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PostPosted: Mon Mar 04, 2013 7:12 pm 
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Well it's happening folks, in fact it's well under way.

Not long now it'll be leaving Woody's workshop running on LPG.

For anyone interested, you can read all about it here:

http://www.pistonheads.com/xforums/topi ... version%29


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PostPosted: Tue Mar 05, 2013 10:40 am 
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Very interesting, coming up to proof-of-pudding stage ! :shock:

It's a shame the reducer couldn't be more tucked away, but every install has some compromise.

The tankage is neat solution given the confines, I doubt a 300 mile range but you does what you can here. Someone mentioned the potential for slosh issues on cornering, but I reckon that won't trouble you in a non-racing environment. Better that than slosh on accel :)

I have to say with my UKLPG inspector hat on, defeating the 80% tank fillstops would get it bounced clean out the door. It's unlikely to be detected in practice of course, but I do think you may also exacerbate the effect of any cross-feed dribbles that occur in multitank installs and suffer unexpected venting.

PS - you can ignore the nay-sayers about "it'll cost more than petrol next year", they've been saying that since 1990 to my knowledge.

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PostPosted: Tue Mar 05, 2013 11:13 am 
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Thanks Rossko, I'm very happy so far.

Like you say the proof of the pudding will be in how the system performs.

I'm confident Keith (Woody) has all the bases covered.

I'm very much enjoying working with Keith, it's tuning into a really fun project.

Keep an eye on the Pistonheads post as that's where I posting photos and updating the TVR community on the conversion.

It's creating a lot of interest and even the doubters are finding it hard to criticise what I'm doing now.

If their best shot is the LPG price going up, then it gives me a great deal of confidence that what we're creating here is a very hard to criticise project.

I've stuck my neck out by converting a TVR, lots of TVR owners were saying I shouldn't do it.

I'm glad to say these people seem to have gone very quiet now, and I've actually received lots of words of encouragement.

I'm under no illusion, the devil is most definitely in the detail.

With the Canems Dual Fuel ECU I believe that detail will be in the quality of the LPG fuelling & ignition mapping.

But I'm lucky here too, there are two very knowledgeable mappers dedicated to making the car run & perform spot on.

And Keith's new the rolling road facility will certainly help them achieve this.

Thanks again, Dave.


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PostPosted: Wed Mar 06, 2013 8:59 am 
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Ross, it looks as though Dave hasn't answered your questions, so I will:-

rossko wrote:
What significant compromise? What 'unique requirement' is not met by a slaved fiddle-factor system?

Dave can map the ignition settings he wants for LPG indepedently from the ignition settings for the petrol side. Also, if the petrol side fails/missfires, the LPG side doesn't automatically follow it, so there is redundancy, rather than compromise built into the design.
rossko wrote:
Staged Injector Control - curious, what does this refer to?

Dave can run both injector types concurrently and decide what %age petrol/%age LPG split he wants to have and when. It's unlikely to be implemented unless the LPG injectors are too small, but for argument's sake, if he were to have Flashlube type concerns, he could run 10%petrol/90%LPG as his LPG setup.
rossko wrote:
I question the apparent lack of LPG fuel density corrections. It'll sorta work without, but not optimally and contrasts with all the other whizzy bits.

You concerns are well founded and have to be dialed into the settings somewhere

ChimponGas wrote:
in theory it should also make for a neater and more efficient conversion to LPG than the traditional piggy back ECU.

rossko wrote:
Can't see why, apart from one-less-box.

No need to splice a wiring loom and shoehorn in a new loom - typically one would simply have a single dedicated (twin fuel) loom so the installation should be neater. It's more efficient because of the abilty to independently optimise the fuel/ignition maps of each fuel type.

There are no concerns about a petrol side malfunction affecting the LPG side. If Dave's petrol trims drift for some reason, he doesn't have to remap the LPG side because of it. Indeed, if both were to drift together - he knows it is likely a problem/sensor common to both and not a fuel specific item, so isn't likely chasing for a solution in the wrong ballpark

Lastly, it's neater because there is wealth of diagnostic detail and datalogging with such ECUs which a piggy-back system can never hope to match.

kind regards
Marek


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PostPosted: Wed Mar 06, 2013 9:40 am 
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Spot on marek you've made an excellent job of highlighting the benefits as I see them.

