and body control ECUs) without creating problems..

As an example, one of my vehicles is an old 1997 Chrysler Grand Voyager. If I fitted your ECU I would lose aircon / heater control / immobiliser / radio / central locking / the auto gearbox wouldn't work / the dashboard gauges wouldn't work. This is why for most vehicles we need to fit slave type systems - to keep the original petrol ECU. I could probably get around all these problems by also keeping the original petrol ECU, but only by making some of my own emulation electronics and buying in other emulation electronics. But if the petrol ECU ever went down on this vehicle I would have to buy another and use it in conjunction with your ECU - Your ECU cannot replace my petrol ECU even though this is a relatively simple 1997 model vehicle with a 12 valve pushrod engine that ha sno advanced features such as variable cam timing etc. But for a Rover V8 powered kit car or a boat, yes I would fit your ECU (if it were much cheaper)....

Simon

_________________
Full time LPG installer
Servicing / Diagnostics / Repairs to all systems / DIY conversion kits supplied with thorough tech support
Mid Yorkshire
2 miles A1, 8 miles M62,
http://www.Lpgc.co.uk
Twitter https://twitter.com/AutogasSimon
07816237240

Nope Simon, definitely never said that, all I said was it only goes closed loop when certain rules are met, this is governed by load, throttle position & coolant temp perimeters, the truth is it's in closed loop most of the time except during cold start enrichment on petrol and when I'm giving the car a good spanking on either fuel




Lets just say I'm the development mule mate, thanks for your interest & support though.




I'm genuinely interested to find out myself, and will share the results here.




Yep, get all that, as I've said the Canems is not meant as a substitute to LPG piggyback systems, its a complete engine management system suitable for the same people that may fit an Emerald, Omex, DTA, or MegaSquirt ect, but can also see the benefits of going dual fuel.




Yep, like I say they're twisting the wrong information and secondhand wrong information at that, the only word for something that works like that is.... compromised!




As I keep saying the Canems is not meant as a substitute to LPG piggyback systems, its a complete engine management system suitable for the same people that may fit an Emerald, Omex, DTA, or MegaSquirt ect, but can also see the benefits of going dual fuel. That same person may well also choose to explore forced induction which is why the Canems system does indeed offer 3D boost control.

Yes its a niche market system, no you wouldn't fit it to a modern street car, but it does have a number of advantages over an LPG piggyback.

Not least the direct independent ignition control of each fuel type, which lets be honest is the very thing you want when you switch over to 110Ron LPG that burns in a very different way to 95Ron petrol, with this in mind it has always amazed me that direct independent ignition control for LPG is the very thing missing from something that's specifically sold as an LPG ECU????

I used the word COMPROMISED earlier, perhaps in the case of LPG piggyback ignition control it would be more accurate to use the word FLAWED!

Lets see what volume correction brings, we probably won't reference LPG temperature as its the temperature that influences volume & it's the volume swings that affect the AFRs. So forget the temp, we'll go straight to the horses mouth and measure the LPG volume changes then build our correction table accordingly.


But I guess we could look at both

Thanks for your interest in the project

Agreed
No probs. I'm looking into making into ECUs myself, I am a fairly accomplished programmer and electronics tech - might be interested in being involved in your project. One of the biggest initial considerations is which chip to use...
Makes sense.
Understood from the outset..
Debatable.. Wrong information? But - can see a point that with slave systems Gnj needs to be above Pinj, wrong information I wouldn't necessarily agree with, particularly if inter modular compatibility is considered.
One aspect where I can see this being used is on engines that run standard fueling without boost on petrol but with boost on LPG... There are little gains to be made by tweaking petrol ignition maps for LPG but cheap ignition mods are available anyway. What you really want when running on LPG is increased compression to take advantage of the higher Ron. All engines and management systems are compromised and flawed at some level.. Fit your system on a P38 and what do you reckon the gains would be compared to a slave system? The slave system could be fitted to even the most recent canbus wired V8 and could be fitted with cheap ignition advance systems. Volume doesn't matter, air and fuel mass matter, you need to know the volume, pressure and temp of each to know their mass?

Simon

_________________
Full time LPG installer
Servicing / Diagnostics / Repairs to all systems / DIY conversion kits supplied with thorough tech support
Mid Yorkshire
2 miles A1, 8 miles M62,
http://www.Lpgc.co.uk
Twitter https://twitter.com/AutogasSimon
07816237240

.

Massively disagree, all our rolling road time conclusively shows ignition delivers the single biggest influence on cylinder pressure (power) and efficiency, we can incrementally dial in & observe EGT & power changes while holding the car at a multitude of specific load sites until we eventually build the perfect 3D LPG advance curve.

