Westwood2006

iTrader: (1)

There are a few of us on here asking questions about LPG conversions but no one seems to have real information about converting an Impreza to run on LPG.

API Dave just pulled a face at me and muttered something about burned out valves. I still asked him to keep an eye out for a suitable project car though.

In the mean time I discovered that Autogas in Newport run 4 day training courses where you turn up with your car, spend a day in the classroom learning about the theory, safety and all that and the other 3 days are spent paired up with someone as you help each other convert your cars. After passing an exam you get a piece of paper saying you can install LPG systems. Scary.

So when Dave offered me a decent MY04 WRX PPP with a brand spanking new engine in it I thought to myself “that would make a good project”.



So I bought the car and it is now run in.

Next step is to book myself on the training course that they run every 2 weeks. I’ll take pictures and report back at the end of each day.

Once it is all installed and set up I’ll do some scientific-ish petrol versus LPG performance comparisons and see how it does in my 50 mile per day commute.

-----------------
Couple of shouts:

A big thanks to Dave at API for the car (I promise to try not to break or melt anything)...

... and another to Gary Moulson (Moley_WRX) at Keith Michaels for treating me like an adult. I generally dislike dealing with insurance brokers but Gary is a credit to them all.

mrmadcap

But why would you go to all the trouble to do this even to the possibility of engine damage. Ultimately the price of LPG will increase if ever gets popular. The exact same thing happened with diesel, it was as cheap as chips a few years ago and now it costs more than unleaded!!!

If you are that concerned about the price of petrol and MGP i am afraid Impreza ownership is not for you.

Westwood2006

iTrader: (1)

Because I can.

Edit. I think I know how much Imprezas cost to own and modify. This is my other one (that I have been working on for 4 years) https://www.scoobynet.com/garage/199...twood2006.html

j200 hew

if your going to convert it to lpg make sure you put a flash lube kit on it that will stop the valves from burning out thi is what i had to do when i got my lexus is 200 coverted to run on lpg.
the lpg will affect the performance of the car.

mrmadcap

So will you be converting to LPG and totally fecking it up?

Westwood2006

iTrader: (1)

Specifically for your reading pleasure. Yes.

This is how I choose to spend my time and money. I think it's an interesting project and I want to share it here. Highs, lows, warts and all.

If it works then great. If it dies then everyone can laugh at my misfortune. Either way it should make interesting reading.

In the mean time have you got anything um, you know, constructive to say? Or are you just trolling around criticizing peoples projects tonight?

s70rjw

iTrader: (2)

Best of luck. Good to see folk literally putting their money where their mouth is .
At least you will be in a position to comment................

fawor

iTrader: (3)

my03 wrx has lpg from august and still drive

mrmadcap

So you have spent considerable time and money on modifications for performance gains, you convert to LPG which will reduce the any performance that have been gained with the modifications and also compromise the integrity of the engine.
And you exppect people to buy into it
Even if it is a fantastic success the prise of LPG will just increase, defeating the object.

Westwood2006

iTrader: (1)

<face / palm>

Westwood2006

iTrader: (1)

Can you read?

stevie1982

iTrader: (16)

Good on you for giving it a go, not sure i would do it myself .... In fact I know i wouldn't but fair played to you. It will be nice to see hoe lpg gets on fitted to an impress but just promise me you won't fit it to your sti wagon, that is a work of art, I'm sure I have seen it up at API just after it was run in and if you do go to fit lpg to it then sell it to me first !!!


Good luck with of all

Westwood2006

iTrader: (1)

Ha ha. Cheers. I'll give you first refusal.

No.... the wagon is staying as it is for now. I just got it driving the way I want it. It took a lot of time & effort!

ukpaisley

iTrader: (4)

Use bigger lines to the vaporizer , hows progress ?

Westwood2006

iTrader: (1)

I'm booked in the first week of may. Had a bit of hasle getting time off work.

Westwood2006

iTrader: (1)

It has been a really interesting couple of days so far. Yesterday was spent in the classroom and today I started on the install. I got as far as installing the tank and most of the pipework.

Westwood2006

iTrader: (1)

We trial fitted several tanks and settled for an 80 litre. You can still get to the spare wheel and access the fuel pump behind the seats and it still leaves plenty of boot space.



