alnielsen

iTrader: (4)

I wish it were easier to do this in the States.

bse50

I have seen at least half a dozen installs. They all failed after a while of course.
There are 2 reasons behind this:
1) PCM programming. Be it a piggyback module or a stock pcm reprogramming, shops get it wrong.
2) Lubrication. Propane doesn't lubricate like gasoline, and have you ever tried mixing it with oil? I mean, our engines already fail with mobil1 for the very same reason. Make it worse and draw your conclusions.
Surely it doesn't create carbon build-up but still, lack of lubrication is a concern.
It also has a lower power rating. 13-15%.

Good installers often add "lubrication" systems to the valves in otto cycle engines because of the increase in wear, btw.

LPG is a cheap solution for cheap people that will lead to expensive repairs in a Wankel engine.
If gas is a problem go buy a prius, don't kill your car.

philmanns

power is slightly less but negligable really. if you need full power you can just switch over to petrol. it's my wife's car mainly and she drives it pretty hard, cruising at 90'ish on runs. she never switches it over to petrol (unless running out of course) i've never worked out the mpg but tend to go by cost. 300 miles for around £60 on LPG as opposed to 220 miles for £75-80 on petrol.

bse50

That's the expense of the gas.
Now factor the added engine wear in, maintenance cost of the lpg system etc.
Petrol costs less.
Oh and if you only cover 220 miles with a tank then fuel isn't the problem...

Band aids solutions are getting popular everywhere. I get 450kms out of 47 litres as an average, in the city.

philmanns

Yeah Yeah Yeah, I've heard it all before from the so called "experts". If LPG is going to kill our engine, how come its covered considerably more miles than many of the engines in U.K. cars? It was compression tested last weekend (@94000 miles) with results weirdly better than it got at 47000 miles. We don't want a Prius or some old diesel shed, we want an RX8 that we can afford to run, and we have it. Don't you dare refer to us as "cheap", if LPG is not for you then fine, no need to be insulting.

bse50

We performed regular compression tests on 3 lpg fuelled wankels, for regular I mean every 10.000kms.
We did the same on 3 gas fuelled cars.
Guess why i'm saying what i'm saying...

Engines in the UK fail for many reasons unrelated to the engine itself:
Bad maintenance,
Short trips,
Too many so called "experts" that should be laying bricks for a living instead of building engines or selling parts.

As I said you can convert a wankel to LPG but the fuelling and timing differences are substantial. You either have 2 maps (and you can't unless you turn the car off, reflash it and restart it) or it will run like crap on either of the 2 fuel choices.
LPG is pretty "dry" lubrication wise. It isn't a huge problem in common engines but in our case oil really needs to do its job on the housings. There are engine oils that are detrimental because they don't mix well with fuel and lubricate as they should. Think about "Not mixing at all". Premix is also vital, and for a reason. Try premixing in an lpg tank
Considering how lpg is usually sprayed and our engine's characteristic you also add the risk of pinging if the seals aren't in perfect shape.
Will you notice it? probably not.
Spark plugs, did you change them with the install? Not a must but highly advisable.

You could build a long lasting lpg powered wankel but that's not the case with the available commercial solutions and definitely not worth the expense.

philmanns

worth the expense for us! it covered 35000 miles last year alone. the conversion was paid for in no time. yes, I change the plugs, as I do the coil packs too. the main reason the uk engines fail (other than the reasons you've already mentioned) is due to coil pack failure and the subsequent unburnt fuel washing the oil away, thus killing the engine and cat. this is less of a risk with lpg. some people i've found seem horrified that someone should want to use their rx8 as an everyday car AND be able to afford to run it. as far as i'm concerned. the conversion has fully met our needs. people can tell me it'll do this or it'll do that but in my case, the proof is in the pudding. Nuff said.

bse50

You got my point wrong i guess.
I'm not saying it won't run, i'm saying it will run for a shorter period of time, ie last less.
Coils were part of my maintenance reference btw.

philmanns

No I got your point, I just disagree that it will last less

Huey52

iTrader: (2)

My home's heat and domestic hot water are propane fired. Yes it is a byproduct of gasoline refining but here it used to be more expensive than fuel oil and gasoline until a couple years ago when they started to escalate wildly. I'm paying about $3.25 a gallon for propane on average these days. Propane has less energy than a comparable volume of fuel oil and of course gasoline but burns more efficiently (same for LPG).

paulmasoner

iTrader: (1)

i dont have any comment about any other aspect, but that alone tells me you had something going on to begin with. Your fuel economy went from average* to only 1-2mpg better than I got on petrol(based on cost to drive a certain distance). my only mods were tuning, coils, and removing the cat. I regularly made 26mpg(9l/100km).

