Heard as a faint, metallic rattle, detonation is accompanied by a loss of power and can cause serious damage to piston crowns.

We must state that unless an engine is detonation through low RON fuel, octane boosters have little use. However, in a turbo or high compression application, the inclusion of a better grade of fuel allows the engine management system to optimize ignition timing and fueling.

The biggest claims the bottles have is the amount of "points" they claim to increase. This is ambiguous as a "point" can relate to either 1.0 RON (Research Octane Number) octane points, or 0.1RON octane points.

The list of entrants in our octane Olympics included:

We had to also find a base fuel to add our boosters to so we went to the closest public petrol station, a Shell on the outward-bound side of the Westgate Bridge in Melbourne.

Being a performance-based test, we chose premium unleaded fuel as this represents the most common high performance fuel (ie: if you start with regular unleaded, you’re wasting money!). We should add that "some" boosters would have improved the octane rating of regular unleaded proportionately more than our tests with PULP.

With a RON rating at a minimum of 95, we first established the exact octane of the PULP. The biggest surprise was our randomly select Shell resulted in a quite high 96-8 RON.

Of less importance but still worth mentioning is the design of the bottles: since most people will be pouring it straight into a tank, the design of a bottle is important to prevent any spillage on paintwork causing damage.

So let’s look at the results!

THE RESULTS

BASELINE OCTANE 96.8

It’s very easy to confuse octane ratings as there are a number of separate international standards. MON (Motor Octane Number) is the number derived from a fuel when it’s applied to a test engine run at 3000rpm rather than 600rpm and higher inlet temps and ignition advance. The Australian importer of 104+, Andrew Holdsworth, suggested MON is seen as a more real-world test.

Though none of the fuel companies promote the MON figure which is normally between 7 and 10 numbers less than RON (Research Octane Number).

Intertek’s Graeme Marks believes RON provides the general public with an idea of which additive works more effectively. And being the most commonly-used reference, we’ve used RON for all our tests.

946ml treats 35 litres RRP: $35

Right from the start, we were told PowerFuel’s additives weren’t necessarily octane boosters, but horsepower helpers. We kept this in mind when testing both the products, but of the two only the Super Street claimed it was specifically designed to increase the octane rating of PULP. With a 20-percent nitro mix, Super Street Nitro-Based still improved octane ever so slightly (0.2RON) but the real test for these two would come on the dyno runs.

946ml treats 35 litres RRP: $45

Containing another 15 percent more nitromethane than the SuperStreet formula, MaxRace doesn’t claim to increase octane, but the verbal recommendation was the same, ie: its main characteristic is to boost horsepower, not octane. For a fair comparison of these two additives, you need to look at the power they produce. As for octane, it proved very similar toe the SuperStreet formula bumping up octane ever so slightly.

350ml treats 57 litres RRP: $10.95

One of the cheapest of the group, the STP was also one of the hardest to find. Auto stores either didn’t stock it, or had simply run out! Claiming to increase the octane 2-5 points, in a well-designed-for-pouring bottle, the STP – used in the ratio determined by the label - improved the octane marginally by just over half a point. A little disappointing unless you interpret STP’s claim actually meant 0.2-0.5 points. Then it’s a good result!

325ml treats 60 litres RRP: $10

The Wynns was the cheapest of the lot and claimed an increase between two and five points, again not actually listing what a "point" related to. Strangely though the 10+ could indicate 1RON and if this is the case going by our tests it almost lived up to its name. It didn’t quite live up to its claims however, increasing the octane rating by 0.8RON.

473ml treats 83 litres RRP: $25.95

The acknowledged winner of all previous testing in this country, Super 104+’s bottle stated we should expect an increase between four and seven point. With a new formula introduced about 12 months ago, identified by an "Eagle" logo on the back of the bottle, the Super 104+ seems to have lost its edge with a marginal gain of just less than 1.0RON.

355ml treats 75 litres RRP: $19.95

VP has a strong reputation with fuels and its high octane formulas are very popular (VP?) with drag racers. VP Racing’s C5 Fuel Additive lacked any indication of contents nor claims, but the C5 additive still provided a reasonable increase of 1.3RON.

355ml treats 60 litres RRP: $28

NOS, a relatively new octane booster, comes in "1/10^th" scale bottles designed to emulate the actual nitrous bottles of its successful NOS systems. The Racing Formula is the strongest of three concentrates and containing Hydrotreated Aliphatics and Methylcyclopentadienyl Manganese Tricarbonyl (try saying that 10 times in a row), it contains a lead replacement which NOS claims increases the octane rating by as much as seven points. Obviously not recommended for street use, it also included with a handy pouring spout. In testing, it proved a good result improving the octane rating by almost 2RON.

1000ml treats 50 litres RRP: $45

"If you spill it on your paintwork, don’t rub it off – rinse it with water" were our works of warning. We were also told to "pre-mix" the ELF before adding it in a fuel tank (which with this test we were doing anyway) as the ELF has a tendency to settle to the bottom of fuel if it’s either not mixed properly or left to sit. This was made somewhat more difficult by the design of the bottle, which tends to drip when pouring. With some nasty stuff known as Aniline, the ELF doesn’t claim any numbers, and provided a decent 1.8 RON point improvement.

