The Jeep 6-230 Tornado engine was the first U.S. designed mass-produced overhead cam (OHC) engine. At engines and gearboxes Jeep Engines are available used, reconditioned or secondhand and 4×4. It was introduced in 1963 and replaced the flathead 6-226 Super Hurricane, which had been in use since 1954. It is still the only engine designed, developed, and built by Jeep and used only in Jeeps.
The Tornado, like most Jeep engines, was undersquare for better low speed torque. It had a 3.34 inch bore with a 4.38 inch stroke. The standard version had an 8.5:1 compression ratio. Output was 140 hp at 4000 rpm and 210 ft·lbf of torque at 1750 rpm. A low-compression (7.5:1) version was also available, with 133 hp at 4000 rpm and 199 ft·lbf of torque at 2400 rpm.
The 4.7 liter version was the first of this family, appearing in the 1999 Jeep Grand Cherokee. The displacement is 4.7 L (4701 cc/286 in³) with a bore of 3.66 in (93 mm) and a stroke of 3.40 in (86.4 mm). It has a cast iron block and aluminum “almost Hemi” heads with two valves per cylinder. It uses a chain-driven overhead camshaft. It produces 235 hp (175 kW) and 295 ft·lbf (400 N·m) of torque. The PowerTech was on the Ward’s 10 Best Engines list for 1999. Applications were to the 1999-present Jeep Grand Cherokee, 2000-present Dodge Dakota, 2000-present Dodge Durango, 2002-present Dodge Ram, 2006-present Jeep Commander and the 2007-present Chrysler Aspen.
4.7 HO. A “High-Output” version of the 4.7 L PowerTech engine, producing 260 hp (195 kW) and 330 ft·lbf (448 N·m) of torque, was introduced in 2002, first appearing in the Jeep Grand Cherokee Special Edition. Applications were to the 2002-2004 Jeep Grand Cherokee available on the Limited, Overland and Special Edition models and the 2005-present Dodge Dakota, 2008 Dodge Challenger.
The EKG is a 3.7 L (3701 cc) version built in Detroit, Michigan. Bore is 93 mm and stroke is 90.8 mm. It is a 90° V engine like the V8, with SOHC 2-valve heads. Output is 210 hp (160 kW) at 5200 rpm with 235 ft.lbf (319 Nm) of torque at 4000 rpm. It has a cast iron engine block and aluminum SOHC cylinder heads. It uses SFI fuel injection, has roller followers, and features fracture-split forged powder metal connecting rods and an assembled reinforced plastic intake manifold. Applications were to the 2002-present Dodge Ram, 2004-present Dodge Dakota 2004-present Dodge Durango, 2007-present Dodge Nitro, 2002-present Jeep Liberty, 2005-present Jeep Grand Cherokee and 2006-present Jeep Commander.
The 2.4 L I4 PowerTech is actually a Neon engine variant. The 2.4 L (2429 cc) EDZ engine is very similar to the 2.0, sharing the same bore and DOHC cylinder head, but it has a taller block and longer 101 mm stroke. It also uses balance shafts to smooth vibrations and is built in Saltillo, Mexico. Output was up to 140 hp when production started in 1994 for the 1995 model year. As of 2004, output is 152 hp SAE (110 kW) at 5200 rpm with 165 ft·lbf (224 N·m) of torque at 4000 rpm. It has a cast iron engine block and an aluminum DOHC cylinder head. It uses SFI fuel injection, has 4 valves per cylinder with roller followers and features fracture-split forged powder metal connecting rods, a one-piece cast camshaft cast, and an aluminum intake manifold. Applications were to the Chrysler PT Cruiser, Dodge Stratus, Chrysler Cirrus, Chrysler Sebring, Plymouth Breeze
Dodge Caravan, Chrysler Voyager, Jeep Liberty, 2003-2009 Jeep Wrangler. and more 4×4 engines.
Hemi (from “hemisphere”) or “crossflow cylinder head” is a design of internal-combustion engines in which the cylinder head’s combustion chamber is of hemispherical form.
The term, “Hemi engine” is a trademark of Chrysler Corporation, though the concept is used by many manufacturers. The hemispherical cylinder head increases the engine’s efficiency through reduced thermal energy loss and increased airflow through the engine. (A hemisphere has the lowest surface area to volume ratio, meaning the most space for combustion while losing the least amount of energy to the engine walls).
