Gas Research - Dedicated LPG tuned, rather than running Dual Fuel. PROS & CONS?

[HamaTime™]

I've been looking into Gas Research recently:

Gas Research

And I've been told that through the old Air Mixer style LPG system (rather than a direct injection LPG system) with the car specifically tuned for Gas rather than petrol/Dual Fuel you can get much better economy and power, compared to running:

• Dual Fuel, tuned either to gas or petrol
• 98 Octane Petrol

Now this rang some alarm bells in my head, it would be good to see what you guys think about gas research and the pros and cons of straight gas in terms of performance and economy over dual fuel and a tuned 98 octane petrol system.

Thoughts?

[Cheap6]

For any mixer system, whatever it's merits or otherwise:

There is very little advantage to dedicated gas without engine mods and that raises the question as to why you want to convert in the first place (usually to save$$$).

You can have a two map memcal that allows optimum ignition timing on both fuels.

You could lose the 15l of petrol, the petrol tank, pump and injectors and rails etc. which saves, what? 40-50kg or so. Against that is the reduced range vs using both fuels - probably not an issue but can allow shopping for LPG on price with a near empty LPG tank - and the loss of reliability due to having redundancy in the form of two fuel systems. Just about the only thing that will stop an LPG/petrol Commodore V6 is the CAS.

LPG can be difficult to start without a petrol fuel assist but that depends on the system.

Without a petrol fuel system you lose the valve cooling at high loads with the dual map memcal.

You might save a little bit in not having to use some petrol but that doesn't amount to much.

[Not_An_Abba_Fan]

My partner has a VN running dedicated gas on the Gas Research system. Just recently put an LPG tune into it and it definitely pulls better higher up. Economy is about the same, power is about the same. The heads have been specifically built for LPG too. We want to go liquid injection but the cost is a bit much for the car.

The only downside is that takes a bit of turning over to start when it is cold.

[HamaTime™]

For any mixer system, whatever it's merits or otherwise:

There is very little advantage to dedicated gas without engine mods and that raises the question as to why you want to convert in the first place (usually to save$$$).

You can have a two map memcal that allows optimum ignition timing on both fuels.

You could lose the 15l of petrol, the petrol tank, pump and injectors and rails etc. which saves, what? 40-50kg or so. Against that is the reduced range vs using both fuels - probably not an issue but can allow shopping for LPG on price with a near empty LPG tank - and the loss of reliability due to having redundancy in the form of two fuel systems. Just about the only thing that will stop an LPG/petrol Commodore V6 is the CAS.

LPG can be difficult to start without a petrol fuel assist but that depends on the system.

Without a petrol fuel system you lose the valve cooling at high loads with the dual map memcal.

You might save a little bit in not having to use some petrol but that doesn't amount to much.

It's not the fact of 'using' petrol that concerns me, as far as performance goes, my car running Air mixer gas, full zorst with extractors, CAI, K&N Filter etc pulls pretty hard from around 3grand up both on gas and about 25 - 30% harder when running 98 Premium Petrol. Being an Ecotec, it does lack on down low power, which I have been planning to get a MACE manifold insulator and Plenum spacer to fix...

However, talking to this guy yesterday who is in the LPG industry, he was saying (albeit not in professional advice, rather in conversation) that Gas Research products paired with a dedicated gas tuned car, tuned for performance on gas can get some pretty impressive figures and street performance.

A full performance tune specifically for 98 Premium Petrol will pull some good numbers and definately increase the performance driveability of the car. Agreed? The comparison I'm making is that how do Gas Research products along with a dedicated gas tune stack up against a full 98 Premium tune?

My partner has a VN running dedicated gas on the Gas Research system. Just recently put an LPG tune into it and it definitely pulls better higher up. Economy is about the same, power is about the same. The heads have been specifically built for LPG too. We want to go liquid injection but the cost is a bit much for the car.

The only downside is that takes a bit of turning over to start when it is cold.

Gas is definately a bit of a shitter to start especially when cold, economy is pretty crap, unless your on a highway where I can get around 400+ k's out of a tank that will cost me around $25 on average.

Any more detailed thoughts on the advantages of GAS RESEARCH?

[Cheap6]

A full performance tune specifically for 98 Premium Petrol will pull some good numbers and definately increase the performance driveability of the car. Agreed? The comparison I'm making is that how do Gas Research products along with a dedicated gas tune stack up against a full 98 Premium tune?

I'm saying that you can have both. With two maps in the memcal the ignition timing can be optimised for both fuels, the maps changed with the fuel changeover switch. What else can you optimise for the LPG with a dedicated gas tune that you can't with dual fuel?

You could make engine mechanical changes such as bump the compression ratio up a bit, probably to about the same as when using 98, you might use a camshaft biased a bit more towards the intake with LPG but the dollars don't work out if the goal is to save money. If you are going to spend money on those things anyway, that might change.

Can you get the car to be faster on LPG than on 98? Yes, but it's like asking if you can get the car to be faster on 91 than it is now (or 95 or 98).

Which of LPG and 98 petrol is a better fuel, at least in terms of power output? Probably 98 but you can figure it out if you want to do some research. Both types of fuel are mixtures of various hydrocarbons but you can make some simplifying assumptions about their compositions and properties. Some things to consider:

The heat released from the fuel weighted by the fuels' stoichiometry. Assume that the intake volume is the same with each fuel.

Number of mole's of products of combustion and their specific heats,. Together with the heat released => pressure developed.

Being inducted as a vapour rather than a mist of liquid (mostly) more air will be displaced with LPG than with petrol but it's not much.