On the subject of LPG fuel density corrections, I have raised this a number of times with Keith Woods (Woody) and he is very insistent this will not represent an issue for him whatsoever.

To be honest I only partially understand the issue, here's how I see it, please feel free to correct & educate me.

Clearly there are corrections required to compensate for gas density changes over a range of temperatures, but surely this is not that much different to air density?

The Canems system responds to air temperature (air density) extremely well on petrol, it simply looks at the signal from the air temp sensor mounted before the throttle body.

Are you both suggesting an additional & similar thermistor signal needs to be taken from the vaporiser to allow LPG injector duration correction over a range of temperatures/densities of the LPG/Air mixture.

Would not the wideband lambda correction step in here (in conjunction with air temp & coolant temp) to correct the mixture & follow the AFR targets?

If there can be a qualified challenge to the LPG fuel density correction point, we do benefit from a close working relationship with the ECU designer.

As you can imagine David from Canems is a well respected expert in engine management, he developed the Dual Fuel system to eliminate some of the theoretical drawbacks of a piggyback system.

I know I'm an early adopter, but the system is proven to work and has already been fitted to a number of vehicles with great success, however David is very open minded, he is a real enthusiast and is open to developing & improving his products.

Perhaps the collective LPG knowledge here can suggest something to make the system even better?

Apologies for my ignorance, I'm relatively new to this fuel, but it does really interest me.

Its clear to me that LPG has many benefits that go well beyond the cost savings, with the right systems in place I can see no reason why even my TVR wouldn't run beautifully on gas with no loss of performance or altering the character of the car.

Your comments are valued and appreciated.

Many thanks, Dave.


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PostPosted: Wed Mar 06, 2013 12:18 pm 
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Dear Dave,

The air temperature and gas temperature are not the same thing. The gas temperature will start life more related to the reducer temperature, and then be moderated by ambient temperature in the engine bay.
The reducer temperature will follow, but be below, the water temperature.
The manifold air temperature could be anything.

The water temperature measured for petrol fuel injection purposes will tell you about the operating point of the engine, but a similar dedicated sensor on the reducer will tell you whether the conversion of LPG liquid to vapour is happening at a sustainable rate, particularly at startup. The piggy-back ECU typically will typically only allow cut-in to LPG above a certain temperature if it cannot produce gas in consistent and measurable quantities.

Correction to a target AFR table will work the way you are suggesting, but highlights that your fuel map isn't yet correct. Operating a wideband lambda sensor is not a fix all panacea - the engine ought to be mapped such that it'll operate happily without one, as widebands are known to fail or drift.

kind regards
Marek


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PostPosted: Wed Mar 06, 2013 1:38 pm 
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Thanks again marek, you explain things well.

I appreciate the time you are giving me here.

So if the reducer temperature follows, but runs a bit lower than coolant temperature, it should reach a point of being constant as it will in effect be governed by the thermostat & cooling fans.

The only other influence in the reducer temperature being radiant heat from the engine, which once warm should also remain relatively constant.

Hopefully I'm on track so far?

If the car is mapped at this constant temperature point, I'm struggling to grasp why the ECU even needs to know what it is?

You just configure you tables at that point, right?

I get that a dedicated sensor on the reducer would tell me whether the conversion of LPG liquid to vapour is happening at a sustainable rate, and I can see how that would be important to only permit the cut-in to LPG above a certain temperature.

But I will be operating a more analogue system of change over, this involves me starting the car on petrol and manually switching to LPG when the coolant temperature reaches a known "good to flick to LPG" temperature.

I'm probably missing something here, I can see how LPG density is influenced by temperature, and I can see how LPG density will influence AFR.

But once the reducer has reached it's constant & consistent managed operating temperature (say 76 degrees) why would the LPG density change?

The only other influencer I can see is pressure, but I thought it was one of the jobs of the reducer to manage that?

I'm probably missing something fundamental here so apologies in advance for my ignorance.

For what ever reason (& I cant really tell you why myself) I am genuinely fascinated by how these systems work, they have moved on massively since my days in the trade where simple mixer rings were used and there was no engine management, just a carb & a distributor.

