hi all, looking to finally get my v6 vx gased. can anyone advise the type of system they are running and if they are experiencing any problems? i would like to go down the path of a vapour injected system though i'm not convinced of the savings involved on a fuel consumption level. Do you really think its close to the petrol consumption figure. i understand the gas valve system is around 18 to 20 L/100 clicks. thanks
You should get, at an absolute maximum, 14L/100km driving in town. The difference in fuel economy between mixer and SVI system is greatest when driving in the city because mixer setups don't respond well to constant changes in engine speed. If you're doing mainly highway driving, a mixer system would only use slightly more fuel than an SVI setup. I know it's a different engine, but hand-calculated, our VZ SV6 gets around 550km on 70L of gas, which equates to somewhere between 12-13L/100km driving around the suburbs. My advice would be to find a fitter who's willing to tune your system properly. Ask around for other people's opinions and/or experiences. You shouldn't be able to feel the power difference between gas and petrol. Also, keep an eye out on your fuel economy after conversion and don't hesitate to ask for a retune if necessary. Regards, Dave
Have a look in this thread: http://forums.justcommodores.com.au/vt-vx-holden-commodore-1997-2002/59296-gas-converted-vt.html its been discussed already. Ive attached a small graph showing the savings(with fed grant) made by converting to lpg for mixer and svi systems, both will save a signficant amount when enough km are travelled. The feature most of interest is the space between the two lines, this starts out at ~$2000 and doesnt reduce to zero until ~ 600 000km. This is based on a 5% efficiency gain for the svi system. Im not agreement with the claims in the previous posts about the efficiencies of the svi system compared to a mixer, especially if you got the fact impco system fitted to you VX, it should be possible for an installer to do this. Im not sure what poweredbycng has in mind when he quotes 14L/100km around town. My VX achieves that on lpg in suburban journeys, but couldnt even achieve 14's running on petrol crawling around the cbd in peak hour. The basic facts of lpg ,depending on exact propane/butane proportions, is that its energy content is only 75% of the same volume of petrol.(if it is measured per kg, lpg has higher energy content) In a vehicle that is properly setup for both fuels, this difference should be reflected in the consumption values for both fuels. This is a best case scenario and the engine will generally be more efficient on petrol, simply because it has been designed from the ground up to work at its absolute best running petrol, (cam, compression ratio, combustion shape + others). The only time when the lpg is more efficient is for cold running where the advantages of already being a gas result in better combustion. If the two values are within 20% it most likely means the vehicle isnt setup right on petrol.
Slightly misleading, commsirac. Firstly, a decent mixer system will cost more than $2000 to install and set up. You're looking at closer to $3000 or maybe even more these days for a quality Impco system professionally tuned, so to start off with you'd be down approximately $1000. Having said that, you'd be down around $2500 initially on an SVI system. Also, there is a HUGE economy difference, especially when driving in stop-and-go traffic, no matter what you want to believe. Single-point metering systems just can't cut it in these instances because engine speeds are constantly changing. At the end of the day it comes down to how long you want to keep your car for. If you only intend on keeping your car for a couple of years, go mixer. If your car carries some sort of centimental value and you want to keep it for a while longer, go SVI. Regards, Dave
Dave, Im not up to speed with the exact prices of these things , what I was trying to put across though is how long it would take to justify an svi system solely on a financial basis at roughly today's prices that have been thrown around on this forum, getting people to think througth the arithmetic rather than blindly seek advice from those who just say "get svi its more efficient". Obviously if you could get the system for the same price then there would be no discussion, but even at $1500 more its going to take the best part of 450000km to pay that off, 22 years......I havent met anyone yet that really thinks they want to keep a current 5 year old commodore that much longer! Cheap 6 put forward the fuel consumption figures for fact impco sytems in this thread: http://forums.justcommodores.com.au/619791-post92.html The city cycle figures for petrol consumption were about the range of 70-75% of the gas consumption. If your claim of the mixer system using way too much fuel in these circumstances was true it would show up on the city test cycle. In fact if you look at the figures there is basically no change in the ratio of lpg/petrol consumption between highway and city cycle. AFAIK, holden had to meet emissions standards on both the city and highway cycles with the lpg system and there is no way this could be achieved if the vehicle was pushing unburnt fuel out the exhaust in quantities that could justify major efficiency gains.
