Rb20det ON GAS??

[R31_GTSX]

hi peoples...

I've just finished reading an article in the latest "ZOOM" magazine about the datsun 1600 SR20det on gas...

From reading the article it seemed to me there were some serious advantages for a straight gas system in a turbocharged application.

Some of the advantages of using straigh gas (according to the article) are;

*better fuel economy "flat out, insterstate travelling 600km to a 60 litre tank"

*The higher octane level in the gas allowed 35 degrees of timing

*High RON rating which is perfect for high boost engines (with no detenation)

*No need for upgrading injectors, fuel pump, pressure regulators...

He's spun up 228kw at the wheels..

To me this seems like the perfect way to go .. but i'm hesitant as i havn't seen many high performance cars using gas.

Is there any disadvantages ?

Any input would be appreciated. As i would consider it for my rb20det.

Travis

[JimX]

Probably the biggest disadvantage in a Skyline is you will lose most of your boot space. The tank and equipment also adds a fair bit of weight to the car so with the same power your car will be a little bit slower. But I have seen several turbo drag cars running on gas, I think the most famous is the 11 second street-driven XE Falcon. Not too sure about this "flat out, insterstate travelling 600km to a 60 litre tank" though, I can already do that with my R33.

Aside from the initial cost and extra weight I can't think of too many drawbacks. I think it's not as popular with the weekend driven cars because it takes a lot longer to recoup that initial outlay due to the relatively low amount of km done.

Oh another advantage to it is you never have to worry about getting defected for emissions

[Duncan]

I thought the key difference with lpg was that it burns significantly hotter, requiring better valve stuff and engine thingies.

Technical, eh? Anyone know what I'm talking about?

[randymoss]

very interesting, let me know your results if you go ahead with it travis

[B6Tmeteor]

Also, all gas systems use a carby setup, meaning you'll never get perfect mixtures at mid throttle, midload situations.

All the fuel maps on your CPU will not be required...

To have a properly setup hipo gas system you would most likely require some changes to your engine, as per the hotter combstion point above and also I think LPG lacks some of the lubrication qualities that petrol has...

And the weight/space dissadvantage, but you do get very cheap 100 RON+ fuel.

[dojobi]

I was always under the impression that LPG had a low octane rating. In the 80s somewhere. One of the guys I work with has a LPG converted Falcon and he says he loses a fair bit of power when he switches over. Also, the stock LPG AU Falcon had less power than the petrol one. Can anyone explain this?

[B6Tmeteor]

It's most likely just in the tuning - think about it, the majority of people that convert to LPG are only really interested in the cost savings - not potential power upgrade.

Also just because it's higher octane doesn't automatically mean more power, if you put a higher octance petrol in your car more than likely you won't pick up much, if any extra power. All a higher octane number means is its more resistant to detonating, meaning you can run more aggressive ignition timing and/or more boost, and in turn getting more power.

[R31_GTSX]

I have heard that you will not get any performance gains if your running a dual fuel system (switchable from petrol to gas) In this method the car is tuned to the two types of fuel therefore compromising performance on either switch.

Running a straight gas setup your car is tuned primarily to gas..

This is only what i've heard..

Travis

[dojobi]

meteor - I'd say it would have been tuned - I mean a car with optimal A/F ratios is usually more economical. He did it for cost savings, so economy was important.

R31 - Fair enough, If it wasn't tuned for both then I can understand that, but that doesn't explain why the stock AU Falcon on gas (from the factory) makes less power than the petrol model. Surely they would tune it?

[JimX]

There are two main reasons why factory cars usually make less fuel on gas. Firstly, they are usually dual fuel which means they can't advance the timing as much, in order to enable it to be run on regular unleaded when needed. The second is that LPG has less energy in it than normal petrol.

[B6Tmeteor]

Originally posted by MIC33R

meteor -  I'd say it would have been tuned - I mean a car with optimal A/F ratios is usually more economical. He did it for cost savings, so economy was important.

A/F ratios are one thing, advancing the timing is another. Also it's possible that the most ecomonical A/F ratios do not provide the best power... But at the end of the day, I doubt it would make that much difference on an NA falcon.

[fatz]

spend 4k on getting a lpg right

or spend 4k bigger turbo ect

if you doing it to a performace car and cant afford petrol by a coroller

[APA]

i also was under the impression that gas had really low octane! thats why most performance cars don't convert!

adrian

[JimX]

Gas has very high octane, but a lower amount of energy. So you get less power out of each stroke, but you can advance your timing more to compensate.

[DCIEVE]

running on gas also helps tough cars pass emissions testing i have heard

2c

[predator]

i don't even know whether straight LPG would be possible without some serious fiddling with the inside and outside of the engine??

Isn't the whole idea of a turbo engine you compress the air and fuel a lot more to get better power out of less (cylinder) space ? Does that translate for gas even at all?

[DAMQIK GTS-T]

Running straight gas could be advantagous as you could lose the the weight of a fuel tank injectors ect, and mount the bottle in the fuel tanks place or run 2 skinny bottles for a 32 thus keeping boot space, the gas jet would need to be mounted before the factory throttle body but after the ic.

boost would help compress the gas more compared to a high pressure fule system with injectors and the gas is already under pressure and compressed in the bottle.

The luberication issues with gas was only with cars running on the old super leaded type fuel wasnt it?

[R31_GTSX]

fatz.... 4k on a gas system??

I got quoted $1700 drive in drive out..

so then i gots $2300 to spend on a massive turbo..

then keep up with me

damqik GTS-T .. u sound like you know a lot about his issue.. do you know anyone who has done the conversion on an RB series engine? in your personal opinion would you say its worthwhile?

Trav

[red17]

I thought gas was a no no on turbo motors? Not sure if its an Urban Myth but a mate of mine used to be a mechanic said he saw a VL Turbo Calais shatter a turbo housing when a backfire occured whilst running on gas?

Anyone care to correct me?

Red17

[DAMQIK GTS-T]

RED17 a vl (rb30) dosn't have a blow off valve to protect the turbo from backfires a rb20det - rb25det & rb26dett dose backfire's wouldnt be an issue. A backfire on gas would be caused from incorrect tuneing or when changeing from one fuel to the other (duelfuel setup).

R31_GTSX I used to work for a shop (in Nundah Qld) that did lpg conversons.

I have only seen the rb30 motor on gas and some vg30's none of which had any issue's.

Damqik