Once the tank was chosen we had to anchor it to the car. The LPGA code of practice says it should be able to withstand 20g shock. All the materials we used are rated properly as parts of mounting kits. We could have used a frame bolted to the boot floor but there is loads of crap under the boot floor to avoid... So we opted for these bars anchored to the inner wings.



We had to improvise a bracket with a bit of 2" angle because the petrol filler was in the way on the drivers side.



Here it is bolted into place.



If the fuel pump dies I will still be able to change it! This photo was taken from inside the car with the seats removed.



Dunno what is under here but I can still get to it.



80 litre tank unwrapped for the first time.



2 holes are drilled to the outside world. One for the filler and one for the feed to the vaporiser. Plus some electrical connections. A solenoid cuts off the flow of gas when the engine is not running (or on petrol) and there is a tank level sender. The holes vent outside the car and must allow at least 450mm squared of vent to the outside world if something goes wrong with the multi-valve. Code of practice says you must not be closer than 100mm to the exhaust. We make that but will make an additional shield... just to be safe.



I can see the floor!



Everything that comes into contact with gas must have 67R written on it (in 6mm high letters). The other numbers point you to the right bit of legislative code that applies to that component. You can only fill a tank to 80% of its max water capacity.... because liquid expands with heat and cars get hot in the summer!! If you run out of vapour space... look out because liquids can't be compressed and Kaboom!



Installing the multi valve and tank box (I will post better pictures later). It does a lot of stuff. It comprises of: Manual cut off valve, one way fill with 80% cut off, outlet with solenoid and excess flow cut off, level sender, pressure releif valve and safety valve plug (bit of lead in a hole - that melts if it catches on fire).



Level sender. Works with magnets which are attached to the 80% cut off float (better pictures coming).




Cut carpet.



Making the straps next. First you bend over the ends with the hole. Code of practice says they must be a certain thickness and width for the size of tank & covered in rubber.



Then you bolt that end to the bars (or frame).



Then you cut to length and fight it for a while.... I forgot to take a pic of the finished tank... I will tomorrow.



This is what you end up with. I just have to tweak this a little to make it straight.



Preparing 8mm (most cars are 6mm) rubber hose with the solenoid & tank level cables.



Here is the filler (black) and feed to the vaporiser (blue) and electrical connections arriving in the boot.



Filler (black) going to behind the number plate. Feed to the vaporiser (blue) and electrical connections make their way down the car to the front.



I decided to go for a stealthy behind the number plate filler.



Trial fit of the filler bracket. I don't want to rely on the flimsy bumper to support it. I will clean this up and paint it properly.



The filler sits behind the bumper. I'll figure something clever out with a piano hinge and Velcro later.
Like



Filler bracket cleaned up & painted. 8mm copper tube connects to the tank inlet.



You can see the route the filler pipe takes to the boot.



Terminating the filler is easy. Fighting the vent tube requires 3 pairs of hands.



The vaporiser feed pipe receives a clever end that goes into the multivalve with the same 8mm olive as the filler.



Twisty "tuna can" clips make sure that in the event of a leak no gas ends up inside the car.



Quick fettle of the spare wheel cover.



That's the back end finished! I'll just tidy the carpet a bit later.




So that's if for the first day on the job! More to follow tomorrow.

Westwood2006

iTrader: (1)

Day 2 went well.

Vaporiser feed and some electrics go up & over the rear diff T bar... or what ever you call it.



Vaporiser feed and some electrics make their way down the car. Code of practice says nothing should be below what is already there.



This is the "front end kit". We swapped out the vaporiser for a bigger one usually used on larger V8 engines and swapped the solenoid / filter for an 8mm version (was 6mm).




The all important vaporiser from one side...



... and the other. Here we see liquid gas in, vapour out, hot water in & out and a safety valve outlet. The wires are for the temperature sensor. The LPG ECU will not switch over to LPG until the water has reached high enough temperature to stop the vaporiser from freezing.



Here's what you get in a front end kit.



This is another safety solenoid which is fitted as close to the vaporiser as possible. This goes between the tank and vaporiser. The big bit at the bottom is a filter and should be changed every 12 months.



LPG ECU, change over switch and the dual purpose pressure sender. It monitors vaporiser output and inlet manifold absolute pressures. We need to keep the relative difference between the output of the vaporiser and the pressure in the inlet manifold constant. In my case we are keeping the relative pressures at 1.4 bar.



