Discovery V8 Engine Improvements

[Petemcc]

Would the p76 have the same bits? It's a rover 4.2 isn't it?

[ice4x4]

The p76 is a 4.4 It has the same bore as the 3.5 litre but a longer stroke with longer conrods and the deck height increased.

[churchill]

We're fitting a 14cux to a P76 at the moment, it's a bit of a mission as you need spacer plates as the block heights are different. From what I hear the 3.9 is the better engine as the block is stiffer and the heads are supposedly better.

[S1V8]

running modified p76 engine, heads valves modified, bored out,different cam four barrel holly,extractors and leave 4.6 rangies in the dust.Have to run ford 9" diff because of the expense of replacing standard diffs.

[oldyella]

Hmm, so starting with a 4.6l would be best for off-roading as its going to maximize low down torque. However, due to the 4.6l having the largest bore, it would probably be worth while getting the machine shop to install new liners to make sure you don't avoid the potential slipped liner issue.

Base specs for the 4.6l are:

Production of the 4.6 ended at Solihull, UK, in 2002. The final version, used in the Range Rover, produced 222 hp (166 kW) at 4,750 rpm and 300 ft•lbf (407 N•m) at 2,600 rpm.

And if you did the following work, Cam, head flowing, Raise CR, you could expect 275hp (205kw). Where a 3.9l you get 235hp (175kW) with the same amount of work which is where I am heading at the moment.

But, instead of the above work, it might be easier to bolt on a S/C and increase the boost & fuel to the desired level of H.P output The 4.6l would be the most reliable in this situation as it has a larger crankshaft and cross bolted main bearings.

[Rotazuk]

Are the dreams that never were .
When I had the classic rangie I had all the parts to make it a 5.2ltr and a supercharger to go on . I was waiting for the 3.9 to give any sort of excuse to come out for some "repairs" but it just trucked on and ultimately the vehicle got sold so all the good bits got sold off . P76 crank , ford 250 pistons and I forget what brand screw type supercharger . Would have been fun seeing how long it lasted thou

Chris

[churchill]

Watch the 4.6's and the 4.0's as they were known for dodgy blocks. Supposedly there where a lot of failures with these engines and the blocks need to be x-rayed to confirm that they're usable other wise you could sink a lot of money into a dud block.

I got this info from a Rover tuning book, might be worth getting your hands on this!

[oldyella]

running modified p76 engine, heads valves modified, bored out,different cam four barrel holly,extractors and leave 4.6 rangies in the dust.Have to run ford 9" diff because of the expense of replacing standard diffs.

Do you know specifically, what modifications were made to the heads?

Might need to talk to a guru about what modifications to make. I'll get some photos of the standard ports this weekend and throw them up.

[LR90NZ]

You could try talking to Tom Taylor of Taylor Automotive.
http://www.taylorautomotive.co.nz/

Tom was upgrading Rover V8 in the 80's & 90's and knows all about 'stroking' them and what is required to get that 'little bit extra' out of them.

Tom was responsible for building the engine in NZ4WD magazine's Project Re-A-Range.

There are several very good books available on the Rover V8 and how to get more out of them.
Among them;
How to Power Tune Rover V-8 Engines: by Des Hammill
Tuning Rover V8 Engines: by David Hardcastle

even Land Rovers own publication "Land Rover 35, 39, 40, 42 and 46 V8 Petrol Engine Overhaul Manual" which is available on line is probably worth investing in if you are serious in rebuilding a Rover V8.

[oldyella]

Big thanks for Rotazuk who is loaning me a copy of Tuning Rover V8 Engines: by David Hardcastle. I'll be keeping an eye out in the mail!

LR90NZ thanks for pointing out that the Rovers engine rebuild manual is readily available online. I used it extensively when the camshaft, lifters and bottom end was freshened up.

Pulled some intake and exhaust valves out of the standard Rover V8 heads I am planning to tweak and had a good look at what I am dealing with.



The exhaust ports look restrictive and look like it could be raised.






Intake port has a few minor defects, but actually better than what I was expecting considering what I have read.