No wonder LPG got a bad name for losing you performance with that type on stone age technology to manage things.

Thanks again for filling the gaps in my knowledge, it's much appreciated.

NB: I must add while I still need to understand what's going on LPG density, ultimately I do trust that Keith knows exactly what his doing, if he says it wont be an issue I'm inclined to put my faith in his many years of first hand LPG experience.

It just one of the reasons he got the job, & I'm very happy with how its progressing so far.

Best regards, Dave.


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PostPosted: Wed Mar 06, 2013 3:44 pm 
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marek wrote:
[re "significant compromise"]
Dave can map the ignition settings he wants for LPG indepedently from the ignition settings for the petrol side.

I appreciate that's a bonus, but I wouldn't call it significant. It can be acheived with bolt-ons too.

marek wrote:
[re "Staged Injector Control"]
Dave can run both injector types concurrently and decide what %age petrol/%age LPG split he wants to have and when..

Okeydoke, not heard the term used for that feature. This is hardly unique of course, but as you say hopefully not needed anyway.

marek wrote:
No need to splice a wiring loom and shoehorn in a new loom

Well no, you're forced to a make new loom altogether, just as you could with a piggyback if you wanted to. Not sure what I'm missing here!

marek wrote:
There are no concerns about a petrol side malfunction affecting the LPG side.

I think this grasping at straws a bit ;) in the end the overall engine management is affected the same by sensor failures, mechanics, misfires etc.
Equally if the single ECU dies they are both broke ;)

I don't have a problem with anyone wanting an integrated tweakable system; and of course there are advantages to doing away with the car makers system for that (esp talking 14CUX here!) but just saying I cannot see a huge advantage over any bolt-on add-on type.
It's horses for courses, I'm just resisting the idea that this soo much better than anything else :)

ChimponGas wrote:
So if the reducer temperature follows, but runs a bit lower than coolant temperature, it should reach a point of being constant as it will in effect be governed by the thermostat & cooling fans.

Kind of, but the temperature of the output gas is only vaguely linked to the reducer temperature. The more you take, the colder it gets. The more you take, the colder the reducer core gets. There's a thermal lag here, so you get cold gas at idle after a thrashing but hot gas after an extended idle.
You can of course setup for a best average ... dare I say compromise ... but the ideal is to monitor fuel delivery temperature and compensate. The injectors are delivering by volume, but as the fuel is a gas the density varies by temperature, so the mass of fuel delivered by the injectors is variable. Every commercial system implements this, even if it only takes a £1 sensor you have to wonder why they bother.
I'm sure it'll be 'acceptable' as the physics work with you - under load (getting colder) you should overfuel, which is preferable to t'other way round.

As an aside, with this integrated setup you should be able to start and run on gas in ordinary climates, the stopper for piggy-backs here is unwanted petrol cold running behaviour. Here be your 'unique advantage' if worked out properly ;)

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PostPosted: Wed Mar 06, 2013 5:33 pm 
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Dear Ross,

The "single ECU broken" = "both fuel systems broken" is indeed a potentially big negative and probably the only downside in this approach, assuming successful installation and tuning.

My viewing the petrol side as not affecting the gas side was in relation to seeing a petrol injector trim drift and thus falsely impact its piggy-backed gas injector when the gas never needed adjusting. There are a not insignificant number of posts by people with lpg problems, who actually have petrol problems.

I do feel that hacking an oem wiring loom is very much the least desirable part of a gas installation. In my case, my starting point was a carburettored engine, so a new loom had to be made as there was nothing to tap into. At this point, chosing the dual fuel ECU approach is easily the neatest solution. The lpg installation was planned (and made) in tandem with sequential fuel injection.

kind regards
Marek


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PostPosted: Wed Mar 06, 2013 7:55 pm 
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The gas temprature and gas pressure corrections are a improtant part of any LPG ECU and should be in there for this ECU to give any advantage over a conventional conversion.

Without those correction you would be better off with one of the better piggy back ECU's and just run a system with 2 ignition maps.

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PostPosted: Wed Mar 06, 2013 8:04 pm 
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Cheers chaps, you have taught me a lot here.

