4.6 V8 with LT95 4-Speed Gearbox in a Defender 90

Hi all, Thanks to some helpful advice from the folks at another Land Rover forum, I am compiling a shopping list of components for what I think will work with a 4.6 Rover V8 installation into a Land Rover Defender 90, but I also thought there would be no harm in hearing a second opinion on how practical my idea is, and what setbacks I may encounter in the installation of this drive-train configuration, to power a Defender 90 pickup truck.

I intend to use a 4.6 Rover V8 engine with all the fuel injection plumbing replaced with a Holley Truck Avenger 470 CFM carbourettor, coupled through an Edelbrock 2198 intake manifold. Smog emmissions compliance is not an concern, since this vehicle is for use in the third world.

Having been impressed by the near indestructibility of the LT95 4-Speed manual gearbox in a 1970's era Range Rover 3.5 V8 I used for a while, I plan to run that same gearbox with this 4.6 V8, so my first question is whether there might be any disadvantage to using the 4-Speed LT95 gearbox instead of the post-1995 R380 five-speed gearbox, since I will be using this Defender for some limited highway driving. Does anyone forsee damage being caused to the 4.6 V8 by the 4-Speed LT95 gearbox, or vice-versa ?

Finally, would I be correct in assuming that the elimination of all the fuel injection hardware from a 4.6 V8 will remove any need to connect the electronic modules and wire harnesses from the original engine, in my proposed conversion ? Any opinions would be helpful.

Thanks in advance.

The R380 is a beefier manual box and was used on the last of the manual Discos and Rangies. With the LT230T transfer box it was a pretty good setup and worth looking at instead of the LT95. There's probably more about as well.

If the 4.6 has distributor ignition, then you won't need any boxes, but if not, then you'll need to think about GEMS or THOR setups, both of which need a lot of sensors to work.

That's my view of it, others will chip in and comment as well, so wait for their thoughts.

Peter

Thanks for the quick response Peter. Sounds like I need to be on the lookout for a 4.6 with that distributor ingnition, since I do want to keep the electronics to a bare minimum. Would you be aware of the years of manufacture in which the 4.6 V8 used that distributor system ?

Regarding the gearbox, I was intitially set on going with the R380, until I read a couple of reviews on the net which suggested that the R380 shares some of the same design flaws of the infamous LT77 five-speed, whose failings I know only too well.

Returning to the LT95 four-speed briefly, are there any significant disadvantages to going with that box, other than the scarcity of parts for that model due to its age ? Would the LT95 work alright with a 4.6 V8, and still get close to the same highway speeds as would the R380 coupled to the same engine ?

Speaking of engines, this website is the first place I have ever heard of the porous block and liner issues with the 4.6. How high is the probability that a given 4.6 V8 would show symptoms of sleeve or block failure, in comparison to a 3.9 V8 fitted in the same vehicle ? While I could use the extra power of the 4.6, I would probably go with the 3.9 if the 4.6 V8's flaws are likely to show up early with normal use.

The LT95 is the strongest box - with a different bellhousing it was used in the 101FC. Better than the R380,in terms of strength,but a bit agricultural in use.
Any of the Rover V8's over 3.5 ltrs - the 94mm bore ones can suffer the porus block/slipped liner problems.The trick here is to use one fitted with top hat or stepped liners.Other than that just stick with a warmed up 3.5.
The only Rover V8's over 3.5 which were OK were the Jaguar Rover Australia ones which were 4.4 ltr,fitted in Leyland terriers and the P76 cars.Not sure how easy to find though.

if you do go 4.6 you will need a front cover and dizzy of an interim 3.9/4.2 with the crank driven oil pump (more reliable).

Eightinavee, you have helped me make up my mind to stick with the LT95 grearbox, and if it is a bit agruicultural, I'd feel at home with that given that I did first learn to drive many moons ago on an old Massey Ferguson135 farm tractor, back when my legs were too short to reach the pedals of my parent's Volkswagen beetle.

I am still very interested in the 4.6 V8 though, and if the use of "top hat" liners would cure that engine block's known faults, I am tempted to go with that fix. You wouldn't happen to know of a UK vendor for those liners would you ? Not having seen such liners before, I would imagine that they consist of the usual cylindrical shape with a "hat brim" shaped lip that extends a short way around the top outside edge of the cylinder bore. I can picture this shape, but have never encountered such a sleeve in any other vehicle, hence my wondering where I might purchase top hat sleeves for the 4.6V8.

Tig9619, I'm giving away my lack of knowledge here, but I am guessing that the front cover to which you refer is the timing chain cover behind all the pulleys, and the dizzy would be the distributor from a 3.9 V8. Please correct me if these assumtions are wrong.

Finally, are there specific years of manufacture for the 3.9 and 4.2 V8's that are referred to as interim models ? If you know off hand what years those might be I'd be grateful for that confirmation, so I can hopefully evade Murphy's Law during this build. I have made a note of the need for a crank-driven oil pump as well. Am I right in understanding that oil pump would be from the same year 3.9/4.2 as I would need for the front cover ?

