Q&A

Q: How do I best store my racing fuel?

The manner in which racing fuel is stored is very important if you want to have the same quality product after storage that you had prior to storage. This can be just as important for your lawn mower petrol as it is for the petrol you use in your race car. If the proper storage procedures are not used, some of the 'light ends' (hydrocarbons that boil at ambient temperatures) can be lost when the storage container is opened. These 'light ends' evaporate in the intake manifold during a cold start thereby providing vapours to the combustion chamber for ease of starting. Even more importantly, the loss of these 'light ends' can contribute to lost octane quality and reduced power, which can be detrimental in racing. These problems can be minimized by following a few general rules.

• Store racing gasoline in a cool place.
• Store racing gasoline in steel drums with tightly sealed caps. This does not include most plastic jugs since their sealing ability will not contain the vapours of gasoline. Some plastic jugs allow the gasoline to be exposed to sunlight which deteriorates the tetraethyl lead in the gasoline which in turn reduces the octane numbers.
• If your storage container is warm or hot, put it in the shade to cool down before opening it. This helps to retain the 'light ends'.
• Sunoco and R racing gasoline has a longer shelf life that normal pump fuel due to lower levels of olefins and higher levels of additives to resist gum formation.
• Storage for two years in a cool place in tightly sealed containers is not a problem.

Q: Is it true that the higher the octane the slower the burn-speed?

Fact: In many cases, high octane racing fuels have faster burning characteristics than low octane petrol. It is rarely slower (the myth comes probably from mislead racers that think that aviation fuel is racing fuel as aviation fuel is really slow burning).

Q: RON and MON - which octane is displayed at European forecourts?

RON (Research Octane Number) is the octane number you will see at all European roadside fuel stations. In America they display the AKI (Anti Knock Index) which is the average of RON and MON (Motor Octane Number). As both RON and MON are vital when chosing the correct racing fuel for your engine, all Sunoco & R racing fuels have both octane numbers displayed.

The British Standards minimum requirement for Premium Unleaded is 95RON and 85MON and the minimum requirement for Super Unleaded is 97RON and 86MON - not sufficient to protect your race engine! Please see questions about RON and MON for further information.

Q: What is detonation?

Detonation occurs after the sparkplug has ignited the air-fuel mixture and the flame front is moving through the combustion chamber. If, during this burning process, the unburned air-fuel mixture reaches a temperature and/or pressure at which it is no longer stable, it will explode (burn up to 10 times faster) and as a result increase pressure on the piston before Top Dead Centre (TDC). Piston burning and rod bearing damage are the result as well of loss of power.

Q: What is MON (Motor Octane Number)?

MON is determined in a single cylinder engine similar to the RON engine with a few changes that make operating conditions more severe and therefore the octane numbers are lower. The MON engine run at 900 RPM with a 300ºF (148.9ºC) mixture temperature. Spark advance varies with compression ratio. In a real world engine, MON is necessary to satisfy octane demands at wide open throttle. This is a very important number for racing engines since they spend a high percentage of their lives under high speed and high load conditions. Racing engines cannot afford to be short on octane quality, since detonation or preignition will quickly reduce a racing engine to junk.

The MON appetite of an engine with 13:1 compression ratio and a four inch bore varies with operating conditions but is normally around 101. To cover yourself for extreme conditions, it is wise to have an octane cushion, but there is no advantage to using a very high octane quality product if you do not need it - more octane does not give more power in that case which is a normal misunderstanding.

Q:What is octane?

The octane quality of a gasoline is its ability to resist detonation, a form of abnormal combustion. Detonation occurs when the air-fuel mixture reaches a temperature and/or pressure at which it can no longer keep from self igniting. Two types of abnormal combustion are common: the first is detonation as previously mentioned and the other is preignition.

Q: What is RON (Research Octane Number)?

RON is determined in a single cylinder variable compression ratio engine that operates at 600 RPM with a 125ºF (51.7ºC) inlet air temperature at standard barometric pressure. Spark advance is fixed at 13º BTDC. In a real world engine, RON is necessary to satisfy part throttle knock problems. High RON values are more important in carburetor engines than in fuel injector engines as the filling of the combustion chamber is not as efficient.

The procedures and hardware for the RON test were originally developed in 1931. The hardware was revised in 1948 with procedural changes made until the late 1960's.

Q: What is pre-ignition?

Pre-ignition is what you really do not want to experience. It is usually started by a hot spot in the combustion chamber which causes the mixture to ignite before the sparkplug fires. Under wide open throttle conditions, pre-ignition will destroy pistons in seconds. It will also occur if the air-fuel mixture can not stay stable - i.e. it will explode - before the sparkplug starts the burn process (this normally only happens in drag racing engines running on Nitromethane).

Q: Why is racing fuels more expensive than normal forecourt fuels?

Racing fuel is more expensive than the forecourt pump fuel due to the fact that it is a much purer product and engineered to increase performance rather than just to meet the British Standards for unleaded or super unleaded petrol. As the racing fuels are made from much purer products it will also burn cleaner resulting in: better throttle response; better power/acceleration; cleaner combustion chambers and most importantly allow you to jet or map your car to the fuel's optimum performance. Normal pump fuels vary so much in octane numbers and specific gravity meaning that you have to set up the engines with a huge safety margin.

All Sunoco & R racing fuels have higher octane than normal pump fuels allowing you to build the engine with higher compression ratio. Your race engine will also run cooler using racing fuels.

Another fact is of course the fact that the fuel will be delivered in new, for hazardous goods carriage, UN approved drums.

Running racing fuel in your high performance / racing car will give you the cheapest power you can buy (or as one of our clubman racers told us: 'before running the R MR in my hot hatch I had to rebuild my engine twice a year due to piston failures. The extra £350 on top of what pump fuel would have cost is easily recouped by saving £1,250 per engine rebuild - and I got 6 BHP more!'