TESTED: Royal Purple Max Boost Octane Booster

by Mike Kojima

To be honest we were not big fans of octane boosters. In the past, we have not been able to get good quantifiable results with them over the years. Older boosters ate up the fuel system or left weird deposits on the plugs and chamber. Engines that usually need higher octane are generally expensive so we have always just used racing fuel in them, Pump gas with conservative tuning for street cars and race fuel for race cars.

Meanwhile, Royal Purple had been bugging us about testing some of their new Max Boost octane booster. They told us that it would give us 30 points in octane which equates to an increase of 3 octane numbers and it would burn clean. Not being too enthusiastic about octane booster in general we let it sit around for about a month.

Well we happened to be dyno testing a Scion FR-S the other day. We hate dynoing the FR-S on our native supper crappy 91 octane California piss fuel. With its 12.5:1 compression and very active ECU with tons of command authority, the FR-S is very hard to dyno accurately on 91 octane. The power can wildly swing making it very difficult to get good data to see if your just bolted on part really did make more power.

You usually have to dyno an FR-S while monitoring it so the intake air temp, oil temp, coolant temp, driveline temp and electrical load can be kept consistent. If everything is kept the same from run to run then maybe you might get some consistency. It is really frustrating testing simple bolt ons for the FR-S because the power variation can be within the expected gains of the part and if the part creates more cylinder pressure, the changes to the knock limit will cause the ECU to dial back timing which effectively cancels out any gains the part might have within days or even hours of installation.

We noticed that guys posting dyno results in other states with 93 octane fuel didn't seem to have as much problems as we had. So when we found ourselves with an FR-S full of 91 octane on the dyno and a can of Royal Purple Max Boost octane booster in our hands we knew what we had to do.

Jeff had made a New Years Resolution/Bet with me. He had to quit drinking and I had to quit Diet Coke. I don't think he really drank the octane booster, or very much. He is still alive as of today. [we were asked kindly to remind our readers that Royal Purple does NOT recommend human consumption of Max Boost Octane Booster… EVER! -Ed.]

With some coaxing, hand model Jeff dumps the Royal Purple Max Boost into the tank of the test FR-S.

The FR-S uses a returnless fuel system so we had to purge the old fuel out of the lines and rail by burning it off. We let the booster circulate in the tank by letting the car idle for about 5 minutes and did some dyno pulls. The power started to rise by the second pull and had stabilized by the 4th pull.

So no crap, the power went up, a lot! Stock the car made 139.9 hp@6600 rpm and 115.3 lb/ft of torque at 6100 rpm. After 4 pulls the car sat at 144.8 hp@6850 rpm and 118.5 lb/ft of torque @5950 rpm. That's nearly 5 hp and 3.2 lb/ft of torque. Note the power gains are across the board for maximum area under the curve. This is a very conservative result as we picked the highest non boosted power level that our car had done and paired it to an average boosted run. If we cherry picked runs, the gains were more like 8+ hp! This makes Royal Purple one of the best single mods you can do to your FR-S! At least a California one on 91 octane. The really cool thing is the Max Boost made the FR-S settle down on the dyno and give consistent readings, all within one hp of each other. We will run Max Boost in our future FR-S dyno tests and if you run your FR-S on the track, Max Boost should be part of your race prep for sure.

We are now pretty enthusiastic about Royal Purple Max Boost and will continue to evaluate it in different cars and report on our results. If you have a turbo or high compression street car, some Max Boost could be a good insurance policy when doing a track day to keep any chance of detonation at bay while running under demanding conditions, especially when you are stuck with 91 octane fuel.