Shall I take your latest responses as thumbs up for the Canems Dual Fuel ECU?

I must say it's performed fantastically well on petrol so far, and has proved to be a huge step forward from the Lucas 14CUX & distributor which I had always planned to replace with something that gives me greater control.

Canems offer a petrol only model, or for an extra £200 the Dual Fuel, so as someone already planning a stand alone engine management installation it made sense for me to upgrade & enjoy the cost saving of LPG at a later date.

If you look closely, the TVR loom was already a splice job from new, TVR took the Range Rover engine bay loom then integrated it with their own loom, which contained a number of school boy errors in itself.

Add 16 years of high under bonnet temps and that rather poor hybrid harness is often the source of unreliability.

So for me another key benefit of the Canems was that it comes with a very nice professionally made loom, the LPG element of this is included.

From what I've seen within the TVR community it's the wiring that most often lets these stand alone ECU installations down, many splice them into the existing TVR loom which wasn't for me.

As marek says, the Canems is indeed a very neat & fully integrated package, giving me new & superior wiring improving reliability, performance & economy benefits on petrol.

Its also given me a neat way to move to LPG, & the potential to offer some advantages over the traditional piggyback type arrangement.

However as I see it, successfully accessing these potential advantages is very much reliant on the quality of the mapping.

But I'm confident in my mapping team & the rolling road facility will be a great tool to help them achieve our goals.

I'm really excited about the project, many thanks for all your input chaps.

I'll update you all when the conversion is complete.

Best regards, Dave.


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PostPosted: Wed Mar 06, 2013 10:11 pm 
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I've read through the Pistonheads thread and must say, it looks impressive although I've got a couple of comments or observations. I wouldn't consider messing with the stop valves in the tanks, they are there for a reason and a very good one at that. While a 300 mile range is nice, it is probably far less important than you would think. I've only got a 200 mile range, less when I'm towing, but have never had to do more than 10 miles on petrol. LPG availability is sufficient in the UK (use Richard's fine site, www.filllpg.co.uk to see where you can fill up wherever you are going) and in mainland Europe even more so (almost everywhere).

My only comment on the install is how you have mounted the injectors. Not necessarily that you have them laid horizontal but because of your argument that it avoids sharp turns in the hoses to the nipples. Surely by laying them down you have a 90 degree bend in them anyway? Although my P38 is currently running a single point system, I plan on updating it to a multipoint later this year (I planned on it last year but cracking two ribs laid me up for a while and other things just got in the way). I've seen some pretty messy looking installs on LR V8's with a bank of 4 injectors sitting nicely on the RH bank but shoved into any space available on the LH bank with unequal lengths of hose on them too. My plan is to use 4 pairs of injectors attached to the 4 corner plenum chamber bolts so there will be two injectors on each corner. That way they can stand upright and have the shortest possible hose run which will also be straight. Straight out of the bottom of the injector into the manifold.

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PostPosted: Wed Mar 06, 2013 10:54 pm 
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Hi Gilbertd,

Thanks for taking the time to look at my project, I'm pleased you like it.

I raised the LPG position question with Keith "Woody" my installer, at which point I was promptly taken to his own converted Skoda.

This uses Keihin injectors as does my conversion, & their position was very similar to mine too, by all accounts the car runs supremely well on LPG.

I am confident enough in the experience of my installer to have no concerns over the injector positioning, just as I am confident in the quality of Keihin injectors, which are beautifully made & supplied as a rail of four.

However, I do like your four sets of paired injectors idea, I would be interested to see it when you have completed the work.

You may be interested to know I have recently updated the Pistonheads post with particular attention paid to the LPG fuel density question.

http://www.pistonheads.com/xforums/topi ... version%29

Kind regards, Dave.


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PostPosted: Wed Mar 06, 2013 11:16 pm 
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ChimponGas wrote:
Shall I take your latest responses as thumbs up for the Canems Dual Fuel ECU?

and

ChimponGas wrote:
As marek says, the Canems is indeed a very neat & fully integrated package, giving me new & superior wiring improving reliability, performance & economy benefits on petrol.

