[Roverandom]

Quick question for you guys. I have a 94 RRC with the 3.9L that needs head gaskets. I'm fixing it. The old Rangie is offroader so useable power and torque along with reliability is what I need from the engine. I would like more power.

I also have a 4.2L that could use a refresh/rebuild (stock rebuild, perhaps a better oil pump and a Crower cam?) that I was planning on dropping in my RRC sometime in the future. Stock the 4.2 are supposed to make 200hp and with hot cam, the one I'm looking at claims a good torque increase.

The question is, should I go ahead with the 4.2 rebuild plan or should I look for a 4.6 and build one of those?
I have never owned a 4.6 so have no personal 'seat-o-the-pants' experience to compare the two engines. I know the 4.6 is stiffer block and has cross bolted mains etc. and also the distributorless ign system to work around but do they not also have issue with the rear cylinder casting thickness? And of course i would need to find one worth rebuilding.

The 4.2 will be a drop in, I already have it sitting in the shop and I don't have a ton of money to spend (did I just answer my own question?) but if the 4.6 is significantly more powerful...........

Any thoughts or advice is appreciated.
Cheers
Matt.

 

[p76rangie]

I also have a 4.2L that could use a refresh/rebuild (stock rebuild, perhaps a better oil pump and a Crower cam?) that I was planning on dropping in my RRC sometime in the future. Stock the 4.2 are supposed to make 200hp and with hot cam, the one I'm looking at claims a good torque increase.

The longer the stroke on a motor the more it is inclined to torque rather than revs. The 4.6 has a longer stroke of 3.2inches compared to the 4.2 of 3.03inches. Standard the 4.2 makes 200 hp and 251 ftlb of torque, whereas the 4.6 makes 225HP and 280 ftlb of torque.

So if you are after power and torque, the answer is obvious.

I have never had a 4.2, but I run 4.6's in a disco 1 and Rangie classic and they supply good power and torque. The earlier 4.6's in the mid to late 90's had issues with the block, but this was largely fixed in the later models. So try and find a motor that was made say 2000 or later.

 

[Roverandom]

Good info there Ian. Gonna need to keep a lookout for a later block I guess.
Cheers.
Matt.

 

[oryx]

A cammed 4.2 will be equal to a stock 4.6. You should also think about the strength of the transmission. A cammed 4.6 might be too much for the stock auto or manual which are only rated to 380 Nm (280 ft. lb.) or so, especially if they are a little tired already. The 4.6 does have cross-bolted mains and a better oil pump, but as Ian said, with a 4.6 you never know what your getting in terms of block, even on the later ones.

 

[grnole]

Hey Oryx - havent tackled this type of a job personally but came across this write up. If you have not seen it, its pretty good.

http://www.eastcoastrover.com/106.html

 

[Roverandom]

I was initially more worried with a 4.2+ hot cam breaking the crank rather than the auto transmission, but I will definitely bear that in mind and maybe overhaul the trans and xcase at the same time.

Having looked around over the last couple of months, 4.6L Rover V8 seems hard to come by in my area without a $5G Range Rover bolted to it so unless a late 4.6 falls into my lap for a reasonable cost I'm probably going to need to go with my 4.2L.

 

[p76rangie]

I was initially more worried with a 4.2+ hot cam breaking the crank rather than the auto transmission, but I will definitely bear that in mind and maybe overhaul the trans and xcase at the same time.

Having looked around over the last couple of months, 4.6L Rover V8 seems hard to come by in my area without a $5G Range Rover bolted to it so unless a late 4.6 falls into my lap for a reasonable cost I'm probably going to need to go with my 4.2L.

As you only need a short motor (block, pistons, crank), check out the price of a new one. If second hand, you are better off buying one that is running in a car so that you can here it, or one that you know has come out of a wreck. Buying a secondhand motor by itself is too risky as you do not know why it was removed.

http://www.johnealesroverv8.co.uk/18.html