Toms928

Does anyone know if 15% ethanol in gas will do harm to these cars? Just read where the EPA is going to mandate 15% vs. 10% now. The article said that it can damage some engines on cars older than 2001 models. If so, what can we do? I wish the government would quit trying to make things better by making them worse.

BC

You will be perfectly fine. Much higher concentrations are physically fine, but cause some tuning challenges.

Without optimization, you will continue to experience some loss in MPG over non-ethanol, but its an additive to boost octane, and the other options are carcinogenic.

jcorenman

No you won't... there won't be any food left to eat...
A previous thread, multiply comments x 1.5:
https://rennlist.com/forums/928-foru...or-sharks.html

robot808

Cue BC in 3, 2, aw $h*t, I'm already too late.

Tails

I have used E10 in my 90S4 for a few years now on an off, including a couple of long trips, 860 kilometres.

I had a good talk with the OPC technical manager and his official Porsche response was Porsche does not recommend its use, but he then gave me his own "unofficial" view - no problems with the 928 engine.

Don't forget that the fuel lines on the MY 89 changed to a polomide material (IIRC) fuel lines as show in the MY98 tech information manual.
Tails 1990 928S4auto

rgs944

I have heard that ethanal can clog cats. Any thoughts on that?

Glenn Evans

I guess that they might get dehydrated and become constipated if they drank too much alcohol and no water. That is more likely than ethanol clogging a catallytic converter.

Glenn Evans

Porsches in the Mid-West have been running on E10 since 1992 or so. Since MTBE fell out of favour as a gasoline oxygenate, many smog-prone regions in the US have used ethanol instead (whether permanently or only seasonally). I understand that the ethanol content has not always been/is not declared at the gasoline outlet, so many drivers have been running on E10 without realising it. You can find which areas use ethanol blends by searching the EPA website.

It seems to have escaped Porsche's notice that many of its vehicles in the US have been running on E10 for years without problems. Certainly, I don't recall problems running E10 being reported here or on the Rennlist e-mail list, unless you include anxiety about using it.

I ran 98RON E10 in my MY80 R0W 4.5 (K-Jetronic, no cats or oxygen sensor) for four years, virtually exclusively, while it was available near my home. Two other 928 owners I know also have used it long-term. None of us have had any problem with it. I could not tell the difference between E10 and gasoline on the occasions I didn't fill with E10; not even in fuel consumption.

Engines which utilise oxygen sensors automatically adjust the fuel mixture to compensate for ethanol or other oxygenates in the fuel. I understand that narrow band oxygen sensors are used in 928s, so they will run out of adjustment if the ethanol content is too high. What that content is, though, I don't know.

17prospective buyer

Best put by Dylan Ratigan, "...ethanol is a scam." Even if 100% of the Earth's surface (even 5% is unachievable) was covered in harvestable corn, there would still not be nearly enough to fuel the world's demand for even a fraction of the oil we use.

Oh and, hasn't E10 been used since the mid 80's??? Virtually every pump in Ontario pumps E10.

Larry Velk

We have a carbed FZR Yamaha which is spot-on from the factory. With ethanol it surges at 40 steady cruise, with non ethanol (from outside the attainment area, Shell 'premium') it doesn't. Mileage with our 928 and Merkurs is 10% better with the Shell from Western Wisconsin. This is absolute evidence that the fuel is different. You can make other arguments, but the fact that the fuel behaves differently is beyond dispute. We have owned all these vehicles for many, many years and kept constant records and the data matches the energy content and oxygen ratio theory. Wisconsin used MTBE for awhile in premium, which was OK, but toxic in groundwater (maybe...). The 1959 "Hot Rod Magazine Yearbook" went over all this years ago - complete with Lewis diagrams of the molecules; it is old news. Nitro, Methanol, ethanol... the benefits and disadvantages are all known, the spin from interest groups can't change the chemistry.

BC

And corn is the only source of ethanol.

Glenn Evans

"Oxygenates" were introduced to forcibly lean older engines, based on measurements/belief that many, perhaps most, ran rich.

A closed loop fuel system (ie with oxygen sensor) will adjust the mixture to achieve the ideal (stoichiometric) air-fuel ratio, provided that the system can adjust the mixture enough. Open loop systems, such as all RoW 928s prior to MY86 and many even after that, and nearly all carburetted engines, cannot adjust themselves for fuels with differing stoichiometric air-fuel ratios. This must be done manually. Obviously, this would be a major PITA if the engine is sensitive to different fuels and you cannot always get the one for which its mixture is set.

The stoichiometric air-fuel ratio for ethanol is 9.0:1; for gasoline it was 14.7:1 in the days when octane ratings were achieved by the addition of tetraethyl lead. For E10 in 14.7:1 base stock, the stoichiometric ratio is about 14.1:1. These days the ratio for higher octane gasoline is a point or two lower than 14.7:1 as the aromatic content is higher to achieve higher octane ratings without lead. The energy content (lower heating value) of ethanol is about 34 per cent lower per volume of gasoline, so that of E10 is a little over 3 per cent lower than for straight gasoline. The Research Octane Number of ethanol is 107 - compared to 98 for premium unleaded fuel in Australia and many other countries - so it will boost the octane rating of the base gasoline with which it is blended. Oil refineries will take advantage of this, when they know that their gasoline will be blended with ethanol, and produce lower-octane base stock, increasing the yield per barrel of crude oil.

For a given amount of air that the engine is pumping, you can burn more ethanol or ethanol blend than straight gasoline, thereby increasing the maximum power output. If you are blending the (pure or anhydrous) ethanol with the same gasoline you would burn straight, you will increase the octane rating and therefore could gain even more power by advancing the ignition timing.

Evidently, your high-performance bike engine is sensitive to mixture and doesn't run well when it is not what it is jetted for. I presume this is why your increase in consumption on E10 is more than 3 per cent. My 928 (let's be honest, its specific output is quite modest) doesn't seem to care. I drive it mostly around the city, where its fuel consumption is high and variable. Even on the highway, I don't drive consistently enough to notice a three per cent variation in consumption. Obviously, there will be a point where even the 928's mixture would need to be enriched to run properly as the ethanol content is increased. If I had noticed any difference running E10, I would have done so. (K-Jetronic makes this easy!) :-)

Glenn Evans

Proof that Australians are weird: we eat, or sell, the wheat and sugar produced by our two major ethanol producers, and they produce ethanol from the waste bio material.

jeff spahn

+1

Larry Velk

I agree with Glen in Australia relative to the science. I can't feel any difference in the cars with ethanol - it only shows up in the mileage. The 3% vs 10% is almost within experimental variation considering the inexact nature of these calculations. Owners in this area consistently report this 10% difference. We have ample opportunity to get data as the Western part of the state often has (had) non ethanol fuel. Our very old lawn mowers also surged with ethanol, but these are crude and I did make adjustments. The octane advantages of the ethanol mask some defects in the fuel itself, especially on our turbos as the higher octane gives some boost and timing advantages on the Fords as they have knock sensors - unlike our crude and backward S3. Our farmers love ethanol and wildly defend its virtues against the considerable evidence that it is a losing game. There are reasons for its use, but they aren't very good reasons.