Project at a Glance
Title: Study of emissions impact of selected aftermarket parts
Contractor: Custom Engineering, Inc.
Contract Number: A0-138-32
Research Program Area: Emissions Monitoring & Control
Topic Areas: Mobile Sources & Fuels
This study was conducted to determine the volume and pattern of sales of selected aftermarket parts in California, the differences in emissions, fuel economy and driveability between vehicles in the unmodified and modified states, and the factors which contribute to changes in emission levels. A survey of manufacturers/distributors and users of the aftermarket parts was conducted to determine the volume and pattern of sales. Four vehicles were obtained for testing. Two vehicles were used to evaluate exhaust headers and aftermarket intake manifolds. The other two vehicles were used to evaluate turbochargers. One vehicle from each group was used to evaluate the aftermarket parts in a "worst case" configuration, i.e., with a number of emission control components removed or disabled. The "worst casel' configuration was representative of aftermarket parts which did not provide for reinstallation of emission control components and/or those persons installing aftermarket parts who would choose not to re- install emission cqntrol components. The other vehicle from each group was used to evaluate the aftermarket parts in a "best case" configuration, i.e., with original emission control components installed and operating. The "best case" configuration was representative of aftermarket parts which provided for reinstallation of emission control components and those persons who would choose to reinstall those components if the aftermarket parts provided for their reinstallation. In the "worst case" configuration emissions increased substantially and fuel economy was generally improved, compared to original equipment configurations. by use of aftermarket parts. In the "best case" configuration emissions were increased slightly or were decreased compared to original equipment. by use of aftermarket parts and fuel economy was generally increased.
For questions regarding research reports, contact: Heather Choi at (916) 322-3893
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