OLD STYLE ROTARY 12V ENGINE

THE 12-VALVE: All 12-Valves are non-electronic injection pump engines and DO NOT require any electronics from the truck to run. The simplicity of the 12-Valve engine makes it the easiest to install, maintain, and most dependable. RPM RANGE 0-2500 Bosch VE Rotary Pump 1989-1993 Stock Equipment (most automotive applications) Max Stock Torque - 400 ft./lbs. @1600 RPM 0-2700 Non-Modified P-7100 Pump 1994-1998 Stock Equipment Max Stock Torque- 440 ft. /lbs.@1600 RPM 0-4000 Modified Inline Pump (we make available) "Rotary Pump" 12 Valve The 1989 - 1993 engines are readily available, inexpensive, get the best fuel economy stock, and have decent torque. These use the Bosch VE rotary pump which can be adjusted to achieve a little more horse power. The 1989 - 1991½ are non-intercooled. The 1991½ and newer are all intercooled. The non-intercooled engines can be intercooled if desired; it is highly recommended if you plan to turn the power up any to control exhaust temperatures. It's possible to add 40-60 HP with an inexpensive fuel pin so intercooling can be quite desirable. The 1993 and earlier engines may have a diaphragm style vacuum pump, which does not work as well as the later style pump in the conversion. If you are planning to use an electronically controlled transmission, you should know that throttle position sensors are hard to come by for these, however, there are alternative sensor options available so it can be solved without much of a problem. The A/C compressor can also be an issue, as they are usually longer than the 1994 - 1998 versions, and may use a different mounting bracket. The vacuum pump and power steering mounting bracket will interchange. Sometimes the 1993 pumps and brackets are the same as the more conversion friendly 1994 - 1998 versions pictured below. In addition to these differences, some of the early engines have a different fan support that is higher and more centered with the engine. These fan supports work ok in the 1969 - 1997 trucks, although the fan is too high for the stock fan shroud it is at least centered. It does not work so well in the 1999 and newer trucks as the fan will not fit under the radiator shroud, and the shroud cannot be raised as easily as the older trucks. We have been told from a few customers that it works ok in the 2003 - 2007 6.0L diesel shroud. The older style fan hub does not work well if you plan on running a tachometer.