Submitted: Friday, Mar 05, 2004 at 18:03
ThreadID: 11038 Views:3198 Replies:7 FollowUps:7
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I know this has been discussed in the past but has anyone an update to the use of Avgas in petrol engines (NM Pajero 3.5 lit ULP).
I wish to run the Great Central Rd but concerned on fuel availability between Laverton and Yulara.
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Reply By: David O - Friday, Mar 05, 2004 at 18:38

Friday, Mar 05, 2004 at 18:38
Avgas has a HIGH lead content. Not sure if your 4B has catalytic convertors or not, if it does you can't use Avgas if it doesn't I'd expect you may be able to but tuning would be a bit out

Probably noone will supply it to you anyway as it is now illegal to use leaded fuel in motor vehicles.
AnswerID: 49300

Reply By: Member - Peter- Friday, Mar 05, 2004 at 19:32

Friday, Mar 05, 2004 at 19:32
Avgas is all that is supplied at the bowser in remote communities, they have an excemption for vehicle use. This is because petrol sniffing is a huge problem and Avgas doesn't provide the 'high' so no point in sniffing it.
If you can't run avgas due to a cat on the vehicle you will have to carry ulp with you. Be sure to lock all containers up if staying at some of the roadhouse campting areas.
Last time we were out there the 3.5l rangie we had with the group went the best it ever had on avgas, 100 octane makes a huge difference.
AnswerID: 49308

Reply By: Slammin - Friday, Mar 05, 2004 at 22:33

Friday, Mar 05, 2004 at 22:33
At the moment there is no low grade AVGAS in Aust, so communities are currently having to stock unleaded.
Ring ahead to find out. There are some good shopkeepers around who may look after you, if you are going thru.
Big Petrol company have advised for modern (cat convert) vehicles to use 50/50. or alternate tanks. BUUUUUT it will stuff your cat convert eventually........
IMHO I would go the 50/50 option and only in a have to situation.
Which means that if you carry 80L odd you should only have to fill up at Tjukulya(sp?) roadhouse or maybe Warburton.
AnswerID: 49326

Follow Up By: Member - Bob - Sunday, Mar 07, 2004 at 15:58

Sunday, Mar 07, 2004 at 15:58
do you know which outlets currently have ULP instead of Avgas. One of the vehicles in our group is going to have to carry enough ULP to get from Marla to Sandfire Flat! If we knew of some ULP in betweensomewhere it would certainly help.
FollowupID: 311252

Follow Up By: Slammin - Monday, Mar 08, 2004 at 23:01

Monday, Mar 08, 2004 at 23:01
Bob as I said just ring ahead. All I know is SW Tanami is at the moment unleaded, buuut a tanker for all I know may rock up tomorrow.

Good Luck.
FollowupID: 311393

Reply By: Member Eric - Saturday, Mar 06, 2004 at 00:06

Saturday, Mar 06, 2004 at 00:06
Guys avgas is almost like a kero , with high concentration of oil to stop detenation on aircrafts due to high compression , unless you beef up your comp to over 11 to 01 , you will not get any benefit , you may even loose some power .
AnswerID: 49343

Follow Up By: nugget - Saturday, Mar 06, 2004 at 01:07

Saturday, Mar 06, 2004 at 01:07
I'm sorry to say but Avgas is nothing like kero. Your probably confused with Avtur or Jet A1 which it is also called. This is similar to kero and used in turbine engines. It definitely will not work in a petrol powered vehicle but does work in diesels. Some oil should be added to lubricate the pump though. Avgas is used in aircraft engines for two main reasons. 1) Being of a high octane rating it reduces the possibitities of detonation. This is especially important with aircraft piston engines because they run at high manifold pressures. A cars engine on the other hand when cruising along isn't under nearly the same amount of load.
2) It is far less volatile than automotive fuel and so at low atmospheric pressures such as when at high altitudes it wont release its vapour or boil as readily.
Avgas doesn't have high levels of oil in it at all. It does have high levels of lead in it to give it a high octane rating in the form of tetra ethyl lead(TEL). Aircraft piston engines don't have particularly high compression ratios at all.
FollowupID: 311167

Follow Up By: Big Trev - Saturday, Mar 06, 2004 at 08:28

Saturday, Mar 06, 2004 at 08:28
Spot on nugget on the Jet A1 issue.

