Jeep 4.7 V8

[Steve F]

As an aside I'm looking at building a stroker from a 4.0lt block, I have the 4.2lt Crank and will have the rods shortly (we ran out of time in the 4.2lt strip down today at Wooders).

Using this crank and rods and stock 4.0lt pistons and a few other tweaks will give me a 4.5lt that looks stock with 260bhp (up from 195bhp) and 321lbft of torque (up from 230lbft of torque). The 4.7lt V8 is 235bhp and 295lb-ft, so my 4.5lt straight 6 will eat it for breakfast Even if I go low compression (8.8-1), which is a possibility, I can get 230BHP and 327lb-ft of torque at 2000RPM which will still be quicker than the V8 and more economical.

In other words, go the Hemi, or a stroked 4.0lt over the 4.7lt V8

Cheers
Steve

[tonysrich]

Apparently Chrysler has improved the 4.7 V8 over the years. The first one wasn’t much better than the current V6 but the latest version puts out a respectable 305hp and 453 Nm of torque.
From Wiki
The 4.7l V8 first appeared in the 1999 Jeep Grand Cherokee. The displacement was 4698. It has a cast iron block and aluminium heads with two valves per cylinder. It uses a chain-driven overhead camshaft. It originally produced 235 hp (175 kW) and 400Nm of torque. The 2010 4.7l has 2 valves and 2 spark plugs per cylinder and puts out 305 hp (225 kW) and 453 Nm of torque.
99–04 4.7l PowerTech V8 235 hp (175 kW) 400 Nm
02–04 4.7l High Output PowerTech V8 265 hp (198 kW) 450 Nm
05–07 4.7l PowerTech V8 265 hp (198 kW) 414Nm
08–09 4.7l PowerTech V8 305 hp (227 kW) 453Nm

[Steve F]

You'd still need that 08-09 engine (did we get the HO here? runs on premium to get that power from the 02-04) to top the little stroker of 260hp and 436Nm, if you bore the 4.0lt out 0.060" (4.7lt Stroker) you can get 284BHP and 470Nm!!! I guess if you can get the 08-09 engine it would be a worthwhile swap.

I'm not trying to say dont do it but you have to wonder if you can get the same power from an engine they started building in 1984 with a few simple/cheapish mods as a 05-07 V8 then maybe the V8 isn't the best engine for a swap especially when you can drop in the 5.7lt Hemi and get 340hp and 529Nm

Cheers
Steve

[Miraz]

That wasn't in my JK ofcourse, I don't think it can go that fast. It was on my 1050 Triumph Speed Tripple.

Ouch....going to get some time without a license too surely?

[reyzor]

steve, are you gonna do a build thread on the motor.....very interested.... sing out if you want a hand swinging spanners... nothign better then pulling and engine apart.

[SteveC]

My 4.7 with 400nm runs like a dream pushing 2.4t. I assume a jk is lighter
And is a lot better in fuel economy than you may think. Though a newer model would be better ofcourse

[SteveC]

Also there are plenty of used wjs with v8. Which you could salvage and then recover som costs selling the rest of it

[Miraz]

Looks like there will be a few kits on the market allowing the use of LSx V8's into the JK in the near future.....steer clear of the 4.7 though, it's just not worth the hassle of doing the conversion.