3.9 v 4.2

[Viggen]

Any input? I read on ECR that they would NEVER put a 4.2 in any truck due to its weak bottom end but then I read that many have no problem with them. I have a 3.9 (14 CUX) and would like more power but having the earlier system, cannot easily drop a GEMS motor in. A 4.2 would be nice as I could get one and it would drop in and hook up to the sensors already in place. A 4.6 GEMS could be made to work but then Im looking at EFI mods. Thanks.

And "evidence" of purported 4.2 weakness:
http://www.eastcoastrover.com/102.html

 

[R_Lefebvre]

Have you considered a 4.6, and a custom EFI setup, such as a Megasquirt? Higher up front cost and effort, but then everything else is easier and cheaper afterwards.

 

[Viggen]

Have you considered a 4.6, and a custom EFI setup, such as a Megasquirt? Higher up front cost and effort, but then everything else is easier and cheaper afterwards.

I dont want custom anything really when it comes to the motor. I would rather be able to shop off the shelf. The 4.6 is an option but it requires sensor changes and then messing with the MAF and chipping the ECU. All of which arent THAT big of a deal and 4.6's have been put in place of 3.9s numerous times but I would like a jump in hp/ tq without having to do all of that. The lower ends are what concern me with the 4.2.

 

[Nonimouse]

Never had or heard of any lower end issues with the 4.2. Only liners and top end issue at high mileage

The 3.9 with megasquirt is easily capable of a decent tractable 225 bhp(uk)

 

[R_Lefebvre]

With a proper EFI setup, you'll be infinitely familiar with the way the engine runs, more than you ever could be with anything OEM. And, everything will be off-the-shelf. Literally. Build it with GM sensors, and you'll be able to find parts anywhere. Not just from a Land Rover mail-order house.

The NA LR crowd is so far behind on this stuff.

 

[sven]

For a 4.2 or a 4.6, you're gonna need a 4.2 14CUX ECU anyways. So dont be scared of going with a 4.6.
4.6 is better in my opinion because of the cross bolted mains. But there is nothing wrong with doing a nice rebuild on a 4.2.

 

[James86004]

With a proper EFI setup, you'll be infinitely familiar with the way the engine runs, more than you ever could be with anything OEM. And, everything will be off-the-shelf. Literally. Build it with GM sensors, and you'll be able to find parts anywhere. Not just from a Land Rover mail-order house.

The NA LR crowd is so far behind on this stuff.

I would love to do this on some vehicle for just the reason you mentioned, becoming intimately familiar with the way an engine runs.

Although I am dragging around a 5000 lb brick with 95bhp SAE @ 4500rpm and 134lbft SAE @ 1750rpm, so I am intimately aware when the carb or ignition are not working perfectly.

 

[R_Lefebvre]

http://forums.lr4x4.com/index.php?showforum=36

 

[Nonimouse]

Oh god why did you have to bring Nige's posts up?

The guy you want to speak to is Bull Bar Cowboy - look for his V8threads on LR4x4 (or LRstabyouintheback.com as it is better known), he also hangs about on Alaska 4x4. He is truly the god of megasquirt.

The pother bloke who is fairly deft is Fridgefreezer - he'll be on House of the flying spanners forum

 

[R_Lefebvre]

I haven't read too in depth, what's wrong with Nige's posts?

 

[Maryland 110]

Had a couple 4.2's. Ran a lot stronger than the 3.9's for the small displacement difference. Hadn't heard of any issues with the bottom ends either.

 

[Nonimouse]

I haven't read too in depth, what's wrong with Nige's posts?

Nothing wrong with Nige's posts. Nige on the other hand is a different matter:wings:

 

[rover4x4]

I think the bottom end is adequate, who really spins their V8's much past 3k ? I believe ARP makes a stud kit for the Rovers, I am sure you could have the mains cross bolted on a 4.2

 

[R_Lefebvre]

Uh, I am, occaisionally. I'm assuming the motor is good to it's redline? (5000rpm)

 

[Viggen]

I think the bottom end is adequate, who really spins their V8's much past 3k ? I believe ARP makes a stud kit for the Rovers, I am sure you could have the mains cross bolted on a 4.2

I do. I live in Va and regularly trip out into WVa to camp and the grades are serious out that way in the mountains. 3k doesnt cut it.

So, is ECR exaggerating the bottom end of 4.2's?