Dear Dave,

I have not mentioned Canems ONCE in any of my posts and I haven't endorsed it - I have no experience of it, but I hope it works for you.

kind regards
Marek


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PostPosted: Wed Mar 06, 2013 11:36 pm 
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Marek wrote:
I have not mentioned Canems ONCE in any of my posts and I haven't endorsed it - I have no experience of it, but I hope it works for you.

kind regards
Marek


I understand Marek, apologies if I made it look like you were endorsing the Canems.

I was referring to the big play you made of your dislike of loom splicing, a point I wholeheartedly agree with & an issue the Canems package helps to eliminate.

Apologies if it appeared I was misquoting you, and thanks again for showing an interest in my project.

Best regards, Dave.


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PostPosted: Mon Apr 08, 2013 7:47 pm 
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A big thank you to Keith Woods at Quest Motorsport who made an excellent job of turning my dual fuel TVR Chimaera idea into reality.

http://www.pistonheads.com/gassing/topi ... n%29&mid=0


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PostPosted: Wed Apr 10, 2013 8:38 pm 
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I'm still not conviced about no gas temp and pressure correction with the ECU setup you have chosen but it looks like it is working well enough.

Looking through your pistonheads thead I'm curious as to when you are going to complete the tank installation. It would be a good idea to put the vent pipes on asap just in case they are needed, more critical after your mods to the valves. You also need to sort the fill pipe so that it exits through the floor to stop water getting in or gas as you fill.

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PostPosted: Fri Apr 12, 2013 5:29 pm 
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classicswede wrote:
I'm still not conviced about no gas temp and pressure correction with the ECU setup you have chosen but it looks like it is working well enough.

Wrong, it works actually brilliantly.

But you do seem to have answered your own question so I'm not really sure what you're trying to say here?

I did have another option with all this, I could have put a piggy back on the 14CUX and cobbled a Megajolt onto it in place of the distributor.

With this type of hash up the piggy back may well have referenced gas temperature, but would it have been better?

I think not?

Only Mark Adams can properly map a 14CUX, so if it's out on petrol, it's going to be out on gas, until I pay Mr Adams way too much money to tweak it.

Things have moved on & there are better systems out there that puts the mapping back in my hands.

Remember this is a 260hp TVR, not an old warn out Disco getting converted at the end of it's life.

It's a 1000kg thrilling high performance sports car, it deserves better than what the average LPG fitter would put on an old Range Rover Classic.

With a system that moves on from twisting second hand petrol injector durations that are completely wrong for LPG in the first place, the Canems Duel Fuel engine management system allows us to create the perfect fuel and spark tables from the outset.

This does however require the skills of an experienced engine mapper and a rolling road, the type of skills most LPG fitters lack because their compromised piggy back ECU systems do most if not all the petrol signal twisting for them.

Performance engine mapping is an art, trust me.

classicswede wrote:
Looking through your pistonheads thread I'm curious as to when you are going to complete the tank installation.

You clearly failed to read the whole post, there lots of pictures of the completed installation towards the end, including the bespoke 8 gallon petrol tank fabricated by Keith Woods, and the twin 30 litre LPG tanks.

The only thing that remains is for the tank system to be professionally trimmed in matching boot carpet making it virtually indistinguishable from a standard petrol Chimaeera even with the boot lid raised.

classicswede wrote:
It would be a good idea to put the vent pipes on asap just in case they are needed, more critical after your mods to the valves.
???? Vent pipes are in place, what makes you think they aren't?

Do you really think we would do all this & not sort the venting?

classicswede wrote:
You also need to sort the fill pipe so that it exits through the floor to stop water getting in or gas as you fill.

More????? What on earth are you talking about?

Why would I cut a hole in my floor, you may do this on an old Jag, but not on my car thanks!

The LPG filler is where the petrol filler was, it's a beautifully neat integrated solution that requires no hole cutting or other crude invasive treatments to my TVR.

In all my years around TVRs I have never seen or even heard of a TVR taking on water through the petrol filler cap, it' resides under the boot lid for heavens sake!!!


All in all Mr "classicswede" (& I don't mean to be rude) I recommend you re-read the post on PistonHeads properly my friend.

It's all there!


