Benefits of 100octane AvGas?

porsche4life · porsche4life's Garage

My uncle has some AvGas that he is willing to give me. If I poured some in say the 944. I mean like a gallon in 14 would I notice a performance increase? Would it tear anything up? I am running 91 already.

slodave · slodave's Garage

At that ratio, nothing. Avgas has lead, so it'll destroy a cat. Oh, make sure it's 100LL (Low Lead). Although, that's all you can really find these days.

m21sniper · 09-06-2009, 09:03 PM

It would probably let you bump your ignition timing a little, which could give you a little more power. If you have a turbo, it would allow you to run a little more boost, but not much. Maybe a pound or two.

Running straight av gas would allow for considerably higher boost or advanced ignition timing. Just how much, i don't know.

porsche4life · porsche4life's Garage

Well Dave what ratio would be beneficial? The cat is close to shot anyways and its not needed in OK.

m21sniper · 09-06-2009, 09:06 PM

Take it off then, those things are heavy, and as they age they gradually restrict exhaust flow more and more.

slodave · slodave's Garage

Check this link out:

http://www.gnttype.org/techarea/misc/Octanemix.html

At your ratio, you'd have 92.5. Not really a boost

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porsche4life · porsche4life's Garage

Ok what about in the blown corrado that is on 89. Say run some 91 plus like 5 gallons of 100

porsche4life · porsche4life's Garage

Hmm 5 and 10 Makes it 94...

svandamme · svandamme's Garage

won't matter a damned thing if the engine and engine management is stock.

Looking_for_911 · 09-06-2009, 09:39 PM

Back in the day I had a friend who raced a Chevy Nova on the round tracks around here. He used Aviation (100) fuel cut with Marvel Mystery oil... not sure of the amount of MM oil he used but I remember him using it.

campbellcj · 09-06-2009, 09:55 PM

Unless the car has an ECU (computer) that can sense and react to the increased octane, or you are currently running lower octane than it really needs anyway, you will not notice much change. For instance I have a second chip for my Audi that is programmed for 100-103 octane and cranks the boost and fuel maps accordingly. Getting the octane too much beyond what the engine needs could actually lead to poorer performance. There are some really detailed articles around the internet that explain this stuff -- it's way over my head.

porsche4life · porsche4life's Garage

I thinking I will just not on the 944 and apparently the Corrado needs to be on 91 anyways...

look 171 · 09-06-2009, 10:02 PM

For us modded turbo guys, we love 100 octane gas. I know a few of us who go out for a hammer session in the hills actually run close to a half tank of race gas. I use to do it all the time. It turns your tail pipes white and looks clean. Sure keeps the motor from blowing up for those who run higher boost.

slodave · slodave's Garage

^^ See, I told you it turns the exhaust pipes white

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porsche4life · porsche4life's Garage

Well the Rado is blown but I really dont want to mess with chipping and all that jazz. Yet.

porsche4life · porsche4life's Garage

Wayne if you would write a book for the 944 I would buy it.

The Corrado isn't pinging but apparently it needs the 91 according to several people.

Dantilla · 09-07-2009, 05:41 AM

My 911 sits quite a bit, especially in winter, so I store it with 100LL because it has no alcohol.

I have also used it in my 944 race car. Neither car has a cat.

Jims5543 · 09-07-2009, 06:40 AM

My Turbo RX7 is tuned for 93 and that is what I run, I tried some 100 in my tank and the car actually ran worse.

Besides, the lead in the gas destroys not only cats but 02 sensors and extended use of it will cause premature failure of your o2 sensors.

I run a Motec M4 in mt RX7 and my Motec rep told me that the lead will reduce my o2 sensor life from 100 hours to 30.

I am running a 4 wire high sensitivity lambda setup but I am sure your run of the mill o2 sensor in a car will take a beating as well.

Not worth it, even in a turbo car unless your tuned fro it and change maps to use it. In my case it was not worth it to even tune for it, I need more HP like I need another hole in my head. I already have HP related traction issues why add to the problem.

nota · 09-07-2009, 07:59 AM

is not there very low to no lead av-gas out there now???

m21sniper · 09-07-2009, 08:09 AM

Quote:

Originally Posted by svandamme

won't matter a damned thing if the engine and engine management is stock.

If you actually take the time to advance your ign. timing or increase your boost when you put in really high octane fuel it can make a difference. But you're right you have to be able to actually make the adjustment to begin with. Used to be no big deal when cars had distributors or manual wastegates. I suppose now they do it on a lap top.