I’m currently getting ready for the HPI East Coast Baja Nationals and gathering parts for some new race vehicles. One of those items is a Gabe Brown Engineering (GBE) Hornet tuned pipe for my HPI Baja 5T. I reviewed HPI’s 2.4GHz Baja 5T for the June 2010 issue of Radio Control Car Action magazine. The truck puts out some impressive power out of the box; it comes equipped with a 26cc engine with high-stall clutch and high-flow muffler. It easily spins the tires and I even saw a few wheelies while testing the truck in stock form. I am modifying the truck to rule the racetrack; as I’m sure you know, speed is king, so the more you can get the better. Tuned pipes are a great way to get more horsepower out of any two-stroke engine. They basically use pressure waves to let the exhaust out of the combustion chamber and keep more of the air/fuel mixture that tries to follow that exhaust out in the combustion chamber. The more of that air/fuel mixture you can keep in the combustion chamber, the more power the engine is going to make. It also increases fuel efficiency at the same time. Gabe over at GBE has a lot of experience with 2-storke engines and knows how to get horsepower out of them. The Hornet pipe was designed and built to get the most power possible out of the HPI engine and it’s lightweight and compact at the same time.
The Hornet pipe is available with a black or nickel finish and comes with all necessary mounting hardware. This two-piece pipe can be used on the Baja 5B and 5T and snakes through the rear bumper and wing mount. The header is secured in place by two studs in the block along with lock washers and nuts. The end of the pipe is securely fastened to the back of the chassis and a rubber coupler seals the header and pipe. The header features a thick flange that will keep it from warping and maintain a good seal with the block and two pieces of welded-together tubing completes the assembly. The pipe itself is made of several sections of steel that have been welded together and the stinger exits straight out the back.
I started installing the pipe by removing the rear shocks and shock tower and disconnected the rear of the roll cage to gain better access to the back of the engine. I removed the high-flow muffler and cleaned up the face of the exhaust port with some fine-grit sandpaper and motor spray. With that out of the way, I installed the two threaded studs into the block and slid the header in place. The header slid on without a problem and I had easy access to the studs when tightening the mounting nuts. I put the coupler onto the header end of the pipe and found I had to remove the rear bumper from the truck so I could slide the pipe in place and attach it to the header. The only issue I had when mounting the pipe was when I secured the lower mounting flange onto the chassis. The holes didn’t line up properly and needed a little persuading when installing the screws. I buttoned up the bumper and installed the shocks, shock tower and the roll cage. The pipe looks great when installed and it has just enough clearance all around.
Once the installation was complete I immediately filled the gas tank and fired up the engine. The sound alone made getting this pipe worth it. It has a low tone and that crackle that you get with a pipe like this. I had to give the carb a slight tune once up to operating temp after installing the new pipe. The engine is noticeably more responsive with every stab of the throttle and I could hear and see a big difference on the top end. I really like how compact the pipe is and it’s location on my Baja 5T. You don’t have to worry it changing the balance of the chassis and there’s no way it can be damaged during a race since it’s protected by the rear bumper and shock tower supports.
I really like this pipe and am glad that I finally have one on my race truck—this was just the beginning of its transformation! I have a few other tricks up my sleeve and will be posting the truck on rccaraction.com when it’s completed. Check out gabebrownengineering.com for more information and to see other products that they offer for the HPI Baja 5B and 5T.