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Sticking a 4.6 in a RRC in place of 3.9


duncmc
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I am becoming more and more drawn by the idea of putting a 4.6V8 into my RRC instead of the 3.9, and I have started to think about getting an engine. So, I have been having a look on eBay. Could I get away with just a short engine, or do I need the lot?

Obviously I would need to swap the sump, front cover and anxillaries as well as the inlet manifold and pleunum chamber from the 3.9 onto the 4.6.

Would I need to use the 4.6 injectors though, or would the 3.9 ones be fine......and if I did use the 4.6 injectors would the loom plugs fit?

Also can people who have already done this give some general things to watch out for.

Cheers in advance. Dunc

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Obviously I would need to swap the sump, front cover and anxillaries as well as the inlet manifold and pleunum chamber from the 3.9 onto the 4.6.

Why ?

I run a p38 gems 4.6 in my offroader as it came out the RR. (Added my own idle control valve).

Just get an aftermarket ECU.

G

Edit : actually, i do have an older plenum chamber on there for some reason....just trying to think why.

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Why ?

I run a p38 gems 4.6 in my offroader as it came out the RR. (Added my own idle control valve).

Just get an aftermarket ECU.

G

Edit : actually, i do have an older plenum chamber on there for some reason....just trying to think why.

My car has the older V belt set up. If I swapped to the serpentine belt the alternator is in a different place for starters, then I would have to change the engine bay loom too.

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You will never get the most out of a 4.6 running standard or even modified 3.9 injection ECU, at best it will be a fudge. I would strongly recommend you go aftermarket ECU. I would, as Zim has, stick the hotwire top end on it (in fact as I have done as well!)

I would keep the serpentine front cover if at all possible (assuming you don't already have a serp V8 in yours), though I know the 4.0 oil filter needs relocation, I think the later 4.6 was different again.

Yes, this probably means fitting electric fans, but in our climate there is no *need* for a super-duper viscous fan capable of pulling the whole earth's atmosphere through the radiator if a couple of electric fans will do the job just as well.

You would want the lot, the heads are different height compared to the 14 bolt.

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My car has the older V belt set up. If I swapped to the serpentine belt the alternator is in a different place for starters, then I would have to change the engine bay loom too.

Which V-setup? There are a few... If it is top right as you look at the front of the engine, and the alternator is top left on the P38 engine, then you can run the alternator wires down the rocker cover to the stud on the firewall, really easy :)

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My car has the older V belt set up. If I swapped to the serpentine belt the alternator is in a different place for starters, then I would have to change the engine bay loom too.

If the issue is that is stopping you is that have to change a few cables out.... Then just keep the 3.9.

Sorry to be blunt.

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You will never get the most out of a 4.6 running standard or even modified 3.9 injection ECU, at best it will be a fudge. I would strongly recommend you go aftermarket ECU. I would, as Zim has, stick the hotwire top end on it (in fact as I have done as well!)

I would keep the serpentine front cover if at all possible (assuming you don't already have a serp V8 in yours), though I know the 4.0 oil filter needs relocation, I think the later 4.6 was different again.

Yes, this probably means fitting electric fans, but in our climate there is no *need* for a super-duper viscous fan capable of pulling the whole earth's atmosphere through the radiator if a couple of electric fans will do the job just as well.

You would want the lot, the heads are different height compared to the 14 bolt.

I had already assumed that I would need to fit a different ECU, the "Mark Adams" one springs to mind I think. Or even go down the megasquirt route....but then I will be modifying it beyond return really. Not sure yet I want to do that. I was only thinking short as I have 10 bolt heads swapped over already, and I'd thought I wouldn't need the Gems inlet etc.

Which V-setup? There are a few... If it is top right as you look at the front of the engine, and the alternator is top left on the P38 engine, then you can run the alternator wires down the rocker cover to the stud on the firewall, really easy :)

Didn't know that. That's is why I am asking you see...thanks.

If the issue is that is stopping you is that have to change a few cables out.... Then just keep the 3.9.

Sorry to be blunt.

Be as blunt as you like, I know nothing when it comes to changing for a different engine. Never done it. When you say it like that "just change a few cables out" it sounds dead easy.

