3.9 to 4.6 upgrade options - Defender Source
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  #1  
Old June 27th, 2016, 09:46 AM
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3.9 to 4.6 upgrade options

I've done some searching and reading but wanted to make sure I had my facts straight.


What are my different options for upgrading a 14CUX distributor 3.9 to a 4.6?


Here's what I think I know:
1) 4.6 crank and rods will not fit in a 3.9 block?
2) I can put 4.6 crank and rods in a 4.0 block and reuse my 3.9 front cover.
3) I can use 4.0 pistons for higher compression. Can I use 3.9 pistons for higher compression as well?


This is for a '95 D1 project. I've been waiting on a built 4.6 dizzy motor from a pretty well known Rover guy for about 4 months now. No money has exchanged hands but its been a long time and I'm starting to look at other options now.


I have headers to install. I have a 4.2 ECU, a good 3.9 ECU, another spare 3.9 ECU, and a 4.6 non-cat ECU Chip.


The engine is coming out no matter what so I just assume rebuild/replace it.


No, I don't want an LS engine. Ok well I do, but that's more $$$ and time than I want to spend.


Thoughts on my above assumptions or comments on how to best proceed forward?
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  #2  
Old June 27th, 2016, 10:08 AM
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You can't use the 3.9 pistons.
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  #3  
Old June 27th, 2016, 10:49 AM
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I'd save up for an LS swap.
My experience with a "built" 4.6l - ported and polished heads, Crower cam, Tornado chip in the ECU, was that I was disappointed.
So then I bought a supercharged 3.9l and promptly blew it up. Had it rebuilt by Rob Dassler even though he wouldn't warranty it because of the supercharger. It was disappointing.
Next I bought a Megasquirt setup including distributorless ignition and a computer programmable ecu to add to the supercharger. Pain in the ass trying to program it and then I had an engine fire and burnt up the wiring, totalling the Range Rover.
So, save your money and do an LS or realize that the 4.6l is not a huge jump up from the 3.9l and will still probably disappoint you after you have spent a lot of money.
Also, the 14cux isn't a distributor it is an ECU (engine controller)
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  #4  
Old June 27th, 2016, 11:00 AM
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I'd have to agree with the above.

I drove a stock '04 D2 with a 4.6 for 2 years and honestly didn't feel like it had any more power than my 3.9 trail truck.

If you're doing the 4.6 on the cheap, then by all means go for it.
I wouldnt put a lot of time and $$ in it and expect much back.

All reports on the LS are win-win.
Be the first to put one in a ragged out Disco.


.
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  #5  
Old June 27th, 2016, 11:20 AM
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I know the 14CUX is an engine management system.
Most LS swaps are coming in at what, $5-7000 at least??
I looking more in the sub-$2000 range. I know the 4.6 won't push me into my seat. My 96 D1 is totally stock and it still pulls pretty good on the highway. Any upgrade over that and I'd be happy.
I won't touch a supercharged Rover engine, I've read up enough to know that.

If I can get my block/4.6 parts for around $1000 I can rebuild the rest for about another $1000. I've already got the headers, ECU's, MSD ignition parts, and a whole slew of other Rover parts.
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  #6  
Old June 27th, 2016, 11:24 AM
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14 CUX is a FUEL management system. As such it manages to use as much as it can!!!
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  #7  
Old June 27th, 2016, 11:33 AM
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Why not just pull a 4.6 out of a wrecked Disco 2?
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  #8  
Old June 27th, 2016, 11:54 AM
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Quote:
Originally Posted by cdb View Post
I'd save up for an LS swap.
My experience with a "built" 4.6l - ported and polished heads, Crower cam, Tornado chip in the ECU, was that I was disappointed.
So then I bought a supercharged 3.9l and promptly blew it up. Had it rebuilt by Rob Dassler even though he wouldn't warranty it because of the supercharger. It was disappointing.
Next I bought a Megasquirt setup including distributorless ignition and a computer programmable ecu to add to the supercharger. Pain in the ass trying to program it and then I had an engine fire and burnt up the wiring, totalling the Range Rover.
So, save your money and do an LS or realize that the 4.6l is not a huge jump up from the 3.9l and will still probably disappoint you after you have spent a lot of money.
Also, the 14cux isn't a distributor it is an ECU (engine controller)
Went through almost the same exact process. A built 4.6 is not impressive, it's just a marginal upgrade over a 3.9. My shop is just about done with an LS swap. I pick up the truck next week and will post my thoughts. I couldn't tell you much now anyway as the computer has a rev limiter on the motor for the first 4 hours anyway and we aren't through that part yet.
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  #9  
Old June 27th, 2016, 12:28 PM
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Quote:
Originally Posted by Red90 View Post
Why not just pull a 4.6 out of a wrecked Disco 2?
Yeah that's an option, too. Will a Bosch 4.6 work?

