Rx400H Lpg Conversion

[Blueboy]

Hi, does anyone have any information on RX400h LPG conversion, I have looked into the idea and am getting close to adding this to my 56 plate. The supplier concerned is of good repute and experience with great workshops etc at the same time he is convinced that this is a straightforward job. The cost should sit around £1800 and will pay for itself in the first year at my current mileage of 30k per yr. hardly suprising when the price of LPG is 50% of petrol. Any thoughts folks?

[rxsurfer]

Hi, i have an RX300 which was converted last year, the unit is a OMVL DREAM 21N multi point with a flash lube system attached to it, so the engine still gets enough oil residue on the valves & seats so they do not suffer valve burn, as LPG runs at a hotter & dryer temperature than Deisel/Petrol, but of course they both have oil in them in the first place.

I have had no problems & at 51p per ltr at a local propane gas supplier who also has an LPG station i just can't go wrong, even the big petrol stations sell for 62p which is still a hell of a saving.

hope this helps

Paul

[Blueboy]

Paul, Thankyou for the prompt response and the mention of the lubrication for the valves which confirms something the supllier has mentioned too. I guess the final bit of question I have relates to the fact that as yet I have not spoken to anyone about the conversion of a RX400 Hybrid although I think the engine itself is the same as yours....51p eh? that is cheaper than anywhere else I have spotted! Regards Phil.

[tonyricha]

it will not last 12 months before your 1st head re build which will cost many times more than you can save, if it works Lexus would offer it as an option. Be warned and ask Lexus what they think. I tried it because I do 50K per year and killed my engine twice in a year and yes I did fit flash lube, if you want to travel this cheaply buy a Fiesta diesel. Your engine is so complex a bloke in a shed can never improve what it is designed to do and make it cheaper to run, no matter what he tells you. When it blows up you will be caught between the LPG company and Lexus each blaming each other.Keep it standard and it will run reliably for ever.

[MartyCee]

Hi, does anyone have any information on RX400h LPG conversion, I have looked into the idea and am getting close to adding this to my 56 plate. The supplier concerned is of good repute and experience with great workshops etc at the same time he is convinced that this is a straightforward job. The cost should sit around £1800 and will pay for itself in the first year at my current mileage of 30k per yr. hardly suprising when the price of LPG is 50% of petrol. Any thoughts folks?

I looked into this a while back & came away with the conclusion that it wasn't as easy as it sounds & probably problematic on a Hybrid. The reason is simple, each time the engine starts it has to run on petorl first & then switch to LPG. As you know, even on long runs down the motorway, the engine switches on & off as required & most of the time you aren't even aware of it, so unless you have an automatic system to work with the Hybrid controls you may well run into problems. Personally I'd seek the advice of Lexus technicians before you spend £1800, because the Hybrid parts of a 56 plate will still be under warranty & engine rebuilds are VERY expensive, probably more than the LPG conversion due to high labour rates.

All that said if you have a wonder-system that does work let us know, for some, as you observe, the cost (& loss of the spare wheel?) may well be worth considering.

[Blueboy]

Thanks for your comments it certainly has put a nail in the plans I have. I think that consensus seugeste that I need to speak to Lexus directly before carrying on with the idea.

[Blueboy]

Hi, does anyone have any information on RX400h LPG conversion, I have looked into the idea and am getting close to adding this to my 56 plate. The supplier concerned is of good repute and experience with great workshops etc at the same time he is convinced that this is a straightforward job. The cost should sit around £1800 and will pay for itself in the first year at my current mileage of 30k per yr. hardly suprising when the price of LPG is 50% of petrol. Any thoughts folks?

I looked into this a while back & came away with the conclusion that it wasn't as easy as it sounds & probably problematic on a Hybrid. The reason is simple, each time the engine starts it has to run on petorl first & then switch to LPG. As you know, even on long runs down the motorway, the engine switches on & off as required & most of the time you aren't even aware of it, so unless you have an automatic system to work with the Hybrid controls you may well run into problems. Personally I'd seek the advice of Lexus technicians before you spend £1800, because the Hybrid parts of a 56 plate will still be under warranty & engine rebuilds are VERY expensive, probably more than the LPG conversion due to high labour rates.

All that said if you have a wonder-system that does work let us know, for some, as you observe, the cost (& loss of the spare wheel?) may well be worth considering.

[Blueboy]

Thanks for your response, I have always had a niggling doubdt about the effects on any interchange that takes place between the engine and the batteries so I guess it is back to Lexus for the final vote.

[tonyricha]

Sorry if I was a little blunt, I can never forget the nightmare I had with LPG on a Lexus and so hate to think of anybody else suffering the same, previous car, an Omega V6 auto ran for 200 000 on gas with few problems and so I thought Lexus would be the same but oh no it just would not work ( as Lexus told me after paying £2000 conversion )I then spent another £5000 re building the engine twice all to save a few hundred quid on fuel, not to mention endless breakdowns and downtime. YUK !!!