However, with Avgas, yes it has an high octane rating, it is probably cleaner than standard petrol (eg no impurities), but you can run it in unleaded car with no dmamge to the engine (it will actually make it perform better & more fuel effieicent). It can damage the cat converter by kind of melting the inards, from what I understand that process takes a fair while. No harm in the short term.

To say no harm to the converter, and I stand corrected here, but I understand all the cat converer does is convert the exhaust gases from carbon monoxide to another form of gas. So it really won't harm "the car" if you run Avgas.
FollowupID: 311173

Follow Up By: Slammin - Sunday, Mar 07, 2004 at 00:13

Sunday, Mar 07, 2004 at 00:13
The high octane will destroy a low compression engine in the long term. Hence the advise of 50/50 by Big Petrol company.
FollowupID: 311227

Reply By: SteveW - Saturday, Mar 06, 2004 at 14:01

Saturday, Mar 06, 2004 at 14:01
i read in 4x4(i think) a while ago about using avgas and it said it can destroy your cat converter but the main thing was that the avgas stops the oxygen sensor from working and thats the main problem...

good luck

AnswerID: 49368

Follow Up By: nickoff - Saturday, Mar 06, 2004 at 21:16

Saturday, Mar 06, 2004 at 21:16
What happens to your cat converter is that the lead in the Avgas poisons the catalist which reacts the dangerous gasses in the exhaust to less harmful ones. The catalist material is the metal Platinium, which when exposed to hyrdocarbons, O2 and heat breaks down the hydrocarbons into water (H2O) and carbon dioxide gas (CO2)with its self being used.The lead in the fuel bonds with the Platinium and destroys it, making your cat useless, and your vehicle a noxious gas emitter. This can cause you to fail rego checks etc.

FollowupID: 311213

Follow Up By: Big Trev - Tuesday, Mar 09, 2004 at 08:38

Tuesday, Mar 09, 2004 at 08:38
I am not suggesting that anyone should be breaking the law, however in Victoria we do not have annual roadworthy's.

I have taken a number of cars to get roadworthy's pre-registration, and I have NEVER seen any of the places check the emissions from the exhaust, in fact I can confidently say that it isn't included as part of the roadworthy's in Victoria.

In my earlier statements I kept saying "in the short term", and that is what I meant.
FollowupID: 311404

Reply By: Billowaggi - Tuesday, Mar 09, 2004 at 00:33

Tuesday, Mar 09, 2004 at 00:33
Hi all . sorry about late posting on this issue, Just be aware that lead contamination of a cat can also completly block it and cause severe restriction of the exhaust system right up to the point where the engine will not run! The lead oxide finishes up plastered over the fine honeycome matrix inside the cat converter, not what you really want to happen way out in the bush. It is also illegal to put any sort of leaded fuel in a vehicle produced after Jan 1986.
Regards Ken.
AnswerID: 49622

Reply By: vk5ex - Tuesday, Mar 09, 2004 at 13:36

Tuesday, Mar 09, 2004 at 13:36
hi all,

It would be really great if there was some quantitive information as to the problems with running AVGAS in moden unleaded vehicles.

ie. How many Kilometers could one expect to do running on AVGAS before there was a real detrimental effect on the Cat. convertor and / or oxygen sensor.


how many kilometers could one expect to do running a 50/50 mix of unleade/avgas before real problems with the cat. convertor and oxygen sensor appear.


are there any other problems other than those previously mentioned ( oxygen sensor , cat. convertor ) that may become evident in the future by using avgas on the odd occasion.

There seems to be a lot of conjecture on this subject , but no real supporting evidence either way !!

cheers .. Andrew

AnswerID: 49654

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