Aviation gas

[baronb55]

Will it be detrimental to the 3.4 L water cooled engine to use 100 LL gas on ocassions? I have removed the catalytic conveerter. Also, if I use it and mix it with 93 octane, will teh two mix or will the heavier 100LL sink to the bottom of the tank in a separate layer? I drive a 996 1999 with manual transmission and 81,000 miles. Thanks for any inputs.

[logray]

I would stick with the unleaded stuff.

Exhaust aside, I would be most concerned about possible valve and spark plug damage from lead deposits over time (if you use it regularly).

Passing emissions might also be a concern if you've removed your O2 sensors and cat converters.

I'm not sure if it is legal (or rather prohibited).

You might be better off looking for 100 octane unleaded fuel, which is available at some consumer pumps.

I'm not sure you are going to get what you are looking for paying the extra money per gallon versus 91 or 93 octane.

Edited September 1, 2011 by logray

[slbates]

Will it be detrimental to the 3.4 L water cooled engine to use 100 LL gas on ocassions? I have removed the catalytic conveerter. Also, if I use it and mix it with 93 octane, will teh two mix or will the heavier 100LL sink to the bottom of the tank in a separate layer? I drive a 996 1999 with manual transmission and 81,000 miles. Thanks for any inputs.

I agree with logray. I have seen 100LL lead foul a plug firsthand Sometimes I would get lucky by doing a runup and leaning the mixture and sometimes my flight ended on the ramp due to lead fouling. The "low lead" is misleading.

[PAULSPEED]

I would find a speed shop that sells racing fuel. Some

race tracks sell racing fuel.

Aviation motors are made for lead fuel to keep them

from knocking.

Paul

[Rob357]

Don't use 100LL AVGAS, here is a little story that just happened regarding this subject.

I was at the fuel farm at the local airport filling my AC for a flight when a guy in a Porsche rolls up and starts filling his 911 Carrera up with 100LL. I asked him if he knows that the 100LL is Leaded and not really Low Leaded. He gives me this look like i just P*ssed in his cereal and asked me what the H*ll i knew about a Porsche.

He told me that he has been filling his 911 with 100LL for several months and has not had any problems. When i finished filling my AC i pointed to another 911 Carrera (2000) and told him that was mine along with a 928 at home.

The look on his face was priceless......

Jump ahead to earlier this week when i was back at the airport playing around in the hanger when the same guy rolls up , except this time in a "Soccer Mom" van. I asked him how his 911 was doing, in a rather low voice with a sad puppy dog look on his face he replied. The 911 is at the dealer being worked on, It started running really bad , Throwing CEL codes over and over again. Long story short, he has to have multiple sensors replaced, catalytic converter, fouled spark plugs, oil has to be changed because AVGAS has additives that when burned collect as deposits in the oil and is corrosive in nature, and a few other items to be replaced. $$$$

Use a good quality gas like Chevron or Shell 93 octane your Porsche will love you for it.

Edited September 1, 2011 by Rob357

[dmfconsult]

I'll add my 2 cents to this as well. I have a few classic cars, and being involved with various classic car clubs, I can tell you that the use of AV gas is common, and it is usually mixed with regular Premium fuels to provide a higher octane with the added lubrication of the lead. The MAJOR difference is that when most of these classics were built, they were designed to run on leaded gas as it provides some lubrication to the upper end of the engine, and this is missing in unleaded fuels, which can cause problems like receding valve seats. Without leaded fuels or modifications to the top end of a classic motor, you have to run some other form of lubricant in the fuel, like a lead additive, Marvel Mystery Oil, or Automatic Transmission Fluid, to keep the engine running well.

Your Porsche, or any other modern vehicle, is designed for unleaded fuels, so if the goal is octane, then stick to racing fuel as mentioned above,and leaded fuel will only cause damage.

[baronb55]

Thanks to everyone who commented. I will forget about that idea. Will leave the 100LL for my Beechcraft. Don't have access to race fuel in Key West so I will stick to 93 octane and save myself a lot of money in repairs. Thanks!!

[j_beede]

I would find a speed shop that sells racing fuel. Some

race tracks sell racing fuel.

Aviation motors are made for lead fuel to keep them

from knocking.

Paul

FYI: Sunoco 110 racing fuel is leaded too.

[PAULSPEED]

I saw the 110 at the racetrack but I used the 102

racing fuel that was unleaded.

Paul

[biopsea]

FWIW, I have been using VP MS 103 (which is unleaded but contains no ethanol). While not cheap ($10 bucks a gallon !), i find a noticeable increase in "power". The real reason i have been using it is that my 997 is not a daily driver and i keep reading the horrors of ethanol, especially in a vehicle/boat/airplane that sits for any extended period. and seeing that i only put a couple thousand miles a year on her, the cost is negligible. also smells good when burning ;-)

any expert opinions out there?

Toby

[logray]

Some people use Stabil additive if the gas sits for a long time, combats ethanol problems and makes the fuel fresh longer. Safe for unleaded engines too.

[Mother]

I ran a tank full 100LL in my 84 bmw years back and the car ran cooler, response was faster and was pleased for a week then noticed that the engine sounded noisier maybe loser is better word in a strange way so mixed rest with standard gas and stayed with that since engine noise quit.

Edited September 4, 2011 by Mother