lpg conversion

[davew]

Originally Posted by classicswede

Hi Phil,

the cost for conversion on the 5 or 6 cylinder car is basicaly the same. The T6 would be a tad more expensive to convert but only beacuse of the extra inatllation time due to the limited space for mounting the LPG system.

With a good system you will not notice any performance difference. As to the tank you are best going for the biggest one that will happily fit with out causing you any space issues.

I was never quoted extra for it being a T6. It was just a quote for a 6 cylinder. Cost was £2100 for a BRC system. You can get cheaper kits but BRC and PRINS were the best. (I say were because apperntly PRINS is going bust) dont quote me though.

I can also say the biggest tank your gonna get in the spare wheel well is 55 litres (or was it 57 cant really remember) Never been able to get more than 50 litres in because you cant fill them right up,and the lights start flashing to fill up again after 160 miles combined driving. (get about 45 ltrs back in)

[davew]

Originally Posted by Rex79

Hello All,

I'm new to forum and the world of volvo's (preparing to buy my first) I'm hoping you can help me though, I'm considering buying an 02 S80 and might covert to LPG later in the year or early next year,

Are particular models better for conversion? I'm currently looking at the the 2.4 (170bhp), 2.9, and 2.9T6

Can you give any advice - currently looking to spend about 1500 on car,

Dave am particulrly interested to know how the T6 is running.

All advice appreciated with regards to the cars in general & the Lpg.

Thanks
Phil

Just remebered I did this.

http://www.volvoforums.org.uk/showth...light=lpg+rica

And...... Just for anyone who is intrested when I was getting all my dyno runs done, on one session I did a quick run on LPG and it was down 2 hp. Well you live and learn eh?

Will be getting another run done soon, to see what I get as LPG as my primary fuel and then a quick run on petrol at the end to see the difference.

I rekon LPG may beat it as the engine would of settled down on LPG and wonder WTF is going on when back on petrol... :-)

[JezF]

Mine was also £2100 for a BRC system, but I've had running issues, currently the lambda sensors been coming on with gas, odd as the afr's are spot on - I've tested it with a wide band sensor.

[cyclogenesis]

I have been getting the Lambda light on as well. I have a BRC system and the codes read "long term fuel trim high" Trying to check for induction leaks first as I think I can hear some hissing on acceleration, which might be causing overfuelling.

[davew]

I Intialy had problems with long term fuel trims.

a)First you need to make sure your car is spot on. (Full stage 0 ) If all is well then go to step c

b) You will then need to go back to your LPG fitter, if you have changed anything as this will throw your trims out even more.

C) once back at you LPG guy tell him this...

What is happening is your fuel trims are slowly adjusting until it gets to the critical point (20%) I think and then it throws a code as it cant compensate any more.

When you get your codes read and the light reset this resets the fuel trims back to 0. Then slowly ovar a few days the trims creep up again and and throw the code.

You need to go back to you LPG guy and get them to go on a run with you whilst they have there equipment connected. They will adjust the lpg / air ratio on the move until it is stable.

[JezF]

Originally Posted by davew

I Intially had problems with long term fuel trims.

C) once back at you LPG guy tell him this...

What is happening is your fuel trims are slowly adjusting until it gets to the critical point (20%) I think and then it throws a code as it cant compensate any more.

When you get your codes read and the light reset this resets the fuel trims back to 0. Then slowly over a few days the trims creep up again and and throw the code.

You need to go back to you LPG guy and get them to go on a run with you whilst they have there equipment connected. They will adjust the lpg / air ratio on the move until it is stable.

This is interesting, Dave. I've had several occasions recently when it has come on after 20-50 miles, but seems to have worked perfectly before that.

Thing is, I went up to Tim Williams recently, we ran the car with his wide band lambda sensor on petrol and lpg and after adjusting the wastegate actuator, it was running really well on both fuels. 30 minutes down the M1 sitting in traffic, the damned lambda sensor light came back on again!

