WJ 4.7L V8 swap into XJ?

[Dr. Dyno]

The history of the V8 doesn't just revolve around short stroke high rpm engine architecture. I grew up in an 'Olds' family, 4.125 bore/4.250 stroke, it was all about torque.

Oh I know about the V8 not being only short stroke high rpm, and your Olds is a good example of a low rpm torquer.

Around here, rpm gets my Jeep up the mountains. 225 ft/lb doesn't cut it. A stroker would give me plenty more torque at an rpm my Jeep just doesn't spend much time at.

Actually, my 4.6 stroker makes subtantially more torque than my old modified 4.0 but the biggest difference is from 1000-4000rpm. Unless your Jeep spends most of its time above 4000rpm, you really will notice the extra torque of a stroker and find yourself using a higher gear to climb the same hill.
I've had mine on the dyno; 198rwhp @ 4650rpm, 254rwtq @ 3550rpm with at least 90% of maximum torque available from 1600-4600rpm. That's about 30% more rear wheel HP/TQ than your average plain vanilla 4.0 XJ.

 

[wolfpackjeeper]

I own both a cherokee with a 4.7 stroker, and an SS camaro with a lightly modded LS1(LT's and a lid) Cherokee has better torque, down low by my ass dyno. On my dyno chart the camaro makes great torque, 352 ftlbs at 5500 rpm, but it is as close to a flat line across the chart as you can ask for. HP curve is a nice gentle curve up. I would love to see an ls1 in a cherokee just to drive it and see. However neither is my choice for a swap if I had to do it over again. The cherokee would get a cummins turbo diesel swap. Buddy did it in a wrangler and that shit was nasty.

The I6 vs v8 debate is just plain stupid-rediculous. What cam is in each? Heads? Exhaust? I can build a V8 that revs to high heaven and makes mucho horsepower at max rpm, or put a different cam and head package on it and make some sick low end torque. There are too many variables in the equation

 

[BBeach]

Like wolfpackjeeper said, it all about the cams and head choice as well. I think the stroker will have a ton of torque..both from http://wjjeeps.com/engine.htm#CURVE

 

[BBeach]

From those graphs, the 4.0 is cleary "out-torqued" by 20% or so at the same rpm.

 

[5.2poweredxj]

My current setup is 33" on the stock 3.55. It still spins the tires in rain and can pull your friend (old f250 with snowplow) out of snow bank when he gets stuck. If the 4.0 is great why with small tires (32") and the same gearing I could never do the speed limit?

Now with the v8 I can get the speedo to go past that 85 mark before it even hits overdrive.

 

[FoMoCo]

My current setup is 33" on the stock 3.55. It still spins the tires in rain and can pull your friend (old f250 with snowplow) out of snow bank when he gets stuck. If the 4.0 is great why with small tires (32") and the same gearing I could never do the speed limit?

Now with the v8 I can get the speedo to go past that 85 mark before it even hits overdrive.

ooooh impressive
not trying to be a dick or anything, its just that isn't such a great qualifier of performance considering how light the ass end of an xj is, I'm pretty sure a 2.5 with the same tires and gearing could still spin em in teh rain (might require a lil more skinny pedal tho )

 

[xjjeeper19]

If I had the time and money, I would do the the 4.7L HO. It is a very good powerplant and makes decent power. However I would still keep my NV3550, just get a bellhousing to match out of a Ram 1500. Yes the motor does have ocasional problems, but since it's arrival in 1999 it has been a very reliable motor. I won't compare it to a SBC, it's just not worth it, you can build the chevy for far less than you could probably buy a 4.7l and a trans. If some one has done this, I would like to see it.

As far as it not fitting in an XJ, I think it will, you will just need to do a little rearanging

Justin

 

[MoparManiac]

You want serious torque in gasoline form? Get a 440.

 

[Root Moose]

I don't know the ChryCo engines. What is the big deal with making the 4.7 (HO or non) fit in an XJ/MJ engine bay?