Better do some reading to find out what other areas I should look to improve on, such as combustion chamber, changing valve grind angles etc.

[oldyella]

Some CNC LS7 intake and exhaust port designs...



The subtle curve around the back to cause the air/fuel to spiral as it enters the cylinder is interesting



And some rover ports which have been opened up.



And same heads looking through the ports. I notice this person has removed a significant proportion of the valve guide. Does anyone know what the adverse effects of this would be? I could see if you did it to the exhaust valve, the stem would get hotter and could stick?

[derk]

so long as you keep a good set of functional unmolested heads aside you can play around and experiment as much as you like to see what sort of flow improvements you can come up with it'll only cost you a set of head gaskets, a box of piss and a pizza everytime you want to swap them over

[muddymatt1973]

You can get 300 bhp from a rover v8 without turbo or supercharger...
Well RPI can
http://www.v8engines.com/faq-graph-5-3.htm

[oldyella]

Yep that's a 5.3l though...

Initially I was hoping to get close to that with a 3.9l but after much reading, I have found 235hp is more realistic for a 3.9l engine in a 4wd application and 275hp for a 4.6l in 4wd application.

A more aggressive cam and head flowing, large valves etc can see over 300hp from a 4.6l as well but might be more suited to the race track.

[bryan.daley]

Here's what I did a while back, 3.5 to 5L
Lit up all fours on the 32"'s but not on the 33's.

http://homepages.paradise.net.nz/~bdaley/rp.htm

Bit extreme and required lots of other bits in the drive train to be uprated.

Used a heap of fuel as well!

[Cheesy_Dave]

Here's what I did a while back, 3.5 to 5L
Lit up all fours on the 32"'s but not on the 33's.

http://homepages.paradise.net.nz/~bdaley/rp.htm

Bit extreme and required lots of other bits in the drive train to be uprated.

Used a heap of fuel as well!

Thats interesting, did the block require machining to give the crank enough clearance? Im trying to figure out what my engine is, definitely started life as a 3.5 flapper efi but after taking the heads off to do the gaskets (needed to do the valley gasket so it didnt sound like that much more work....) it has different pistons and an 89mm stroke. From what I gather there is a guy in CHCH that does or at least did these stroker kits

[Ralfie]

Here's what I did a while back, 3.5 to 5L
Lit up all fours on the 32"'s but not on the 33's.

http://homepages.paradise.net.nz/~bdaley/rp.htm

Bit extreme and required lots of other bits in the drive train to be uprated.

Used a heap of fuel as well!

Thats interesting, did the block require machining to give the crank enough clearance? Im trying to figure out what my engine is, definitely started life as a 3.5 flapper efi but after taking the heads off to do the gaskets (needed to do the valley gasket so it didnt sound like that much more work....) it has different pistons and an 89mm stroke. From what I gather there is a guy in CHCH that does or at least did these stroker kits

Tom Taylor of Taylor Automotive in Mt Eden Auckland did a lot of these 'stroker' enhancements to the Rover 3.5 and 3.9 engines. He used to run a Range Rover himself so knows all about them.

[bryan.daley]

Here's what I did a while back, 3.5 to 5L
Lit up all fours on the 32"'s but not on the 33's.

http://homepages.paradise.net.nz/~bdaley/rp.htm

Bit extreme and required lots of other bits in the drive train to be uprated.

Used a heap of fuel as well!

Thats interesting, did the block require machining to give the crank enough clearance? Im trying to figure out what my engine is, definitely started life as a 3.5 flapper efi but after taking the heads off to do the gaskets (needed to do the valley gasket so it didnt sound like that much more work....) it has different pistons and an 89mm stroke. From what I gather there is a guy in CHCH that does or at least did these stroker kits

No, just a bearing race ground down.
If I was to build another I would start with a P38 4.6 block/engine. They are nice engines and you really don't need any power boost mods.

[Cheesy_Dave]

The cheapest way to get power is probably start with something else... It would be pretty easy to put a couple of turbos on a 3.5 though