Quote:
Originally Posted by defender1844 View Post
Went through almost the same exact process. A built 4.6 is not impressive, it's just a marginal upgrade over a 3.9. My shop is just about done with an LS swap. I pick up the truck next week and will post my thoughts. I couldn't tell you much now anyway as the computer has a rev limiter on the motor for the first 4 hours anyway and we aren't through that part yet.
I'm on a Disco budget, not a Defender budget.
What's your out the door price on that swap?
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  #10  
Old June 27th, 2016, 12:33 PM
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4.6 will work but not Bosch with different electronics etc. Can you change the front end back to 14CUX? Word I hear is that the D2 blocks are falling by the way side in ever increasing numbers.
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  #11  
Old June 27th, 2016, 12:34 PM
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Odd. I'll chime in an say that my built 4.6 had noticeably more usable power on my previous D1; while in the current 4.0 5 speed I can control the application better there is a noticeable difference in 'seat of the pants' feel-at least there was in the various trucks that I've owned.

I do wonder what people are looking for in the way of power output of course, if we're expected it to be a supercharged Rangie feel it won't get you there.

I'll go ahead an also be contrary and say that the LS swap has seemed like a great internet idea for what, a decade-but how many people have effectively executed it in a cheap and easily repeatable fashion?

I'd go 4.6l w/4.0 pistons and swap over the 14CUX & associated necessities and I think you'll be pleased enough with the return on investment, esp if you do the work yourself to mitigate cost.
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  #12  
Old June 27th, 2016, 12:47 PM
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You should buy Tony's built 14CUX 4.6. I was going to but ended up just fixing what I have. You can't do it yourself for what he is asking. Shipping to you via fastenal will be about 2-250.
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  #13  
Old June 27th, 2016, 01:15 PM
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Quote:
Originally Posted by Ray_G View Post

I'd go 4.6l w/4.0 pistons and swap over the 14CUX & associated necessities and I think you'll be pleased enough with the return on investment, esp if you do the work yourself to mitigate cost.
r-
Ray
That's where I'm headed I think. I do all my own work.

Quote:
Originally Posted by o2batsea View Post
You should buy Tony's built 14CUX 4.6. I was going to but ended up just fixing what I have. You can't do it yourself for what he is asking. Shipping to you via fastenal will be about 2-250.
Got a link or full user name?
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  #14  
Old June 27th, 2016, 01:23 PM
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Quote:
Originally Posted by fishEH View Post
Got a link or full user name?
Tony Brooks, forum name Abrooks

Listing here:
http://www.defendersource.com/forum/...tml#post726271
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  #15  
Old June 27th, 2016, 01:35 PM
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Quote:
Originally Posted by o2batsea View Post
Tony Brooks, forum name Abrooks

Listing here:
http://www.defendersource.com/forum/...tml#post726271
Thanks. Seems steep for an untested engine in pieces that I'd stillhave to convert to serpentine belt.
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  #16  
Old June 27th, 2016, 01:52 PM
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Huh? I thought you wanted a distributor motor.
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  #17  
Old June 27th, 2016, 02:23 PM
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Quote:
Originally Posted by o2batsea View Post
Huh? I thought you wanted a distributor motor.
94 and 95 D1 are distributor, but with serpentine belts.

------ Follow up post added June 27th, 2016 01:25 PM ------

Quote:
Originally Posted by fishEH View Post
Yeah that's an option, too. Will a Bosch 4.6 work?
Since you aren't going to be using the crank sensor anyway, there isn't much difference between a Bosch block and a GEMS block. A d2 engine should work fine, after you swap the D1 stuff that is different over.
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  #18  
Old June 27th, 2016, 02:56 PM
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From a performance perspective you might consider re-gearing options. 411's made my NAS90 more civil compared to the 354/ZF stock combo.
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  #19  
Old June 27th, 2016, 03:15 PM
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Originally Posted by 1of40 View Post
From a performance perspective you might consider re-gearing options. 411's made my NAS90 more civil compared to the 354/ZF stock combo.
Already done. I've got Ashcroft 4.12's with Ashcroft lockers front and rear. Final tire size should be between a 255/85 and true 35. I know it could be lower but it will be closer to stock gearing than my 235/85's on 3.54's.
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  #20  
Old June 27th, 2016, 03:50 PM
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Already done. I've got Ashcroft 4.12's with Ashcroft lockers front and rear. Final tire size should be between a 255/85 and true 35. I know it could be lower but it will be closer to stock gearing than my 235/85's on 3.54's.
Yeah, you'll probably notice a peppiness with the 412's. Be careful re exhaust. The higher rpms will give you a drone that sucks at highway speeds over long periods of time. Double check tire size again. My 255's are true 33's not 35's.
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