ScottyNic

Member
Hi guys, probably a question that's been asked many times before but anyway here goes.

Currently my 90 is running a 3.5 EFI.
I will at some stage be looking to upgrade the engine.

which V8 is best to go for? open to all options.

I know you can get LS kits but they're quite pricey, would a 4.0-4.6 lump from the P38 RR drop in easy enough?
and also which ones best for forced induction i.e Supercharging at a later stage too.

Thanks
Scott
 
IMO you'd be best off refurbing what you've got as long as it is high comp and binning the twin carbs if that's what you've got
 
As cooltide said.

The 3.5 is the most robust of all the V8, no liner issues!

Stick an efi system on it and a 3.9cam with a good free flow set of headers and your away.
 
Cheers guys. Shes a 3.5 EFI anyway so no carb.
From what I gather from the previous owner had her rebuilt by John Eales himself only 1000 miles before I got her.
and evidence would suggest that shes running higher comp as when I tested her (to find out where the water was going) all cylinders other than 5 & 8 were at 205Psi. (14bar)
5 & 8 being 175psi (12 bar) & 145psi (10 bar) respectively.
I believe the standard compression on these engines was around the 160-165 psi mark.
Any way I can identify whether or not my cam is a 3.9 or the normal 3.5?
I haven't gotten around to getting the engine number off the side of her so I can verify with john whether or not he did do the rebuild on her.
Yes Ive noticed my exhaust manifolds aren't the most free flowing, she still has the old square cast jobs on her, which is a shame considering the rest of her exhaust system from the cat back is SS.
gonna look at getting SS manifolds so thatll help free things up even more.
 
I'm not an engineer but you are correct regarding HC 3.5efi pressures at 160-165, so 205 is :eek:
I'd also be interested in knowing what sort of improvement a 3.9 cam gives as I've considered the change myself, for the grunt point of view rather than outright power.
Interesting (to a pleb like me anyway) that the cam profile is different on the efi compared to the carb version. There were other differences as well of course, for example when I scrapped a '85 efi a few years ago I kept the dizzy, thinking it would be handy as a spare, only to find out (via the serial #) that it was off a carb engine o_O
 
Hi guys, probably a question that's been asked many times before but anyway here goes.

Currently my 90 is running a 3.5 EFI.
I will at some stage be looking to upgrade the engine.

which V8 is best to go for? open to all options.

I know you can get LS kits but they're quite pricey, would a 4.0-4.6 lump from the P38 RR drop in easy enough?
and also which ones best for forced induction i.e Supercharging at a later stage too.

Thanks
Scott
This is a really interesting question.



The main answer is – what’s your budget!



Followed by – what do you actually want to achieve.



With big power, comes the potential for big borkage!!!



The 3.5 lump is ok and yes many claim it to be the most stout Rover V8 variant. But there is no denying you simply won’t extract the same performance from it, certainly not naturally aspirated. And by the same measure, there are many many 1000’s of larger displacement RV8’s out there across the globe.



By far the easiest and cheapest route would be to buy a 4.0 or 4.6 RV8 stick a cam in it and add some good breathing mods. It’ll mostly fit, but will likely require some changes. The other year I swapped out a cammed 3.5 for a late 3.9 serpentine in my TR7 V8. Despite the 3.9 technically making less PEAK hp over the cammed 3.5, the extra torque it makes across the rev range makes it feel far more powerful.


You’ll get a genuine 200-240hp potential, which in a 90 is likely more than enough.



As for forced induction. All of the supercharger kits are expensive tbh. And likely to cost in the same realm as an actual engine swap. Blowers work quite well with moderate CR levels, so almost any RV8 will be fine with them. The internals of the motor are more likely your limiting factor.


Have you considered a turbo setup? Might be worth investigating rear mount turbo setups. Quite popular in the USA. Much more home build friendly as you don’t need custom manifolds for the turbos. In the UK the lack of suitable large single turbo’s is likely to be your biggest hurdle. And with any FI setup you’ll probably want a more tuneable EFI setup.


Turbo setups will generally like lower CR levels. But a low boost system will work perfectly fine with the stock CR of most RV8’s. Really depends how far you are wanting to go powerwise.



Not sure what gearbox you are running, most will be fine with n/a RV8 power levels. But if you start going BIG power, expect to have lots of drivetrain problems to solve too.



In terms of engine swaps.


The Chevy LS is an option as is the older classic Chevy 350 series of engines. There are adapters to mate to Rover gearboxes, or to use a GM auto box and mate to the Rover LT230. Lots of fab work will be involved. But it’s quite a doable conversion.



The Lexus 4.0 V8 has also been used, but you may have to investigate a custom bellhousing adapter. Just as much fab work as the LS engine option, the big difference is the Lexus lump is usually a lot cheaper to buy.



Ford modular V8. The current 5.0 in the Mustang mates to the 6 speed gearbox in a Puma Defender. I think the older 4.6 and 5.4 variants of this engine might too. But these engines are even rarer than LS lumps in the UK. Again lots of fab work.



