Designed for stock or slightly modified four-stroke motor-cycles and other off-road vehicles used in competition, unleaded/oxygenated and ethanol-free T4 is a direct pour-in replacement for premium pump gas. Pump gas has a short storage life and could cause greater need for repairs due to its ethanol content, and T4’s 100-octane rating (R+M/2) provides greater protection against detonation compared to pump. Compared with more expensive performance parts that increase power along only a small slice of the power curve, T4 claims 2 to 3 percent more power and better throttle response across the entire rpm range. I decided after the 2014 450cc Motocross Shootout (February 2014) to give it a try in our ’14 RM-Z450 for a while to see if the claims were true.
The biggest advantage of T4 over pump gas is that our current pump gas contains ethanol, an alcohol-based alternative fuel manufactured by fermenting and distilling starch crops that have been converted to simple sugars. This is not good for the lifespan of valve trains, fuel pumps, and top end gaskets on small engines like those found in dirt bikes. Ethanol in the fuel can leave a gummy substance that clogs fuel pumps (or jets on carbureted bikes) and causes early deterioration of head gaskets and O-rings, shortening the life of your engine. Another major problem is phase separation; if water gets into the fuel, this can cause the water/ethanol mixture to sink to the bottom of the tank where the fuel pickup is. Water inside your engine can cause the fuel pump to stop working and also can make your bike miss and sputter.
Is the on-track performance gain from T4 worth the added cost? For the average guy putting around on open land, maybe not so much. For the true enthusiast who rides hard and wants a reliable power gain? Yes, it is. VP T4 comes in an easy-to-pour 5-gallon pail or a 55-gallon drum. I ran several gallons of T4 in the RM-Z and it took me less than two laps to feel the added throttle response. Coming out of corners and rolling the throttle on in second gear, I felt like the bike had more pull down low. Shifting into third gear I felt a better pull and the Suzuki actually ran crisper and cleaner throughout the rpm range. I didn’t feel too much gain in the top-end as most of what I felt was down low and up through the midrange. An added benefit was that the bike was easier to start (this especially is great because the RM-Z was the hardest to start out of all the new 450s). Riding longer motos on a sandier-type track I also noticed that the bike kept consistent power. Usually when I ride this type of track with this bike the power falls off a little as the bike gets hot—but not so with the T4.
If you're in the market for a lower-cost race fuel (versus some of VPs higher-end products) that gives you power gains and helps your bike just run better, then T4 is a good choice. —Kris Keefer
