Reducing the Time of the Racing Engine Development Cycle at ECR Engines

Brian Kurn – Lead Engine Analyst, ECR Engines 2015

Introduction

• During this discussion we will demonstrate how we use virtual tools to shorten the time of the Development Cycle

• These tools allow us to answer critical questions needed for making quick decisions that have long-term effects

2014 Daytona Prototype Engine

Problem Description

• New Rule – Sonic Restrictor Mandatory in Airbox

• Displacement increased from 5 liters to 5.5 liters

• Parts not available for months

– Intake manifold

– Airbox w/Restrictor

• Engine configuration frozen at beginning of season and performance adjusted with restrictor diameter increase/decrease

Questions we need answered FAST

• Performance Optimization

– What will be the new operating RPM range?

– How can we shape the power curve to our advantage?

Drivability Fuel Economy Endurance

Questions we need answered FAST

• Valvetrain

– How will increased displacement and changes in manifold tuning affect valve timing?

– Will Limit Speed be higher or lower?

– Will last years components meet these new requirements or will we need to purchase new inventory and validate new designs?

Engine Simulation Challenges

• Simple 1D model requires calibration of trumpet lengths - Why?

– Unknown Pressure drop from Restrictors

– Trumpet length “end correction”

Restrictors

Dyno Assembly

Trumpets

Engine Simulation Provides Direction

• Use 3D CFD models of Restrictor, Airbox and Manifold to couple with 1D Engine Simulation code

Engine Simulation provides Direction• Establish behavior of Restrictor

– Couple Restrictors with 1D Airbox and Manifold to understand Restrictor Pressure Drop

Engine Simulation provides Direction• Establish behavior of Airbox and Manifold

– Couple Airbox and Manifold with simple 1D Restrictors to characterize tuning characteristics

Manifold w/Equal Length Trumpets

Engine Simulation provides Direction• Establish baseline behavior of

Restrictor, Airbox and Manifold

– Model equal trumpet lengths to determine the tuning behavior

Intake Pressure-Time Histories

Engine Simulation provides Direction

• Characterize 3D behavior in 1D model

– Correlate 1D model to replicate 1D-3D port pressure-time histories and observe peaks and valleys in individual cylinder Torque

Intake Port Pressure-Time Histories IMEP vs. RPM of 1D model

1D Engine Simulation Study

• Conduct Design of Experiment to Improve Initial Design– Trumpet Lengths

• Trumpet geometry dominant mechanism for shape of Torque curve

– Valve Event Timing• Maximize efficiency of induction system with

optimized valve events

• Improve fuel economy and drivability

– Header Geometry• Fill in any “holes” in the Torque curve with exhaust

tuning

Engine Simulation Study Results

• Recommended Changes

– Improved Trumpet Lengths

• Smooth Torque curve for improved Drivability

• Maintained average Torque

Average TQ identical between the two trumpet

configurations

Engine Simulation Study Results

• Recommended Changes

– Improved Valve Event Timing

• Higher Valve lift

• Wider Lobe Separation, 105.5 110

DoE: Lobe Centerline vs. Lobe Separation Valve Events – 2013 vs. 2014

Engine Simulation Study Results

• Recommended Changes

– Improved Header Geometry

Primaries

Secondaries

Collectors

Engine Simulation Study Results

• Recommended Changes

– Improved Header Geometry

• Shorter primaries

• Longer Secondaries

• Header pairing options

• 180/540 favors high-speed• 270/450 better for low-speed

Validation• Ensure predicted performance captured

accurately

– Intake port tuning and Individual Cylinder Torque accurately predicted

Measured vs. Converge-Lite Measured vs. Converge-Lite

Summary

• 1D Simulation inadequate by itself to characterize induction system tuning behavior without correlation to measured data

• Converge CFD was coupled with 1D model to characterize tuning behavior with sufficient accuracy to evaluate multiple design iterations

• Simulation allows critical decisions to be made with confidence months before physical testing is possible

Questions?