rover 4.6 upgrades.

matchmetisse · Post by **matchmetisse** » Fri May 30, 2008 2:23 pm

Hi I have just purchased a 4.6 engine to fit in my LR disco2 to replace the 4.0 that is currently fitted and has a bad tapping noise,before the engine goes in I was thinking of getting some more torque/power from the engine would a cam change be best for this and if so what profile is considered the best?I also have a new pair of heads,what would be the best to do to these and if possible who to do them?Thanks a lot for any info.Ant

RoverP6B · Post by **RoverP6B** » Mon Jun 02, 2008 10:34 pm

Going from 4.0 to 4.6 you will notice a big increase in torque, which will be felt in terms of increased pulling / overtaking ability.

In a Discovery, I would feel that you would want to keep as much low down to mid range torque as possible.

Therefore, leave the heads exactly as they are. If you open out the ports etc, the gas flow velocity decreases for a given engine speed, with throttle response reduced. This is not want you want in a Discovery!! Especially at low engine revs.

As for the camshaft, same largely applies.

Ron.

matchmetisse · Post by **matchmetisse** » Tue Jun 03, 2008 11:09 am

Thanks for the info Ron,so the best bet is too leave the 4.6 standard?I did forget to mention the disco has manual transmission,and it is mainly used for road work except for pulling a trailer when we go motocrossing.

kiwicar · Post by **kiwicar** » Tue Jun 03, 2008 2:57 pm

For my two pence worth, I would treat the heads to a 3 angle valve seat job, open out the throats (behind the valves) as far as you can using standard valve inserts, blend into the bowl area, bullet valve guides and waisted valve stems leave the surface about 80 grit roughness (or medium fine wire brush) don't take anything off the port floor on either inlet or exhaust, match the head to the inlet manifold runners but do it without increasing the port face area by more than 10%.
Relieve in the area where the pushrod goes past the port but only there no more than 1/2 inch either side and only in that area (and don't go through the port wall).
With cam choice you could safely go for 10 deg extra timing on inlet and exhaust provided when you do you get more lift (ie. don't buy a pattern that just gives you more duration) and choose one with an LSA of 110 to 114 degrees and it should give you stomping torque. I would add a set of higher ratio rockers if you can. I ran an R87 cam in a 3.5 which has a bit more timing and lift than standard with a set of heads to roughly this spec in a Range Rover, worked a treat.
Mike

matchmetisse · Post by **matchmetisse** » Tue Jun 03, 2008 7:08 pm

Thanks Mike thats great info,would you reccomend anyone to do the headwork?

kiwicar · Post by **kiwicar** » Tue Jun 03, 2008 9:15 pm

The guy who did mine was based in High Wycombe, and it was about 9 years ago. The guy who did it used a tool that was centred using the valve guide to bore out the throat to about 1/4 inch into the then used a set of seat cutting tools to do the seats, the rest was blending using a die grinder. The bullet valve guides can be bought form various of the sponsors of this site as are the valves (sd1 valves). It is a basic stage 1 (some would describe a stage 1/2) but leaving the surfaces rough.
A description of what to do is in "how to build, Modify and power tune Cylinder heads" by Peter Burges and David Gollan ISBN 1-901295-45-1.
Again if you contact one of the sites sponsors and describe what you want they will port a set for you.
I think though you could do them yourself if you had access to a piller drill and seat cutting tool to do the three angle job and opening out of the throat area and a die grinder to do the blending.

Robrover · Post by **Robrover** » Fri Jun 06, 2008 3:47 am

I'm building up a 4.6 to put into my Disco 1 in place of the long serving (and extremely reliable) 3.9. My intention is use to high torque cam along the lines of the RP4, with buckets of toque low down, Outlaw extractors, re-curved dissy and . The heads will be re-used from the 3.9 but cleaned up and 3 angled, nothing too dramatic as the main aim here with a heavy 4x4 is big torque rather than outright hp, so big ports and valves are out.

I'll also need to fettle the Hotwire 14CUX to fuel the bigger capacity, either by re-chipping or more probably adding a Unichip module to the existing ECU and setting it up on the dyno.

I'm looking at developing around 240 -260 bhp, but with 300+ ftlb of torque which is what's important in shifting a heavy 4x4.

Some years ago Litchfield fitted a 5 litre TVR into an otherwise pretty much standard auto Disco, re-engineered it specifically to provide massive torque, and it did 60 mph in under 7 seconds.

CastleMGBV8 · Post by **CastleMGBV8** » Fri Jun 06, 2008 9:01 am

Peter Burgess does a Stage 1 Econotune pr of heads at £615.00 + VAT which would be a good choice for your engine. He is one of the most respected cylinder head modifiers in the Uk and has customers all round the world. He would also advise you of a suitable cam to match the heads and provide plenty of low down grunt.

http://www.mgcars.org.uk/peterburgess/page18.html

Kevin

matchmetisse · Post by **matchmetisse** » Fri Jun 06, 2008 3:24 pm

Very intresting stuff.Would fitting the pistons from my 4.0 with new rings from the 4.6 be worth while as it will increase the compression?I remember Burgess from my MG days,I had a Aldon 1950cc 1973 roadster

Boosted LS1 · Post by **Boosted LS1** » Fri Jun 06, 2008 9:16 pm

Peter is definately the guy for head work. You get no bullshit, just a very comprehensive service, plus he's the only bloke I know who made his own flowbench using 3 hoovers and it works a treat:)

I've known him for probably 20 years and wouldn't go anywhere else.