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How does ethanol in gas affect 356 engine/fuel system?
http://forum.porsche356registry.org/viewtopic.php?f=1&t=27108
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Author:  Larry Coreth [ Fri Apr 11, 2014 8:48 pm ]
Post subject:  Re: How does ethanol in gas affect 356 engine/fuel system?

George
2500 miles is a long way to get some straight gasoline !
Actually I've very few problems with E10 in the Speedster or the '81 BMW R100RSwhich has plastic (Styrene closed cell foam, I suspect) floats. Both are 9:1 compression and each has been known to sit idle for 3 months at a time. I have checked the gas tanks and float bowls, no sign of the dreaded phase separation. I guess the automotive gods have been kind to me in my old age.

Author:  George Walling [ Fri Apr 11, 2014 9:21 pm ]
Post subject:  Re: How does ethanol in gas affect 356 engine/fuel system?

Larry, Ya I know the old unleaded fuel is hard to find we are lucky Oregon just allowed the sale of non ethanol fuel. Some it seems a few stations in most cities offer it of course it is about a dime to a quarter more than premium. it is mainly targeted for marine and other small engine use but we can fill are cars up at the stations. The main problem I've have with the ethanol fuel wanting to boil in the carbs or filter that are in the engine compartment. we get pretty warm here and very dry as it is high dessert country. winter time I can run it without a problem and I always add ethanol stabilizer at each refuel. So it isn't all that bad I just don't care for the mileage reduction I get using it. Plus I'm just old enough to remember 18 cent a gallon leaded fuel so maybe it is just a old habit hard to break. plus might be the cars I drive have a hard time with changes also.LOL

Author:  patrick fisher [ Sun Mar 15, 2015 5:37 pm ]
Post subject:  Re: How does ethanol in gas affect 356 engine/fuel system?

what about octane rating ? I have heard that in carbeurated engines lower octane actually works better because there is less resistance for ignition and it burns easier

Author:  Larry Coreth [ Mon Mar 16, 2015 3:20 pm ]
Post subject:  Re: How does ethanol in gas affect 356 engine/fuel system?

patrick fisher

Be cautious there are a lot "old wives tales " out there many of which concern the beloved "E10 fuel" !

Actually,today's motors with electronic ignition, fuel injection and knock sensors do not require as high of an octane rating as carbureted motors. This is due in part to fuel injection giving better fuel atomization and more precise ignition timing, not to mention a hotter spark. My 356 with 9.2:1 compression does not like anything below 93 ROZ fuel but my '04 VW with 10.5 compression will run easily if not very happily (lower fuel mileage) on 87 !

Author:  George Walling [ Mon Mar 16, 2015 4:12 pm ]
Post subject:  Re: How does ethanol in gas affect 356 engine/fuel system?

I'm currently running 91 octane non ethanol in my 356 which runs well on it, my car ran well on the 89 & 91 ethanol E10 fuel also the problem I had with the E10 was that in the summer time tempature of 80 and above at 4500+ elevation was my fuel would boil in my fuel lines and filter when I parked it and went into store shopping would come out and she would not start until I poured water on the filter housing and steel lines then she would fire right off. I have been around carb engines since the Ford Flat Heads and GM straight 8's so I know what vapor locking is or fuel boiling in the fuel lines. I would not be spending extra money on the non E10 fuel if I didn't have this issue. I do not run much over the 91 or 92 octane fuel even when it is available as I don't feel it is needed in my 356 which is right at 9.5 or 10to1 compression ratio. We are lucky here in my area of Oregon as non E-10 is available in lot of the station but it usually runs about 35 to 50 cents more than the premium E-10 fuel.

George

Author:  Mike Horton [ Mon Mar 16, 2015 9:45 pm ]
Post subject:  Re: How does ethanol in gas affect 356 engine/fuel system?

George, when I was commuting in my '68 912, up in the West TX Panhandle, from Lubbock, to Amarillo, especially in those 3 bad draught years, the ambient temps would be 100+*F for 4-5 months, and on Interstate 27, if I had to do a quick refuel stop, I too, would have vapor lock, on the 10 % ethanol. I never had that issue with my old 356s, on real gas. When I take this engine down for overhaul, I plan to inspect closely, for any fuel line, or component, which may be too close to a heat source. I too, have been around for a while, and down here in HOT TX summer weather, know the symptoms of vapor lock all too well. I've had the boiling of the 10% from the float bowls, as well... electric pump here, with momentary spring loaded switch helps it to get by,

Author:  patrick fisher [ Tue Mar 17, 2015 12:08 am ]
Post subject:  Re: How does ethanol in gas affect 356 engine/fuel system?

hmmmm. my 1960 beetle runs best on regular. If I give it super it feels like it need a tune up. I know 356s are not vws and have dual carbs, but when I bought my 1962 356 it had super in it. I filled it with mid grade and it ran better. Dunno. Mysterious !