It takes time but a rolling road is without doubt the most effective tool in extracting peak efficiency and conclusively proving it. This isn't hot air, its scientifically measured and totally unequivocally proven using sophisticated and correctly calibrated measurement equipment. All our data proves beyond question LPG is burning in a very very different way to petrol, so after hours & hours of careful mapping on the rollers what you end up with is a totally different ignition map to petrol.

To finally prove or disprove this map really delivers the goods over running the petrol ignition map on gas we simply uploaded the petrol ignition calibration to the Map 2 (LPG Map) and did the same run, then laid the graph over our LPG ignition run graph.

Depending on the load site you immediately see a 7-15% power drop using the petrol ignition map when burning LPG, the results are indisputable fact, proven in the real world in front of my own eyes, then back checked.

As soon as we upload our dedicated LPG ignition calibration back to Map 2 the power returns, I'm not sure how much more proof anyone would need that ignition has the biggest single influence on getting the best from this fuel.

I'm sorry but if you still believe there are little gains to be made by tweaking petrol ignition maps for LPG you either have never done the level of testing and development we have, or you've not had the benefit of dedicated fuel specific proper 3D ignition control and a rolling road.



Sort of, yes the resistance to knock plays its part but the real reason forced induction works so well with LPG is because gaseous fuels carry less energy by volume compared with a liquid fuel, in simple terms LPG takes up more space in the combustion chamber for the same energy value.

This is where a compressor can really help, the fuel's resistance to detonation is just a happy coincidence that plays a useful but less important role in making LPG and forced induction such happy bedfellows.

To this end we with be fitting a Rotrex supercharger to my TVR very soon, we predict a 43% increase in power and torque at a safe and very modest 8psi of boost.

We also predict a 4-6% improvement light load cruise economy due to the increase in volumetric efficiency delivered by the highly efficient oil/friction driven centrifugal compressor.



Correct (ish), what we really need for our new ECU input is a something like an air flow meter to give us a true fuel mass figure from which we can build and reference our correction table to, we have our own ideas but I'm interested in what sensor you'd suggest?

Personally I'm still not convinced it'll make much difference, but as I've already said I remain open minded to it as there's a strong case that says it should. If I wasn't open minded I wouldn't be playing with LPG on a performance car and I wouldn't be involved in the development of an innovative engine management system that is a world apart from the plug & play type LPG piggyback ECUs.

Let me have your sensor input - no pun intended

I might suggest that on a rolling road, under bonnet and intake air temps rise above what you would normally see on the road... Your system doesn't account for LPG temp, pressure and I'm not sure about IAT. When IAT rises, ignition cannot be advanced as far particularly on petrol as on LPG without suffering detonation... The differences you see between petrol and LPG might be less in real world situations than on a rolling road, particularly when knock sensors are built into many modern applications. Meanwhile, any fueling changes made to LPG maps on a rolling road might, without compensation for gas temps, might mean the mixture is richer in on the road driving. Would be interesting to see how your ignition maps compare between petrol / LPG and to see if they match with others findings / anticipations on serious hot-rodding forums etc. There are aftermarket standalone programmable ignition map modification units that are an easy addition to any aftermarket slave type LPG system.

Agreed on all points on volumetric efficiency but where do you expect the 4-6% part load efficiency gains to come from with the supercharger fitted? Will this vehicle still run on petrol with the 8psi boost with the supercharger fitted?

Might suggest a PHF000140 air flow meter, as fitted to supercharged Rangerovers...

Simon

_________________
Full time LPG installer
Servicing / Diagnostics / Repairs to all systems / DIY conversion kits supplied with thorough tech support
Mid Yorkshire
2 miles A1, 8 miles M62,
http://www.Lpgc.co.uk
Twitter https://twitter.com/AutogasSimon
07816237240

First few fill ups on LPG and running my normal commute.

Petrol 36.4 mpg average (Over the last 20'000 miles)
LPG 29.4 mpg average (Last three fill ups)

Think it will get better as the system loosens up.

However at 59.9p a liter its working out about £10 for 107 miles give or take.

Nah mate.. Not unless you just rebuilt the engine too...
Not to worry though, you just went from 36.4 mpg to the equivalent running cost of over 60mpg when costs of the two fuels are considered!

Simon

_________________
Full time LPG installer
Servicing / Diagnostics / Repairs to all systems / DIY conversion kits supplied with thorough tech support
Mid Yorkshire
2 miles A1, 8 miles M62,
http://www.Lpgc.co.uk
Twitter https://twitter.com/AutogasSimon
07816237240

Also found a new local LPG supplier that does LPG @ £0.54 flat.
Thing is its only open certain times and doesn't take card payments. Which isn't the worst thing in the world.

