Buc-ees Gasoline

[Miguel Antonett]

They just opened one of those here in B'ham, and they offer 93 oct fuel without ethanol... what do you guys think about it, have you tried? I have used Chevron for ages on all my cars including the 930 and 356 without any serious issues regarding water condensation... soooo I would appreciate a feedback. The beaver fuel gives me a little concern

[RarlyL8]

Hey Miguel how are you!
Unless you are running higher boost the added octane is not needed and can actually be a detriment. I stick to octane levels used when tuning the car, typically 89 as that is commonly found. I run 91 in the summer to combat heat induced detonation.

[reclino]

The correct answer is 92 for those of in the US, as this isn't an option it's safer to just use premium gas at 93 octane. Yes pure gas is preferred as the 10% ethanol will not only a absorb moisture but also result in a slightly leaner mixture.
Ok, this should be a simple answer, however it's not. According to Porsche you need a research octane rating (RON) = 96.
There are two ways of measuring octane, Research Octane Number RON and Motor Octane Number MON
How do we get that # when in the US pump octane is a calculated value of (RON + MON) / 2
Rule of thumb is the calculated method is 4-6 points lower than the the RON...... You can check wikipedia, or just refer to your owners manual.
https://en.m.wikipedia.org/wiki/Octane_rating

[xbmwguy]

Miguel that’s why I only use 116 octane corn fuel

[RarlyL8]

The correct answer is 92 for those of in the US, as this isn't an option it's safer to just use premium gas at 93 octane.

You need to tune for the fuel you have available now not for what was suggested in the '80s when these things were produced. I tune for 89 octane and bump to 91 in the summer to combat the effects of added heat on detonation.

[reclino]

Rarly8,
I always run cheap gas in cars designed for it. I sure would not recommend to someone that they run lower octane fuel in a car designed and tuned for high octane fuel. These cars have an old school fuel injection, and adjustment of said system is probably best left to an expert such as yourself. There is no safety net of a knock sensor to pull boost or timing if and when knock or detonation happens.
Can you describe the detriment of running fuel that's too high octane vs the possible damage that can happen running on octane less than a car is designed for?

[RarlyL8]

The higher the octane level the hotter the burn. You don't want that. The adjustment is not made in the CIS but rather in the ignition timing. If you can only get 89 octane fuel in your area best to tune for it by reducing the timing a degree or two for added safety. Ambient heat and humidity also have to be considered, which is why I run higher octane fuel in the summer time. Lowering boost level would have same effect.

[flightlead404]

Higher octane *gasoline* in and of itself doesn't burn any hotter than lower octane. It may burn slower, resulting in a later peak pressure and a slightly higher EGT if you're monitoring that. It doesn't give you better mileage, or easier starting, or most of the other myths associated with higher octane *in and of itself*.

However, because if the slightly increased anti-knock characteristics, if you have a modern and advanced EFII setup you *might* be able to tune your system to take advantage of the higher octane gasoline to slightly increase compression (ie raise boost) or slightly advance ignition possibly resulting in a little better hp at a slightly lower rpm. However by doing so you eliminate any protection the higher octane gives you.

The gasoline itself doesn't have any additional chemical energy.

That gets much more complicated when you start comparing non-gasoline fuels and fuel blends, like ethanol and methanol. Alcohols have a lower energy per unit volume, burn cooler, and have a much higher octane rating (pure ethanol is rated at 113 despite having no isooctane in it, remember octane rating is just a reference). So, adding ethanol to the blend slightly increases octane, slightly lowers the burn temp, and slightly reduces SFC.

[Miguel Antonett]

Hey guys, nice hearing from you, its been awhile, and all good! I understand all your comments, however my question is much simpler... Basically: how Bucees gets the octane number without ethanol? may be they use Methanol instead or isopropyl... those are still alcohols that absorb water.
They have a sticker at the pumps stating "No Ethanol added" don't say "No alcohol added". All I'm trying to do is minimazing water condensation in the tank. I'll contact Beaver fuels directly, ask the question and report back

[reclino]

Other types of hydrocarbons are traditional for boosting octane. TOLUENE is one of the possible components. I am guessing it depends on what's cheapest for the refinery at the time of blending. It would be interesting to know what they are blending in, but I suspect they won't have a report they can share.

[flightlead404]

Throw a handful of old school mothballs into a 55gal drum.

[dos531]

Run the highest octane gas you can get in your area, especially if you're still on the garbage CIS. Non-ethanol is even better.

[lindbhr]

Originally Posted by Miguel Antonett

Hey guys, nice hearing from you, its been awhile, and all good! I understand all your comments, however my question is much simpler... Basically: how Bucees gets the octane number without ethanol? may be they use Methanol instead or isopropyl... those are still alcohols that absorb water.
They have a sticker at the pumps stating "No Ethanol added" don't say "No alcohol added". All I'm trying to do is minimazing water condensation in the tank. I'll contact Beaver fuels directly, ask the question and report back

Miguel - they use isobutynol or some related blending components.

[flightlead404]

Originally Posted by dos531

Run the highest octane gas you can get in your area, especially if you're still on the garbage CIS. Non-ethanol is even better.

Calling CIS garbage is just plain stupid.

Like calling a P-51 garbage because it wouldn't go supersonic.

CIS was the most advanced option for its period, and still works very well today if you keep the individual components working properly.

Many of us are smart and diligent enough to get significant performance out of it, I've got ~400hp at the wheels.

[dos531]

CIS may have been considered advanced in the 60s and 70s, but by the 80s it had no business being installed on a turbocharged Porsche. Even the 3.2 carrera had EFI and those started in 1984! Running it into the 90s is just plain ridiculous. Besides originality, there is no upside to running CIS.

Originally Posted by flightlead404

Calling CIS garbage is just plain stupid.

Like calling a P-51 garbage because it wouldn't go supersonic.

CIS was the most advanced option for its period, and still works very well today if you keep the individual components working properly.

Many of us are smart and diligent enough to get significant performance out of it, I've got ~400hp at the wheels.

[flightlead404]

Originally Posted by dos531

CIS may have been considered advanced in the 60s and 70s, but by the 80s it had no business being installed on a turbocharged Porsche. Even the 3.2 carrera had EFI and those started in 1984! Running it into the 90s is just plain ridiculous. Besides originality, there is no upside to running CIS.

All true. None of which justifies calling it garbage lol

[krasuskyp]

Miguel my friend, so great to hear from you again! Hope all's well with you wayway down thar!!!

(and FRANNNNNNNNNNNK!!!)

(and Brian!)

cheers, gentz

[dos531]

Originally Posted by flightlead404

All true. None of which justifies calling it garbage lol

IMHO it is a terrible system and I stand by my statement that it's pure garbage.

[Miguel Antonett]

And there's PAUL!!! awesome hearing from you, all good down here... goto get together sometime before it's too freaking late

Anyway, finally contacted a Bucees' dispatcher engineer... the so-called "ethanol free" gas is actually alcohol free, they run that particular grade thru a different distillation tower getting the desired octane number. So, already three tanks on the 356 with no issues at all, the 930 is next.

And BTW, some of you guys, never forget the heritage and key elements that brought the brand to what it is today.

[Mocker]

Originally Posted by Miguel Antonett

the so-called "ethanol free" gas is actually alcohol free

Ethanol=ethyl alcohol=grain alcohol