Fitting LPG - hey, it's a gas, man!

[hughezee]

Sounds like a good result, maybe not ideal for aesthetics  but its working I had to do something similar with a civic, Lambda signal was poor despite fitting a new sensor (single wire) still runs very economically 8 years 40k later

[Laird_Scooby]

Very true - i'll tidy it up next week some time. Going to investigate fitting a pair of KV6 Lambdas as they are heated and more readily available "off the shelf". Granted they're dearer than original single wire jobbies but should respond a lot quicker from cold.

Also going to fit a switch so i can switch between front and rear sensors at will and also a gauge that shows air-fuel ratio - in simple terms it just measures Lambda voltage but will be a good indication if anything is going pear-shaped!

[Laird_Scooby]

Right - got the wiring lash-up improved, not perfect but better than it was and sort of got it tuned - it runs but is a bit slow/lean so got to be gentle with it for now. Will give it an edumacated guesswork tweak in t'morning and see how things go.

Either way it's definitely going better on the bigger mixer!

[Laird_Scooby]

After much tweaking with no results i decided the original mixer was too small (went rich at the top end), this one is too big (goes lean at the top end) so today i bored out the original mixer from 31mm or whatever it was to a gnats whisker under 36mm as that seemed about the right mid-point between 31 and 42mm and hopefully i should be able to get it to run right across the rev range now.

Won't be trying it tonight as it's dark, wet and 'orrible out there! Fingers crossed for dry weather tomorrow and i'll get it fitted on the coupé and see how things go from there!

[hughezee]

Fingers crossed indeed buddy

[Laird_Scooby]

Fingers and all possible other appendages i think! This has been quite a headache for me, can get both mixers to run ok up to about 3000rpm then the small bore one went rich and the big bore one went lean. Now i'm somewhere in the middle hopefully i can get a good compromise across the rev range. I took it to just under 36mm for two reasons, one it was a good mid-point in terms of diameter and cross sectional area and secondly (perhaps more importantly!) the wall of the mixer was getting very thin by then and i was in danger of removing the small holes round the edge of it and creating a groove instead!

So much of the sizing of the mixer has been guesswork and as the secondhand kits i bought were all allegedly off 3.5 to 4.0 litre engines, they should have been somewhere near the mark. The only exception is the mixer (too big) currently on there as that was meant to have come from an 827 that ran perfectly on LPG for many years. I think some peoples definition of perfect is very different to mine! Also if they never took it above 3000rpm they wouldn't have seen a problem.

I'll try to get a pic tomorrow of what i mean, hopefully the weather will be kind and i can get on with it!

[Laird_Scooby]

Well here's a couple of pics of the "mutilated mixer"

If you look very closely you can just see the witness marks where i bored it out from 32-33mm to a smidge under 36mm and also how thin the metal is where the small holes are.

I fitted it this afternoon and after an initial tweak to get it roughly right, i took it for a spin to see how it drove.

The answer is pretty good, not perfect yet but best it has been on LPG! It soon settled down so that while driving, even under WOT and cruising with a light foot, about 3/4 throttle and light acceleration it kept the mixture where it should be without any wild variations in the stepper motor/actuator position. In other words, by some fluke i got the size more or less spot on!

The only "fly in the ointment" is occasionally the idle mixture goes incredibly weak for no apparent reason. I'm hoping this is the remains of a dead spider working its way out of the vapouriser but i do wonder if maybe it needs cleaning out or perhaps just a really good run to blow the cobwebs (maybe literally!) out of the vap. At the moment this is causing the default position of the actuator to jump about a fair bit but it soon corrects itself once under way or if the blockage clears itself and ither way, it keeps the idle mixture more or less where it should be. As such i'll leave well alone for a couple of weeks as it might also be i'm low on gas - done about 180 miles on this tankful and it's still running plus i've had about 3 hours of "diagnostic running" so have used a gallon or two that way as well.

I'll recheck it after refilling, it all might just settle properly then after a run and a refill.

[Laird_Scooby]

Refuelled today, 193 miles and it took 39L which is about 8.5 gallons. That gives about 22.7mpg which is an improvement on what it was before. However last night i spent a couple of hours tuning it so the engine was running, revving and idling during that time.

Based on when petrol was £1.50/L i used to reckon the MoT cost me an extra tenner as that was how much fuel was used during an hour idling for the MoT test! That's about 1.5 gallons so even if i said i used 2 gallons of LPG last night tuning the vap and mixer, that makes it 193 miles on 6.5 gallons or 29.7mpg - not too shabby!

