91 Octane (no ethanol) vs. 93 with

Don't know the speck for the 328 but the manual will have the required RON (Eruro) octane requirement. Then you can calculate the required US octane as US = RON x 21 / 22.

A US 308 requires RON 91, or 87 US. Yes, a US 308 runs fine on regular.

 

I run 93 no ethanol in my boat. It's great stuff but the price sucks. It wouldn't surprise me if your car ran better on the 91 without ethanol.

 

Is 100 octane unleaded w/o ethanol O.K. to use in a 328???

Wasn't sure about the 100 part.

 

I would go with quality 93 vs "pure" 91. I run BP most of the time and Shell if not available. Sunoco 93 detonates more than BP or Shell 93 in my experience.

 

Avoid ethanol when ever possible. If it detonates on 91 retard your timing a little.

Too low of octane can cause detonation under certain conditions, Ethanol is damaging to the fuel system 24 hours a day 7 days a week.

 

If you run to high of octane you will lose power and potentially foul spark plugs, but no long term damage is caused.

 

If you want to pay for it but not needed until you bump the compression or add boost.

 

Hmmm. So I have all modern fuel hoses on my car. What exactly is being damaged by ethanol?

 

The pump

 

Just hoses and seals of a certain type, and in cooler climates if left standing over the winter, "separation" can happen, and the Et-OH can allow water to mix with it and cause corrosion in the tank - a lot of "ifs" there, and I think mostly BS.
BTW, ethanol raises the RON a couple of points, and so reduces the risk of detonation, not the other way around. Our cars are barely 9:1 compression, so should run fine on 91 RON.

 

Gotcha. Well I keep it topped up for that reason. Also have a standby pump but no issues thus far.

Tanks are aluminum so not too concerned there personally.

 

Alcohol corrodes Aluminium. That is why aluminium fittings must be anodized to use.

 

No ethanol choice if possible. The 91 octane will be fine, the compression on the 3x8 engines is not high enough to cause knock issues. Ethanol is doing damage to the stock CIS fuel system every second it's in there, along with the hoses and the tank. It also reduces mpg and BTU so the 93 with ethanol though having a higher knock index would have less BTU's of energy then 93 of pure gasoline.

Also for the CIS system it's based on the molar mass of gasoline not gasoline and ethanol that little difference affects how the system delivers fuel, with ethanol based fuels due to the lower BTU's you actually need more fuel to achieve the same power output. So my recommendation is stick with ethanol free fuel whenever you can.

 

+1

And well put

 

What does it do to it?

I believe the moisture that can be pulled in is the issue no; not the actual alcohol? Hence why you should keep them topped off if not in use.

 

In Europe and South Africa we use 95 RON( Octane) and its being step up to 97/98 but according to some tests done, drivers using 95 reported better fuel consumption, no idea why - was under the impression higher octane will give more mileage...

the Euro 328 specifies 95 or 98 octane fuels, so its designed for higher octane fuels, so I presume its a higher compression engine designed to output more power (kW) with higher RON(Octane ) values, running 93 or less will result in lower power output IMO of course.

Modern fuels should have less Ethanol content but it varies from country to country..

cheers
Johnny

 

No. Higher RON means less detonation at higher compression ratios. Higher compression engines produce more power and are more efficient. Modern ECUs use knock sensors to detect detonation and retard the ignition, almost instantly, so engines can run very high compression. If you put high octane fuel into a modern engine, it will advance the timing, giving more power and better fuel economy.

Our engines are a bit less sophisticated, and will run the same over a wide range of RON - higher octane will make no difference to power or economy. Ferrari was petrified of high speed detonation, so these engines are relatively low compression, and high octane fuel was specified.

 

A small nitpick from my part, just for the sake of precision:
keep in mind that the euro version of the 3,2 engine without cat (F105C) has a slightly higher compression ratio at 9,8:1 than the US variant with cat (F105C 040) at 9,2:1.
Not that it changes much, but nevertheless...

Rgds

 

That, combined with the lack of smog gear, would probably make a big difference in power - does anybody know the difference?

 

In fact, it is rather small:
270 cv for the Euro engine without cat
260 for the US engine with cat
255 for the Swiss engine with cat

I don't have the torque figures in mind at the minute.

Rgds

 

Aluminium gas tank,fuel injectors gum up,hoses if you have the origional,every time i take my lawn care machines in for tuneup ethanol dos the most damage there is this brown film all over the carbs,i run Shell 91 Ethanol free in my 88/328 for years now no broblem at all it burns a bit hotter that,s all.

 

Yes, Nerofer it actually does carry some weight since Europeans cars after 1986 were designed to run RON 95, since my 1989 - 328 Owners manual recommends 95/98, why would I pour anything less than 95, I don't want 'pinging ' or knocking sounds that can damaged my engine in the long run, this simply means the fuel is detonating in the engine instead of running smooth, I can tell you RON 95 or 98 runs very smooth on my 328, I get 26 Miles/Gallon on a long drive and I'm very happy with that !

I'm referring to Premium Unleaded 95/98 and according the the data sheet it contains less that 2% ethanol with a very low sulphur content of 0.05%

 

Having recently switched from ethanol V-Power Shell to non-ethanol 90 let me say that the improvement in response, power and mileage is noticeable.
The 308s really don't need the higher octane fuels but some think that the extra additives in the premium gas makes it worthwhile.

Your milage may differ.

 

I agree completely. I have used 90 non-ethanol in my 89 GTS for 13 years with no problems. It runs very strong and smooth. We don't have anything higher up here.

I had a lot of problems with fuel injectors and sending unit in my 20 year old truck when it was in the lower 48 and using ethanol 91. Truck ran better when it got back here with the 90 non-ethanol (even though it has a computer chip that recommends 91).

As a side note, both my snowblower and home generator say in big letters in the manuals, do not use gas with ethanol at all. Different type of engines, but something about it isn't good.