Many thanks, fellas, for these disaster-preventing pieces of the jigsaw puzzle. I can actually see myself pulling off this engine install with no surprises now,

yes the timing chain housing is the one. basically you need one from a later 3.9 engine, 1994 on which has a serpentine ancilliary belt as opposed to the older v belt arrangements. it would be easier to find an earlier cover with the cam driven oil pump but the cranks have a different nose length pre 94 all have a 35mm keyway, 94 on interim have a 60mm keyway with the same 70mm nose length and 4.0/4.6 have a 60mm keyway with a 90mm nose.
the 4.6 crank will work with the interim cover no problem.
Any distributor will work, better an electronic from an efi model. a later one the better as the troublesome ignition amplifier is not attatched to the dizzy so you dont have to remove it to replace the amp!
You will have to fit a skew gear from a 3.9/4.2 cam for the dizzy to run from. not 100% sure this will fit a 4.6 cam but you could always fit your own "hot" cam which will always be an improvement over a low spec range rover cam!
There are many benefits from a 4.0/4.6 block despite the dreaded liner and block problems but with the right work can be eliminated for good. Any block with a daub of red paint under the valley gasket is worth getting work done on as it has the thickest walls between liners.
When you replace the timing cover you must replace the chain and sprockets as they tend to be made of cheese resulting in a mistimed cam,not good. there are plenty of people making heavy duty replacements at a good price.
Hope this makes sense and you are not too confused!!
Tig

If you are going to do this,I'd add three further comments; First use an old points type distributor and fit a Lumenition Optronic kit to it.Second,for an engine source I would contact Frida at Turner Engineering here in the UK - Richard Turner is very serious about doing the job properly rather than having lots of BS in adverts etc.He warrants his stepped liner blocks for 3 years - you dont get this elsewhere.
Lastly,I'd build a bigger capacity sump with decent baffling,later P38 engines had their sumps made smaller - big mistake.An oil cooler is fine,but its better with more oil to start with.

Wow, thanks again for this very specific information, Eightinavee and Tig9619.

Come springtime, I'll be visiting my cousin who builds Morgans in his garage in Halewood, Liverpool, and I'll be taking along a cut-and-paste copy of the details you have both provided above, so that with his help, I will hopefully be able to assemble a 4.6 V8 that can stand up to the use it will get.

My hat is off, and I thank you both very much.

I have a 4.0 on a 4 speed manwell.

the box was rebuilt with desired ratios...

I hear ya, Beast, that 4-Speed LT95 definitely stands up to the test of time, and I 'd rather have than dependability than the luxury of a 5th gear in a gearbox that could go belly up with hard use.

ive just popped lt77 in work wagon... reckon the 4 speed wont be in workshop for long...

Oh noooo. The horror. The horror of the dreaded LT77. I got stranded repeatedly due to the curse of that gearbox, back when my '87 Range Rover was still alive. The most memorable incident I had with the LT77 gearbox was the time when the gear-shift lever just up and flopped to the floor like a dead salmon, 200 miles from home. We had to abandon ship and have her towed home later.

grasshopper said:

Oh noooo. The horror. The horror of the dreaded LT77. I got stranded repeatedly due to the curse of that gearbox, back when my '87 Range Rover was still alive. The most memorable incident I had with the LT77 gearbox was the time when the gear-shift lever just up and flopped to the floor like a dead salmon, 200 miles from home. We had to abandon ship and have her towed home later.

Click to expand...

ive had disco boxes the like last 250kmiles and still sweet.lucky dip.

I need a beell house to mount 200 tdi to lt rr 4 speed box anyway...


was gunna hunt after xmas cos no doubt ill need to swap at some point.

Beast o Bodmin said:

ive had disco boxes the like last 250kmiles and still sweet.lucky dip.

I need a beell house to mount 200 tdi to lt rr 4 speed box anyway...


was gunna hunt after xmas cos no doubt ill need to swap at some point.

Click to expand...

Zeus from Exeter made them - out of case hardened cheese.They are ****,dont bother.Plus the 200tdi does not work well with it,the gaps between gears are too big for it to cope with,they come off boost and bog down badly unless you rev the brains out of them.We gave up after a year and got an LT77 from Ashcrofts - top job,goes really well now.The zeus bellhousing was literally wearing away,when it was new I spent about 2 hrs fettling it with a die grinder to make it fit.

Grasshopper thank you for posting here, I am thinking of doing the same engine conversion and also using the range rover drive train in my defender 110 1997. My defender has many miles on it so I am thinking that the entire drive train must be as tired as my engine.

I have and old range rover that i don't use much and have all the parts with much less miles than my defender. It has a 4.6 liter engine and an automatic transmission. I am an ignorant novice with no experience changing engines so I was thinking (maybe incorrectly) that it would be easier to replace the entire drive train. Is this feasible? I need all the help I can get. Is this a good or bad idea? Is it less difficult than just changing the engine? Is it less time consuming? I could use a shop to do the change if it is a better option but the land rover knowledge base for shops here in ecuador is lacking so it would need to be an easy swap.

Also is there a better land rover engine that I could use? Is the best land rover engine to put in my defender a 4.6 ? I want more power without too much more weight.

If it is a better idea just to rebuild the original engine and drive train in my defender does anyone know of any performance parts that i could use to give it some more power? Right now I have trouble passing a donkey on a hill.

I would appreciate some help. Thank you.

Might want to read this before you get to involved with the 4.6.
Tuning the Rover V8

eightinavee said:

The LT95 is the strongest box - with a different bellhousing it was used in the 101FC. Better than the R380,in terms of strength,but a bit agricultural in use.
Any of the Rover V8's over 3.5 ltrs - the 94mm bore ones can suffer the porus block/slipped liner problems.The trick here is to use one fitted with top hat or stepped liners.Other than that just stick with a warmed up 3.5.
The only Rover V8's over 3.5 which were OK were the Jaguar Rover Australia ones which were 4.4 ltr,fitted in Leyland terriers and the P76 cars.Not sure how easy to find though.

Click to expand...

spot on, saved me some typing