rotorygas

D Rotaries and Gas mix??

This question has been asked many times, and I feel the answer is Yes, Rotaries and Gas mix very well indeed!
Please note - pics are coming!!! Give me a few weeks -please check back!
Firstly, some general facts about Liquefied Petroleum Gas
- Gas has an octane rating of 105-110.
- Gas is stored in your tank as a pressurised liquid
- Gas is a waste by-product of petrol and is sold ranging from 15 - 35 cents/litre in price ( These days 25 cents is about average)
Why run your car on Gas??
- Once the conversion done, cheaper running costs. LPG conversions can cost anywhere between $1000 - $2300, depending on the type of system that you want and components you use. Around $1750 will get you a very good Straight Gas conversion.
- Higher octane rating of fuel means you can run higher compression/ more turbo boost without resorting to exotic fuels. Gas is also a 'cool' fuel and often won't require intercooling even in high boost applications.
- More torque - Gas has the characteristic of increasing bottom end torque of a rotary ( from 3Nm to about 5Nm!!!!!)
- Throw away your pollution gear for good - Legally!!! With a STRAIGHT GAS conversion it is legal to run no catalytic converter, thermal reactor, and all that bullshit - and the cops can't say a thing!! (Although noise emissions are a different kettle of fish altogether!!! 8-) )
- You get to put a red sticker on your number plates and friends call your car 'the taxi' or 'the forklift' e.g. 'I was following your car and it smells like a forklift!!' .....(thanks Brett!!)
Gas system components-
There are 3 main parts to a gas system
- the Gas Tank - this holds your pressurised liquid gas. Gas is stored at around 900 psi so no fuel pump is required.
- the Converter. This is usually mounted in the engine bay (close to mixer) The converter "converts" the pressurised liquid to an atomised gas.
- the mixer\throttle body - this basically functions as a carby.
Types of Gas systems
There are 2 main types of gas systems, Straight gas and duel fuel. Straight gas means that the car is setup to run ONLY lpg., i.e. - the entire petrol system is removed and a dedicated Gas system is fitted. Duel fuel means that the original petrol system is retained and a gas system is 'added' on to it. This equates to a smaller gas tank (or no room in your boot) and alot of power and economy restrictions. I think duel fuel is crap and dislike it. It is a constant compromise. One advantage of duel fuel is the expensive throttle body mixer ( which straight gas requires)) is not required as your orig carby and throttle control is used. A cheap mixer only sits on top of your aircleaner. Disadvantages is that your car will on run ideally on one of the fuels, not both - plus you'll probably use lots of gas too.
With Straight gas you can set up to run fine on gas ( e.g. you can advance your spark timing a because of higher octane rating, this couldn't be done with duel fuel as fear of detonating when running petrol) Straight gas systems also are quite economical at times. With a decent quality mixer/throttle body ( such as the Gas Research 63mm unit) your car can be setup to run better than your original petrol system. As mentioned earlier with a Straight Gas system pollution gear can be tossed to the shitter - just run your extractors and exhaust and you are 100% emission legal. This is NOT so with duel fuel. As petrol can still be run, all petrol emissions still apply!! Noise emissions have nothing to do with petrol or Gas, but I always say the louder the better. As I found out the police don't share my views! Hhhmmm... 110 dB Rx3......
Safety!!
LPG in your tank is a big bomb waiting to go off - Always use a licensed gas fitter who is up to date with regs. E.g. - Your gas system is required to have TWO ignition switched solenoid valves, One on the tank outlet, and another in the engine bay. An ignition pulse detector module must be fitted - this unit monitors your spark pulse and the instant there is no spark ( e.g. stalled engine, car prang etc) closes both of the gas solenoid valves. Check your components for gas leaks regularly ( suddy water is good for this - look for the bubbles). I've had my car on Straight Gas for one year now and haven't been blown up yet ( touch wood!) I saw some 'world's worst drivers' tv show which had a VN Commodore ( 6 cylinder family car for over sea'ers) on some highway, the family smelt gas, jumped out, grabbed the video camera and filmed a bloody huge explosion - they were very lucky!! Obviously a very dodgy $900 gas conversion!
Power Loss??
Do you lose any power on gas?? ( note - I will only be referring to Straight Gas conversions from now on, as duel fuel is shit and doesn't count!) ..... Answer -yes and no?!? With a naturally aspirated car ( such as my stock 13B - at the time-) I found that I lost a some power in-between 7000 - 8500 rpm but made up power in-between 3000 - 6000 rpm, compared to my previous 48 IDA Weber. With a turbo car, any top end power loss can be made up with a simple wastegate adjustment - a little more boost. Infact a gas turbo engine has a higher power potential than a petrol ( pump petrol anyway) engine because of gas' higher octane rating and 'cooler' properties, ie less prone to detonation, able to run higher boost, higher boost equals more power 8-). More power equals fried clutch, broken gearbox ( take your pick - broken input shaft, broken output shaft, stuck in third, stuck in fourth.. we've had them all!), snapped uni's or broken diff and/ or axles!
One other problem with gas is that it pumps at only half the speed of petrol - so it takes twice as long to fill your car at the servo.
Michael Goldberg's Straight Gas conversion.
My car has been running straight gas for over a year now - and I haven't had any problems. The total cost for my system was $1750 and was fitted by Chris Dalton at Dalton Automotive , Geelong , Vic, Australia. I used Gas Research components ( which I believe are the best in Aust, maybe the even the world?) - Gas Research are really only experienced in V8 (shitbox) conversions and have no manifolds already made up for rotaries , plus I didn't like their manifolding ideas ( they wanted to use my 4-barrel manifold, Not my IDA manifold which I wanted), so I approached Chris Dalton who was very keen. My system uses a Gas Research single Mixer/throttle body. This has a single 63mm throttle body and the 'carby' is easily tunable to any rotary application with a simple jet and 'rod' change. This unit bolts to a custom side draft adapter manifold which then bolts onto my original Weber IDA manifold. I have a high flow converter and an 80l tank in the boot, sitting where the fuel tank used to. ( Note an 80l gas tank can only hold 65l of gas - it is very dangerous to overfill a gas tank- only fill to 80% capacity - service station pumps have an auto cut out anyway). My system can flow for 350 Hp which is plenty for me at the moment. The gas filler is where my original fuel filler was ; no-one was drilling holes in my rear panel!!!! Starting the engine is fine - start up is just as good , if not better than the Weber. Cold starting is taken care of with a priming system. Once warm, all you do is turn the key, no throttle. Idle is good and idles straight away from cold. Oil metering is run just the same as if running petrol. I also get alot more km's out of a tank than with the Weber - straight gas systems are very efficient, although a 22 cents/litre it doesn't matter!! As I mentioned before I lost a little power top end ( compared wit the 48 IDA) but made up heaps down low. The engine is now much more responsive and not so peaky, much better for hooning around town and daily driving. Overall, I'm very happy with LPG and my conversion - but take my advice, if you're going to do it, do it properly 8-).