Vehicle & Technical > Range Rover

Swapping 4.2 for my tired 3.9-Any Info

(1/3) > >>

kjj0506:
I am curious about the Injection and ECU , Exhaust , and any other tricks or info. I have heard that the ECU is mapped differently and I don't know if I should grab the ECU or use the old 3.9 stuff. Is one or the other detrimental or higher performance or ??

Any one used headers on this set up ? Is there a benefit? I thought I might freshen up any hardware and then do a cloth header wrap to cut under hood heat a little ... anyone?

I understand that I will have to remove the manifold anyway to get to hardware on the back side.... Should I throw a cam in there since I am part way to it anyway? Any upgrade cams that don't take away from reliability or mileage ?

If there is anything I am missing or comment or info that may help - your help is greatly appreciated.

Thanks in advance
KJ

BTW - I am not looking for a barn burner - just reliability and if there is a reasonable gain available I will take it as long as the trade off is not too extreme.

Range Rover Blues:
This is something I looked into myself.  IF you can get a complete set up from an LSE then it's probably worthwhile.

The 4.2 is lower compression than the 3.9, it uses the same dizzy but timing is advanced to 10 degrees static, rather than 4.  CR is lowered from 9.35 to about 8.9 IIRC.

You will need the ECU remapped, the 3.9 one will not cope and the early 4.2 ran the engine too lean which is why you often find these cars have new engines in them.  I suggest a RPI tornado chip, but they aren't cheap.

If you use tubular headers then they need wrapping but the 4.2 used the same cast iron manifolds as the 3.9, all 4.2 had cats and lambdas.  My LSEappears to have reworked cast manifolds, but then it's a 5.0l TVR derived Rover V8 :shock:

Swapping the cam means taking the front end off, I'm not sure about what cam I'd put in TBH but if you get the angine and EFi system than fit it as-is, the only difference is the chip in the ECU.

Anything else you need to know?  just ask.

If you drop on lucky you might pick up an :SE that's had an engine blow.  I say lucky because the 4.2 was no-longer available after production of the LSE ceased, the engines became the cross-bolted 4.0 and 4.6.

So chances are you might find either a nicely rebuilt 4.2 so you needn't worry about the block cracking, or a 4.6 :D

Guess what I found in my spares car :(biggrin):

A John Eals 4.6 with remapped ECU :(biglove):

kjj0506:
So if I grab the ECU from the donor would I still need it remapped? Are you saying get the RPi Tornado as well or in lieu of the Factory ECU ( sorry havent dealt with this on a RR and all cars are a little different. ) ?

Is there a benefit to the headers ? I figured I would have hardware issues and such when I removed the manifolds so I thought if I could get a cheap gain and not lose much I would add the wrapped headers with all new hardware and a dose of anti seize.

I was thinking of throwing the 4.2 on a stand when I get it out so I can drop the pan and do a little look over and check for gaskets that may need replaced and such. Since I am there I thought it would be a good time to change the cam and t chain. Any thoughts? I would rather do it now out of the car than later in it.

You are always very helpful .... Thx again

Range Rover Blues:
General wisdom is that the standard ECU can just about cope with a free-flow air filter and a sports exhaust (headers) and no more.

Given that the 4.2 had a reputation for being a bit on the lean side to start with I'd think with those mods on it would be at the absolute limit.

SO if you are thinking of a cam then get it remapped (chipped).

Now, given that in the UK at least a 4.2 ECU is still worth a good few quid, whereas 3.9 ECUs are now much cheaper than they were I'd suggest the following.

If the ECU is more money on top of the engine, save you money
If the ECU comes with the engine, think about selling it on and having your current 3.9 ECU remapped.

Once remapped, the companies that do it make many claims like better throttle response, better economy, cooler running etc etc but it may be worth considering instead of a cam change and certainly before it.

If you are going to partly strip the engine then definitely a new crank rear oil seal, it's hard enough to do with the engine on the bench.  Whilst doing it you will have to loosen the back crank main bearing cap as it's combined with half of the oil seal housing (what a s*** design) so you will see the state of one bearing.  If you can see the copper backing through the white metal (Babbit's metal) bearing surface then I'd strongly suggest a new set of mains if not big end bearings whilst you are in there, V8 cranks rarely need re-grinding if the bearings are swapped in time.

Leave the pistons alone unless they need to come out.

If you are taking the heads off then check the top of each liner with dye penetrant (checking for leaks around the liners ie cracked block).

Rebuild the heads, valve grind, new springs and seals.  Have the heads skimmed and fit composite gaskets.

Strip the oil pump and pack with petroleum jelly, I also like to polish any scoring out of the cover plate.

If you do the cam then fit a new chain (possibly gears too).

How far you go depends on the depth of your pockets :wink:

Range Rover Blues:
P.S. I fitted a tubular system (headers etc) to the LSE on Wed (it's why I've not been on here much) and I only got to drive it today.

Well my mate recons it sounds sweet :(biglove): though from inside you can hardly hear it (just sounds a bit tinny under the hood).

I've wrapped the headers but I may wrap the Y pipe too, though there is precious little room around the headers if they are wrapped.

Navigation

[0] Message Index

[#] Next page