The vaporiser was installed in the inner wing just above the near side chassis rail. It was pretty much the only place it could go. It fitted pretty well and only needed 5 minutes to modify the supplied bracket.



Next, the job I was dreading the most: Drilling the inlet manifold for the injectors. The brass one is for the inlet manifold pressure sensor. Experience has lead to them never using a T piece because you don't always know what else that pipe is doing and can lead to strange symptoms and mis-fuelling.



The best £35 you will ever spend in this game! The combined drill tap.



The inlet manifold was connected to a compressor via the brake servo line so that when you drill into the manifold the bits fly out. It worked really well. I had to wear goggles!



Eeek. Stomach in knots.



Well, that worked out OK!



LPG injector nozzle in place with locktight.



The start of the wiring. I thought this would be the easy bit but the Impreza loom is dark and mysterious and it didn't yield its secrets easily. I only need the +12 feed to the injectors and then to intercept each injector signal so that the LPG ECU can: turn them all on & off, turn them on & off one by one for fault finding, or use a combination of gas and petrol as per whatever you set it up to do! This might take some mapping tomorrow



That's it for day 2. Tomorrow the wiring will be completed, LPG injector plumbing done and then, the set up. Cant wait.

eggy790

iTrader: (20)

Nice write up! looking forward to tomorrow, well detailed . will be following this up for defo , make sure you update it after 3 months/6months usage

Westwood2006

iTrader: (1)

LPG injector attached to the inlet.



Solenoid & filter immediately before the vaporiser. All wiring complete. The tape hides connections for rear solenoid, tank level and vaporiser temperature. The copper hoop is to allow flex if the vaporiser moves with vibrations etc.





Here you can see the "T" pieces I put into the heater pipes to heat the vaporiser. This keeps the vaporiser from freezing as the propane evaporates.



Wide shot showing the second solenoid / filter, plumbing , wiring and a bit of the vaporiser.



The only decent place I could find for the LPG ECU was right on top of the air box. Everything is a compromise. You can still remove it OK. Just unplug the 2 looms and then everything is as before.



Couple of nuts on the inside of the air box help by locktight.



LPG ECU in place on top of air box.



Wiring connected but not tidy... just wanted to check if it works! It did, first time!



Taking data feed from pin 7 of the ODB port. Used by the LPG ECU to read lambda.



After checking that everything worked OK I did a quick and dirty job to tidy the cables up. By this stage I just wanted to get behind the wheel to start mapping!



This is the LPG Manifold. I am going to tidy the wiring up later ... it is a little on the rough side. The small pipe to the left goes to the pressure sender (to keep an eye on relative pressures), the 4 pipes at the front go to each of the injectors and the pipe to the right comes from the vaporiser.



Dual purpose pressure sender reads absolute manifold and vaporiser pressures. Situated behind the intercooler.



The control for inside the car. Pretty much speaks for itself.



Blank drilled for the wire.



That will do for now. I'll do something less amateurish later on.



First fill is 15 litres then back to check for leaks before running on LPG for the first time.



Leak detector spray in the tank box. You can only check the filler for leaks at this stage because the blue solenoid still hasn't been opened. The ECU has to be set up and happy before you can go any further.



Leak detector spray behind the bumper. All good here as well.



Time to connect the laptop and configure the LPG ECU.



Basic readings. Temperatures, pressures and so on. Checking that the numbers all made sense. Then a quick & dirty "auto calibration"... I will go into more detail about how we mapped it another time.



Once the LPG ECU had the right basic settings to run the car on LPG we could check the rest of the system for leaks. This is the filter / second solenoid right before the vaporiser.



No leaks detected so we could completely fill the tank with LPG. Here you can also see the rear numberplate hinge sorted. 2 little squares of Velcro hold it shut OK.



The flash lube system sucks oil through the system and allegedly saves the valves from receding into the heads.



The observant will notice these 2 manifold nipples are new. The left hand one goes from the flash lube kit and the right to the manifold pressure sender as previously described.



Flash lube reservoir stuffed between the headlight and battery.



Over all shot showing the flashlube reservoir and plumbing.



