Technology Initiative for Emissions Readiness (TIER-5) Consortium

The Technology Initiative for Emissions Readiness (TIER-5) Consortium, hosted by Southwest Research Institute (SwRI), is a precompetitive consortium formed to de-risk technology pathways for off-road diesel engines ahead of California Air Resources Board’s (CARB’s) proposed Tier 5 emissions standards.

The CARB Tier 5 rulemaking, expected to start in 2036, will apply to a variety of engine sizes. The TIER-5 Consortium will focus on 19- to 56-kilowatt (kW) engines, which face CARB-focused nitrogen oxide (NO_X) reductions of roughly 75% and particulate matter (PM) reductions of roughly 90% under cold start, low-load and transient conditions, without giving up fuel efficiency, performance or cost competitiveness.

The TIER-5 Consortium brings together United States-focused off-road OEMs and suppliers to build a shared, hardware-based dataset and calibrated empirical models identifying the most viable compliance pathways, while each member keeps control of its own proprietary designs and calibrations.

For more information, please contact Shubham Patil or call +1-210-522-5431.

TIER-5 Consortium Focus Areas

TIER-5 will pursue research across three interrelated areas:

Engine Technology Pathways: In-cylinder and out-of-cylinder technology levers, including combustion strategy, injector and piston design, compression ratio, boost control and intake charge cooling.
Aftertreatment and Controls: Novel aftertreatment solutions — DOC, DPF and SCR management strategies — along with EATS controls development and demonstration.
Systems-Level Compliance: Total cost of ownership analysis, technology tradeoffs for cost and reliability, and probable electrification platforms for this power range.

Consortium Structure & Participation

TIER-5 will run for a two-year period from January 2027 to December 2028. Members vote at each stage to guide the direction of the research, which proceeds in three phases:

Phase 1 – Baselining: Members vote on engine architectures to baseline and test, generating calibrated combustion and engine models and validated empirical data for member review.
Phase 2 – Prioritizing Levers: Members vote on technology levers to prioritize; SwRI performs empirical architecture and durability validations and delivers demonstrated pathways to potential Tier 5 compliance with relevant system calibrations.
Phase 3 – Trade-off Analysis: Members select a configuration for compliance demonstration; SwRI develops machine-learning-based total-cost-of-ownership-versus-benefit tradeoffs and compliant architecture recommendations by application.

The consortium holds two in-person meetings per year, in March and October, along with monthly written progress reports and conference calls. Target program goals are systems solutions for 2035+ capable of tailpipe NO_X of 1.0–2.5 g/kWh, PM of 0.008–0.15 g/kWh, NMHC below 0.19 g/kWh and CO below 5 g/kWh.

Deliverables & Member Benefits

Consortium members will receive a comprehensive suite of deliverables, including:

Full Test Cell Data: Automated mapping campaign data from empirical testing of baseline engine architectures.
Calibrated Models and Software Tools: Access to the validated combustion and engine models developed during the program.
Monthly Reports and Conference Calls: Regular written documentation of research progress and findings.
Biannual In-Person Meetings: Full attendance with topic voting rights to guide research priorities.
Full IP Rights: Complete ownership of all intellectual property arising from the consortium’s work.
TCO-Based Compliance Recommendations: Architecture recommendations tailored to member applications and duty cycles.

Members are entitled to all consortium data, with confidentiality restrictions in place to protect sensitive information for a predetermined time.

Membership

The TIER-5 Consortium is open to U.S.-focused off-road OEMs and Tier 1 suppliers developing or supplying engines in the 19 - 56 kW power range, including manufacturers of tractors, loaders, compressors, generators, excavators and forklifts. Founding members shape the initial scope, platform selection and test matrix, and gain first-mover access to program data and insights.

Contact Shubham Patil or call +1-210-522-5431 for details on pricing and logistics.