Tony

[ihpj]

I'm not a fan of LPG; apart from the reasons described above, LPG provides around 40% less mileage than Unleaded. So although it costs a little over half the price of petrol, it also does around 40% less mileage too - so you're filling up twice as often with LPG than with petrol. I really don't see the advantage?

[Blueboy]

Tony, thanks for the reply and no worries about bluntness at all I didn't see it that way and to be frank am impressed that the club has memebers who are will ling to share the nightmares - as well as the good stuff. Thanks again.

[Blueboy]

Thanks for the reply - I do not intend to take any chances with the car re LPG or anything else. I do love it in it's full orginal glory and want to keep it that way despite the pain of such a small tank for such a large vehicle. I did also ask the Lexus Tecdoc desk who have just pushed me to the local dealership who in actual fact gave the same response as another club member that related to the hybrid stop start system rather than the the blown head nightmare that another member has endure. So no LPG for me. Thanks. Phil.

[Phil Price]

I have run a RX300 and now a RX400h both on LPG with no problem it's the old story it the jobs done right

there will be no problem. Program the ECU to start on gas and there is no issues on change over and still able to

change to petrol when required.

[mmm!]

I have run a RX300 and now a RX400h both on LPG with no problem it's the old story it the jobs done right

there will be no problem. Program the ECU to start on gas and there is no issues on change over and still able to

change to petrol when required.

Hi Phil,

I am very impressed that it worked for someone as I am really wanting to convert my RX400h to LPG. Are you able to share how much it cost you to get the job done right and if possible recommend the garage?

Many Thanks

[Mike evans]

Just wondering, what caused the cylinder head to go? What actually failed, and did you get to the root cause? Was it running lean?

Did the LPG installer check the system for correct running?

I've been using LPG in loads of eclectic high performance cars for years, and never had any problems, but then again, I've always used a converter that really knew what he was doing, and paid close attention to the running of the car. In fact, I'm training to become an installer myself.

I've seen loads of bad LPG conversions in my time.

With simple errors, like the evaporator connected to the wrong point on the manifold, injector pipes kinked and blocked.

Incorrect size nozzles used.

There are loads of people claiming to do a 1 day conversion for less than £1k - I find this worrying. I cant see how thisis really possible without cutting serious corners in the installation and setup. There is a good 6-8 hours installation time in any lpg kit. Plus the setting up.

A good example is the cold start/ warmup check. This really needs to be done a couple of times to check the changeover is ok.

Also, there should be a good test drive, up to temperature, with the diagnostics plugged in and continually monitored to check the mixture, and to tweak the calibration. No matter whatnthe kit manufacturer says about "auto calibration" only a fool would rely completely on this, and not check it manually. The manual checks would highlight any lean running.

Also, many "kits" have a marginally specified evaporator. This would result in lean running and engine failure. There should always be adequate headroom in the kit specification, e.g. Using a 210 hp kit on a 200 hp car. You really need the 280hp kit to make sure you don't run into problems.

In reality, a good LPG Kit costs about £1k for the parts, with a fitting cost of between £500 to £800. For a 6 cylinder.

Yes, you get a poorer mpg, but only by about 10% if the system is installed and set up correctly.

On my Saab 9-3 Viggen (235bhp 2.3 litre turbo) I average 30 mpg on LPG, 33 mpg on petrol. On a run, I get 45 on LPG, 47 on petrol. From experience, this is typical on modern cars with knock sensing.

In some applications, like my tuned rover v8, the engine spec has been created to run specifically on LPG, with a high compression ratio. I have to run it very rich on petrol to stop detonation.

Power is reduced on LPG, but if you really want the full power, you can tune the LPG system to revert to petrol at full throttle, thus restoring the 10% ish lost power - this is particularly useful on smaller engined cars.

I'd be interested in finding out more about the 400h conversion - more details please.

Mike.

[solidgold]

As ive stated on another thread ive had my car 12 months on gas with no problems,it was converted several years ago.Having said that im not convinced im saving loads and you will have to fill the tank lots if you do lots of miles.i'll buy a diesel car next time,but thats more to do with the general reliability of my lexus and the price of parts etc than the gas system.

[eXOBeX]

I have run a RX300 and now a RX400h both on LPG with no problem it's the old story it the jobs done right

there will be no problem. Program the ECU to start on gas and there is no issues on change over and still able to

change to petrol when required.

Hi Phil,

I am very impressed that it worked for someone as I am really wanting to convert my RX400h to LPG. Are you able to share how much it cost you to get the job done right and if possible recommend the garage?

Many Thanks

Phil does LPG conversions himself, he converted my GS300 back in 2005 (90,000 miles ago). I took his gas-converted RX400h for a spin earlier today, what a cracking machine. I expected a hybrid to be a real pain to convert, but apparently apart from initially calibrating the gas ECU following installation (keeping the engine running long enough is the tricky bit) it's much the same as converting a normal petrol engine. The 75 litre tank is in the spare wheel well.