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PostPosted: Fri Apr 12, 2013 7:08 pm 
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ChimponGas wrote:
I did have another option with all this, I could have put a piggy back on the 14CUX and cobbled a Megajolt onto it in place of the distributor.
Or you could have fitted a later GEMS or Thor engine with matching control system. Let's face it, the 14CUX hasn't been used by LR since 1994 and it never was very good in the first place ( I own and use a 14CUX and a GEMS and I know which one is the better of the two and it certainly isn't the 14CUX). That way you could have mapped it on petrol and used a standard piggy back LPG ECU to do the job. V8 Developments do tuned 4.6 litre and a 5.3 and 5.5 litre version of the engine which are good for over 400 bhp. You'd also have OBD compliance too so would be able to use one of the LPG systems that connects to the k line and self corrects any anomalies in the mapping.

ChimponGas wrote:
Do you really think we would do all this & not sort the venting?
We don't know. The final picture on the Pistonheads thread shows that you appear to have only used 1 vent tube from each gastight lid. I would suspect that with the fill and feed pipes running through it the remaining cross sectional area is below the 450 sq mm that CoP11 stipulates. Even a single copper feed pipe through a 26 mm vent tube reduces it below this. That's why there is the option for two from each gastight box. Where's the gas going to go when the pressure release valve opens if you did mess with the fill stops?

ChimponGas wrote:
The LPG filler is where the petrol filler was, it's a beautifully neat integrated solution that requires no hole cutting or other crude invasive treatments to my TVR. In all my years around TVRs I have never seen or even heard of a TVR taking on water through the petrol filler cap, it' resides under the boot lid for heavens sake!!!
Yes....... I would be interested to hear Keith's view on this as he is the one who is likely to be certifying it. CoP 11 clearly states:

It should not be necessary to keep any passenger door, bonnet or load compartment door open during the filling process.
No gas should enter the vehicle during filling or on connection or disconnection of the filling gun. A gas tight sealing "boot" should be fitted to the part of the filler assembly inside the vehicle unless other effective means of ensuring a seal during service are provided.


To my way of thinking, the fact that you have to open the boot to fill means that the install is non-compliant. It also means that when you remove the filler gun, that pssst you hear is LPG that is dropping into the lower recesses of your boot to pool in there. With no hole in the bottom to allow it to escape, it's just laying waiting for an opportunity to ignite. You may not like the idea, but you do need a hole in the boot floor.

Don't get me wrong, I'm not knocking your efforts but I do feel you have been re-inventing the wheel a lot of the time. You've decided that the 14CUX is carp, a fact that I doubt anyone would disagree with, so you have no desire to piggy back an LPG ECU onto it. But rather than updating to a later, manufacturer developed, system that can be mapped (or just buy the Tornado chip to go in it) and piggy backing off that, you've spent an awful lot of time, effort and, presumably, money virtually starting from scratch with an unknown system. You admitted there was a problem with the impedance of the injectors but the Canems manufacturer was able to sort it. What would you have done if it couldn't be sorted?

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PostPosted: Fri Apr 12, 2013 7:21 pm 
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The photo near the end of your thread is how I know that you have not yet done the tank venting.

Image

You are only using half of teh available venting space.

The filler is a trap for heavy LPG. Fantastic idea that.

You have an exposed joint in the form of a T in the boot area

To me you have a nasty habit of jumping to conclusions. You come over as a sales rep premoting the camens system.

The early injection systems (Dream xxi etc) did not have a gas pressure sensor or gas temp sensor and worked ok. The updated N systems with the pressure and temp sensors were a great leap forward. A mappable petrol ecu with switchable map would have done the job better combined with a specialised LPG ECU rather than a experimantal system. The camens system is obviously still very experimental at this stage and as you have already found there are still some bugs in it.

Fortnaly for you your engine is not eaxctley demanding and still fairly unstressed. On a more highly tuned engine the years of development put into the piggy back LPG systems would pay off over some experimental electronics.

I'm glad it is all working ok for and I was sure it would be acceptible to you with the way it would work. The trouble is there is a lot of comprimise over what could have been done. I'm sure with further development and testing with the additional imputs the cames system could be very good

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http://www.classicswede.com/
http://www.classicswede.co.uk/LPG/cat17 ... 10800.aspx

LPG installer Anglesey North Wales

DIY LPG Kits

07824887160


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