The V8 Owners Forum -

Hi, Im a newby to V8's. Learnt alot from this forum already reading various post. Grea Forum!!!:)

have a 3.9 V8 Discovery which Im using for off-roading and pulling a 3T trailer during the week.
Im looking in cost effective ways to increase the torque . I want to improve the torque band , ideally from Idle to 3000rpm.

I was wondering if I use a Intake manifold from a 4.0/4.6 Thor V8 which has slightly longer runners instead of a plenum chamber, will that give me the torque from lower rpm, and is it possible to fit above mentioned intake to a 3.9?
I will use the throttle boby that match the Thor intake.

Do I need the change the AFM for 65mm one

What will be the best CAM for my application? (RC87; piper270????)



If the above modifications are possible, will I be able to run LPG?

Thanks
Bosvark



Im also going to clean up/smooth out the exh manifold.

By far and away the best idea is more cubes!, fit a 4.6 bottom end.

Chris.

The cost of changing over to the thor manifold would not be cost productive for the small gain in torque,if you need low down grunt a long stroke 4.6 is the answer.


You can buy a half engine and swap over your heads and ancillaries.

Give Alan Coote at Range Rover heaven a call 07711 369785

Kevin.

Thanks for the replies.
I have a limited budget at the moment and try to make do with what I have.

I will deffinitaly go down the LPG route to make it more cost effective to run. I just looking for ways to make up the power/torque loss when running LPG.
Should I rather look at force induction with the LPG? Will that be a more cost effective way to make up losses and improve power/torque.

Changing the cam may improve matters, but the thing to bear in mind is that Land Rover tuned their engines for torque rather than power, so tweaking is unlikely to make a significant difference.

A blower of some sort will of course help a lot, and can run just fine on LPG if you get a decent kit (which will cost you at least a grand!) The cheapo kits will give more trouble than they're worth.

Chris.

Seriously, try a 3.5 EFI camshaft, ETC6099. Be aware that this is NOT the same cam as a 3.5 carb or SD1, it is the cam for a rangerover classic 3.5 EFI circa 1985ish.
In a 3.9 this will boost the low to midrange torque considerably, but you may have to get some re-mapping work done also, by someone like Mark Adams. Don't cut corners, get the mapping done right and this cam will do what you wish.

Thanks for all the info.

I'll start with the re-mapping, and get in contact with Mark Adams.

Badger, do you know wher I can start looking for that cam, I'll scan E-bay for starters.

Is there any spesific LPG kit I need to look for?
Is this kit any good? MARRELLI OSCAR sequential injection LPG conversion kit .

Cheers

what does it do to top end?

prins are a good make

That cam won't really alter the top-end by much at all. Try Rimmer Brothers.
As for LPG, personally I'd fit something like OMVL Dream or OMVL Superlight (same thing really), Prins is good but wa-a-a-ay too expensive for what you need. Stay clear of the lesser-known/polish import junk and stick with the mainstream Italian stuff (OMVL, BRC, Tartarini, BiGas etc) and you'll be fine.

Let us know how much mark adams wants for re-mapping - especially as you discounted the 4.6 engine as too expensive.

Eliot wrote:Let us know how much mark adams wants for re-mapping - especially as you discounted the 4.6 engine as too expensive.

Can he really re-map successfully without having the individual vehicle on a dyno?

Can't really see the point on a mark adams chip at £400.00 + setting up costs on a standard spec engine.

If looking to obtain more torque with the standard cam recommended earlier I would think the most gains will come from setting up the advance curve in the Lucas dizzy to take advantage of LPG by steepening the curve and limiting total advance so that you can run increased initial advance.

An increase in compression will also assist torque production specially on the detonation resistant LPG.

I would recommmend a 25thou skim off the heads which will get you to approx 10/1 on an existing 9.35/1 engine which will be very cost effective.

You will need to reset the lifter preload but shims under the rocker pillars will be ok for a low reving engine, 15 thou. should be ok but to measure is better and 25thou, betwen the lifter piston and C clip retainer should be fine.

If fitting new cam a new set of lifters must be fitted and the cam broken in to manufacturers spec. You may be able to achieve the same result by fitting an offset key to your existing cam if in good condition to advance the cam by 3-4 degrees but I haven't done this on a Rover V8 but was standard practice on other engines to move the power curve up or down.


So for the cost of a heads skim a pair of advance spring for the dizzy and an offset woodruff key for the cam say £60 you could achieve your requirements.

Just checked Real steel do a 4 deg. offset key for the rover for £10.00 and the shims for the rocker pillar are £16.00 + head and valley gaskets £35.00

Kevin

if you are on a budget and want more torque, go for a second hand 4.2 crank and a set of suitable high compression pistons, I've forgotten which ones but but one of the standard rover ones with a bit skimmed off the top of each one. You don't need to go for the full 4.6 conversion so it saves on the cost of the whole rotating assembly and block and no worries about top hatting the liners.
I would forget Mr Adams, don't know anyone who is really happy with the results of one of his remaps, and he is not cheep, you will have parted with at least £1k by the time you decide you are throwing good money away after bad. If you want to go for an after market ecu talk to Phil at Extra efi.
Best regards
Mike

Hi, thanks fo all this info

The 4.2 crank, will that give a longer stroke? = more torque?
This will be a low revving motor.

So to recap: 1. 3.5 efi RRC cam with new lifters
2. 4.2 crank
3. Heads skimmed 25 tho
4. shimming rocker pilars 15 tho
5. stiffer advance spring in dizzy

Is this cam package any good? at £340?

ROVER V8 ENGINE fast road hydraulic camshaft kit.

KIT INCLUDES 200HCAM/ heavy duty metal timing chain set, lifters , valve springs,BASIC gasket set. INC COMP HEADS AND VPAN.

THIS IS OUR BEST SELLING FAST ROAD CAM KIT.

FITS ALL CLASSIC ROVER V8'S

INSTALLS WITH NO MOD'S IN A STD ENGINE,

YOU MUST STILLCHECK CLEARANCES, AS GOOD PRACTICE

VERY TRACTABLE , GOOG LOW END TORQUE AND MID RANGE ,PROGRESIVE POWER , FREE REVS UP TO 5500 STD RED LINE .

GOOD IDLE. DEVELOPED FOR THE MODERN ROVER V8


If I only run LPG, can I use the injecter holes on the inlet manifold to connect the LPG up too.
Is there propper injectors for LPG? I understand that LPG injct at higher pressure than petrol, will you be able to use diesel injectors instead?
Will intake design have any influance on torque/power?
What about inlet flapper size?

Regards Chris