 

[alex22]

My thoughts on the subject. As "wolfpackjeeper" said, its the displacement of the engine or the format (I6 vs. V8). The cam has a very large impact on the torque/HP curve. If you called up a cam manufacturer and told him what you wanted to do with the engine he could change the lift, duration and overlap to meet your needs. Intake and headers will aslo make a diference.
My other concern with a V8 is the transmision. I asked one of the area's leading transmision tech about the strength of the AX-15. He said he has built a few AX-15's to go behind a small block chevy. They broke the stock input shafts. I am not sure if anybody is making stronger inputshafts for the tranny's.

~Alex

 

[5.2poweredxj]

Why if your using an chrco V8 motor you couldn't use a v8 trans? The way mine mount I just grafted the the center section out of my crossmember and changed the input shaft of my 4.0 transfer case and reused it. Cut down the rear driveshaft alittle and used the longer zj front shaft.

I went out measure the 4.7 in dakota it about half inch wider and about 1.5" longer than my 5.2 but the valve covers could be an issue by the heater core.

 

[alex22]

I mentioned the transmision because I did not see the thread starter mention a transmision swap, or comment standard vs. automatic.

~Alex

 

[JJacobs]

Here's an interesting graph..
http://www.allfordmustangs.com/foru...0-s197-dyno-graphs-zoomers_stock1-mustang.jpg
This is a bone stock Mustang 4.6L. I know, it's a little too wide to fit in an XJ easily but it makes my points about v-8 power delivery. Note how this bone stock engine makes more torque than Dino's stroker at a lower rpm! Also notice how the power rises to significantly above the stroker as well, and at a less than stratospheric rpm. We are comparing apples to apples here, standard SAE correction to the wheels. 254 tq @ 3550? How about 250 tq @ 2000 rpm?

Strokers- out torqued and out HP'd by the same displacement v-8. Hmm.

 

[Root Moose]

Here's the GM Vortec 4.8 V8 (LY2). This is a Generation IV engine, not the old school stuff. Iron block sibling of the LS1.

http://media.gm.com/us/powertrain/en/product_services/2008/HPT%20Library/Gen%20IV/Gen%20IV%20Truck/08_LY2/2008_Vortec_48L_LY2_Silverado_SAE.pdf

295hp @ 5600 rpm, 305 lb-ft @ 4800 rpm. Bad graph but looks to start at around 250 lb-ft.

LY5 (5.3 l) is even better and according to fueleconomy.gov gets even better mileage in the Silverado. In a one ton lighter XJ...

I figure I have about 4 years left in my engine at curent mileage rates. Junk yards should be lousy with them by then.

Compact, pushrod engine, RV cams out the ying-yang through the aftermarket soon if not already.

 

[wolfpackjeeper]

1) that is a 4.7l according to the dyno chart, it is also the 3 valve in a new mustang. If ford could make a good small block they would have something.
2)that is not a stock motor, stock mustang motors do not make that kind of power, unless it is in a whipple cobra.


I built my stroker because for the money there was really no other option. A v8 swap would have cost too much to make a motor with the torque band I wanted. Plus the cost of swapping a good transmission. The other thing I wanted was to be able to work on the truck without having to do it by braille. If I pop this motor I will not be doing the same swap, nor will it get a v8. I am feeling a 4 cylinder cummins turbodiesel.

 

[JJacobs]

Ford doesn't make a 4.7, it's a 4.6. If that was a blown Cobra motor it'd be over 400 hp to the wheels. The engine in the graph is stock. You are correct about the 3 valve part.

 

[alex22]

Here's an interesting graph..
http://www.allfordmustangs.com/forums/attachments/2005-mustang-gt-tech/15271d1143071880-s197-dyno-graphs-zoomers_stock1-mustang.jpg
This is a bone stock Mustang 4.6L. I know, it's a little too wide to fit in an XJ easily but it makes my points about v-8 power delivery. Note how this bone stock engine makes more torque than Dino's stroker at a lower rpm! Also notice how the power rises to significantly above the stroker as well, and at a less than stratospheric rpm. We are comparing apples to apples here, standard SAE correction to the wheels. 254 tq @ 3550? How about 250 tq @ 2000 rpm?

Strokers- out torqued and out HP'd by the same displacement v-8. Hmm.

