From: nataraja@rtsg.mot.com (Kumaravel Natarajan)


The technology Cummins is applying to diesels to comply with
the newer Ca. emissions laws involves three things I know of:

1. All compliant diesels are turbocharged.
2. All use an "aftercooler", which cools the air which was heated
   by compression by the turbocharger (up to about 25 PSI).
3. A gismo on the injector pump which senses the pressurized air
   intake, and limits full delivery of fuel while the pressure is
   low.

No scrubbers, catalytic converters, etc, are used.  The path from
the turbocharger to the exhaust outlet is kept very free.

Interestingly, except for the low-pressure fuel limitation, power output 
and mileage are enhanced by these measures.  One can buy aftermarket
turbos and aftercoolers which generate more power, lots more power,
and these are approved by the CARB.