MOPAR 4.7L Stroker
Posted: January 13th, 2010, 2:20 pm
I'm sure you guys have already seen this and I hope it's not a repost, but.........
http://www.trucktrend.com/features/trav ... roker.html
There was a short blurb about it in JP magazine too. I love the part where he says
http://www.trucktrend.com/features/trav ... roker.html
LOL. I wonder where they got most of their research for that recipeWe talked to engineer P.T. Muldoon, who told us the engine is still in reliability testing but looks good. "We ran the heck out of it all week at Moab. I brought it home and we're running the heck out of it right now," he said. The engine will have to survive the same powertrain test schedule as other Mopar remanufactured engines before it can be offered in September 2009. The prototype stroker engine in the XJ makes about 260 horsepower and 290 pound-feet of torque at 4000 rpm, with 260 pound-feet available at 2000 rpm. "We put the torque in the right place, in my opinion," Muldoon said. The final production output specs will be determined by dyno testing prior to release.
The engine was developed using roller rockers to actuate upsized valves housed in new heads. Hypereutectic pistons, which contain a percentage of silicon to harden the aluminum and prevent scuffing, are supplied by Sealed Power. The new cylinder dimensions are 3.875 by 3.906 inches, because "4.7 is about the limit," Muldoon told us. "Beyond that, you're pushing it." The engine also contains a heavy-duty timing chain and a high-volume oil pump. Also featured on the XJ Stroker test mule are a 2.5-inch suspension lift and 31-inch tires.
There was a short blurb about it in JP magazine too. I love the part where he says like they engineered it up from scratch or something.We put the torque in the right place, in my opinion
After all, 3.875 is the stock bore size and since the 258 crank has a 3.895" stroke, they must have offset-ground it slightly. Even then, displacement comes to 4529cc so it's "only" a 4.5, not a 4.7.