FSAE Engine

A large image dump while I had our engine block open.  What a beauty!

The engine is a CBR600 F4i model, though heavily modified for our use.  The crankshaft and flywheel have been lightened by four pounds, the pistons are high compression (14.5:1) from WiseCo, the pistons and head have been coated with a high performance, low thermal conductivity ceramic coating, and first gear has been locked out to make finding neutral easier (first gear is useless as the car is so light that the wheels just stay lit in first).

She’s super sexy.  Once everything’s back together, I’ll post pictures of the dyno readouts and let you know what kind of specs she has.

Till then, enjoy the pics,

-Cd

The open crankcase with our beautiful lightened crank all hanging out

A shot showing all the power components in the crankcase

Close-up on the crank with connecting rods and polished journal bearing surfaces prominent

Lower half of the block with journal bearings exposed

Combustion side of the head, showing the spark plugs and valve surfaces

Our ceramic coated pistons and cylinders, with a dirty water jacket surrounding

The head of the engine with intake ports covered in tape to prevent dirt from getting in. Also note the valve buckets on top, which get hit thousands of times a minute by the cam and wear very little

The cam carrier for the head, journal bearings evident

Our homebuilt dynocell, using an eddy brake. Note the soundproof, explosion proof walls, built by your very own

The alternator for engine, showing the three phase windings

The clutch pack, which transmits power from the crank to the transmission via the back gear, through the friction discs, and into the center spindle

The computer to run the dyno cell

Diff Brackets

A crucial part of any racecar is having a powertrain that won’t explode on takeoff.  Designing this requires some really careful attention to detail and ensuring that both the models and the simulations aren’t lying to you as an engineer.

These new brackets hold the differential to the car.  The diff receives load from the engine via the drive chain and applies it to the two rear wheels, all the while allowing some relative slip between the two wheels so that turning isn’t impossible.  I’ve designed these brackets to be made out of 7075 Aluminum, a high strength, low-weight alloy.  The design is based off a concept known as “trussed webbing”, which allows for high strength with minimal material by placing most of the material in only the load bearing plane.  To prevent buckling from occurring, trusses are implemented to give strength to the thin webbing elements.

I first modeled the bracket in solidworks, generating the beautiful stress profiles seen below.

Solidworks Simulation FEA of stress profile in a loaded configuration

Many, many design iterations later, a successful model was developed and Keith Durand, the grad student responsible for FSAE even happening these days, machined up the marvelous little beauties.  Here they are in full glory.

A view showing the finished brackets with trussing

Here’s an image showing the clamping zone up close.  This region’s fascinating as the inner circle is actually a clamp that holds the bearing on the differential.  The small hole below holds a nut, and a bolt comes from the end, squeezing the circle and pre-loading the bearing properly.

The neat technique used to pre-load the diff bearings

Up close shot showing the webbing. The low material is only .095" thick!

The back side of the bracket, showing the flush face.

Formula SAE

Ohh racecar.  The Formula SAE team at MIT, otherwise known as racecar, is a second home to me.  We reside in building N52, behind the MIT Museum, in a shared machine shop space with several other MIT vehicle teams.  I’ve slept in that shop, BBQ’d for the masses, and executed more mad engineering over  all nighters than any other place on campus.  It’s home to me in a lot of ways.

Here are a few of the pieces I’ve worked on.

Our first render of the new MIT FSAE car

The team teaches what few other projects at MIT can, which is the necessity of quality engineering in any project.  Our driver’s life lies in our hands when we finish putting the car together, and we must have complete faith in our engineering and design of the critical components on the car.  If we machine a part wrong, don’t check our sums, or don’t use our tools properly, the car can quickly fail once put to the ground, and this is our shared responsibility and liability.

Fortunately the team has a lot of background in executing rigorous design loops, and at the end of the day we haven’t had any major failures to date.  One of the greatest learning experiences I’ve had at MIT thus far has been building a part for FSAE, slaving in all the design and machining hours, only to put it on the car and have it fail utterly and completely.  Then the fun of analyzing the failure, looking for what variable was missed in the model or what error was made in the assembly.  Being in such an environment really brings out the true innovation and meat of an engineer, and in no other fashion do I think you can learn in a more genuine MIT way; really being out there using your mind and hands to assemble a very cool, very fast race car.

Various parts designed can be found throughout the website.  If it looks fast, it’s probably for racecar.

-Cd