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I had already assumed that I would need to fit a different ECU, the "Mark Adams" one springs to mind I think. Or even go down the megasquirt route....but then I will be modifying it beyond return really. Not sure yet I want to do that. I was only thinking short as I have 10 bolt heads swapped over already, and I'd thought I wouldn't need the Gems inlet etc.

Didn't know that. That's is why I am asking you see...thanks.

Be as blunt as you like, I know nothing when it comes to changing for a different engine. Never done it. When you say it like that "just change a few cables out" it sounds dead easy.

Cool :)

If you already have 10 bolt heads, then a short engine would probably do you well :) Break and the bank and you could go with a remanufactured engine with top hat liners...

http://turner-engineering.co.uk/html/V8enginesreman.html

As for megasquirt modifying beyond return... I would not say that really. You can build to use the P38 coil packs that sit along the back of the engine for tidiness, so bolt-on, the only other addition is fixing the VR sensor to the front cover -again, bolt on.

You can pull the Hotwire loom out (it unplugs under the dash, as you probably know), stash it somewhere safe, and build your new MS loom as a replacement. One of Nige's kits would likely make things simple if you've not done something like that before, though as above, you wouldn't really need the coil packs/brackets/EDIS if you didn't want them :) Make it plug-in in the same way the Hotwire loom plugs in and you can swap very easily.

If you ever wanted to go back to stock, then unplug and re-plug... simples :)

Only other bit I can think of directly, is the coolant hoses, and PAS hoses, but these are easily solved (see Fridge's Ambulance thread on the PAS pump hose), and you'd need an aluminium tee in the bottom hose to hook up the header tank, rather than the horrid pigs heart thing (put the stat where it belongs, in the inlet manifold).

Not saying it is easy, but all the problems have already been solved if you look for it :)

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If you do decide to go V belt you'll need a spacer for the crank - I have one sitting on my bench gathering dust, PM me if you'd like it. Megaquirt sounds like an interesting new product...

quirt

noun
  1. 1.
    a short-handled riding whip with a braided leather lash.
verb
  1. 1.
    hit with a quirt.
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If you do decide to go V belt you'll need a spacer for the crank - I have one sitting on my bench gathering dust, PM me if you'd like it. Megaquirt sounds like an interesting new product...

quirt

noun
  1. 1.
    a short-handled riding whip with a braided leather lash.
verb
  1. 1.
    hit with a quirt.

You would feel that in your bones if done enough I think!

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ISTR some later RRC's do not have the separate unpluggable engine loom, worth checking!

The full serp setup is much nicer IMHO than the old multi-V, but yes it's more work to change to.

Middle ground if you're not certain may be to start with a full engine (buy a running P38 so you've got all the bits), but strip the lump and fit it "short" into your motor. Then you have all the P38 bits if you later decide to go the whole hog.

It's possible to fit a megasquirt ECU board inside a 14CUX ECU with minor mods, Geoffbeaumont did it on his RRC (have a search, you may find the thread / info) and as it happens that very ECU is in my shed gathering dust. That could well lead to you NOT having to modify your engine loom (maybe just add wires for EDIS & coil packs).

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ISTR some later RRC's do not have the separate unpluggable engine loom, worth checking!

Thanks. Better check that.

Middle ground if you're not certain may be to start with a full engine (buy a running P38 so you've got all the bits), but strip the lump and fit it "short" into your motor. Then you have all the P38 bits if you later decide to go the whole hog.

I had sort of come to that conclussion myself already. I need to fix the Sport first as that is giving issues, then sell that before I start work on changing engines etc. So it might be 2017 before I actually start.

Oh, and my plan will be buy a P38 4.6 as a runner. Make sure it all works OK, swap the engine. Make sure it still works. Megasquirt it, and then finally fit LPG and run that from the Megaaquirt too.

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Why ?

I run a p38 gems 4.6 in my offroader as it came out the RR. (Added my own idle control valve).

Just get an aftermarket ECU.

G

Edit : actually, i do have an older plenum chamber on there for some reason....just trying to think why.

 

Maybe for the kickdown cable for the auto? The idle control is in a different position as well, needs a bit of Devcon to work with a Bosch valve

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