90 octane - no ethanol or 93 w/ ehthanol

[dyhunter]

A local station sells 90 octane w/ no ethanol. Is that better in my '89 3.2. than 93 octane w/ ethanol?

Thanks

[IROC]

Hard question to answer without knowing anything about the engine in your specific car (mods, etc.), but if your engine does not require 93 octane, then there is no reason to put 93 octane fuel in it. All things being equal, I would use the lowest octane fuel your engine requires and if that happens to be fuel with no ethanol, you win.

[KNS]

I would avoid ethanol any way you can.

[chuckr]

The 90 octane no ethanol WILL perform better in your car than the 93 with ethanol.
Ethanol is evil !

[Chuck.H]

Of course the easy answer is avoid ethanol, and I agree, but that may not be practical for all of us, depending on where we drive. Ethanol seems to have hit the large boat industry pretty hard, with lots of stories of delaminated fuel tanks, but I'm not sure our 911's are all that succeptible to ethanol damage.

If they are prone to damage to fuel lines etc, I'd rather have it happen close to home rather than 500+ miles away when I have no alternative but ethanol!

FWIW, I've driven for years on the '10%' blend (all that seems to be widely available in the south east) with no apparent problems.

I imagine soon 100% non-ethanol gas will go the way of leaded gas, and all that will be available is some blend.

Please don't take this to mean I take one side or the other of the ethanol debate, I don't!!!

Chuck.H
'89 TurboLookTarga, 332k miles

[dyhunter]

Thanks for all the replies. I do have a Steve Wong chip installed. I will have to check to see if it is set to run on 93.

[IROC]

Originally Posted by dyhunter

Thanks for all the replies. I do have a Steve Wong chip installed. I will have to check to see if it is set to run on 93.

This is important. I would not run 90 octane fuel (regardless of ethanol or not) in an engine with a chip requiring 93 octane.

[chuckr]

I also have a Steve Wong chip programmed for 93 octane. I can get and use 93 octane NO ethanol gas. When I leave town all I can get is the ethanol gas. My car does not run as well
on the ethanol gas, I can "feel" it at the higher RPM's
As best as I understand it, although ethanol increases the octane level, the actual power from that increased octane is lower, in other words, you are getting about the same power from the 90 octane no ethanol as you are with the 93 octane ethanol .

[IROC]

Originally Posted by chuckr

As best as I understand it, although ethanol increases the octane level, the actual power from that increased octane is lower, in other words, you are getting about the same power from the 90 octane no ethanol as you are with the 93 octane ethanol .

All this is moot, though, as the higher octane is absolutely critical to prevent detonation (assuming the engine requires 93 octane), so even if the engine produces less power on 93 (versus 90), it will prevent the engine from destroying itself, so the slight power difference is not relevant.

All additives in fuel to increase the octane level reduce the amount of "energy" to some extent, so it's not just ethanol. Higher octane numbers have nothing to do with engine power output (on 3.2 liter 911 engines). That's why you should run the lowest octane fuel that you engine will tolerate. Anything higher is just a waste of money.

[WW911]

I've been having starting problems with my 89 Carrera. Have been researching until blue in the face and getting frustrated. I've been using 93 octane/ethanol and the car has been running great, but never know if it will take 1 or 5 attempts before starting. I had about 1/3 tank of fuel left and filled it up with 90 octane/no ethanol. Ever since, it has been starting on the first attempt every time. Coincidence ? And it still runs great with no detonation that I can tell. I don't drive it as often as I should ( 2000 miles a year) but has anyone else experienced this ? 90 octane / no ethanol is readily available to me in my area.

[OsoMoore]

My 79 SC is on its fourth tank of 93 octane w/ ethanol, with no problems so far. I don't have any other options within 50 miles thanks to Milwaukee laws, but so far I haven't had any issues.

I'm considering seeing if it is OK with lower octane gas - I'm not tracking it and as long as the engine is healthy and running OK I don't need the extra umph.

[tharbert]

Originally Posted by WW911

I've been having starting problems with my 89 Carrera. Have been researching until blue in the face and getting frustrated. I've been using 93 octane/ethanol and the car has been running great, but never know if it will take 1 or 5 attempts before starting. I had about 1/3 tank of fuel left and filled it up with 90 octane/no ethanol. Ever since, it has been starting on the first attempt every time. Coincidence ? And it still runs great with no detonation that I can tell. I don't drive it as often as I should ( 2000 miles a year) but has anyone else experienced this ? 90 octane / no ethanol is readily available to me in my area.

So few miles a year suggests you leave you leave it sitting for longish periods? Two problems: a) Gas is formulated to be burnt, not stored and b) Ethanol absorbs water.