I'll see how it goes on this "modified mixer" but so far it is doing everything it should and doing it right. I gave the coupé some beans to overtake something on the way to fill up and was genuinely shocked how quick it took off past the car i was overtaking - definitely the best it's ever gone! A lot of that will be down to the handbrake problem i had for so long but that's obviously had a bearing on the fuel economy as well.

After filling up there was some EuroBlob in front of me pootling along at 45-50mph. I had hoped it was going straight on where i turned off but no, going my way. Got a nice straight bit and nothing coming - it sped up to 55-60 so i eased my speed up to match, looking to overtake. As i pulled out to overtake he hoofed it.

Gave the coupé just enough to pull alongside and get past slowly while he was still giving the blob everything it had. When i was almost past, i floored it, hit kickdown and left him in a cloud of dust, LPG fumes and V6 howl!

 

[hughezee]

Nicely nicely buddy

[Laird_Scooby]

The big test now will be the next fill-up - that's when i'll know if i really have got it right but it's looking good so far!

[hughezee]

On 23/08/2016 at 11:04 AM, Laird_Scooby said:

The big test now will be the next fill-up - that's when i'll know if i really have got it right but it's looking good so far!

I'm confident you've cracked it buddy

[Laird_Scooby]

I really hope so Stu! The poor fuel economy (even on petrol) has always been a pain with the coupé and to be honest i was at the end of my tether when not only would it not run right on LPG but was drinking more than the Jeep on it! Let's face it, the engine is 2/3 the size (roughly) and the coupé is about 200kg lighter than the Jeep so for it to be using more fuel there has to be something seriously wrong, especially when its stablemate does considerably better on fuel.

I'd actually got to the point of seriously considering binning the single point system and just going straight for the SGi system on the coupé although that would defeat the object of converting both cars, one on single point, the other on SGi to get a comparison. I also thought about just leaving the coupé on petrol and converting the Sterling to SGi and hoping for the best.

At least now i can give it a proper road test and economy test!

[hughezee]

Might even consider LPG conversion on my shuttle as we have been using the Accord V6 all week and its hardly used any fuel by comparison

[Laird_Scooby]

It's well worth it Stu - my "weapon of choice" for the past year for anything long distance has been the Jeep for the simple reason it's so cheap to run by comparison. I'm fairly sure LPG round your neck of the woods is even cheaper than here so you'd make even more savings.

Looking at the map, it's still about 50p/L locally to you but go to the West Bromwich area and it's as low as 37p/L :

http://www.filllpg.co.uk/index.php?page=lpg.php

If the coupe is now sorted as i'm fairly sure it is, then that will be the "weapon of choice" for any distance work from now on. At least until i get the SGi kit up and running on the Sterling anyway!

As for the Volvo, i'm torn between keeping it standard and fitting LPG to it, so far it seems to be returning about 19mpg but that was before i cleaned out the breathers, adjusted the throttle cable, rod and kickdown and changed the thermostat. If it was a 4-pot B230E i'd say it would now be nudging 25-27mpg but this is the first V6 B280E powered one i've had so i'm on a learning curve. There are no Lambda sensors on it either which could make life interesting!

[Shaun]

On 21/08/2016 at 11:25 PM, Laird_Scooby said:

Well here's a couple of pics of the "mutilated mixer"

If you look very closely you can just see the witness marks where i bored it out from 32-33mm to a smidge under 36mm and also how thin the metal is where the small holes are.

I fitted it this afternoon and after an initial tweak to get it roughly right, i took it for a spin to see how it drove.

The answer is pretty good, not perfect yet but best it has been on LPG! It soon settled down so that while driving, even under WOT and cruising with a light foot, about 3/4 throttle and light acceleration it kept the mixture where it should be without any wild variations in the stepper motor/actuator position. In other words, by some fluke i got the size more or less spot on!

The only "fly in the ointment" is occasionally the idle mixture goes incredibly weak for no apparent reason. I'm hoping this is the remains of a dead spider working its way out of the vapouriser but i do wonder if maybe it needs cleaning out or perhaps just a really good run to blow the cobwebs (maybe literally!) out of the vap. At the moment this is causing the default position of the actuator to jump about a fair bit but it soon corrects itself once under way or if the blockage clears itself and ither way, it keeps the idle mixture more or less where it should be. As such i'll leave well alone for a couple of weeks as it might also be i'm low on gas - done about 180 miles on this tankful and it's still running plus i've had about 3 hours of "diagnostic running" so have used a gallon or two that way as well.

