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Portable Engine Tier Ratings
 


Tier Ratings

EPA emission standards for NOx, hydrocarbons (HC), and PM from new nonroad diesel engines >50 horsepower include a 3-tiered progression to low emission standards. Each tier involves a phase-in (by horsepower rating) over several years. The Tier 1 standards were phased in for different engine sizes between 1996 and 2005, reducing NOx emissions from these engines by 30 percent. The more stringent "Tier 2" emission standards include engines from 2001 to 2008 and the most stringent "Tier 3" standards apply to engines between 50 and 750 hp from 2006 to 2011.

Tier
0
Tier
1
Tier
2
Tier
3

Model Year

Horsepower

1996 1997 1998 1999

2000

2001

2002 2003 2004 2005 2006 2007 2008
 >50 < 100 bhp 0 0 1 1 1 1 1 1 2 2 2 2 3
 >100 < 175 bhp

0

1 1 1 1 1 1 2 2 2 2 3 3
 >175 < 300 bhp 1 1 1 1 1 1 1 2 2 2 3 3 3
 >300 < 600 bhp 1 1 1 1 1 2 2 2 2 2 3 3 3
 >600 < 750 bhp 1 1 1 1 1 1 2 2 2 2 3 3 3
 > 750 bhp 0 0 0 0 1 1 1 1 1 1 2 2 2


 
This page updated: October 30, 2008
URL: http://www.aqmd.gov/comply/PERP/tier.htm