300bhp/ton said:

10% power hike is probably optimistic, hugely so. But the cams and followers do wear, so replacing a worn one with a new one will make a big difference.
All you need to do is look at the figures. An EFI 3.5 is 165hp and a 3.9 is 182hp.... if all you had to do was put the 3.9 cam in the 3.5 to gain 16.5hp (181.5bhp). Why did Rover go to the expense of adding an extra 0.4 litres of displacement. These figures would also suggest that 0.4 litre is only 0.5hp extra over the cam swap, which just doesn't make any sense at all.

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norseman said:

That's why I used the term allegedly, although in my experience there can be disparity between figures & real-world driving experience.
I will however stand by my advice re. stroking the 3.5efi as I knew the LR mechanic who carried out the rebuild on his Classic. He was in the habit of towing a large twin axle caravan & needed more grunt but didn't want to go for a 94mm bore V8. Grunt it certainly did, to the eventually detriment of the HP22 'box

Another choice might be an ECU remap ?

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300bhp/ton said:

BTW - if you stroke the 3.9 you get 4.8 litres and even more power and grunt than the 4.3.... but for the same basic cost.

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