This is Part 9 of a series written by guest writer Ricky Nietubicz on his experience on the Formula SAE team at the University of Delaware. FSAE is a competition where students design, build, and compete with small formula-style racing cars. Ricky was President of his FSAE club, and his team went to the Nationals in Detroit during the 2006-2007 season.

Even the most well-thought out designs will hit some rough spots during the build. This is true for professional engineers with years of experience, and even more true for budding engineers who are just gaining experience. If everything went together nicely and properly, and the build was simple, it wouldn’t be much of a competition, now would it? Accept the challenges and learn from them, but here goes:

Intake: Designing a good intake, particularly when a restrictor is involved, is tough work, especially for engineers who may have only taken a single fluid dynamics class. A good rule of thumb is that the plenum should be about one and a half times the displaced volume of your motor, so that you have a good air charge in there so that the motor can tach up like the restrictor isn’t even there coming off turns. Careful design of the restrictor section itself is also key, to maximize airflow. Be careful using composites here, our first intake was carbon fiber, and collapsed on the dyno.

Exhaust: Seems pretty easy. Either bend to fit or weld together out of sections of tube. Welding will hurt flow unless you make sure you have NO penetration into the tube at all, but it’s cheaper than buying a bender, so have at it. The trick comes in with the sound test, and there is a specific way of measuring sound per the test, follow it and make sure you meet the spec. Or original dual exhaust was far too loud, we had to go to a single, with the stock R6 muffler, and it was still too loud, albeit barely. We welded a 4” tip on the end of the muffler, and that did the trick. Sometimes you have to think outside the box.

Computer: One car we had went through three of them. We tried building our own, to get away from the expensive MoTeC that was really hurting us in the cost report. We ended up using a Tec3R, which worked quite well. It helped that we had a friend of a friend who could dyno tune it, at a heavy discount, extremely well. (Andy at Xotic- thanks!) This is an expensive area to play trial and error, so search around and do your homework for something that works well and is relatively easy to tune and adjust on the fly. Make sure it’s weatherproof, too, as if it rains, you’ll still be running the car. Many ECUs aren’t, as they are expecting you to mount it inside a car somewhere. Again, do your homework.

Bodywork and seat: I lump these together because we made them the same way, which was molded carbon fiber. Sounds simple enough- mix up some two-part foam, mold it into a giant, sculptable block, sculpt it, cover it in bondo, sand it smooth, coat with mold release, lay up carbon fiber. Sure, it was that simple. Everything was easy, except for the part about the molding of the foam, the shaping, the bondoing, the sanding, and the layup of carbon fiber. We figured it for a couple weeks, it took more like a couple months. Our carbon fiber bodywork came out quite bumpy and required quite a bit of bondo to get it smooth for paint, and it was much lighter when we scrapped it for aluminum. I also ruined several sets of clothes due to the foam. The only way to remove carbon fiber resin from concrete is to soak it in lacquer thinner before it hardens, and then set it alight. OK, so maybe there are other ways. But that’s the way we used to not leave a mess.

Pedalbox: You have to design the car for a weekend autocrosser from the 5th percentile female to the 95th percentile male size. That’s a tall order. The seat won’t be adjustable, so the pedals have to be. And you should be able to heel-toe them. Consider both hanging and floor-mounted pedals. It’s cramped in there, and if it’s all steel, it’ll be really heavy, not something you want to hang off the front of your car. The master cylinders can limit movement. It’s an area that frequently gets neglected, but requires a great deal of forethought.

Wheels and tires: Offset wheels may look cool, but they don’t necessarily help your handling. Remember, when you’re calculating your weight distribution and figuring out what width tires to go with, to figure in for the driver. Your car may be 40/60 F/R without a driver, but stick a driver in there and it may go to 51/49. All of a sudden it doesn’t seem like the best idea to have tires an inch and a half wider on the rear than on the front, as the car is plowing like crazy. Also, wider tires aren’t always better. If they get too wide, they won’t heat up to the proper temperature to stick well. 4 inches is about right for an FSAE car.

There you go, those were the real rough parts that we hit and eventually plowed over and through. We managed, although it would have been nice to have not hit them at all, as they greatly thwarted forward progress. However, the nature of FSAE is not one of smoothness and ease of completion, it is one of learning by doing. If you don’t hit these, you’ll hit others, just remember to take a step back and a deep breath, and analyze the problem before you go attacking it the wrong way.