Post by 1tontoy on Nov 29, 2007 3:34:16 GMT -5
The 4.0 L (242 in©ø; 3956 cc) straight-6 was an evolution of the 4.2L and 2.5L and appeared in 1987. It had the same 3.88 in (98.4 mm) bore as the 2.5 with a longer 3.41 in (86.7 mm) stroke. The 4.0 was discontinued at the end of the 2006 model year as the redesigned Jeep Wrangler uses Chrysler's 3.8L OHV V6.
The first 4.0 engines in 1987 had RENIX (Renault/Bendix) engine control systems, which were quite advanced for their time, but are now handicapped because there are very few scan tools which can be "plugged in" to a RENIX system for diagnosis. The Renix also used a very advanced engine knocking sensor, which allowed the computer to know if detonation was occurring, thus allowing the computer to make the appropriate changes to prevent this.
The 1987 RENIX 4.0 made 173 hp (129 kW) and 220 lb-ft (298 N¡¤m) of torque. In 1988 the 4.0 received higher flowing fuel injectors, taking output to 177 hp (132 kW) and 224 lb-ft (304 N¡¤m) respectively.
In 1991 Chrysler Corporation, then the owners of the Jeep brand, redesigned the RENIX engine control computer and raised the intake ports approximately 1/8¡È for a better entry radius. Chrysler also enlarged the throttle body and redesigned the intake and exhaust manifolds for more efficiency, and the fuel injectors were once again replaced with higher flowing units. The camshaft profile was also changed. The net result of all these changes was an engine that made 190 hp (142 kW) and 225 lb-ft (305 N¡¤m) of torque. Badging on Jeeps equipped with this engine read "4.0 Litre HIGH OUTPUT". The new cam profile combined with altered computer programming eliminated the need for an EGR valve and knock sensor, but make the engine more sensitive to alterations, especially where emissions are concerned.
Small changes were made to the cylinder head for the 1995 model year. In 1996, the engine block was redesigned, and a new strengthened unit was then used. The new block made use of more webbing cast into the block, and a stud girdle for added rigidity of the crankshaft main bearings. The cylinder head was also again changed around 1998 to a lower flowing, but more emissions friendly, design. Engines installed in 1999 Grand Cherokees carried the Power Tech name, which was subsequently passed on to 4.0s in all Jeep models.
The 4.0 engine was in production in North America until 2006, when the Jeep Wrangler TJ was replaced by the new JK design that uses Chrysler's OHV 3.8 L V6. It is foreseeable that this engine may be made for many more years in the People's Republic of China, where a slightly modified version of the XJ Jeep Cherokee with 2.5 and 4.0 engines are still being produced.
Output as of 2004 was 190 hp (142 kW) at 4600 rpm with 230 lb-ft (312 N¡¤m) of torque at 3000 rpm.
This engine is considered one of the best offroad engines ever made. The extreme low end torque is ideal for trailing and rock crawling. The only downfall to the engine is the low power output for mudding applications but this can be fixed with various aftermarket options including a supercharger for the engine. Interchangeability within the late AMC/Jeep engine family is superb. The better flowing 4.0 L heads can easily be modified to fit earlier engines right along with the fuel injection system. The longer stroke 258 crankshaft and rods will drop right in the slightly larger bore 4.0 L block, easily creating an even higher torque 4.5 L engine with the stock bore (4.6 L bored 0.030¡È over, and 4.7 L with a 0.060¡È overbore). Blocks should be sonic checked for adequate cylinder wall thickness before boring 0.060¡È over.
Retrieved from "http://www.jeepiki.com/wiki/index.php/4.0L"
The first 4.0 engines in 1987 had RENIX (Renault/Bendix) engine control systems, which were quite advanced for their time, but are now handicapped because there are very few scan tools which can be "plugged in" to a RENIX system for diagnosis. The Renix also used a very advanced engine knocking sensor, which allowed the computer to know if detonation was occurring, thus allowing the computer to make the appropriate changes to prevent this.
The 1987 RENIX 4.0 made 173 hp (129 kW) and 220 lb-ft (298 N¡¤m) of torque. In 1988 the 4.0 received higher flowing fuel injectors, taking output to 177 hp (132 kW) and 224 lb-ft (304 N¡¤m) respectively.
In 1991 Chrysler Corporation, then the owners of the Jeep brand, redesigned the RENIX engine control computer and raised the intake ports approximately 1/8¡È for a better entry radius. Chrysler also enlarged the throttle body and redesigned the intake and exhaust manifolds for more efficiency, and the fuel injectors were once again replaced with higher flowing units. The camshaft profile was also changed. The net result of all these changes was an engine that made 190 hp (142 kW) and 225 lb-ft (305 N¡¤m) of torque. Badging on Jeeps equipped with this engine read "4.0 Litre HIGH OUTPUT". The new cam profile combined with altered computer programming eliminated the need for an EGR valve and knock sensor, but make the engine more sensitive to alterations, especially where emissions are concerned.
Small changes were made to the cylinder head for the 1995 model year. In 1996, the engine block was redesigned, and a new strengthened unit was then used. The new block made use of more webbing cast into the block, and a stud girdle for added rigidity of the crankshaft main bearings. The cylinder head was also again changed around 1998 to a lower flowing, but more emissions friendly, design. Engines installed in 1999 Grand Cherokees carried the Power Tech name, which was subsequently passed on to 4.0s in all Jeep models.
The 4.0 engine was in production in North America until 2006, when the Jeep Wrangler TJ was replaced by the new JK design that uses Chrysler's OHV 3.8 L V6. It is foreseeable that this engine may be made for many more years in the People's Republic of China, where a slightly modified version of the XJ Jeep Cherokee with 2.5 and 4.0 engines are still being produced.
Output as of 2004 was 190 hp (142 kW) at 4600 rpm with 230 lb-ft (312 N¡¤m) of torque at 3000 rpm.
This engine is considered one of the best offroad engines ever made. The extreme low end torque is ideal for trailing and rock crawling. The only downfall to the engine is the low power output for mudding applications but this can be fixed with various aftermarket options including a supercharger for the engine. Interchangeability within the late AMC/Jeep engine family is superb. The better flowing 4.0 L heads can easily be modified to fit earlier engines right along with the fuel injection system. The longer stroke 258 crankshaft and rods will drop right in the slightly larger bore 4.0 L block, easily creating an even higher torque 4.5 L engine with the stock bore (4.6 L bored 0.030¡È over, and 4.7 L with a 0.060¡È overbore). Blocks should be sonic checked for adequate cylinder wall thickness before boring 0.060¡È over.
Retrieved from "http://www.jeepiki.com/wiki/index.php/4.0L"