Author:  Larry Coreth [ Tue Mar 17, 2015 1:11 am ]
Post subject:  Re: How does ethanol in gas affect 356 engine/fuel system?

patrick fisher

The grade of fuel required is independent of the number of carburetors the motor has, it is a function of compression ratio and valve timing. Hence putting super (>87ROZ) in a VW bug with 7:1 compression or a 356 Normal with 7.5:1 is silly, not to mention will degrade performance


Yes guys, vapor lock can be a problem with carburetors and mechanical fuel pumps especially at high ambient temperatures and lower ambient pressure, i.e.. higher elevations. The 10% ethanol only adds to the problem. Modern cars with high pressure fuel systems, >30psi, where the fuel pump is located in the fuel tank could care less !
My suggestion during hot and elevated trips with stop overs keep the tank full ( more head pressure) and a thermos of water.

Author:  patrick fisher [ Tue Mar 17, 2015 2:27 am ]
Post subject:  Re: How does ethanol in gas affect 356 engine/fuel system?

thank you larry...... so if i understand your post, you are saying putting super in either the beetle or 356 normal is not worthwhile ? additionally ROZ is a very misunderstood rating and is not real straightforward in trying to convert to what is being dispensed at the us pump which is usually the average of the RON and the MON, called the Anti-Knock Index (AKI), and often written on pumps as (R+M)/2)

so super (91) or regular (87) ?

Author:  George Walling [ Tue Mar 17, 2015 8:50 am ]
Post subject:  Re: How does ethanol in gas affect 356 engine/fuel system?

Patrick, I run the 91 Octane fuel in my engine which is running about 8.5 to 1 compression, I have ran the 87 octane when using the E-10 fuel. other than the fuel boiling with the E-10 no real notice in performance for street use. The main thing to keep a ear out for is pre ignition or as some call it pinging. Which will cause engine problems. The pinging is mainly caused by in proper timing and also the grade of fuel. So for street driving and stock factory engine I run factory timing setting and as close as I can to the fuel rating the owners manual recommends. Also on a side note remember when are 356 were being made why most all fuels had a lead additive mixed in them. After stating all this I'm no expert on fuels or the 356 but over the years of working on the old carb and point engine equipped cars with out any of the mandated emission equipped this is my take on the modern day fuels.
Good luck with your fuel choice.

George

Author:  Mike Horton [ Tue Mar 17, 2015 11:18 am ]
Post subject:  Re: How does ethanol in gas affect 356 engine/fuel system?

Patrick, the issue to which you are referring, has been fairly well written about, by our David Jones, a professional in this field, and his writings can be found in the tech articles with a search. I read all David writes, to my benefit...

Author:  Larry Coreth [ Tue Mar 17, 2015 2:08 pm ]
Post subject:  Re: How does ethanol in gas affect 356 engine/fuel system?

patrick fisher,

Yes using high octane fuel in a low compression motor is a waste of money and fuel.

Per my research ROZ and RON are the same , ROZ being the DIN (German) terminology and RON being English. I should have written R+M/2 which was what I was really thinking, my error !

Author:  patrick fisher [ Tue Mar 17, 2015 5:05 pm ]
Post subject:  Re: How does ethanol in gas affect 356 engine/fuel system?

cool... thank you for the feedback larry, george and mike.... i will do the research and find the notes written by david jones. kind regards.

Author:  David Jones [ Thu Apr 09, 2015 7:34 pm ]
Post subject:  Re: How does ethanol in gas affect 356 engine/fuel system?

I guess I really should have posted this here to start with, Thanks Wes

http://www.damninteresting.com/the-ethy ... ned-earth/

Author:  Bill Peters [ Mon May 28, 2018 9:14 pm ]
Post subject:  How does ethanol in gas affect 356 engine/fuel system?

In 356B T5, a fine silt forms in the gas tank and plugs carbs. Ethanol induced? Is there coating for interior tank.
Thx:
B. Peters

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