Octane number
 

I know that 93 is recommended according to the note under the gas cap lid. Around here (NW Indiana), 92 is all that I have found. I'm sure it's no problem. A buddy of mine has a premium only vehicle (Nissan 350 or 370, I can't remember which) and he alternates between 89 and 92. He just passed 100k with no problems. Also when I was in Oklahoma, I went to 6 different gas stations looking for something more than 91 and 91 was all I could find. So I wondered how much different can 89 be from 91?

I guess my question is what are your thoughts? Is 91 or 92 OK? What about 89? Is alternating between 89 and 92 OK? I'll always use the highest available octane, but it's just something I was thinking about on the drive home the other day.

The DME in these cars is perfectly capable of adjusting ignition timing to successfully cope with fuels ranging from 83 to over 93 octane; there should not be any issues other than a slight loss of total power output.

I'm in nwi and I've yet to find a station that doesn't have 93...all of the speedways do...recommend you come across the state line and hit the speedway on calumet in munster or somewhere close. They all have 93. I've used 92 in a pinch but don't make a habit of using less than 93...I figure if I wanted to save money on gas I wouldve kept my nissan sentra. Instead I bought a porsche so I do what porsche says it needs.

With we had 93 or even 92. All we have is crappy 91.

You could get away with the 89. I don't believe it's recmended and I would be concerned with 10% ethanol and 89 octane. In the end you should probably add a fuel injector cleaner. As soon as you do you may as well have bought the more expensive 93 octane.

Torco Accelerator - It's not just an octane booster - Torco Race Fuels

torcoracefuel.net/pro-accelerator.html

Torco Accelerator is not just another octane booster or fuel additive, it's a race fuel concentrate.

They have mixing charts for different octanes.:cheers:

From an article in USA Today:

All Porsche engines are designed for premium, too, but it's not available everywhere. "Our cars must be able to drive all over the world, and so we are able to run on regular," says Jakob Neusser, director of powertrain development at Porsche's research and development center in Weissach, Germany. "You don't have to feel that a mechanical problem or anything else will happen" using regular gas, even in the highest-performance, regular-production Porsches.

10% Ethanol is no issue for Porsches made after 1995.

Classic News - News & Events - Porsche Classic - Dr. Ing. h.c. F. Porsche AG

So this is old school (literally) but I had a fuels and lubes course as part of my engineering degree, and we had a lab. The lab setup was half mad scientist, and half API testing rigs. a small part of the class revolved around determining, and changing octane ratings in gasoline using a knock engine in the lab. This was a big electricallty driven rig with a single cylinder, the compression ratio of the engine could be changed by turning a crank until detonation occured. Made a h3ll of a noise, all great fun (for engineers). The upshot was that experimentally, using the octane engine, the greatest increase in octane was not obtained with off the shelf octane boosters, but by mixing different octane gas (low and high ) from different producers. Why? Because at that time different chemicals were used to boost the octane in different brands, and the octane booster level in the gas was usually slightly in excess of what was needed so there was a little booster left over in each gas blend. Mix the gas blends together and you get a synergy that uses the left over boosters in each gas brand/blend to increase the overall octane of the mix you created. Because gas blends change constantly, as do the octane boosters, this is not reliably repeatable, but we were getting blends that were between 95 and 100 octane. There was an octane booster that claimed 101 octane that wasn't even close. I've made a point to use different brands ever since for higher octane.

As long as all your injectors are firing and the knock sensors aren't wigged out.

My experience is that Octane number for premium grade gasoline depends on whether it is a 10% ethanol blend or not. Usually the non-ethanol premium is 91 or 92 and the ethanol blend is 93. The ethanol blend requires a higher octane rating because the ethanol makes it a less efficient fuel.

When I was in South Dakota last June, there were several stations that had their mid-grade 89 octane gas priced 10c/gal higher than premium 93 octane b/c the mid-grade did not have ethanol while the premium did.

DBear

knock sensor location
 

Where do I look to see if the knock sensors have "wiggled" out?

I built street cars back in the 60's and I would mix premium American White 93 octane with Sunoco Blue Plus also 93 octane. These were leaded gasoline, anyway you could feel a change in how the engine ran and the mix also changed the smell of the coming out of the tail pipe. When I went to drag strip I would mix airplane fuel to gas. I was running a 327 Chevy engine, 12-1 pistons, polished and ported heads and high lift street Crane cam. My best guess was my octane was around 105. Engine screamed and it performed perfectly. If you are using racing fuel you would be disqualified. Racing fuel has very unique smell. So octane makes a big difference high performance engines.

Finally put fuel in today. I guess they are 93 around here. If it was summer, I would have remembered that. I guess all the travelling through MO and OK made me misremember.

I live by the airport in Lansing so the BP on Ridge and Calumet is my spot. I just like BP for no reason at all. Unfortunately, they seem to have run out of premium or broke something. Anyway, Hopefully I have my winter car fixed tomorrow so I can clean and park the Boxster and maybe I'll see ya on the roads this summer.

In the US, available octane in the various gasoline grades changes with altitude. Since the air is less dense at higher elevation you don't need as much octane to prevent detonation. That's why all 3 grades have less octane as you climb in elevation. I assume the 93 number recommended by Porsche is based on seal level elevation. You can't even buy 93 where I live at 8700 ft.

Maybe because BP diluted Mobil 1 oil & our Gulf of Mexico. :(

I built muscle car engines in the '80s & the best pump gas was Amoco 93 which was white/clear. If cylinder pressure was high enough to cause preignition or detonation I would add 130 octane low lead "blue" aviation fuel. Avgas lacked some lubrication additives that road gas has, so I also added Marvel Mystery oil. Experimented with the Cox model fuel & mothballs that were 100% Naptha. The Amoco 93 had a very distinctive exhaust smell, & so does the Avgas. I'm guessing the American White 93 became Amoco later.

Great, muscle cars where a lot of fun. American White was the best, but it is no longer the same because all fuels are now unleaded. The aviation fuel was fantastic add to the mixture, but you still destroy an engine if you weren't careful. Chevy man here. Owned a 55, 56, 57, 58. A 67, 68, 69 Camaro's. My new one off the lot in 64 was a Chevelle, built in June as a half year version. Had a 327, 300hp vette engine, Munice close ratio 4 speed and positraction. I changed the side flags to the 283 flags. So now I had a sleeper. Had a buddy with 64 Plymouth Valiant, 2 door and was the cheapest body style made. But, it had a V8, 4 speed and positraction too. Another sleeper looking for a pray.