What engine to install, 4.6 vs. 3.9, to my 1986 RRC

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Not sure but I dont think the RRC ever came with a 4.6 as original and certainly not a THOR.
Acceleration wise the 4.6 is better but it is a Rangie so who cares?
They can both pick up their skirts and move when they want to especially when remembering that they weigh pretty close to two tons
 
Just to put my experience with the rv8 on this thread, I've rebuilt a few over the years and the old 3.5's were put together well, I'm just putting a 4.6/3.9 together and both motors on strip down had major issues caused by really bad engine builds...
 
oakey said:
Not sure but I dont think the RRC ever came with a 4.6 as original and certainly not a THOR.
Click to expand...

I believe Overfinch transplanted a few, but the only factory option (other than the standard motors) available on Classics was the 4.2, normally specified for the LSE.
 
sabini loren said:
Just to put my experience with the rv8 on this thread, I've rebuilt a few over the years and the old 3.5's were put together well, I'm just putting a 4.6/3.9 together and both motors on strip down had major issues caused by really bad engine builds...
Click to expand...

That has been my understanding as well. I believe matched (balanced) pistons were used in 3.5 assembly for one thing, whereas larger capacities units were built up from line-side components then the assembled engine was dynamically balanced with weights added to the crank pulley?
 
norseman said:
nb. 'Real Steel' used to market a stroker kit for the 3.5, taking the capacity to 4.3 as you say.
Don't know if the product is still on the market.
Click to expand...
The Buick version of the engine also lived on the USA and was even converted into a V6 that was in production right up until the mid 1990's I think.

The stroker kit people used to sell was picking parts available from the US versions. If you know the part numbers you could do the same still.

3.5 would stroke to 4.3 litres and the 3.9 to 4.8 litres.
 
Budaah said:
I would like to thank you all for your kind responses, sharing your experiences and opinions. A quick recap of your discussions lead me to believe:

1. I should not worry about the millage;
2. 3.9 is preferable to 4.6;
3. The quoted prices to me seem to be fair.

I did not notice any comments about the acceleration of 3.9 engine vs. 4.6. Is this because the difference is negligible, or as a Range Rover driver, it is the last thing on anybody's mind?
Click to expand...
If the money difference is not a direct concern, then the 4.6 will easily out perform the 3.9. It isn't just the PEAK power, it is the extra torque trough-out the rev range, that you only get with extra displacement (or boost).

Having top hat liners fitted to either engine will be pricey. You may want to research this before proceeding.

I would also recommend a new cam and followers. RV8's are renown for wearing them, causing low power. A slightly more perkier cam would also wake any engine up too.

4.6 engines come in two flavours. The earlier ones 1994 - early 1999 use the same injection system as you RRC. From 1999 on they used a Bosch injection system and a different intake manifold. If you are getting a latter engine, then I suspect the person fitting it will swap over the intake from your current engine and use the injection system from your current one too. You'd need to do more work to retain the latter intake manifold and Bosch injection or some other standalone injection system. Which means more money.

For reference, the 4.6 block is the same as TVR used in the Chimera, only they called it a 4.5 litre.
 
300bhp/ton said:
If the money difference is not a direct concern, then the 4.6 will easily out perform the 3.9. It isn't just the PEAK power, it is the extra torque trough-out the rev range, that you only get with extra displacement (or boost).

Having top hat liners fitted to either engine will be pricey. You may want to research this before proceeding.

I would also recommend a new cam and followers. RV8's are renown for wearing them, causing low power. A slightly more perkier cam would also wake any engine up too.

4.6 engines come in two flavours. The earlier ones 1994 - early 1999 use the same injection system as you RRC. From 1999 on they used a Bosch injection system and a different intake manifold. If you are getting a latter engine, then I suspect the person fitting it will swap over the intake from your current engine and use the injection system from your current one too. You'd need to do more work to retain the latter intake manifold and Bosch injection or some other standalone injection system. Which means more money.

For reference, the 4.6 block is the same as TVR used in the Chimera, only they called it a 4.5 litre.
Click to expand...
There was even a 5.6 litre version:eek:
 
The 3.5 was built on the old Rover engine line, back in the days when Rover took pride in how things went together. Standard pistons came in a range of sizes, with about half a thou difference between. Each piston was matched to a specific bore to give the exact tolerance required. In addition each piston and con rod set was weighed so that a matched set would be fitted to the engine. Between these two operations you got a very well balanced and smooth engine.

Rover used to go to extreme lengths to ensure they produced the best product. For example they has a gear testing jig where gear sets would be composed and run, with a fellow listening to them through a special ear piece to determine if the noise they generated was within acceptable limits. If not, then he would take out one of the gears, substitute another from the box and try again until he liked the sound of the two gears in mesh.
 
Marshall8hp said:
The 3.5 was built on the old Rover engine line, back in the days when Rover took pride in how things went together. Standard pistons came in a range of sizes, with about half a thou difference between. Each piston was matched to a specific bore to give the exact tolerance required. In addition each piston and con rod set was weighed so that a matched set would be fitted to the engine. Between these two operations you got a very well balanced and smooth engine.

Rover used to go to extreme lengths to ensure they produced the best product. For example they has a gear testing jig where gear sets would be composed and run, with a fellow listening to them through a special ear piece to determine if the noise they generated was within acceptable limits. If not, then he would take out one of the gears, substitute another from the box and try again until he liked the sound of the two gears in mesh.
Click to expand...
blocks and pistons were matched ie a h block would have h pistons
 
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