I'd run it dry, fill it up and add some gas dryer and gas stabilizer. There may be a product that does both. Either way, you simply need to drive the car more. It's telling you something!

[WW911]

You are correct in saying I don't drive it enough. I am going to run this tank low and re-fill with 90/non ethanol and run it hard. If my starting problem seems to be gone and there is no pinging, than maybe I found the problem.

[KFC911]

Originally Posted by dyhunter

A local station sells 90 octane w/ no ethanol. Is that better in my '89 3.2. than 93 octane w/ ethanol?

Thanks

Depends upon your SW chip requirements as others have noted. We only have 87 non-ethanol readily available here so that's what I use in my other vehicles and a bunch of small motors (ethanol IS EVIL ), but since my 911 (and high performance bass boat) require a higher octane, I use 93 ethanol in both. Carrera is a garage queen and driven only a few K per year. If I had an SC (CIS is more prone to ethanol issues), I'd opt for the 90 w/o. So far so good...although I had some issues with "drunken gas" in smaller motors when sobor gas wasn't available for a while, the 911 and boat have been doing just fine over the past few years.

[KFC911]

Originally Posted by WW911

You are correct in saying I don't drive it enough. I am going to run this tank low and re-fill with 90/non ethanol and run it hard. If my starting problem seems to be gone and there is no pinging, than maybe I found the problem.

I would not run a SW chipped for higher octane "hard" in hot weather with 90...you may never hear the pinging in these motors before the damage is done. If I was adamant about using non-ethanol with my SW chip, I'd probably have Steve detune it just a bit to be on the safe side. Ethanol is bad...predetonation is worse imo...YMMV.

[ScottT80]

I'd go with the non ethanol gas if at all possible even if its lower octane. Get on PureGas.org to find a list of local stations where you drive that carry it.

Unless you're a corn farmer, ethanol in cars does no good for anyone. It goes bad so much faster, a huge problem if you don't drive your car that often.

[KFC911]

Originally Posted by ScottT80

I'd go with the non ethanol gas if at all possible even if its lower octane. Get on PureGas.org to find a list of local stations where you drive that carry it.

Unless you're a corn farmer, ethanol in cars does no good for anyone. It goes bad so much faster, a huge problem if you don't drive your car that often.

I'm going to respectfully disagree. While I despise ethanol too, and it's given me all kinds of grief in two-cycle motors in the past, your assessment that it's a "huge problem" for a Carrera hasn't proven to be the case for me. That said, if one runs 87 non-ethanol "hard" during the hot months with a SW chip that REQUIRES a higher octane to prevent predetonation (due to the timing advance)...that's potentioally gonna cost you BIG $$$...just not worth risking one's motor over. I'd suggest anyone opting for non-ethanol, lower octane fuel to reinstall the stock '87-89 version of the chip which accomodates the "crappy gas" that folks in CA are required to use...YMMV.

[IROC]

Originally Posted by KC911

I'm going to respectfully disagree. While I despise ethanol too, and it's given me all kinds of grief in two-cycle motors in the past, your assessment that it's a "huge problem" for a Carrera hasn't proven to be the case for me. That said, if one runs 87 non-ethanol "hard" during the hot months with a SW chip that REQUIRES a higher octane to prevent predetonation (due to the timing advance)...that's potentioally gonna cost you BIG $$$...just not worth risking one's motor over. I'd suggest anyone opting for non-ethanol, lower octane fuel to reinstall the stock '87-89 version of the chip which accomodates the "crappy gas" that folks in CA are required to use...YMMV.

This is correct and I think this is the important point and needs to be emphasized. IMO the octane rating is more important than whether or not the fuel contains ethanol. Using lower octane fuel than your engine requires (ethanol or not) is simply a recipe for disaster.

FWIW, I've been using 93 octane fuel (w/ethanol) for years in my 10.3:1 3.2 engine with no issues.

[CCM911]

Originally Posted by chuckr

As best as I understand it, although ethanol increases the octane level, the actual power from that increased octane is lower, in other words, you are getting about the same power from the 90 octane no ethanol as you are with the 93 octane ethanol .

Just one clarification. A higher Octane gas does not give you more power, rather it slows the burn rate to prevent detonation. So if your engine is all hopped up, there would be a need for higher octane levels.

[lukeh]

I asked this question to Bruce Anderson in Excellence magazine. Please note that I have a 88 turbo that needs 93. His opinion was you need to make sure that if a car calls for 93 octane it is more important to get the 93 octane than to avoid the ethanol. He recommended I use the 93 but add Sta-bil to the tank. They have a marine formula that I think they might now call the ethanol formula that fights the effects of ethanol. I've been using it for a few years now with the 93 ethanol and have yet to have a problem (knock on wood).