Do octane boosters really work? | Fuel Tips

Photograph by Chris Hristov

We want it all and we don’t want to pay for it. Sound familiar? Of course it does. We’ve all been there.

So when it comes to race fuel, instead of paying for the good stuff, why not buy an additive and mix up your own? You can do that, notes Zachary J. Santner, manager of product engineering and business optimization at Sunoco, but there are some caveats.

First, he says, realize that not all octane boosters and race gas concentrates are equal. Octane boosters–picture the brightly colored bottles full of hopes and promises lining the shelves at the local auto parts store–often contain octane-raising aromatics like toluene.

Note that we’re talking about very small quantities of active ingredients, and the effects aren’t always as good as promised: An octane point, the usual claim, only equates to one-tenth of an octane number. (So, for example, boosting 91 pump fuel by an octane point yields an octane rating of 91.1; now picture how many bottles you’ll need to significantly move the needle.)

The story changes a bit when discussing methylcyclopentadienyl manganese tricarbonyl, aka MMT. This additive is often found in products billed as race gas concentrates, and Santner notes that it’s rather effective at raising octane–but with some considerations: MMT degrades in sunlight, and it can produce an orange soot. “MMT is still a metal,” he notes. “You can’t burn it, but you can oxidize it.” Additives containing MMT generally also cost more than those built upon aromatics.

But all these fuel additives rely on one common ingredient: the pump fuel, which, as Santner notes, can vary depending on the season and location, never mind the retailer. A 93-octane fuel sold in Miami during the summer, for example, will feature a different blend than a 93 delivered to a Michigan station during the winter. Sunoco race fuels, he continues, are always mixed to consistent recipes year-round.

Comments

jerel77494 Reader
2/27/25 11:51 p.m.

A friend of mine tried to campaign an F Production Midget using octane boosters. He had to run it rich to keep from burning pistons and if he stalled it on track, it wouldn't start. Ran fine on race gas though.

Andy Hollis
2/28/25 3:13 p.m.

When we ran the CRX in One Lap back in 2014, E85 was not plentiful enough to complete the trip -- but it was a Mid-Western route. So that meant 91 octane. At 12.5 compression, the car was borderline on 93 and knocked badly on 91 -- especially if lugged at all.

So we carried a case of Torco Accelerator for transits when 91 was the best we could find. Worked a treat. Tracks all had 100 octane at the pump so we were good to go once there.

MadScientistMatt UltimaDork
2/28/25 3:55 p.m.

Octane boosters–picture the brightly colored bottles full of hopes and promises lining the shelves at the local auto parts store–often contain octane-raising aromatics like toluene.

And it's often cheaper to just grab toluene by the gallon at the paint or hardware store.

David S. Wallens Editorial Director
2/28/25 4:19 p.m.

In reply to MadScientistMatt :

Hey, we mentioned adding toluene, too, in another piece: Toluene or Xylene: Legit low-buck octane boosters?

confuZion3 UltraDork
2/28/25 4:33 p.m.

I have a tune on my car that was written by guys running 94 octane. I only have 93 octane near me.

I ran a third gear pull log on 93. Then, a little while later that day, I ran a third gear pull log on 93 with a bottle of octane booster. Timing was pulled back on the 93 run. It was not when running that same fuel with octane booster. Just one guy's observation. I now just run 100 unleaded race gas.