Av gas for 100 series cruiser

Submitted: Friday, Apr 09, 2004 at 14:28
ThreadID: 11946 Views:1719 Replies:5 FollowUps:11
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Hi all .
Can anyone tell me whether one can run on avgas without detrimental effects . As that is all that is available in some outback locations .Thanks in anticipation .
Cheers dingdong .
Whiskey746 .
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Reply By: Topend - Friday, Apr 09, 2004 at 15:16

Friday, Apr 09, 2004 at 15:16
Avgas has a high lead content (even low lead) and will damage your catalytic converter. If there's no other alternative and your prepared to replace the converter it will be OK.
Dispite what some people may think there are no power gains from running this fuel. The higher octane rating only allows the engine to run at a higher compression ratio like in a race car which will then improve power.

AnswerID: 53770

Follow Up By: Member Eric - Friday, Apr 09, 2004 at 17:30

Friday, Apr 09, 2004 at 17:30
About tile some else agreed with me lol
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Follow Up By: Member - Bradley- Tuesday, Apr 13, 2004 at 16:09

Tuesday, Apr 13, 2004 at 16:09
Ah a fellow AME i see, Hows it going there Topend ? i assume you work with light aircraft / ga stuff ? . Myself - AME Mech heavy RPT ( a320 b767 b737 etc..) Unfortunately out of scene for a while (ansett) and working out and about. Whats the go up there at the moment, plenty of work or is it a bit slow..

I agree 100% on the avgas , unless you have a drag car running about 12:1 comp. and like overheating etc..

Cheers Brad.
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Follow Up By: Topend - Wednesday, Apr 14, 2004 at 08:26

Wednesday, Apr 14, 2004 at 08:26
Hi Brad,

I have experience on F-111 and F/A-18 aircraft and worked as a Tech Advisor on Blackhawks during Timor. I no longer work on aircraft as I had a complete change in career.

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Reply By: GO_OFFROAD - Friday, Apr 09, 2004 at 17:41

Friday, Apr 09, 2004 at 17:41
And you could always get a cat con, and have the case welded around your existing exhaust to make it look like it has one....8-)

Avgas is just a higher refined, more pure fuel, and should be ok.
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Reply By: Slammin - Friday, Apr 09, 2004 at 19:42

Friday, Apr 09, 2004 at 19:42
Avgas has higher octane rating hanks to it's high lead content as above.

It is not good for your vehicle if used a lot.

We have been recomended by the Big Petrol company to use it every 2nd tank or better still to dilute it 50/50. I don't know how much it will take to stuff the catalytic converter but it will happen.

If you're travelling thru and only get a tank or two I wouldn't stress.

It will also damage combustion components over time, rings etc.

Unless you have shaved the head or have a high compression engine you shouldn't notice any power gain but lot's of people reckon they do.
AnswerID: 53804

Follow Up By: GO_OFFROAD - Friday, Apr 09, 2004 at 19:49

Friday, Apr 09, 2004 at 19:49
Why would it damage internal components?

It doesnt hurt the planes engine components.
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Follow Up By: Slammin - Friday, Apr 09, 2004 at 22:51

Friday, Apr 09, 2004 at 22:51
Sorry Go_offroad Im not a petro chemist.

I live in a community that has recently switched back to AVGAS after @15yrs?

The communities don't like it because they notice/oticed their cars dying quicker when running it. Which is why a lot of communities didn't go to AVGAS or swapped back to conventional fuels over time.

Our fuel supplier is not BP but BP were kind enough to donate their petro chemists time to studies relating to the use of AVGAS in standard engines as well as studies into the effects of AVGAS if it is cut or mixed with anything to aid ingestion.

I don't think you can really compare plane to car engines: altitude of use, :temperature of use, :compression ratios, : cylinders, : power outputs, I've got no real knowledge but they're the items I can think of that would explain differences.

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Follow Up By: Slammin - Friday, Apr 09, 2004 at 22:54

Friday, Apr 09, 2004 at 22:54
Sorry hit the wrong button.

Anyway what I said previously about mixing AVGAS and the long term use etc is straight from BP's studies.

I thought the stuff would be good for my motorbike but they basically said how much do you like your bike? If you like it don't use it.

FWIW the community is back on AVGAS.
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Follow Up By: GO_OFFROAD - Saturday, Apr 10, 2004 at 09:53

Saturday, Apr 10, 2004 at 09:53
A pet engineer could never recommend for a vehicle designed to run on ulp, to run on a lead based product, as its against the law ;-)

Like I said, avgas is just an ultra refined and filtered good quality petroleum product.
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Follow Up By: Slammin - Saturday, Apr 10, 2004 at 23:00

Saturday, Apr 10, 2004 at 23:00
Go_offroad i'm not sure if you're dead serious or not?

It is not illegal to sell Avgas in a community for the use in cars etc.

The studies had no reason to be biased in any way for or against the use. They had nothing to gain or lose as they don't sell the stuff here. They were merely sorting out the fact from ficiton so that the community could make their choice without the myths.

Basically no it's not good for your car old or new.

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Follow Up By: Topend - Sunday, Apr 11, 2004 at 06:46

Sunday, Apr 11, 2004 at 06:46
I am an Aircraft Maintenance Engineer and what I have said above applys. The only problem you may get from prolonged use of Avgas is a build up of lead bromide. For the purpose of the original question, using a couple of tanks of Avgas to travel through a particular area will only damage the converter.

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Follow Up By: GO_OFFROAD - Sunday, Apr 11, 2004 at 08:04

Sunday, Apr 11, 2004 at 08:04
you may need to read my post afew more times to understand it.

I didnt say anyone was biased, and I didnt say they couldnt sell avgas.
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Reply By: ianmc - Friday, Apr 09, 2004 at 21:43

Friday, Apr 09, 2004 at 21:43
Oh boy, some of you guys must be very young.
Before unleaded our cars went better & more economically on leaded fuel & DID NOT burn out valves & rings.
Lead was a lubricant too for the top end and the switch to unleaded gave less power & poorer economy due to retarded ignition & lower compression ratios.
All in the name of cleanliness -- haha, ever stood behind an unleaded motor particularly in warm up mode.
Cant see how it would hurt to use avgas but I am not a pet. engineer.
AnswerID: 53815

Follow Up By: Slammin - Friday, Apr 09, 2004 at 23:06

Friday, Apr 09, 2004 at 23:06
Hi Ianmc, yeah I'm not that young or old but I do know that the leaded fuel made my motorbike run a lot better. It pings on unleaded so have always used the leaded and now the lead replacement or premium

Your point about the lead being good is correct, it actually helped the valves in those engines not harmed them but the lead content in AVGAS is so high, it is and has been against the law to use it in conventional car engines. Communitites have special dispensation to sell the stuff, by the way FWIW it's not always available.

The octane rating of AVGAS is higher than the old super and from what I remember I think that boost is simply from the lead. As I said in the above posts, I'm no expert but this info comes straight from BP's chemists. They also advised against running it in my 11.5 compression bike engine if I wanted it for longer than a good time....... I was expecting that it would be good for this sort of engine but nope.
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Reply By: awill4x4 - Monday, Apr 12, 2004 at 20:31

Monday, Apr 12, 2004 at 20:31
As has been posted previously, Avgas will damage the catylitic convertor but it also damages the oxygen sensor in the exhaust manifold as well.
As for Go Offroad's suggestion of replacing the cat/convertor with one bodged up to like like it's there, be aware that if you are caught doing this in Vic it is a $10,000 (that's right $10,000) fine.
Regards Andrew.
AnswerID: 53955

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