changes through model years

[burnt_servo]

ran across this , thought it might be of interest to others here ;

http://www.dodgeram.org/tech/dsl/Facts/epa_changes.htm , cut and paste is below .

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The 1991 "Super B" diesel

Improvements to meet Jan 1, 1991 EPA standards

Charge Air Cooling - reduces the intake air temp to 120 degrees F and reduces NOx.
Turbocharger boost reduced to control NOx
Turbine housing increased from 18 to 21 sq cm
Head Casting improvements - to improve fuel combustion and reduce PM
intake ports modified to increase intake swirl to a factor of 3.5
injector bore diameter reduced from 9 mm to 7 mm
Piston bowl geometry modified to enhance intake swirl
Larger piston pin bearing area - increased to handle increased cylinder pressure
Piston to piston pin and piston pin to connecting rod bearing tolerances tightened
Torque plate cylinder honing used to control oil consumption, PM, and HC emissions
Piston top compression ring finished with a lapped surface
3 grades of pistons used to mate the piston to each bore
Injector bores reduced from 9 mm to 7 mm and fuel pressure increased
Reducing the injector size and increasing injection pressure raises the combustion pressure which required
improved cylinder head bolts and head bolt torque procedures
three lengths of bolts
increased thread length
improved head gasket with more metal banding, and a thicker crush ring around the cylinder
new piston cooling nozzles with a larger diameter and longer length for improved piston cooling
16% more flow from the oil pump to feed the piston cooling nozzles
Larger oil cooler Oil pressure regulator and spring replaced to improve oil pressure regulation
1992 1/2 engine changes
turbine housing reduced to 18 sq cm to answer complaints of low power

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The 1994 "Killer B" diesel (begins January 1 1994)

1994 models built from July 1993 to January 1, 1994 DO NOT have catalytic converters.

Improvements to meet Jan 1, 1994 EPA standards

Inline Bosch P7100 injector pump for higher injection pressure an more precise timing
52 pound pump required stronger and wider gear housing for support
Fuel lines redesigned for higher injector pump output
Fuel filter relocated from a head casting to an intake manifold bracket
Piston rigs moved up - top ring changed from 14 mm to 8 mm from piston top to reduce "dead space" and cut
Piston pin bore and connecting rod bushing reduced to tighten piston / pin / rod clearance
To withstand increased load from valve train:
Camshaft material changed from chilled iron to chilled ductile iron
Cam lobes widened, lobes machined for finer surface finish
camshaft tappet faces hardened
Wastegate added to H1C turbocharger (WH1C), 12 cm turbo housing replaces 18 cm housing
Filter Minder add to indicate intake restriction
Catalytic converter added after Jan 1, 1994
Clutch weight reduced and clutch engagement improved
larger harmonic balancer used on 175 hp crankshaft
prop shaft damper added to reduce drive train pulses
1995 engine changes (begins July 1994)
Holset HX35W wastegated turbocharger replaces the WH1C.
1996 215 HP engine changes (begins July 1995)
Piston rings lowered so that top ring is 14 mm from piston top
CA engines rated for 180 HP and use EGR valve
1997 engine changes (begins July 1996)
OBD-II required on PCM
The 1998 ISB diesel (begins January 1 1998)

ISB Improvements over the 12 Valve Cummins TurboDiesel
Information obtained from TDR issues and Chrysler Master Tech No 2 February 1998.

New piston design features a symmetrical combustion bowl
(combined with vertical centered injector and higher injector pressures) for improved power, fuel efficiency and oil control
New vertically housed thermostat is easier to access for service and has fewer leak paths for improved in-cab heating
New electronic fuel system improves engine control, driving performance, engine cleanliness and provides engine/vehicle diagnostics
New Bosch VP44 Electronic Fuel Injection Pump has higher injection pressures, electronically controlled timing and fueling for precise, instant control. The pump is driven at half the engine speed by the front gear train to reduce operating noise
New engine-matched Holset turbocharger is custom-designed for high-speed ratings and wastegated for improved engine performance at all speeds
New fuel filter has an integral water separator and water-in-fuel sensor. An environmentally friendly cartridge is rated at five microns
New 24-valve cylinder head produces improved air and coolant flow, more torque over a wider range and improved fuel economy with reduced emissions
New valve train has wider lobes on the tappet face, on the cam, and longer push tubes.
To reduce camshaft wear, an electric lift pump eliminates the need for a mechanical lift pump lobe.
The 60 pound standard valve springs are compatible with engine braking
New single-piece valve cover allows faster access and easier servicing
No-adjust overhead has improved lubrication and requires its first check at 96,000 miles to reduce scheduled maintenance
The EGR valve (CA) and catalytic converter are eliminated.
See Master Tech Issue 2 from Feb 1998 for more ISB details

