The V8 Owners Forum -

I may be able to get some 5 litre TVR big valve heads to use on my 4.6 Thor Range Rover.

Would the effort in changing things be justified in the expected gains over the standard Rover 4.6 heads given that the car is at the mercy of the learning capability of the Bosch Motronics ECU? (which is not mappable AFAIK at the moment) I would prefer not to mess with the electronics other than mapping on my daily driver!

I'd like a bit more power at high revs for motorways and ideally better fuel economy, but I know not to push my luck too far I know TVR heads flow pretty well for standard Rover castings since I have a Griff with the same heads.

And what are a set of TVR big valve heads worth, assuming they are in good condition? They look to be complete with valves, rockers and so-on.

Thanks.

I would think you would benefit from changing or modifying the existing inlet manifold with the extremely long runners to one with shorter tracts, might be at the expense of some low down torque but should let it breathe a lot easier especially at higher revs, = more hp

TC

Hi
I would think, if you are planning to only change the heads that you would get a better result with a basic 3 angle valve job and basic clean up of the standard heads (opening the seats inserts out as far as you can) with the back of inlet and exhaust valves cut back to 30 degrees to the seat. The TVR big valve heads will be ported to give their best improvments in flow at higher lift than your standard cam produces probably at the expence of low lift flow and port velocity. If you were going to go for headers and more lift from the cam then I would go for the big valve heads aswell.
Best regards
Mike

Never used TVR heads but have been told the ports are too big for the smaller or lower revving engines. If this is the case you will probably turn your heavy Rangerover into something not that nice to drive specially in the lower revs.

mmmm 5.0 TVR big valve heads
got some stg3's here

kiwicar wrote:Hi
get a better result with a basic 3 angle valve job and basic clean up of the standard heads (opening the seats inserts out as far as you can) with the back of inlet and exhaust valves cut back to 30 degrees to the seat.

I agree.
That thor manifold isn't designed for top end power - I've got photos on them on the manifold archive, not what I would call a performance part.
Come on dave, stop messing around and drop an LS1 in it!

(i've recently updated the archive, someone has converted the RPI boxer manifold to EFI!!)

I can't afford an LS1

I wouldn't be against fitting a compatible cam during the operation. I expect the original has passed its best anyway.

I like the Thor manifold. With a bit of work, I think it could flow quite nicely. (Not as well as my twin plenum of course!)

Fancy some TVR heads then Tony?

dnb wrote:I can't afford an LS1

I wouldn't be against fitting a compatible cam during the operation. I expect the original has passed its best anyway.

I like the Thor manifold. With a bit of work, I think it could flow quite nicely. (Not as well as my twin plenum of course!)

Fancy some TVR heads then Tony?

I would love a set mate,
as i think they would work nice on the new 4.6
but none never seem to come up,