Jeep 4.7 V8

[tonysrich]

I have been looking at Hemi JK conversion kits on the net. Not that I can afford one, just dreaming. Everyone seems to think that the hemi motor is the best choice for a Jeep conversion because it mates in with the on board computer better than anything other type of motor. That seemed to make sense but then something occurred to me. Jeep already makes a 4.7 V8 for the Grand Cherokee but you don’t you hear of anyone using that motor? Surely it must use the same computer as the JK.
Anyone have any ideas about that?

[reyzor]

im pretty sure they would be compatible...BUT the hemi is a far better motor.........if your going to the expense of swapping motors, you might as well do it with somethign worthwhile.......the 4.7 is a good motor, but its not in the same league as a hemi....

[tonysrich]

I would love the Hemi but I'll never be able to afford one. I just thought that the 4.7 might be a lot cheaper

[reyzor]

im sure if u pulled one out of a crashed 300c it wouldnt be to bad......remember with engine swaps, work out your budget....double it and you will still probably go over......

[Hunno]

remember with engine swaps, work out your budget....double it and you will still probably go over......

Then double it again.

[bogged]

4.7 isn't much cop. The 4.0l puts out about the same power for less fuel!

[Steve F]

I've also noticed a run of 4.7lt engines dieing recently, have a look in the Grand section on Ausjeep.

Personally If I was going to do the swap I'd go for the small Hemi (5.7lt) or maybe even the 3.0lt Turbo Diesel, more power and torque (without enough to worry the drivetrain too much) and only 208kg and a V6 should fit in where a V6 came out :)

Cheers
Steve

[reyzor]

if youre gonna go the hemi swap though it wouldnt jsut be a motor your looking at...... gearbox, drive line, diffs etc....... i heard the one in qld (7LHEMI) kept blowing up gearboxes...... but if possible id look at a blown LS2.......

[tonysrich]

Yeah that is one big issue with big increases in power, the rest of the drive train isn't up to the task. I thought that the 4.7 might be a more sensible choice over the 5.7 litre RHD Hemi conversion. More grunt than the misserable standard V6 but not too much of an increase to stuff the tranny and diffs. And it would have to be cheaper than paying $11 K for a Hemi kit plus the shipping plus the install. I was looking at RIPP super chargers too but they don't do a RHD version so you would have to modify it to make it fit yourself. Good thing I have no money otherwise it would be a hard choice. BTW the little money I did have I just threw away (110kph on the spit bridge and 145kph on the southern freeway, $1300 plus ten points, ouch!).

[tonysrich]

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

[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.