Excess petrol can be added to quench knock (up to a point) but that doesn't work with vapour phase LPG.

Losing the weight of the petrol fuel system would likely be the cheapest "power increase", more so than any engine power differences between straight gas and dual fuel.

[HamaTime™]

Righto!

Thanks, that was a very comprehensive and thorough answer. As I said in my first post, when that guy was telling me that you can do alot better with Gas Research products on straight gas 'ALARM BELLS RANG'...Despite the higher octane of LPG, it is not a fuel used and renowned for 'power' particularly not through an air mixer system. Which is why I was very skeptical of what the guy was telling me.

A complete retune of the memcal was always on the cards, however I've been struggling to find where to get a good quality one done, that will be for both Petrol and Gas, looks like you've just answered the question.

Any suggestions on where to go or who to talk to in regards to getting the dual map of the Memcal?

[VN_Luke]

I've done a bit of research on this topic lately, here's a quick summary of what I found:

LPG minimum MON is 91.5 - which works out to roughly around 99-100 RON (see here for more info on fuel standards).

You can buy propane from supagas which is roughly 114 RON @ 52cents a litre, last time I checked

Vapour LPG doesn't have the 'cooling effect' that petrol does because it's introduced as a vapour already - and does not change state on it's way in - chances are the engine will run slightly hotter on LPG. (which shouldn't be a problem if your cooling system is up to scratch etc)

The gas research setup is pretty agricultural compared to some nice vapour & liquid injection setups, and that's reflected in the price difference between the two/three. Having said that, while agricultural, it's been proven reliable and it works well. You may find a drop in throttle response compared to petrol, particularly in the midrange - I believe this is to do with having to draw the gas vapour into the manifold, and the time it takes to do this.

The trickiest part with the whole GRA setup is the tuning. There's not too many people around that can tune well with the metering rod setup - They are around, though - I suppose it's just a matter of calling around enough

Browser Warning There's an article outlining performance of the conversion in a VN V8. - I reckon with a good tune, correct timing maps and everything correctly setup, there's very little difference in peak power with LPG/petrol. - but you can't expect LPG to perform as well as petrol with timing maps to suit petrol.

As far as the 'little' things go
- GRA offers an idle-block to mount your GM style IAC valve into. I would imageine their 'kit' would come with this - which, when setup properly, gives you ECU idle speed control for cold mornings etc.
- GRA also does a 'vapour injection' closed loop mode setup. This will be required to be installed as per AS1425 to maintain 'closed loop' operation to minimise emissions. This is basically just a solenoid on the secondary outlet from the converter. When you're cruising, it flicks open a bunch of times to keep your mixtures nice.
- I believe this 'vapour injection' also doubles as a cold-start primer. I.e. b efore you start your car, on ignition, you can depress the accellerator and get vapour flowing before trying to start the engine - which means no nasty cold starts.

The biggest concern with carby-style LPG setups is backfires. If you're running N/A - then they're jsut girly small backfires and nothing to stress about. Maybe put a flap on your airbox or something, just in case - it's when you're intake plenum is a combstive mixture of propane vapour and air, compressed to 30psi when you have to start taking anti-pipe-bomb measures .

I have read, though, that a good, healthy ignition system with the correct plugs etc, and a well tuned car will not backfire unless something is 'wrong' - the good thing is that when it does backfire, you know pretty much right away that there is something wrong and can get to fixing it pretty quick.

Having said that - a few friends of mine run LPG setups, with one having a GRA twin converter/single mixer setup on a XF drift ute. He's had that for about 2-3 years without incident.

The other bonuses of LPG are that:
- it is EPA friendly up until a certain point. If you find a non-muppet VASS engineer - you're able to make some pretty big engine modifications to pre LPG stipulant emissions ADR vehicles (i.e. ADR37/01 and earlier.. which I think covers VS) without the engineer having to see an emissions test to approve it. (although 4.5% CO @ idle still applies) - so things like camshaft, turbos, etc can be made fully legal much easier than petrol.
- CHEAP fuel - go cruising @ half the cost of petrol.
- don't need charcoal canister, petrol tank, petrol lines, etc if you go straight LPG.
- You can buy 114RON propane at supagas for like 50c/litre (while this will need a re-tune, it's good for cheap fun @ drags etc)


Down sides:
- backfires
- running out of gas
- lots of tuning required to get it spot on
- decreased mid-range throttle response


Have a chat with:

Swift Automotive in Dandenong - (03) 9706 6322
or
Smithy's LPG in Bayswater - (03) 9762 2333

They're both quite helpful and have extensive experience with GRA systems.

[VN_Luke]

And for those that say LPG is no good for performance.... This setup made 546kw @ wheels on 15psi on a 'base tune'




This thing has been around for many years - GAS747 VL that's run 10's on the old setup you see pictured. Now fitted with a larger turbo etc - yet to see the new times




And of course, the famous 9 second XE falcon - driven to the track, run a 9, and drove home





And an up and coming mustang that will definately draw some attention (old setup pictured)


... plus many others.

[W84N01]

As NAAF stated, my VN is straight gas on Gas Research. In it's time it was an extremley good system.

Now they have the injected gas and they try not to do the research anymore. the injected gas goes so much harder, hence why i was looking into it for mine.

I've done some work on my VN, ported heads, copper sleeves and some other things, and she goes very hard as a straight gas V6 manual.

When she is cold it takes a couple of turns for her to start, as gas hates being driven cold, whilst with fuel you try and cool the car down to get better performance, i find with mine i have to wait for her to warm up to get that better performance from her.