I'll recheck it after refilling, it all might just settle properly then after a run and a refill.

What are you using to bore this out with Dave, have you got a lathe or access to one or does it not need that amount of accuracy ?

[Laird_Scooby]

I have got a lathe Shaun, it's a 73 year old Myford that it turns out (no pun intended!) was only made for about 18 months so is in fact incredibly rare! I bought it simply as an "Old Myford Lathe" no ebay a couple of years back but it's just about big enough to do most (maybe all) of what i need. I've bought a few tools for it such as a tailstock chuck, turning, parting and boring tools etc.

As i was doing it by guesswork then arguably accuracy wasn't that important but as i didn't know how much material i could remove and still leave the holes round the inside of the bore it was handy being able to take a thou or two at a time instead of going in with a 36mm drill bit for example. I have a few more "mini-projects" to do on the lathe and they will need a bit of accuracy so i'm glad i got it now!

[Laird_Scooby]

Bit more of an update on this - it's running really nicely on the modified mixer, economy still isn't great but a friend pointed out i'd used the wrong factors when converting LPG to Petrol mpg figures. Apparently i should multiply the LPG figure by 1.3 to get back to the petrol mpg i started with. With that in mind, 22mpg on LPG which is what it seems to have settled at works out as 28.6mpg on petrol - this is probably one of the better figures i've had from the coupé during my ownership and is pretty respectable for a lot of short journeys. Been using the air-con all the time as well!

After going round in circles hunting for those elusive mpg figures, they were there all the time!

[Laird_Scooby]

Bit of an update on the mpg from LPG figures! After tweaking the idle screw on the vapouriser for the MoT i thought i'd see how it did. I filled up a couple of weeks before the MoT so i'd have a more or less full tank for the test, knowing it's quite often running for an extended period.

After a bit more running round here and there since the test, i took it to Milton Keynes yesterday and had to stop for gas along the way.

I'd done 219.7 miles and had to fill up with 41L - using 220/9 that's 24.44mpg and multiplied by the correction factor of 1.3 to get the petrol equivalent is 31.8mpg.In terms of cost, that's about 10p/mile. Putting that into equivalent return from a petrol engine and £6.10/gallon (134p/L) i'd have to achieve 61mpg to get the same distance per £

[hughezee]

Always wondered about fitting LPG to one of my motors, sounds like a worthwhile venture at those figures

[Laird_Scooby]

Definitely! If you fitted an SGi system (Sequential gas injection) it would follow the OE map (you have to tweak the multipliers in a map on the laptop) and you could achieve nearer to what you're getting from petrol in terms of mpg figures but at the price of LPG you'd be saving a fair bit.

Unless i've got the wrong location you're more or less halfway between Derby and Walsall and not many places near you but..............

in Walsall there is a place selling at 49p/L :

https://www.filllpg.co.uk/?page=lpg.php

You can enter your address, postcode or whatever in there and see the nearby stations with up to date prices. There's also an app which works dynamically as well so even if you're in a different part of the country it will find the nearby stations and up to date prices. The people who use the app and website regularly update it so we all know the places that have LPG and the prices.

Bottom line is you can more or less halve your fuel bill, give or take a bit. Use your recent holiday as an example, you said you got 46mpg from Bagheera, presumably on Shell V-power at ~ £1.30/L which is about £6 (roughly). Assuming you tanked up at 49p/L (£2.25/gall approx) for LPG, if you got say 40mpg on gas you'd still have a hefty saving.

I don't know how many miles you did on your holiday but as an example, let's say 900 - 300 there, 300 back and 300 running about through the holiday. Keeping the figures easy, let's call it 45mpg on petrol at £6/gallon - that's 20 gallons = £120 on fuel. On LPG it would be a bit more fuel at 22.5 gallons (using 40mpg as an example figure but probably close) at £2.25/gallon or 49p/L which works out at £50.63 - nearly £70 saving on fuel or a good chunk towards an extra activity (zoo?) during the holiday.

[hughezee]

I know of a couple of LPG filling stations in Tamworth so no biggy really, I used to travel to Tamworth just to fill up with BP Ultimate and still saved money over the cheapo stuff. They also changed the formula last year and MPG dropped a little and I've been told they've been tweaking again, still using it in the four pots without any significant losses or gains in MPG atm, just hope it goes back to the last blend in terms of MPG.> http://www.bp.com/en_gb/united-kingdom/media/press-releases/bp-rolls-out-its-best-ever-anti-dirt-ultimate-fuels.html