To set it up you adjust the **** on top of the flash lube reservoir until you see 4 drips per minute drop through this sight glass when the engine is idling. The vacuum sucks it through the system.

Westwood2006

iTrader: (1)

So what is it like? Surprisingly good. I have already done 360 miles!

It is early days of course but it is honestly difficult to tell the difference between petrol and LPG performance.

LPG conversions have certainty matured. It took us an hour to get it running properly and I'm a fussy bugger.... just ask Bob Rawle and API David!

You can set up the LPG ECU to do all sorts of interesting things.

Currently it is set up to switch over once the vaporiser is up to temperature, one cylinder at a time, every 10 revolutions and during acceleration through 1600 rpm. You can't feel the change over at all.

Right now it stays on LPG all the time (as long as it has some) but after 4500 rpm & after 15ms pulse width on the petrol injector signal it also introduces 10% petrol. But you could choose to switch over completely to petrol or stay on LPG.

With this set up it seems very happy indeed and performance seems pretty much identical to petrol.

I'm going to run it for a couple of months then take it for a remap. Bob reckons is should be good for 270/300 ish on petrol but LPG has a RON of 110... so we *might* get some interesting results.

Time will tell.

ScoobyDoo69

iTrader: (17)

Very interesting read. What you're saying in essence is that you could use LPG when cruising, and switch over to petrol when you boot it past 4500rpm. Sounds neat

Westwood2006

iTrader: (1)

Yes that's totally correct. And you can choose any rpm / "load" to switch over.

Have done another couple hundred miles since the last post. Today was a spirited A and B road hack. 2 pasengers and heavily loaded with stuff. She ran flawlessly. I can hardly believe it.

beanys

iTrader: (3)

I run mine on 100% load so even at full revs its stil on LPG runs flawless

JonMc

iTrader: (51)

Great write-up and really interesting info. So the flash-lube works like oiling a 2-stroke and prevents long-term damage, LPG get similar performance and MPG but is half the cost without the need to uprated fuel lines like ethanol - can't really see any major drawbacks if you want a road car that is fun

craigoscott

excellent thread and excellent detailed posts, very interesting!!

chaffe

iTrader: (1)

Well done for taking the time to document and share this with us. I wish you all the best with the LPG. I did something very similar with my last car, a 2.9 24v turbo cosworth sierra. What costs were involved with your kit and the course, and are you intending on installing kits now?

Westwood2006

iTrader: (1)

Cheers mate. Glad to hear you and some others appreciate it. Unlike some other Fu ckers on this site.

Depending on location in the uk this would have cost you 1250 to 1450 using these parts fully fitted. There are cheaper kits available though. Lots of Polish stuff out there

The course cost 1750 for the 4 days one on one tuition. You come out with your self converted car.... and if you plass the exam at the end you get a certificate, access to a national support network, unlimited phone support and a trade account.

I wont be doing this for a job although there is good money to be made for sure. I'm doing my mates 45hp Lawnmower and some of my future cars, but that's about it.

sunny1989

Very good read! thorough to say the least..

I've always been interested in this type of conversion, makes sense on a daily driver especially at the moment with these ridiculous fuel prices!

Just a shame theres a complete lack of lpg suited filling stations where I live, out in the sticks.Or petrol stations for that matter

Westwood2006

iTrader: (1)

Quick update. I have covered about 1000 miles since the conversion and everything seems to be going very well so far.

The only snag seems to be that the float on the multi-valve doesn’t , erm, float very well so the fuel gauge seems to be a bit spastic and it doesn’t automatically cut off at the 80% fill point. At some stage I need to run it out of gas to replace the multi-valve.

It’s only 30 minute job and doesn’t affect the car except that you have to manually make sure you don’t over fill the tank! I’ll post some pictures when I get round to it.

So a 70 litre fill (the UK doesn’t get as hot as some countries so I can safely over fill it a little) gives me about 350 to 370 miles… 23 ish mpg. That’s not too shabby. At today’s prices (76p) that’s about £53 per tank…

…. and with a full tank of petrol I have over 600 miles combined range!

Just in case anyone was wondering about weight. An interesting factoid about LPG is that in its liquid state it only weighs half that of water! So 1 litre of water weighs 1kg but 1 litre of LPG only weighs 0.5kg!

Another little factoid is that LPG in gas form is 1.5 times heavier than air! Weird eh?