Talk Morgan Forums Community The Malvern Arms Is it worth using super unleaded in a Plus 4?

Cereal Surfer, you're a real professional and you've been in business a long time. So I would revise my statement and attribute the improvement at 98 octanes in the 4/4 rather to the better lubricants and the lower ethanol content. Maybe it's the illusion and the slightly higher price as well (but she really drives a bit better with 98 octane:)

It is interesting to learn that in the more modern ECU era mainly static ignition is used and also that there are only some examples for dynamic ignition adjustment, like the mentioned Aston Martin.

Your reasoning also makes sense that the mass-production manufacturer does not want to take any risks in all the different markets. So he orients his mapping to a safe petrol standard, but not to the highest premium.
And as Peter J writes, if it's geared to the highest premium, like the AMG, they can take back the early stage of ignition if only worse gasoline is available.

Since the 4/4 Ford Sigma engine as a worldwide mass market engine also has a static ignition setting as you write, (statically related to the knock sensor, not related to rpm)
I am glad that 1.5 years ago the garage who made a real rolling test when the ECU mapping was done, they recommended to keep the ignition to 95 octane sacrifying a few HP but being on the save side if 98 is not available. Therefore I had 95 octane in the tank during the mapping and I thought it would adapt anyway to higher octane as I wrote in my first post, but it's good that way now also. I‘m happy with sufficient power regarding the small car.

Heinz, I agree with what you say about manufacturers playing safe.
I had a Ford Focus turbo diesel. It came with two engine options of 90 or 110 ps.Before buying I did some research and a test drive. As far as I could find the only difference was in the mapping. No indication of other modifications. Even tne salesman (Ford) was non committal.
Manufacturers will simplify things to make it easier for production (less variation to deal within the factory), and also a safety margin to keep engine components well within limits of strength.
If you tune an engine then there is a small range available within design limits bevore you need to replace components with stronger ones. Knowing the limits is very important!

Yes, Sospan, and as I mentioned earlier in another thread, the benefit when tuning/mapping the 4/4 engine doesn't focus on tickling out the last bit, but the biggest effect comes from the fact that built-in torque limits at the mid revs can be deleted. They were effectively present. I can only guess, either to save the front drive shafts of the Ford (Fiesta), or to reach Euro 5.

That article makes for an interesting read- many thanks HKNYMOG
Cheers
HB

Although my 4/4 was reputedly fine with the 95 unleaded, I always used to fill it with super unleaded as pretty much all of the 95 in France has a high level of Ethanol in it.

I had no doubts that the Ford Sigma engine would cope with the fuel, but the hygroscopic nature of ethanol made it seem like a bad idea to me for a car such as a Mog.

There is an interesting discussion on the topic of ethanol here.

Thank you for sharing the link, Peter. Very interesting read. I knew this and that on a laymens base e.g. that ethanol is hygroscopic. but here, the first answer is a enjoyable post of an expert who draws an understandable picture including some aspects of the fuel production.

The first Q is interesting as well if more and more people will use hybrid cars and need the petrol only occasionally.

What I am curious about is what the energy balance of E 10 looks like. Tropical forests are being deforested for this purpose. It is added to petrol. But in the end the gasoline is therefore less powerful and the same car uses up to 10% more gasoline...approx. the amount of the added ethanol.

Why would it be a bad idea?

The link Peter posted expressed my reservations quite well. particularly for a car that may not get used every day in the wet months.....

"pure ethanol is hygroscopic; it attracts water, to the point that it will pull it out of the air. Ethanol and gasoline will mix, but ethanol, gasoline and water will not; the ethanol-water mixture will come out of solution and settle on the bottom of your tank. Add a little oxygen to the mix, and you get rust. However, the more common side effect of this is more immediate; turn the car on, and the fuel pump will draw the water from the bottom of the tank into the engine, where it will promptly kill it, and require a costly dry-out process."

"https://chemistry.stackexchange.com/questions/4270/is-there-a... " I believe.

All true. Plus the ethanol in petrol will destroy some old style fuel hose, as you often see with garden power equipment like hedge clippers and chain saws.

But how likely are you to get a pool of water / ethyl alcohol mix at the bottom of your tank and how likely is it to be drawn into the engine. My experience is that its unlikely. The most probable causes of water in your fuel tank are condensation over winter best avoided by storing the car with a full tank, and water drawn in from the fuel station petrol tanks. Both apply just as much to high octane fuel.

There is another issue. Ethanol has a higher octance rating than petrol and so is used in some race fuels. Tesco have said that they use it in their 99 octane fuel and since Tesco fuel comes from the same refinery as Shell and BP etc , its possible to be in their high octane fuels too. Probably only at the 5% level but I could find no information to confirm or deny this.

Last point. In boating we have a problem of what is called diesel bug, which is a bacterial growth that occurs at the interface between water and diesel fuel at the bottom of the boats tank. The water gets in in just the same way as described above and bio diesel is just as bad / good as alcohol petrol in attracting water. The bacteria dies off, and the resulting sludge blocks pipes and injectors. The aviation industry have a similar issue at small airfields apparently, and the only thing that makes it uncommon with motor fuel is the consumption rate ie the turnover of fuel in petrol station tanks. I havent seen it happen in cars in storage but I would guess that it could. Best either complete;ly empty the tank before the car goes into store or completely fill it to minimise condensation