Mopar to offer the ATK 4.7-liter Stroker Motor

[dejablu311]

yeah the weak link here is the transfer case. There is a reason jeep didn't put the NP231 in the V8 Grand Cherokees. Hell the 5.2L in the GC's only made 225 hp and 295 lbft but that was apparently enough to upgrade the np231. The chain stretches and the shafts are small. It was never designed for big power. Perfect excuse for an atlas II. :wings:

 

[Black Dog]

That would be a good excuse for an Atlas II.....if you're made of money! my wife was mad enough at me last summer for spending $700 on tires.

 

[Beowulf]

The Rubicon models have an NP241OR instead of the NP231. I'm not sure how much beefier it is, but hopefully it would hold up.

 

[Black Dog]

A brand new Atlas II is only a couple hundred bucks more than a brand new NP241OR isn't it? Unless you could find a 241 for cheap in a junk yard, I think I'd invest a little extra in the Atlas because the extra features are worth it.

 

[Beowulf]

kc0tma,

I totally agree, if i had to get a new tcase it would be an Atlas, but I already have the 241. I don't know if it would be strong enough or not.

 

[Black Dog]

I know a lot of us XJ guys swap the NP231 with a NP241OR to get the 4.0:1 low range, and supposedly it is a direct bolt in replacement. The Novak site says it has "increased strength and capability", so I bet it would be fine with more horse power. And being a fixed yoke is a big bonus over the 231.

I'm kind of thinking that the stroker isn't really enough more powerful than stock to cause a catastrophic failure of an NP231 though. Maybe if you were going to put in a V8 engine it might be too weak, but I don't actually envision it exploding into a million pieces otherwise.

 

[Root Moose]

People run 231s behind V8s all the time (when swapping engines). Run it.

Grand Cherokees never got the 231 but I'd expect that was more of a marketing decision than technical. Also, isn't the 231 used in some V8 Dodges?

NV241OR is more than enough strength for expedition / trail riding style use. The NV241 is used in full size vehicles. And the NV241OR is more robust than those from a case perspective. Probably lots of other strengthening in there as well.

IMO the 4:1 ratio is nice but not really needed for expedition / trail riding type of 4x4 work.

 

[Black Dog]

There's a few old forest service roads up here that are steap enough that even in low range and first gear I have to use my brakes to keep from feeling like I'm flying down the mountain at 100 mph, so a 4.0 would be nice. Maybe if I ever get any money from that Russian lottery my email said I won I could get an Atlas 4 and do 2.73 and 4.0 for two of my low ranges and have the best of both worlds plus some. :wings:

 

[ztech1]

Feelings on stroker motor

ATK 4.7-liter Stroker Motor

ANNOUNCEMENT:
Following up on Mopar’s announcement last year that it would investigate adding a stroker motor to its portfolio, the parts maker displayed a 4.7-liter engine on the XJ Stroker vehicle at Moab. This is the same motor that won the 4×4 SUV category at the 2008 Score International Baja 1000 in Essenada, Mexico. Mopar plans to launch the ATK 4.7-liter Stroker motor for Jeep vehicle applications starting in September 2009.

With this announcement from Mopar, do you think they will be offering this for all model years of Cherokees and Wranglers that came equipped with an inline six?

Do you think that since it is from Mopar they will include an ECM Flash that matches the needs of the new engine?

What do you think the asking price will be? A new engine from ATK is only $2500

http://high-performance-engines.com...?Screen=PROD&Store_Code=ATK&Product_Code=HP24


HP: 275+
TORQUE: 320+
Engine Type: AMC Straight 6 Cyl
Displacement (cu.in):242
Block: Cast 405
Bore / Stoke: OE .040 Bore
Crankshaft: 258 CI /2.125 Snout .850 Pilot Hole
Rods: 258 CI
Pistons: Hyperutectic
Rings: Moly

Specs are impressive, do you personally have feelings on this kit or know of someone who has installed this in their Cherokee? I have 97 XJ 4 liter auto 4 wd,

Thanks
Joe