354ml treats 57 litres RRP: $23

Recommended for off-road and racing use, the Amsoil Series 2000 claimed to increase the octane rating by up to seven points. It came up a little short, but still proved surprisingly good with a full 2.0RON improvement. And good enough for the bronze medal in our Octane Booster Olympics.

20 litres treats 100 litres RRP: $48

Since toluene (pronounced toll-you-een – also known as methyl benzine) isn’t a commercially advertised octane booster. We were unsure of exactly what ratio to mix the clear Toluene to the fuel, with recommendations between 10 and 30 percent. From personal experience, we have seen high percentages increase octane even further, though 30 percent is considered the maximum. Available only from various fuel distributors (it is a special order through services stations), under advice we ran a 20 percent mix (quite a lot more than the others) and saw an impressive improvement of 2.5 RON, for the silver medal.

250 ml treats 80 litres RRP: $29.95

Time for an Aussie-made product. From Perth, the NF Octane Booster Racing Formula was the smallest bottle in the field, but looking at the mixing ratio, also the strongest NF relies on an incredibly small dose – a mere 3 percent! Claiming to increase octane as much as 6.0 RON, NF took the gold medal in a surprising tie. If it were a split decision based on concentration though, it would be the clear winner.

500 ml treats 60 litres RRP: $20.95

Note: Also available in four-litre container for $110

The Australian-made Nulon Pro Strength Octane Booster is the top of the range Nulon fuel product, claiming to boost octane "up to seven number". The Pro Strength gained a test-winning, gold-medal-gaining and Nf-equalling 2.8RON increase. And at $21, it’s good value too!

Used straight fuel (20-litre minimum) RRP: $70

Purely for interest, we decided to also test a straight racing fuel. While there are a number available (such as ELF) for no particular reason we chose VP. The highest octane VP fuel which was still totally street-legal was the Motorsport 103. Working out at $3.50 per litre and "designed for maximum power and throttle response", the VP was very impressive with an octane rating of 107RON – more than 10RON points more than PULP. Obviously more expensive than the boosters, if octane is problem, racing fuel like VP may be the answer.

The world standard is a one-cylinder two-valve four-stroke engine with exposed valve gear. Archaic in appearance, a carby is fed from any one of three fuel bowls to allow three different fuels to be run back to back. The mixture is actually controlled via gravity feed and by raising or lowering the float level of each bowl!

Run under load via a belt-drive linking the flywheel and load system, it ensures a real world situation and ensuring minimal variation between tests, oil temperature, intake air density and air temperature are all monitored and controlled.

The engine is somewhat agricultural, however its unique ability to vary the compression ratio while running between 5.0:1 and 15.0:1 is quite amazing. The operator simply winds a handle and the entire head and cylinder assembly moves up and down relative to the crankshaft.

A knock sensor measures both the frequency and intensity of the ping (as displayed on a knock metre). Figures are then cross-referenced on a chart using the information provided by the knock meter, plus the height of the head and barrel.

Finally, knock intensity is figured in and the fuel’s octane rating determined.

Taking two hours to warm, this $200,000 engine is super robust and rarely needs rebuilding. Individual tests can then proceed at approximately $120 per test sample.

Being subjected to so much detonation, you can only imagine how much maintenance an engine of this nature must need. Interestingly, this isn’t the case as the piston and rod assembly are rejects from a monstrous ship engine (just kidding)! They’re frigging huge with the incredibly thick piston crown contributing to a combined gudgeon pin and piston weight of 1794 grams! Likewise, the rod weighs an astonishing 1929 grams. The bottom line is these engines which have replacement value of over $200,000 and almost never require rebuilding.

So, we took those two products, and the two best-performing octane boosters to MRT Performance for some Dyno Dynamics dyno testing. Interestingly, we were going to use MRT’s rally Civic, which normally runs on avgas. On PULP – even with the booster – it was pinging too much, so a Jap-spec EF Honda Civic was used with a 1.6-litre VTEC and about 10.0:1 comp ratio.

The graphs tell the story though, and to be fair to the products, with variables such as heat soak, the results weren’t as conclusive as could be gained from an engine dyno. But that is not to say the products don’t work. As our test prove, they do, but it’s not as easily measured on a chassis dyno. Plus the Civic had no detonation problems on PULP, further hampering the "apparent" effectiveness of the boosters.

With changes too small to accurately measure, we would suggest if your engine is sensitive to octane, a booster is for you. If not, try the nitro or racing fuels.

Both the Nulon Pro Strength and the NF Racing Formula rated the best octane boosters in our test. And considering that less NF was needed than Nulon, it evens out a little with a slightly higher cost. Still, both proved extremely effective at increasing octane, even outranking Toluene, which needs much higher levels of concentration. The VP Motorsport 103 fuel was an interesting exercise, and if a little more effort (ie: buying it from the selected outlets) is worth the octane, it’s a good representative of what to expect from straight racing fuel. As for the nitro additives, if you’re not experiencing any type of detonation, they’re definitely worth a try. So whether you detonate or not, we’ve found a fuel additive for you!