I've also had the turbo going into limp home mode when running on gas over the last month or two, it goes back to normal after five mins on petrol.

Re renewal of parts, I've had everything, including a new ignition coil and lambda sensor.

When you mean about the installers running it on the road, do you mean with a wide band lambda as they don't have one?

cyclogenesis, very interesting that you have the same problem, do you have the same boost issue too?

Regards,



Jez

[lpg224kw]

Originally Posted by Rex79

Hello All,

I'm new to forum and the world of volvo's (preparing to buy my first) I'm hoping you can help me though, I'm considering buying an 02 S80 and might covert to LPG later in the year or early next year,

Are particular models better for conversion? I'm currently looking at the the 2.4 (170bhp), 2.9, and 2.9T6

Can you give any advice - currently looking to spend about 1500 on car,

Dave am particulrly interested to know how the T6 is running.

All advice appreciated with regards to the cars in general & the Lpg.

Thanks
Phil

Hi phil I can't comment on the specific suitability of volvos, my lpg car is a impreza wrx (285 bhp on gas 250 miles for ~£26 at todays prices) but here are some things I learnt on the conversion road:

naturally asperated engines are the easiest to set up, next low pressure turbos and then most difficult high presure turbos. so choose a large engine with no turbo for an easier life (turbo engines can be made to work but present more difficulties wrt fuel pressure regulation due to the wider range of inlet manifold pressures. (nat asperated say 0 bar to -0.7 bar, low pressure turbo say 0.7 bar to -0.7 bar, high pressure turbo say 1.5 bar to -0.7 bar... ))

You'll get better fuel ecconomy from a naturally asperated engine due to it's higher static compression ratio. turbo cars are less thermally efficent unless your on boost, by which point the fueling is starting to go rich to ease detonation concerns.

LPG has a significantly higher octane rating than petrol but a lower calorific value. So you can run higher compression ratios and more advanced ingnition timing with lpg and this will increase power and thermal efficiency (within limits), however you get less energy from a given mass of lpg which will make for less mpg and less power, so the two effects kinda balance out. On my car I actually get more power on lpg but it's 1000rpm up the rev curve and is due to the higher octane allowing more aggresive fueling and ignition at high load and boost. petrol is more torquey but it can't handle the same ignition settings further up the rev range. Of course modifying compression ratios is not your run of the mill DIY mod... but theoretically at least a nice big engine with fairly high compression ratio and a decent (modern)ECU would be things I'd look for.

The first time you fill you tank it takes the full volume. Mine is 70 lits. A refill maxes out at 56lits, the reason being that lpg system relies on the pressure in the tank to deliver the fuel to the injectors, and as the tank empties the tank pressure falls until eventually the control system says... stop! not enough pressure! try petrol instead! On an lpg system there's no fuel pump and importantly no fuel return.... (because the return pressure would always be lower than the tank pressure). The fact that there is no return is one of the reasons that wider ranges off inlet manifold pressure are harder to accomodate, and pose greater demands on the fuel pressure regulators and injection control system.

Early Lpg systems were pretty crude and many bad reputations were made. Subaru tried a system that wrecked a few cars I believe. These early systems tried to maintain Closed loop fuelling right across the load range. They failed, engines ran weak and detroyed themselves. Modern system are far more sophisticated and interface well with cars own ecu. On my system the lpg fueling takes it's primary signal from the petrol fueling map. the lpg fuel map is then a set of scaling factors to adjust for the pressure effects already mentioned. Mine came with an auto tune facility but the guy who installed it ended up having to do a lot manual mapping to get it to run smoothly at low loads (low fuel flows) (again it's largely down to the pressure range thing)

Don't be put off by any of this cobblers, mine was a high risk projected but it's done 30k miles on lpg now and it's cheaper to run than the missues D5!! (and loads more fun) I would expect Volvos to be much easier. Large engine bay; straight 5/6 cylinder engines; big bodies to hide the bit's in... you know it makes sense. Despite my comments on turbo engines i'd bet a T5 or 850R would be hugely entertaining and probably cheaper in fuel than the diseasels.

