Having owned several O.S. Engines in the past, I was excited to see what kind of power their new OS 18TM would generate. The 18TM is supposed to be a direct drop in/replacement for the Traxxas Revo truck, and
can even handle the Traxxas E.Z. Start system. Not owning a Revo at the time, I decided it would make a good power plant for the project truck I was working on. (Check the projects section for more information coming soon).
The engine installed into the project truck without too much trouble. I did have to do some drilling of the chassis since the TM is a slide carb, and the truck was setup to take a rotary carb. I needed to hook up a way for the linkage to work correctly, it wasn't a big deal, but did take a little time to get it all just right.
Once installed, the break-in went very smooth. OS usually has a pretty good manual that's easy to follow, and this was no exception. The engine fired up quickly, and it has held a tune very well. I have been running the O.S. 8 glow plug with 20% O'Donnels fuel, and this has been a good combination. After just a few break-in tanks, I could tell that this engine was going to have some serious power. After another refuel, I decided to really blip the throttle to see what it would do. My eyes just about fell out of my head when the truck (probably one of the heaviest small block trucks you'll ever weigh) popped a wheelie rolling up onto it's back. This wasn't from a standstill, this while rolling at about 10 mph! WOW! I was also happy that I had the roll-cage on. I have had many engines in this truck, and none of them have been able to pull wheelies with all the weight. This engine was now pulling wheelies on demand! I have to admit, wheelies don't win races, but man it's fun to do!
So after tearing up the parking lot, and pulling a few more wheelies, I heard a pretty bad sound come out of the truck. One of those 'uh-oh.. that's not going to be good!' sounds. Well, since the truck suddenly wasn't going anywhere, I walked over expecting to see a torn up spur gear, or maybe a trashed clutchbell. Nope, nada. After further investigation, it turns out my transmission gears were now shredded cheese! This is a powerful engine! It turned out that I had a problem with one of my differentials, and when it locked up, the motor was strong enough to destroy anything that was going to stop it from spinning. I dropped some coin and went to all steal gears in the transmission, and also fixed the differential problem.
It was now time to get some dirt testing in. Our local track is closed while they work on building a bigger and better one, so I did the next best thing. Called up a buddy at the local BMX track, and begged for permission to run there for a little bit. Now this is no standard bike track. The first jump is a 12 foot high, 7 foot wide table top, and I cleared it! The first 4 jumps are all about this size, and the the track is just brutal on RC vehicles. (Your not supposed to run RC there, so don't go out thinking you can do this at your local track.) I'm pleased to announce that the O.S. 18TM did great! I was a little worried that I might not have the power to make it up some of these jumps. They were so huge, it was like I was doing a hill-climbing contest! The engine powered up and over with no problem at all! The oversized head also kept the temperature surprisingly cool.
