UICSC Efficient Turbocharged Two-Stroke Engine

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University of Idaho Clean Snowmobile Competition 2014.
Team Name Turbo-Flakes (UICSC)
Duration Fall 2014 - Spring 2015
Faculty Advisers
  • Crystal Green
  • Chris Jerue
  • Ryley Reese
  • Dillon Savage

Turbo-Flakes is a senior design team that endeavors to develop a two-stroke turbocharged 600cc engine that is economical and shows vast improvement in efficiency and emissions relative to any other turbo two-stroke engine. This will be done on a Ski-Doo Snowmobile chasis with a 600cc E-TEC engine. This project is sponsored by the University of Idaho Clean Snowmobile Team.


The University of Idaho has been competing in the SAE Clean Snowmobile Challenge since 2001. The goal of this challenge is to make a clean, quiet and fuel efficient snowmobile. This challenge helps to give students real world engineering experience while pushing the envelope on industry standards. The University of Idaho has won the Clean Snowmobile Challenge in 2003 with a four-stroke platform and in 2007 with a two-stroke platform.

The University of Idaho has a long background in engine research and technology where we like to push the limits. The concept of a turbocharged two-stroke engine is not new. The concept of a turbocharged two-stroke that is efficient is. This idea was conceived from long talks about what should be the industry standards. This is to answer the question, is it possible to substitute the power lost from running an engine lean with boost from a turbocharger?

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Design Specifications

Tuning Strategy General tuning of the engine Have the tuning complete and ready to put the configuration on engine Have a basic tune done to where the engine will run with turbocharger
Tuning Map A before and after look at fuel ratios and emmisions to prove efficiency An in-depth way to tune for maximum engine efficiency A tuning strategy that makes the engine w/turbocharger run-able
Packaging Packaging of the turbocharger and all of the components Have everything mounted properly on chassis Have a solid model plan for the packaging
Turbo Turbocharger and components fit within the sled bulkhead Minor modifications needed to install the turbo Major modifications needed to the bulkhead
Exhaust Incorporate turbo into exhaust and modify tune pipe Tune pipe with turbo attached and running Tune pipe does not significantly increase in db
Intake Attach plenum to intake air box Have intake plenum match up with air box and fit nicely inside the chasis Have intake plenum that mount to the primary air box with minor modifications to the chassis and air box
Inner cooler Mount the inter cooler for maximum cooling capacity Mount the intercooler in a manor where it has close to maximum cooling and only requires minor modifications to the chassis Mount the intercooler in a manor where it has acceptable cooling capacity and only requires minor chassis modifications
Vacuum Lines The vacuum line from the turbocharger that must be hooked to the engine Attach the vacuum hose for the actuator to the existing lines with no modification Attach the vacuum hose to the engine with minor modification
Engine Modifications Modifications to the engine in order to maximize efficiency Rough plans for modifications done Have ideas and options of how to increase efficiency
Valving Change to engine exhaust and intake stroke to provide higher compression with turbo Plans of what types of valving are most feasible Have ideas of types of valves
Porting Changing of the timing of exhaust and intake ports to reduce scavenging Plans of what port timing Idea of what types of port timing are best
Testing Testing of the turbocharger on the engine Have a 5-mode emissions test done Have it running on the engine
5-mode emissions test A standard EPA emission test for snowmobiles A five mode emission test ran with E-score and BSFC taken at all five points A five mode emission test ran with some data collected
Run-ability Test A test of the engine to see if it runs Everything mounted on snowmobile and it running Everything mounted on dynamometer and it running

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Design Conceptualization

Design Paths


Team Turbo-Flakes endeavors to develop a two-stroke turbocharged 600cc engine that is economical and shows vast improvement in efficiency and emissions relative to any other turbo two-stroke engine.

  • Create a proof-of-concept engine platform
  • Develop a tuning strategy for turbocharged DI engine
  • Baseline dynamometer testing to show operation
  • Computer simulation of turbo vs. NA Pv diagrams
  • Computer control of variable vane geometry
  • CAD modeling showing packaging in chassis

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Project Learning

TurboSled TurboFlakes.jpg
Researched different turbocharger installations and decided to replicate how aerocharger installs their turbochargers to the best of our abilities
TurboDyno TurboFlakes.jpg
Read multiple old these of a turbocharged two-stroke and decided to replicate the set up used
TurboRend TurboFlakes.jpg
Reverse engineered the turbocharger that we currently have in order to ensure proper mounting points in chassis

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Dynamometer Steps

  1. Install
  2. Get Running
  3. Start Tuning
  4. Get Baseline Data
  5. Detune Engine
  6. New Baseline
  7. Begin Sweeping Points

Estimated Dyno Time Required: 500+ hours

Tuning Steps

  1. Fuel Quantity Sweep
  2. Injection Timing Sweep
  3. Spark Timing Sweep
  4. Boost Pressure Sweep
  5. Repeat Until Adequate

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Final Product

Math Modeling
Pressure-Volume diagram of a naturally aspirated engine vs a turbocharged engine Theoretical Power Results
  • Naturally Aspirated = 115 hp
  • Turbo with 5 psi boost = 121.5 hp
  • Turbo with 15 psi boost = 158.6 hp
Controls System
TurboServo Control.jpg
A variable electronic control for the variable vanes Adds a way to control boost at different engine speeds
Dynamometer Setup
The setup of the turbocharger and plumbing on the dynamometer Engine did not start due to lack of software

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Future Work

  • Dynamometer testing of turbocharged engine over full operating range
  • Detailed fuel, ignition, and boost tuning to fully characterize engine
  • Will use about $300 in fuel
  • Will probably use ~$2500 in parts
  • Will likely require 250+ hours of dyno time
  • Use software to model the fluid flows within engine under NA and turbo conditions
  • Virtual experimentation with port timing

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  • Capstone projects need an external client
  • Small budgets lead to small outcomes
  • Research requires you to balance the original project plan with flexibility for the unknown

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Team Members

Crystal Green, M.E.
I am a senior mechanical engineering student at the University of Idaho. I grew up in a small town in the Interior of Alaska on a grain and hay farm. When it came time to go to school I decided that I was done with the cold but not with the outdoors so I chose Idaho. When I came to the University I found the Clean Snowmobile Team and have been a member ever since.
Chris Jerue, M.E.
I am a senior mechanical engineering student at the University of Idaho. I have grown up in Eastern Washington where I have worked on a farm and in a shop since I could walk. I choose engineering because of my passion to learn more about how things work, and how to improve on previous designs and technologies. I will graduate with a B.S.M.E. in May of 2015.
Ryley Reese, M.E.
I am a senior mechanical engineering student at the University of Idaho. I grew up in western Washington and then moved to northern Idaho in 2011. I decided to pursue engineering from a very young age due to my love for building contraptions with Lego's. I will be graduating in the spring of 2015.
Dillon Savage, M.E.
I am a senior mechanical engineering student at the University of Idaho. I love going fast, almost more than living. Evel knieval is my idol. So I was very excited to TURBO a two stroke. I can't wait for the feeling of cold wind in my hair, as I hit the throttle and hear the TURBO engage!

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Document Archive

Retrofitting Direct-Injection and a Turbocharger to a Two-Stroke Engine for Snowmobile Applications

University of Idaho's Reduced Speed Isobutanol Flex Fuel Direct-Injected 797cc Two-Stroke Snowmobile

Turbo-Flakes Design Specification Chart

Gantt Chart

Mid-Project Design Review

Turbo-Flakes Expo Poster

Turbo-Flakes Expo Presentation


In progress