commsirac, obviously you don't know what a three-way catalytic converter does then, do you? Even if the engine were to pump out unburnt fuel, most of it would be burnt in the catalytic converter (to an extent). BTW, ever wondered why a lot of gas cars smell strongly of gas? It's because a lot of unburnt fuel comes out of the exhaust. You see, most cars out there don't regularly get tested for emissions, and the results correspond to this fact. As long as there's no smoke coming out of the exhaust, authorities seem not to care. If you want a better idea of fuel consumption mixer vs. SVI, look under the LPG Forums on Ford Forums. There's a nice 2-page thread in there titled "LPG economy". Feel free to argue your case there if you don't agree with me. Also, fuel consumption figures on paper mean nothing to me. Real-world fuel consumption figures are more meaningful. Regards, Dave
you shouldnt look at how long it would take to pay off an SVI system over a mixer system..for a duel fuel setup you should look at comparing BOTH systems to petrol..not SVI vs MIXER..no car (except the e gas-falcon) was manufactured straight gas..so yes you are right if for example your e-gas falcon had the mixer setup and you wanted to change to SVI...BUT the majority of cases people are converting there PETROL cars to either mixer or SVI.. what i am trying to say is thats always relate it back to petrol for both systems and then you can work out how much longer it would take to re-cuperate the difference..kapich?
Dave you're right about the catalytic convertors they do burn HCs, was stuck in the thoughts of tuning my old 78 holden with its mixer system, which by the way achieves comparable hc emissions to current cars with cats. However, you are not right about the smell of gas coming from the exhaust being unburnt HCs. Butane and propane are odourless and a "odourant" is added to the mix that is not destroyed in the combustion process, unlike that used in our domestic methane supplies where the odour is destroyed with combustion. I believe the smell is less coming out of a cat system where the odourant can also be reacted more completely........not really sure on this one though. The fuel figures supplied by the government testing are the only ones that I would take seriously. People may not achieve the same results in real use, however, what is consistent is that the relative ranking of the vehicles will be the same in "real" use(whatever that may be) ie if a car ranks 12L/100km city cycle in the test, it will represent a more economical car for the consumer for city use than one that comes in at 14L/100km. Suburban use of the vehicle is probably the most variable in the outcomes of fuel consumption, however, the highway cycle no.s should be generally achievable as most of us drive along the highway in a predictable manner. Muney: Muney, the graph I supplied earlier in the thread shows exactly what you are after, where the two lines meet is where the difference between svi and mixer is recovered by the owner ~600 000km. Its really nothing to do with the price of petrol on this one, its the price of lpg that determines that.
thanks for the responses umm looking further into these it appears as though the impco gas valve system is what the vx was designed around. the current ecu has the lpg data within it and a simple reflash of the ecu brings on all the lpg settings. holden and impco have done some serious work together setting up this system, though i am really being draw to the svi system.... funny how the impco svi system looses traction control, trip meter and cruise control though the parnel system manages to retain these. anyone here using the parnel svi system? just another question....those with vz's are you running the lpg engine or are you just converting an normal standard vz. i heard there were valve issues with the 3.6's runnning incompatible lpg valves? great forum....thanks again.
Dont know anything about the parnel system, however,the above appears to be a common piece of misinformation: the fact vx system only "looses" traction control on lpg, tripmeter/computer and cruise control work fine on lpg.
If you wanna find out about Parnell, I suggest you take a good read of this posting, it's about a dud who had his BA XR6 ute converted to LPG by Parnell, interesting reading! Australian Ford Forums
Prins VSI kits (distributed and rebadged as Parnell in Australia) aren't as good as other kits such as Tartarini or OMVL (Sprint Gas). From everything I've heard, it seems that Prins systems are more difficult to tune and are less efficient than other systems. Regards, Dave
commsirac what do you mean by this......impco told me themselves that these items are lost....especially with the injected version.
With an SVI system, NONE of your car's original functionality will be lost while running on gas. In fact, you can actually switch between fuels without any side-effects even while traction control is activated! It is only with mixer systems where you lose the ability to use traction control while running on gas. Regards, Dave
Well, I dont know who you spoke to at Impco, however, the cruise control on my vx and the trip computer works fine on lpg or petrol. Traction control is disabled with lpg, but can be switched on with petrol. Perhaps the person you spoke to thought it was just easier to say it cant be done rather than commit themselves or take the trouble to find out one way or another.
