"Upgrading" engine by fitting later manifolds?

I was just wondering if it's possible to fit later manifolds onto an earlier VR? So that'd be like say thro manifolds onto a 3.9? And there'd be anything to be gained by doing so? Maybe better flow or improved powerband / delivery?

You could try fitting tubular manifolds.
Or porting & polishing your existing ones, but if you're looking at improvements then you need to consider doing all the ports - inlet & exhaust.
Fitted a stainless sports system with tubular manifolds to my 3.5EFi years ago but apart from the noise - nice, but can get a bit tiresome on long journeys - I'm not really sure it made much difference.

Assuming you have a 3.5, changing the camshaft to a 3.9 item is allegedly good for 10% more power, but I would imagine the torque (curve) is more important on a heavy 4x4.
Generally speaking success in creating more power means a package of improvements rather than a single modification. Bolt-on gizzmos have their limitations

Jayridium said:

I was just wondering if it's possible to fit later manifolds onto an earlier VR? So that'd be like say thro manifolds onto a 3.9? And there'd be anything to be gained by doing so? Maybe better flow or improved powerband / delivery?

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The manifolds all appear visually to be the same with 3.5 or 3.9 a cast lump of metal.

The EFI ECU that the 3.9 has wont like the alteration so it and will re-adjust… maybe.
12 years ago I fitted a Janspeed cat-back system to my 3.9 and on first startup the engine went up to 2000 rpm and sat there for two minutes, the ECU thought about it, and then rpm dropped straight back down to the normal 750rpm.
With the exhaust replacement was an instant improvement to the throttle response and and a bit of a change to the exhaust tone, thats it.

Cool - looks like it'd be very small gains for potentially big upset, so I'd best leave it alone then.I had been thinking on sportier exhaust manifolds and or Thor inlet manifold:


But in light of what's been said here I've decided to leave it alone, and instead ordered Rover-Gauge / ECUmate set up and an ignition upgrade kit comprising of a MSD Mallory Uni-Lite transistorised distributor, the matching fancy MSD highpower coil and a MSD Street Fire Capacative Discharge Ignition module. That way I've got a right good spark and can play with the ECU

Might be a wise move, esp. if it's an EFI
Best improvement I am aware of (by an indie. mechanic on his own 3.5efi auto) was to stroke the lump to 4.3L using a kit from a company called Real Steel, but I don't know if they are still trading.

norseman said:

Might be a wise move, esp. if it's an EFI
Best improvement I am aware of (by an indie. mechanic on his own 3.5efi auto) was to stroke the lump to 4.3L using a kit from a company called Real Steel, but I don't know if they are still trading.

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That sounds interesting! More power is always a good thing, and I have no interest in reboring an otherwise perfectly fine engine block!

hef19898 said:

That sounds interesting! More power is always a good thing, and I have no interest in reboring an otherwise perfectly fine engine block!

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That's what LR did to produce the 3.9 & that was the beginning of the slipped liner syndrome
The downside of the 4.3L mod. is that the output is close to (or possibly over if you have a heavy right foot) the standard ZF 'box's handling capacity.

The plan is to stick with the LT95, which on theory supports a Isuzu 3.5 turbo diesel. Well, we'll see what a new timing chain and gears and the new cam shaft do first anyway. But no, I don't want any slipped liners! It's an offroad car and not build for racing!