*I say average because from what I've seen over the years the average RX-8 gets economy similar to what you saw on petrol. But I've seen NO reason why people get such poor economy other than ignorance(as in not knowing any better, not calling people idiots for that- though they are anyway). There are too many examples I know of where people got similar results as me. And too large a percentage of people complaining about MPG who in short order show they have no clue what they are talking about or how to do basic maintenance.

This car/motor will never get great fuel economy. But it has no problem making 24-26MPG(<10L/100km) highway and low 20's mixed/city

xedosclau

motor is lubrificated by oil..not by petrol, gas

wcs

iTrader: (2)

Great read,
thanks

bse50

yeah but...

xedosclau

phillmans i'm glad you put thet video on youtube...for a long time i search for lpg rx8 instalation and i couldn't find a thing...i only have seen an rx8 on sale in germany wich has lpg combustion.
i guess it only a mit that petrol(benzin, gazoline)has a better burn than gas(lpg)wich they said it has a dry burn...bse50...your car engine is lubrificated with gas...what is oil for?
anyway...it is a soulution for lpg cars.
i have a 626 mazda on lpg for 6 years and i had no problem with it...everybody told me i will broke the engine with gpl...but it is still runing.
my father has a v6 xedos 6 on lpg and is almost power as on petrol and is still working great.
i understand that rx8 has a wankel engine and it is a difrent king of engine...but if philmans said that his rx8 is running ok...i believ him...rx8 engine are breaking off with petrol enyway...i don't think it is a such a risk lpg instalation.
philmans...what is the name of the lpg instalation system? i'm from romania and i don't want to take all the way to england for the lpg conversion install.
put some pictures with the lpg computer...all kit.
a video with you driveing your lpg rx8...maybe you convinced more people that is real ..it is a miracle!
we had to be more open minded...i'l put even a ferrari on lpg because 35-40 litre at 100 km is still a lot...and maybe i want to do something else with my money...not on petrol station
sorry fr my bad english.
rx8 is a special and superb car...if it has mps engine mazda would sale a lot more than it was.
i love rx8 but it's consume it to big for it's power...and why we had to drive a diesel fiesta every day and rx8 we drive only in weekend or when we gad petrol money
it is better to drive rx8 as a avery day car with almost the same cost as a diesel fiesta

bse50

Piston engines have valvetrain problems with lpg systems. That's why the really good manufacturers offer a separate lubrication system. The bolded part clearly explains that you lack the general knowledge on how the wankel works and why it is fundamental for an oil to mix and burn well with the fuel. Philmans only said that his car runs well, he didn't actually tear the engine open and document it. Engines can be running "fine" even when they're working in sub-optimal conditions. They can go for 10,20,30,40,50.000kms but the wear rate will be accelerated.

philmanns

I think what he lacks is difficulty in putting his point across as clearly, english is not his native tongue (for which he apologised). I've had several LPG vehicles in which I have covered high mileages, one for instance being a Renault 25 which I covered 250000 miles in with no issues. David at rotary specialists Rotechniks has covered something along the line of 300000 miles in his Mazda 626 and it keeps on going!

Yeah, so I'm going to strip and document a healthy engine to prove it's okay? NOT! I'm happy with the compression test results thanks. Yes they can go for 10,20,30,40,50.000kms, and they can also go for considerably more miles as mine has. I don't know why you are so hell bent on trying to prove why it doesn't work when it clearly does, I'm the one with the car mate, not you!

