Why Octane Booster Is A No No

Since the government is going to officially introduce RON 95 into the market on Sept 1st and float the price of RON 97, we can actually see the RON-related or octane topic is increasing as every local forum in the internet is eagerly to discuss about this matter (well, I'm afraid I'm also included into the statistic). Some 'self-claimed experts' among the forumers even stated boldly that RON 95 will eventually destroy their pimped twin cam rides and suggested to use octane booster to rectify the additional octane requirement. But wtf is octane anyway? Octane numbers are something we see every day and probably take for granted before this. It is a rating means to measure a fuels resistance to pre-ignition. Let's first assume you have a car that runs well on 95 octane. What could you gain by altering the fuel you fill up with? By going down to 92 octane you might achieve better mileage (due to no ethanol which commonly used to raise octane in fuels) but could risk detonation depending on your cars engine. By going up to 97 octane you might allow your car to advance the timing gaining horsepower (but some cars didn't benefit the higher octane at all). Due to lower BTU (British Thermal Unit - unit of energy) per liter you will give up a few miles per liter. So right off you can see that it is a balancing act.

Looking closer at this, you notice that the extra horsepower comes from the ability of the car to advance timing and not the fuel itself. Higher octane fuel has less BTUs, but still nets power due to the timing advance and higher boost (in turbocharged application) it can achieve. In modern vehicles with knock sensors the ignition timing is constantly varied to achieve the best balance between performance and economy. Because this adjustment takes time, simply switch to higher octane at the track is not good enough. The fuel needs to be run in advance to allow the ecu to compensate for it. So using 92 all he time and then going to the track and filling up with 95 is not going to help your track times. You will have a faster car on the ride home though.

The other end of the spectrum is less octane. The down side here is the risk or pre-ignition and high EGTs (Exhaust Gas Temp). Both of these can lead to melted or bend pistons. Valves and the head are also at risk. If you have a modern vehicle it will detect this and retard timing to prevent damage. This timing modification is easy to detect with an OBDII scanner and it an easy to diagnose too fuel with too little octane.

Because of the above reasons, a lot of people turn to the boosters as a way of having both good fuel commonly and good performance at the track. The problem with them is most do not work as advertised. If you do find one what works, adding it to your tank a day before you go to the track can be beneficial. Despite the benefit, use boosters sparingly as most rely on MMT (Methyl cyclopentadienyl manganese tricarbonyl - what a freaking kind of name though..) or Toulene as a means of boosting the octane. While MMT is a pretty good octane booster but it leaves combustion chamber deposits very quickly. These deposits lead to pre-ignition and knock so people will evually add more octane booster which leads to more deposits, more knock ... you can see where this is going. MMT based boosters also quickly reach a point of diminishing returns i.e. the more you add the less it helps. And how much this booster cost in the market?? Much more than you actually pay for your fuel.

Toluene has the advantage of being relatively cheap, and fairly effective at raising the octane even in fairly high percentages. Plus it has good resistance to pre-ignition which is an important consideration in a high compression engine; in this case such as 4G92 MIVEC. The downside is as you raise the percentage of Toluene, the throttle response quickly becomes flat and mushy. So the engine won't knock, but it probably won't run any better either.

Commercial octane boosters are a scam. They are simply as bogus as those loan sharks. For example, if one says it'll raise your octane by 7 points, this is what they meant:

92 Octane + 7 Point Octane Boost = 92.7 Octane and NOT 99.

Most of addtive says "up to 5 points", "up to 10 points", or "up to 20 points". What does that mean? It means it goes up anywhere from 0 to 20 points, so you might get only 1 point after all. Who knows? 1 point is still within the number range to 20 and you can't sue them for misadvertising though.

92 Octane + 0.1 = 92.1 Octane = pathetic

By now you are probably confused again by what all of this means. To sum it up, if your car has no changes to compression, no raised RPM limiter or lots of boost, you should probably fine using the fuel without any booster added. If you have a beefy race built motor, stick to premium or race fuel that meets the need of your engine. If you have a lightly tuned engine and enjoy the occasional track day, regular fuel is already adequate. Don't touch octane boosters at all cost.

extracted from Octane Boosters and the Truth Behind Them ezine