But that will save me 10p a litre per fill up or about £3.70. So can't moan at that. Just need to time my fill ups.


System has quietened down a bit but as fuel is now pretty cheap I tend to boot it a bit more.
So running costs have gone gone but I can see my tyres and brakes are going to be eaten up a bit more.
I got the average down to 26mpg.

Still its over 50mpg as an equivalent on petrol. Either way. Its still far cheaper. It just looks a bit depressing as an average mpg figure.

I bet BENTLEY 6.0 PETROL ON LPG £40 250 MILES IF DON'T BEILIVE IT CALL ME ON PHONE OR CHECK OUR WEBSITE NO ONE DO IN UK BENTLEY & V8 V10 ALSO AMERICAN SINCE 1995 CALL US THEN THINK ¿

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OPTIMUS LPG SINCE 1995
CALL FEEL FREE MON-SAT 09:00 18:00
0116 2736 123 - 07712 660 662
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250 miles on 13 gallons isn't overly impressive, maybe just a little more than might be expected for a 6L Bentley depending on the type of driving done - This must have been on a motorway cruise?

What you're actually doing.... Is showing everyone that you don't write, or probably speak, English too well.

Unless the engine management comes on the dash, if you can get the Bentley to do 250 miles on £40 gas, so can any installer... If the mixture is wrong the engine management light comes on, if the mixture is correct everyone gets the same mpg. It is in driveability, reliability, quality of fitting and performance where any differences are seen, as opposed to steady cruise conditions.

I convert a large number of performance / luxury vehicles, including a disproportionate number of V8 / V10 / V12 megacars... All run very well..

Simon

_________________
Full time LPG installer
Servicing / Diagnostics / Repairs to all systems / DIY conversion kits supplied with thorough tech support
Mid Yorkshire
2 miles A1, 8 miles M62,
http://www.Lpgc.co.uk
Twitter https://twitter.com/AutogasSimon
07816237240

Simon Thanks your comment

We do LPG CONVERSION SINCE 1995 we have awards from UK goverment.

Also im not typing your website ads or something we are almost 20 years experiece for LPG Conversion


We allready sold many bentley's with LPG also

3 years warranty all our cars same special

optimusmotors.co.uk

_________________
OPTIMUS LPG SINCE 1995
CALL FEEL FREE MON-SAT 09:00 18:00
0116 2736 123 - 07712 660 662
www.optimuslpg.com

I seem to be getting 19mpg from my 4.4L valvetronic BMW 545i on LPG.
It's a heavy car (1800kg), plus two passengers and suitcases, and a boot full of computer junk,b but doing mostly ~60mpg on the motorway.
I'm a bit disappointed at those numbers!
It's supposed to do ~30mph on petrol on the motorway. maybe that's just BMW bullcrap.

this equates to a petrol equivalency of 35mpg, given I pay 64.9p for LPG.

_________________
--
Carl
BMW E60 545i automatic, KME Nevo Pro (was Stag 300 Premium), Hana, KME Gold.
BMW E46 330i automatic on Zavoli Zeta-S/AEB/PANs

I don't know I think the equivalent running costs of an engine half that size that doesn't sound bad. I can imagine a bit better would be good. But its a 4.4L engine... I'd be okay with those figures for the size of engine.

I got my mpgs and mphs mixed up there..
I meant at 60mph on the motorway, it's doing 19mpg on LPG, which equates to around 34mpg petrol equivalent. The car is supposed to do 30+mpg on petrol.

Anyway i have started logging every fill now so I will report back urban usage soon.

_________________
--
Carl
BMW E60 545i automatic, KME Nevo Pro (was Stag 300 Premium), Hana, KME Gold.
BMW E46 330i automatic on Zavoli Zeta-S/AEB/PANs

I dont know many 4.4l engines doing 30mpg.

I got my 2.5 v6 once to hit 30mpg on a run. But I drove so slow and virtually all motorway.

109 miles on £10 worth from a 4.0 litre V8. Admittedly that was yesterday running on Belgian LPG at the equivalent of 32.3 p per litre....

_________________
'96 Saab 900XS, AEB Leo, sold
'93 Range Rover 4.2 LSE, Lovato LovEco, sold
'98 Ex-Police Range Rover 4.0, Singlepoint AEB Leo, my daily motor
'97 Range Rover 4.0SE, eGas multipoint, a project.....

Proud to be a member of the YCHJCYA2PDTHFH club.

around 3.5 kilometres per litre when towing.
Thats with the goal of sitting on the speed limit everywhere.

_________________
Disco II 4.6 with Kent H180, and a Tornado chip on OMVL sequential Inj.
Tows a 2T caravan.
Mostly East Coast Australia.