I would stay far away from the Ford 4.6. The main reason is the cylinder head itsself. the spark plugs will strip out if you look at them funny, sometimes even if you sweet talk them. They only have 3 to 4 threads for the plug in the head. Ford has lost millions on warantee issues due to that. The stock connecting rods are not very strong, they are PM, and not very strong PM at that. I have seen a 4.6 ford with a hole in the side because it spun a rod and part of it broke through to daylight. I believe if it was a standard cast rod it would have held together much longer before catastrophic failure.
I doubt that is a bone stock ford 4.6 for a few reasons. The dyno sheet says it is a 4.7, implying it has been honed to the next oversize which most likley means it has other nice parts.
Back to the cylinder head. The stock ford head only only flows 170 cfm (@ 28 inches of water) at full lift. Ported you can get them to flow 230 cfm. A stock Jeep 0331 head will flow 214.3 cfm. I will know what a ported head will flow in a few weeks.

EDIT: one more thing to add Bristol Dyno's website Scroll down to the Ford 4.6 It lists a 4.6 as making 299.7 torque and 273 HP and a Supercharger, steeda tune and a magnaflow catback as making 371.6 for torque and 368.5 HP. The 4 valve per cylinder cobra engines will make more power, but they arent cheap.

~Alex

 

[JJacobs]

I would stay far away from the Ford 4.6. The main reason is the cylinder head itsself. the spark plugs will strip out if you look at them funny, sometimes even if you sweet talk them. They only have 3 to 4 threads for the plug in the head. Ford has lost millions on warantee issues due to that. The stock connecting rods are not very strong, they are PM, and not very strong PM at that. I have seen a 4.6 ford with a hole in the side because it spun a rod and part of it broke through to daylight. I believe if it was a standard cast rod it would have held together much longer before catastrophic failure.
I doubt that is a bone stock ford 4.6 for a few reasons. The dyno sheet says it is a 4.7, implying it has been honed to the next oversize which most likley means it has other nice parts.
Back to the cylinder head. The stock ford head only only flows 170 cfm (@ 28 inches of water) at full lift. Ported you can get them to flow 230 cfm. A stock Jeep 0331 head will flow 214.3 cfm. I will know what a ported head will flow in a few weeks.

EDIT: one more thing to add Bristol Dyno's website Scroll down to the Ford 4.6 It lists a 4.6 as making 299.7 torque and 273 HP and a Supercharger, steeda tune and a magnaflow catback as making 371.6 for torque and 368.5 HP. The 4 valve per cylinder cobra engines will make more power, but they arent cheap.

~Alex

I said a supercharged Cobra motor- which that one apparently isn't. The Cobras push over 400 all the time. I've seen a bone stock 4V 4.6 (with the exception of exhaust and proper tuning) push 320 to the wheels.

My point, though, isn't to pick nits about this and that Ford related. It's that too many people on this forum are drinking the purple Kool-Aid and have got it in their heads that the almighty 4.6 stroker outtorques V-8's. I offered proof in one dyno graph, and there are many, many more out there. There was even a Kool-Aid response to my dyno graph post- "A v8 swap would have cost too much to make a motor with the torque band I wanted." Indeed, like left it stock?

Here's a couple of numbers from the latest issue of Popular Hot Rodding. It's a typical dyno shootout with various v-8's of all makes, note all numbers are torque, not HP, at the flywheel, and all at 2500 rpm. Chevy 400, 474. Chevy 302, 340. Chevy 350, 403. Chrysler 318, 337. All these engines go on to make 450-600 horsepower on top. They are most certainly not optimized to make low-rpm torque- but still, there it is, big torque numbers down low, even where they're not setup to run.

 

[alex22]

I'm doing the 4.0 based jeep based engine mainly because it is a plug and play mod. no need to swap computers, tranny's or engine mounts. That is probly a big reason many people like to build strokers.

~Alex

 

[wolfpackjeeper]

a v8 swap would have cost too much to get the torque and power I wanted. I can put one in the jeep for the exact same price I built a stroker for....

but good luck getting it to bolt up to the AW4. Any other motor you swap will require another transmission. Advance and Novak dont make adapters for the Aw4.


And I still dont believe that "4.6" was stock. they dont make that much at the wheels stock. They just dont, that would put them at the same power to the wheels as a LS1 car.