Twin 250 for Formula Car

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Total Twin 250 for Formula Car Assembly

Team Name SXE
Duration Spring - Summer 2017
Faculty Advisers Dr. Edwin Odom
Team Members
  • Zhengsong Xia
  • Sammy Stuhlman

The Twin 250 Formula project lives on at the University of Idaho through the Department of Mechanical Engineering and the Formula champions competition.The engine design combines two 250cc 4-stroke motorcycle enginges, with one output for both leaving the same crankcase. The engines are oriented 180° from one another, so that the moment caused by one rotating crankshaft is corrected by the other crankshaft rotating in the opposite direction.


Dr. Edwin Odom started planning the project in 2012, and in 2015 students Dustin Clelland and James Founds started phase one of the twin 250 cc design. Clelland and Founds modeled a design which eliminated the chain drive, reduced the size of the engine envelope (shown top right), and corrected the moment caused by the rotating crankshafts.

Problem Statement[edit]

It is desired to have an engine-drivetrain combination consisting of two 250cc YZF motorbike engines. The engines mount in opposite orientation from one another in order to cancel moments caused by the reciprocal motion inside the running twin engine. The clutch output leads to a sequential manual transmission, then to a ring and pinion, through a limited slip differential, and finally to the wheels. The twin 250 project has many unknowns (linkage, rear differential alignment, strength analysis, weight distributions, etc.), but the end goal is to have a well-designed and analyzed plan for manufacturing, ordering, and installing the engine system in the formula car.

Project Goals[edit]

  • Utilize as many stock (existing) parts as possible from previous projects.
  • Design a safe and functional crankcase and rear-end.
  • Complete fatigue analysis on the entire design.
  • Manufacture and install the engine system in the formula car.

Updating Previous Design[edit]

Starting spring semester of 2017 students Zhengsong Xia and Sammy Stuhlman started phase two of the project. With engine orientation and output design outlined the team is focusing on designing a crankcase for the engines, a driveshaft, and custom fitting a ring, pinion, and differential into one rear end.

Drivetrain design.JPG

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Spring/Summer 2017 Design[edit]

Crankcase parts and assembly.

Clutch Side of Engine Case

Photo Overview
Clutch Side Engine Case
  • Accepts roller bearings for crankshaft, clutch, and transmission
  • Provides mounting for timing chain cover
  • Accepts clutch case
  • Designed to fit YZF 250cc cylinders
Clutch Case
  • Fits YZF 250cc Clutch
  • Fits stock waterpump, and ...
  • stock oil pump
  • stock Yamaha clutch cover
  • stock oil filter and oil filter cover
Clutch Cover
  • Stock YZF 250cc clutch cover
Timing Chain Cover
  • Custom cover because the timing chain is originally internal and has no cover

Oil Filter Cover
  • Stock YZF 250cc oil filter cover
Water Pump Cover
  • Stock YZF 250cc water pump cover

Gear Side of Engine Case

Photo Overview
Gear Side Engine Case
  • Accepts custom gear cover
  • Transmission and shaft housings
  • Fits stock YZF 250cc magneto cover

Magneto Cover
  • Stock YZF magneto cover

Gear Cover
  • Custom cover as gearing is for twin engine design

Stress Analysis of Engine Case

Final Sub Assemblies[edit]




Team Members[edit]

Photos Bio Discipline
ZhengsongXia: I’m am a student at the University of Idaho that is graduating with my Bachelor’s Degree in Mechanical Engineering in summer 2017. I'm from China. After four year studing at University of Idaho, I learnd a lot of knowledge from UI general course. Even though it was really hard to compelete my Engineering degree, but I really enjoy it. In the future, my future work will keep focus on the vehicle engine design or jet engine. Also, My another dream will travelling round the world ME

Document Archive[edit]

Photos Bio Discipline
Eric and i.jpg
Sammy Stuhlman: I am a senior at the University of Idaho studying mechanical engineering. It has been a pleasure working with Zhengsong, whom I consider a friend and my closest colleague during my studies. I plan on finding a career in solar energy and humanitarian engineering. ME