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
o (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.
so 60lbs valve springs were not available until the 24 valves to answer your question farmboy1989
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99 DODGE 24VALVE, FASS 150, EDGE COMP/SMARTY REVO STACK/100HP COALTRAIN STICKS ,BHAF,TC LOCK UP SWITCH 5"MITER CUTS, 3.55 ANTI SPIN ,SMOKE SWITCH, SILENCER RING KILLED, GAUGES (FUEL PRESSURE, TRANS TEMP, BOOST, EGT))INFAMOUS 53 BLOCK 293,780 no crack