The Only really big conern you have is... how long will the price differential last... dunno, it's lasted 3 years for me, the sooner you do it the more money you'll save!!

all the best

[davew]

Originally Posted by JezF

This is interesting, Dave. I've had several occasions recently when it has come on after 20-50 miles, but seems to have worked perfectly before that.

Thing is, I went up to Tim Williams recently, we ran the car with his wide band lambda sensor on petrol and lpg and after adjusting the wastegate actuator, it was running really well on both fuels. 30 minutes down the M1 sitting in traffic, the damned lambda sensor light came back on again!

I've also had the turbo going into limp home mode when running on gas over the last month or two, it goes back to normal after five mins on petrol.

Re renewal of parts, I've had everything, including a new ignition coil and lambda sensor.

When you mean about the installers running it on the road, do you mean with a wide band lambda as they don't have one?

cyclogenesis, very interesting that you have the same problem, do you have the same boost issue too?

Regards,



Jez

Hi,

When I go out with my lpg guy he has his laptop plugged into the BRC ecu (with a cable going from under the bonnet and through the passenger window) and a code reader in the odb port. The code reader monitors the long term fuel trims in real time. we go for a drive and if the fuel trims start creaping up or down he adjusts the percentage of gas/air just by maybe 1 percent saves it and we drive a bit more. We kept doing this till it all settled down. It was all done on the fly without stopping and didnt take very long. You need to make sure you do a few wot tests though as sometimes it will flick back to pertol becuase of pressure issues. this can be sorted by either increasing the maximum pressure allowed (as in my case) or lowing the minimum pressure allowed (if cutting out when gas low)

This does seem a common issue as I have seen this quite a few times before. Its not an issue with any of the hardware, more of incorrect setup once fitted. I gave this advise to another guy and this was his response.

"A big thank you to davew. Iemailed my installer and copied the reply you gave me about the 20% and needing to reset the system, and lo and behold it was sorted out today. We drove up a long straight road and on petrol the ratio was 8.9% but on gas it was 22%, hence the light. The engineer increased the amount of gas going to the injectors by a small amount and the ratios were then comparable with petrol."

[cyclogenesis]

Jez F,

Not sure what boost issue you are on about. Thanks for the posts above. It explains why if I need to see off some Golf, I switch to unleaded obviously more torque.

Notwithstanding the minor issues light the Lambda light, I have been very happy with my conversion. 18 months now and it has saved me a fortune in fuel. I can normally achieve 10pence per mile economy (LPG price dependant) which equates to what I was getting in my old Audi A4 19.TDI although with much more power, comfort and space. It has meant that I have kept hold of the car rather than selling. I can normally get about 200-220 miles from a tank and the country is now pretty well covered with LPG, except if you go north of Perth!

I too had a drive with the LPG installer....a very frightening high speed run up the A31 with the laptop on my lap trying hard not to Cr@P myself, whilst adjusting the mixtures. Still get the lambda light though.

Just have to slowly conduct the stage 0 and see him again at the annual service.

One to watch, when I did my PCV replacement, I broke a couple of the 90degree nozzles that fit into the inlet manifold, so if you do the same, be careful they are very fragile.

[JezF]

Dave, are you referring to AFR's?

IMO, you cannot properly set up a lpg system without a wideband lambda sensor, the stock one will not work above a certain throttle opening. If you just drove while the other guys adjusted fuel trims via the OBD port and there was no sensor bolted onto your exhaust pipe, he wasn't using wide band. Anyway, as per the previous posting, the AFR's were very good on my car, that was 250 miles after the gassers had last fiddled with it.

cyclogenesis, I've also saved a load, 16,000 miles on gas so far, if it was just the lamdba sensor, fair enough, but mine is currently hauling back the boost too.

Anyway, it's back in the garage this week, I really hope it's sorted as I really have had it with this gas system.