Jaguar AJV8. Big project, but you could look at fitting a Jag V8. Two ways of doing this. JE Engineering mate these to the 6 speed manual from a Disco 3. But you’ll need to fab up a flywheel and some other bits. As well as get the engine running. Or you could look at lifting the entire driveline from a D3 or similar. But lots of work I suspect.
 
budget I can make work, looking around the high 200 low 300 mark, would prefer to Supercharge as everyone straps turbos to things where I live. (myself included as im putting a T25 onto my Rs2000 Van)
So SCing would be something different, that and the fact I had a go of a friends supercharged jag a few years ago and the wail from it has stuck with me haha.
Still have the bog standard LT77 but I have a R380 that has only covered 28k miles so I could always use that If I wished.

I know about the LS swaps as me and a friend with a 110 have discussed it regularly but have opted for the more adult decision to get our own houses first haha.
Seen that Lexus def for sale on ebay last year sometime.

plenty of options to look at but would prefer to play with the engine I have until it decides to go pop
 
Nitrous oxide might be another option if you just want on road wide open throttle performance.

Super chargers are cool. But I struggle to see them really being cheaper than an LS swap. As there is no real donor Vehcile to knick the bits off of.

Btw an R380 is not really any stronger than an LT-77. They are largely the same unit. The R380 is rated at 380nm which is something like 260ftlb torque. Essentially it wasn’t rated high enough for the 4.6 which is why Land Rover offer the manual gearbox with anything other than the 4.0 litre.
Not saying you can’t use the Rover boxes. But you’ll need to treat them a little gentle if you don’t want them to expire once you get higher HP levels.
 
get yerself on the TVR forums..........supercharged / turbo'd 4.0 and 4.6 making over 400 gee gees reliably :eek:
 
Or of course if you want THAT much poke buy a vehicle designed & built to handle it in the first place :rolleyes:
Personally I would have thought a well set up high comp. 3.5 more than enough for a Defender, especially if you want a happy transmission & insurer, but then I'm an old fart.
 
Or of course if you want THAT much poke buy a vehicle designed & built to handle it in the first place :rolleyes:
Personally I would have thought a well set up high comp. 3.5 more than enough for a Defender, especially if you want a happy transmission & insurer, but then I'm an old fart.
No, you're talking sense. Having had a rrc with a decent 4.6, I can confirm the gearbox halfshafts and diff's can't cope. You don't even need to abuse it off road to show it up. I broke a diff bouncing down a kerb pulling away at full throttle from a standstill. Most insurers don't touch mods anymore, so much so that my usual broker is unable to quote anymore, so you end up at the mercy of think of a number and double it types like our sponsor. The op is embarking on chucking 5 figures in a money pit and I can say he'll have regrets at some point unless he's got it to burn
 
Or of course if you want THAT much poke buy a vehicle designed & built to handle it in the first place :rolleyes:
Personally I would have thought a well set up high comp. 3.5 more than enough for a Defender, especially if you want a happy transmission & insurer, but then I'm an old fart.

But where's the fun/pride in building something to your own spec & slightly unique? haha. cant be many SC'd 3.5 V8 defender 90s now can there?


No, you're talking sense. Having had a rrc with a decent 4.6, I can confirm the gearbox halfshafts and diff's can't cope. You don't even need to abuse it off road to show it up. I broke a diff bouncing down a kerb pulling away at full throttle from a standstill. Most insurers don't touch mods anymore, so much so that my usual broker is unable to quote anymore, so you end up at the mercy of think of a number and double it types like our sponsor. The op is embarking on chucking 5 figures in a money pit and I can say he'll have regrets at some point unless he's got it to burn

Its a hit or a miss with some mechanicals whether they fail or not. the case with your diff going sounds like a case of bad luck/ sh**e casting. yes I know extracting more power will put greater strain on the drivetrain, but I'm only talking mid to high 200s in HP its not like im sticking a rocket booster from the space shuttle into it! plus even if it does decide to go it gives me the excuse to replace it with beefier Ashcroft parts.
As for the insurance and mods I recently declared all mods on my mk5 escort van to the insurer after building it.
it was a 1.3 OHV carbed engine to begin with but is now sporting the fuel injected 2.0 16v from the rs2000 oh and there is a T25 turbo strapped to that now.
with engine change + turbo and bigger brakes suspension etc i got a quote of £400 from greenlight & that's with no NCB as all of that is on the defender at £290 for the year.
not too shabby for a 24YO ships engineer.
 
No, you're talking sense. Having had a rrc with a decent 4.6, I can confirm the gearbox halfshafts and diff's can't cope. You don't even need to abuse it off road to show it up. I broke a diff bouncing down a kerb pulling away at full throttle from a standstill.

You don't even have to be so enthusiastic with the gas, I broke a supposedly bullet-proof Salisbury rear diff on a 109 safari, fitted with a Rover P5 engine, whilst doing the same as you but only on a gentle throttle.
 

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