[eXOBeX]

I'm not a fan of LPG; apart from the reasons described above, LPG provides around 40% less mileage than Unleaded. So although it costs a little over half the price of petrol, it also does around 40% less mileage too - so you're filling up twice as often with LPG than with petrol. I really don't see the advantage?

I don't know where the 40% figure comes from. I get 240-260 miles on a 60 litre tank of LPG. I certainly won't get 500-540 miles out of a 75 litre tank of petrol!

[alan-partridge]

40% less... you're talking absolute b@lls ihpj.

[NEV72]

Have had my RX300 for 4 years now, first thing I did when I purchased it, was to convert it to LPG plus Flashlube, I purposely went for a low mileage 2003 mk1 (32k), rather than a higher mileaged 2003 mk2, due to the fact being the tyre well is ideal to install the LPG tank in the mk1, as I didn't fancy the idea of having it underneath and being pretty close to speed bumps, as it would have been in the mk2. May I say the detractors of LPG in here, have obviously had a fair bit of bad luck, but I certainly wouldn't place the blame at the door of LPG, in the 4 years of owning the RX300 its only cost me two sets of tyres two sets of EBC6000 series brake pads, new front discs, and a Battery, which after almost 80k of mileage I'd say was pretty decent, I've been advised that in the near future I'm going to need to replace the exhaust system, and due to the mileage its advisable to replace the timing belt. Another thing I did when I bought it was to take it to Tony at Wheels in Motion, to have the geometry set up, as apparently the adjustable chassis is set up for Japanese roads, and not ours, best £75 quid I ever spent, as this definately gave the Pirelli Scorpions their longevity. I initially came in here as I'm going for the RX400h as my next car, and was looking to see the reviews on LPG conversions in them, but in seeing the mixed reviews I for one, wouldn't be put off in converting a RX400h to LPG. Regular services on the Lexus, and an annual service on the LPG has worked ok for me.

[eXOBeX]

Well I can certainly vouch for Phil's workmanship and after-sales service. All of his rally cars (look on Google for Phil Price Rally School) run on LPG, plus he's converted his own RX400h so he knows exactly what to look out for.

Having taken his RX for a spin my next car could well be a 400h (I've had two Corollas, then two Carinas, then two GS300s so I ought to keep the pattern and get something else next time :) ). There's plenty of life in the GS yet though, and with the extra mods (satnav conversion, on-board video with GPS overlay) I'm in no rush to part with it.

Whether its replacement gets converted will depend on my mileage. The conversion on the GS has more than paid for itself, but my annual mileage has now dropped from around 20K to around 7K, so I'd have to re-examine the figures. If LPG turns out to be worthwhile then Phil will definitely be getting a return customer :)

[Westyfield2]

Going slightly off topic, but related to ECU programming... I'd read that the Lexus ECUs were impossible to remap. Was that incorrect and it is possible to remap Lexus ECUs? Or do these LPG conversions use a different ECU (either as replacement or as piggyback ECU)?

[eXOBeX]

The LPG system uses a separate ECU. Connections to the petrol injectors are diverted through the LPG ECU, which also connects to the LPG injectors. As far as the petrol ECU is concerned it's running on petrol and running the petrol injectors. The LPG ECU takes the petrol injector timing and provides an equivalent LPG injector timing (with its own map) instead, whilst the petrol injectors do nothing. If the job's too much for the LPG system (running at high load and high RPM for example) the system can seamlessly switch back to petrol, or (with newer ECUs and newer firmware) run on both simultaneously (topping up the LPG intake with a dash of petrol). When the load eases off it switches back to LPG, again seamlessly.

To aid fault diagnosis the individual LPG injectors can be switched off using the ECU programming software, so the engine can run for example with 5 cylinders on LPG and 1 on petrol.

[Westyfield2]

The LPG system uses a separate ECU. Connections to the petrol injectors are diverted through the LPG ECU, which also connects to the LPG injectors. As far as the petrol ECU is concerned it's running on petrol and running the petrol injectors. The LPG ECU takes the petrol injector timing and provides an equivalent LPG injector timing (with its own map) instead, whilst the petrol injectors do nothing. If the job's too much for the LPG system (running at high load and high RPM for example) the system can seamlessly switch back to petrol, or (with newer ECUs and newer firmware) run on both simultaneously (topping up the LPG intake with a dash of petrol). When the load eases off it switches back to LPG, again seamlessly.

To aid fault diagnosis the individual LPG injectors can be switched off using the ECU programming software, so the engine can run for example with 5 cylinders on LPG and 1 on petrol.

Thanks.

I'd hoped that it involved remapping the original ECU, and consequently the "Lexus ECUs are impossible to remap" that I'd read was wrong.

I don't get why the Lexus ECUs are impossible to remap though. Even the latest BMW ones can be done!

[eXOBeX]

The LPG ECU has its own map, but I'm not sure whether this can be remapped to boost performance whilst leaving the Lexus ECU untouched. An installer would be able to tell you more.