Thread: Manifold options for 3.5 V8

The early EFI Rangies are a bit finiky when it comes to cam replacements. I remember my old man's 88 Rangie they put a performance cam in it and it was never right. It idled like crap and although we had set the valve timing spot on, the std flapper injection wouldn't want to tune or run properly, mainly because you can't adjust it. Aftermarket ones are much better in this sense (duh )

My suggestion, keep the cam standard. A free-flowing exhauist will set you right, extractors are a waste of brass on a EFI rangie. Also on dad's old 88 Rangie, we had extractors fitted and performance was very minimal and not worth the $$$ for extractors. Older carbie RR's benifit from extractors as the exhaust manifolds are very restrictive compared to the EFI 2-pot manifold which are a better flowing manifold as far as stocko ones go.

Good luck with it.

Trav

I have done lots of things over the last 15 years to try to improve economy on a 3.5 and later a 3.9.
I got down to about 13.2L/100Km on a 3.5 with a fairy overdrive and a Federal injection setup running 245.75X16 tyres at 105-110KMh. This was on very flat ground.
BUt it was a pain to drive with the overdrive, as the merest hint of hill demanded a changedown( with a 77 LT95).
On my 3.9 I have a unichip , Thor manifold, Flowmaster exhaust, modifed heads, and several dyno tunes to set up. I have over 50% more power down low. My theory was/is that it must save fuel if the auto does not change down all the time , due to smaller throttle openings. I also have full synthetic oil in engine, auto, transfer, and diffs.

Well the extra power is great , but I do not think that the economy has changed much. It still takes a certain amount of horsepower to drive all of those gears, and carry the weight. I tend to take off much harder now, because I can!!!! LOL.

So if you are concerned with fuel economy ONLY, I would look at the rolling resistance ie skinny tyres with road tread ( I just fitted a set of 205.16 BFG Long Trails and they seem to give quite an improvement over my 245.75X16 BFG ATs , taking into account the 6% diameter drop My estimate is 1-1.5 L per 100 KM).
Put friction modifiers in oils in gearbox, transfer, diffs
Lighten the car by taking off steel bullbars and rear steps
Reduce the weight of your camping gear
Maybe fit thermo fans if you never intend to drive in sand on hot days.
HEI would be good but IMHO will do nothing for economy unless the current system is worn out and causing misses.

Forget the cam. A D11 cam is a longer duration cam than say a 3.9 injection. 3.9 is about ideal.

Exhaust mods do help at full throttle high revs for power but at cruise when the engine is just lazing along there is no difference.

With more power you will use more fuel in trying to keep up with modern traffic up hills etc.
I have also tried a hiclone on the 3.9 and have those tin pellets in the tank of my motorcycle to test whether there is an advantage. ( before committing $300 for the size for the Rangie)
The answer is NO NIX NADA.
So just optimise what you have by maybe getting a dyno tune and bringing the old injection back to what it should be, and concentrate on reducing weight, rolling resistance, frontal area.
BUT I know all that is not fun like hotting a motor. Good luck.
Regards Philip A

Originally Posted by PhilipA

I have done lots of things over the last 15 years to try to improve economy on a 3.5 and later a 3.9.
I got down to about 13.2L/100Km on a 3.5 with a fairy overdrive and a Federal injection setup running 245.75X16 tyres at 105-110KMh. This was on very flat ground.
BUt it was a pain to drive with the overdrive, as the merest hint of hill demanded a changedown( with a 77 LT95).
On my 3.9 I have a unichip , Thor manifold, Flowmaster exhaust, modifed heads, and several dyno tunes to set up. I have over 50% more power down low. My theory was/is that it must save fuel if the auto does not change down all the time , due to smaller throttle openings. I also have full synthetic oil in engine, auto, transfer, and diffs.

Well the extra power is great , but I do not think that the economy has changed much. It still takes a certain amount of horsepower to drive all of those gears, and carry the weight. I tend to take off much harder now, because I can!!!! LOL.

So if you are concerned with fuel economy ONLY, I would look at the rolling resistance ie skinny tyres with road tread ( I just fitted a set of 205.16 BFG Long Trails and they seem to give quite an improvement over my 245.75X16 BFG ATs , taking into account the 6% diameter drop My estimate is 1-1.5 L per 100 KM).
Put friction modifiers in oils in gearbox, transfer, diffs
Lighten the car by taking off steel bullbars and rear steps
Reduce the weight of your camping gear
Maybe fit thermo fans if you never intend to drive in sand on hot days.
HEI would be good but IMHO will do nothing for economy unless the current system is worn out and causing misses.

Forget the cam. A D11 cam is a longer duration cam than say a 3.9 injection. 3.9 is about ideal.

Exhaust mods do help at full throttle high revs for power but at cruise when the engine is just lazing along there is no difference.

With more power you will use more fuel in trying to keep up with modern traffic up hills etc.
I have also tried a hiclone on the 3.9 and have those tin pellets in the tank of my motorcycle to test whether there is an advantage. ( before committing $300 for the size for the Rangie)
The answer is NO NIX NADA.
So just optimise what you have by maybe getting a dyno tune and bringing the old injection back to what it should be, and concentrate on reducing weight, rolling resistance, frontal area.
BUT I know all that is not fun like hotting a motor. Good luck.
Regards Philip A

So... what you're saying Phil is trhat I should just do the exhaust on my 3.9 Disco because it will sound ****ing heaps better

Jeezzzz... There's loads you can do to the V8, it just comes down to $$$

The flaw, however, to your initial question is trying to get an increase in power while increasing efficiency.... In the words of Scottie "You can't break the rules of physics".

If you want to improve the efficiency, buy a diesel. Simple as that! The V8 does have a drink problem and it can't be cured. You can make the cost of running the V8 cheaper by fitting an LPG system but it's all artificial as the savings are through tax breaks. Once fitted, your savings are then in the hands of the government.

For performance... Well, the sky's the limit. If you want to tune it, you can:

Fit a custom exhaust system.
Fit a hi-lift & long duration cam.
Pocket the pistons (for the cam).
Holley carb & manifold.
NOZ....

You get the picture.

Mark.

95 Disco.
Yeah, but watch out for the dreaded drone. Most glasspacks will drone.

I have fitted a Flowmaster lightly baffled muffler and have a nice "mouse" sound at low revs , but no drone. At first I had only a straight through resonator at the back, but SWMBO thought too loud, so I fitted the biggest dog leg straight through that would fit and now its perfecto.( but you do not hear the nice Brrrrr so much inside)

By mouse it has a definite V8 beat like a 350 chev, which very few systems give you on a Rover.
Regards Philip A

To get all those mod's done will cost a lot of $$$$ and in the end you could use the $$$$ for petrol to run the thing

Yeah I know I'm pushing ****e uphill trying to get it more economical but I'm going to do it anyway. I like tinkering so I wanted to do as much as I could before I put it on gas.

If I get jack of it all then I will just bung in the 4.4, EFI it and run it on gas. Brings me to another question..........

what sort of compliance issues (wrt emmission control) are there with putting this motor in an 86 model?

Mango

Its illegal for Range Rovers produced after 1976 when a particular ADR was introduced (ADR28?)saying that an engine can be fitted as long as it is of the same age or younger than the recipient car and has all emission controls. coincidentally I think the last P76 was 76.

BUT lots of people have them and do not seem to have any problems getting RWCs or transferring rego. I imagine you could have a problem if you were defected and went over the pits or had a RWC inspector who actually knew enough to recoginise a P76 motor.

regards Philip A