Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 Unleaded or Super unleaded ?

Well it won't "kill" it but it will have to be purged before it works again.

Jet A is amazing stuff. You can be standing in a shallow puddle of it and drop a lit match and the match will go out.

Benzine, not so much. That will get exciting!

I mentioned aviation fuel as the octane numbers are usually 98 or better. The S&S loves high octane and, in the US of A, this is the only way to get it.

I don't think we mean the same when we say "aviation fuels".

This is what I mean:

http://en.wikipedia.org/wiki/Aviation_fuel

(AVGas= Leaded petrol + Jet fuel=JetA1 etc.=Kerosene).

You obviously mean something else (I.e. super high octane (unleaded) petrol).

Here is info on the various Avgas variations - they are all leaded:

http://www.shell.com/global/products-ser...ypes/avgas.html

Maybe you simply mean "High Octane Race fuel" (those are usually unleaded).

In New Zealand, 100ll and race gas are one and the same thing. I fly a Remos microlight with a Rotax engine that happily runs on both avgas and mogas but you have to shorten the oil changes with the avgas as a grey sludge builds up in the oil reservoir.

It all depends upon your engine whether Super Unleaded is worth the extra money.

If the engine is designed for 95 octane unleaded (also referred to as EuroSuper on the continent) it makes little , or no , sense to feed it a diet of higher octane, from a engineering viewpoint.
The one exception to this is if the ecu is capable of making use of the additional octane by advancing the ignition timing. Many of the modern units used by Morgans with their sophisticated management systems can make use of the additional octane. I am afraid I don't have enough knowledge to specify which particular engines, except with the +8.
The early Moss Box cars need Super Octane to cope with the 10.5:1 compression ratio. When the compression ratio dropped to 9.25:1 it could be fed a diet of 95 octane , but on early cars this could be a bit marginal , so occasional tanks of Super are probably a good idea. When the injection systems came in first "Flapper " and then "Hotwire" or "GEMS" none had any knock sensors, so 95 octane is enough. However the GEMS system does have the ability to detect knocking , but MMC did not fit the knock sensors ;-) Some owners did retrofit these and these cars can benefit from a diet of the Super Unleaded for the extra performance.

The old tests of listening for knocking when wide open throttle is used as the engine is under high loadings from low speed will only detect one type of pre-ignition. This can generally be "driven around" by using lower gears and not letting the engine slog. Far more damaging to the engine is high speed pre-ignition which is encountered mainly on German autobahn type driving (continuous high speed) You cannot detect this by ear.

Yes, you have a plane. When I talked about high octane race, I was talking about usual high octane petrol used for racing cars and motorcycles. Those are usually unleaded. With your plane, you do not have a catalytic converter, hence you can (somewhat) run avgas 100LL which is leaded, without too many ill effects. However, in a (modern) race car, even without a catalytic converter, sludge in the oil reservoir and therefore in other places is not really something you want.

Higher octane is better, have wondered about water injection as this is an octane modifier added 400bhp to a Vought Corsair.

Sometime in 1941 the Germans noticed that the Spitfire was suddenly hugely superior to the Me109 eventually one landed and was not destroyed and they found 101 octane in the tanks as opposed to the 75 octane then common, as there was no way the Germans could match this product then they went in fear thereafter.

So shoot down the other guy with higher octane petrol!

If you are worried about the valves always be sure that you use "V twin" oil. This already has the stuff in it to protect rubbing parts. In a pinch you can use regular oil but put in some ZDDP to protect the parts. $&$ REQUIRES high octane pump gas in their information, this not only is what the engine and electronics are built for but protects the cats as well.

On the subject of "Octane Rating" there are two different scales, a but like Centigrade and Farenheit for temperature.

In the USA they use something called the "Anti Knock Index or AKI", we use the RON or Research Octane Number. The AKI shown in Canada and the United States is 4 to 6 octane numbers lower than elsewhere in the world for the same fuel. So when we talk about 99 RON, which is premium gasoline in Europe the same in the USA is 93 Octane in the USA.

AVGAS is usually 100 octane and lead free versions are now available. Lead Free AVGAS works wonderfully in cars, it has a long shelf life and is both ethanol free and has a very low water content. But get caught using it and HMRC has a sense of humur failure: it has a lower fuel duty rate than motor fuel yet it costs about 30p/L more than car fuel.

It is still possible to get 115/145 Octane AVGAS, it contains 1.29g/L tetra ethyl lead..but big old radial engines must have it!

Lead-free avgas is far from widespread. Most places it is not available at all. The reason for this is obvious: Most planes that need avgas has an engine that is designed for leaded.