HiFlite999

iTrader: (2)

To clarify the concern: The rotary gets part of its lubrication via oil injected directly into the combustion chamber. No normal 4-stroke piston engine does this. Gasoline and oil do mix. If LPG and oil do not, or are agonists, then apex seal lubrication may be at risk. A rotary will run "just fine" without oil injection ... for a while. Personally, I have no clue if a LPG rotary will or won't work well, but extrapolation from the piston engine experience may be unwise.

Second, the "native" cost of LPG in the USA is not hugely different from gasoline. It is in Europe because the cost of motor fuels there is around 50% tax, making untaxed LPG much more attractive. Diesels are so popular in Europe, not strictly because of their fuel economy, but because diesel fuel (for some unknown reason) is taxed less. (Which drives up the cost of diesel fuel in the USA, 'cause domestic producers can get more by exporting it to Europe.)

alnielsen

iTrader: (4)

Oil, gasoline & lpg are all petroleum products. Different brothers of the same mother. Gas & Oil will mix. Actually, gas will dilute the oil.
The difference between US and Europe is the refining. They use a different process in Europe to get more Diesel fuel when cracking the crude oil during the distillation process.

bse50

Lpg and oil don't mix that well. The wear marks you see are just like the ones you notice on the valvetrains of our piston brothers equipped with older systems.
Of course who spent money on an lpg conversion will vouch for it, just like the shop selling it won't admit the product's limitations.
However I feel like I can talk... i have opened some of these ******* engines and dully noted that lpg is a serious no-go in my book, for a wankel.
You can make it work, it just won't be worth the expense and will hinder the performance with common fuels.

HiFlite999

iTrader: (2)

The cracking can be slid to favor one product over another, but only to a limited extent. A "natural" spread from a barrel of crude is around 19% diesel, 47% gasoline. With over 50% of new cars in the EU now being diesel as a result of preferential tax treatment, something's gotta (eventually) give. What's giving at the moment is the USA is increasing diesel fuel *exports* to the EU. The EU is outbidding USA domestic consumers.

The point relavent to LPG is that in many cases, and certainly in the case of LPG, what's driving the relative advantages of different fuels is not a technical issue, but of tax/political/social/etc ones.

xedosclau

wankel engines are breaking even when they are running on petrol...in romania rx8 is not going mre than 50000km with original engine...and it cost 5000 de euro to buy a new one...so..if is going to break down on lpg...at least we were driving a cheaper 50000km with ours rx8
in romania disel and petrol has the same price 1.5 euro per litre...and lpg is60-70 eurocenti per litre...that way many cars are running on lpg...even cayenne porsches.
i hope that lpg will work fine on rx8.
rx8 hydrogen how is it working?
in romania a guy invent a lpg instalation for disel engines...and for petro engines has invented a simple hidrogen instalation wich reduces the consume with 30%...the car was running with petrol...and water

philmanns

I agree, the only reason for this conversion has been the cost savings due to the tax advantages, there would be no other reason for doing it otherwise. And one day the LPG prices here will more than likely match the ripoff prices we are forced to pay for all fuels, hence making LPG conversions uneconomic. Unless of course you frequently visit London where alternative fuel vehicles are exempt from the £8 per day congestion charge! Diesel is actually more expensive here, but the greater economy they offer is what has made them so popular. At one time we were being encouraged to buy diesels as they were being considered more environmentally friendly, and diesel was cheaper. Once they became so much more popular they hiked the price up. I know fuel prices in the U.S.have risen but they still seem dirt cheap to us!

I know that this can only be used as a rough guide, but the fuel savings calculator here http://www.egasuk.com/ can give you an idea of the £ savings. Our RX8 covered 35000 miles last year, LPG prices vary from 68.9 (cheapest) to 83.9 (most expensive i've seen) so i've gone for somewhere in the middle. Giving a saving of over £4K in that year, so more than covering installation costs, and making the RX8 (more) affordable to run.

bse50

If your engines last less than 50.000km then the users are the problem.

xedosclau

bse50..you are right..the users are the problem...they don't know haw to take care of an rx8!
with 4000 savings...you can buy a new engine every year..
what is the name of the lpg kit? what was the price ?