1999 ISB engine changes (begins July 1998)

Diesel towing capacity has been increased
To reduce oil pressure during a cold start, excess oil from the pressure regulator is now routed to the sump instead of the lub pump inlet.
A new turbo charger wastegate mount is located on the compressor cover. As before, the wastegate dumps boost at 20 psi.
The thermostat is redesigned for increased reliability.
The fuel injection pump bracked has been strengthened for improved durability; it is now cast instead of stamped
2000 ISB engine changes (begins July 1999)

The red and silver aluminum valve cover replaced by a black and silver magnesium cover.
The wiring harness was revised to plug directly into the fuel transfer (lift) pump, which no longer has a pigtail connector.
The fuel filter is redesigned resulting in a new top loading fuel filter housing and filter element.
The low pressure fuel system added fuel inlet and outlet pressure test ports. Fuel line routing changed to accommodate the test port connections.
A 10 cm2 HY35W turbocharger replaced the HX35W turbo.
2001 ISB engine changes (begins Jan 1, 2000)

235hp / 460 ft. lb. ETC engine installed in 5-speed and automatic equipped trucks
ETC continues to use a 10cm2 HY35
245hp / 505 ft. lb. ETH engine became available with the DEE 6-speed.
ETH returns to the 12cm2 HX35W turbocharger.
ETH receives a higher output fuel injection pump.
Compression ratio is increased from 16.3 to 17.0.




2001.5 ISB engine changes (begins July, 2000)

None reported
1998-2002 ISB Engine Components Specific to Chrysler

Fuel Injection Pump – Chrysler ISB engines are equipped with the Bosch® VP44 fuel pump. The VP44 fuel pump used for Chrysler ratings has a unique fueling map to obtain higher governed speeds. The Chrysler ISB injection pump is not interchangeable with other ISB fuel pumps. The VP44 is an electronically controlled rotary distributor fuel pump and is controlled by the Cummins ECM.

Engine Mounted ECM – The Cummins ECM is mounted on the left side of the engine block below the fuel filter. The ECM controls the Bosch® VP44 fuel pump by issuing fueling commands based on engine speed, load, and accelerator position. It also monitors the sensors on the engine to be sure that it is operating properly. The ECM logs fault codes generated internally to the Cummins electronic system as well as fault codes generated by the Bosch® VP44 fuel pump.
This ECM is specific to the Dodge pickup application. It is equipped with a single 50–pin connector which allows it to connect to engine mounted sensors as well as to the trucks electronic system. For this reason, other ISB ECMs, engine harnesses, and calibrations cannot be installed on Dodge trucks.

Wiring Harness – The wiring harness has a 50–pin connector that is specific to the Dodge pickup application. It connects the engine-mounted sensors, as well as the Dodge chassis computer (JTEC), to the Cummins ECM.

Throttle Position Sensor (TPS) – The TPS assembly is engine mounted and is specific to the Chrysler ISB application. The TPS is calibrated by the manufacturer and is not field adjustable. This part is available through the Chrysler parts network.

Electronic Service Tools – INSITE™ Version 4.2 in conjunction with INLINE™2 datalink adapter will have the capability of communicating with the Chrysler ISB engine. The service tool connection can be found above the fuel pump and will be a 3–pin Deutsch plug connection. A 2–pin Weatherpack connection is also available for datalink power.

[Bookshelf]

Good info, I was never aware of all the differences in pistons, bearing clearances, oilpump, headbolts, etc between the early and late firstgens, as well as increased fuel pressure? I wonder what the real world impact of all that is though, besides the head cracking the early firstgens seem to live just as long as the late ones. Read further down in that, they changed the ring height on the piston in 94, then back to what it was in 96. Interesting reading.