Rover p6 tuning

[paolow]

can anyone help? Im looking to bin my modern jap nonsense and take on a P6 but im fully aware that the power output wont be what Id like. to that end im going to be winding up performance using second hand parts etc but dont know what the best carbs etc are. can anyone help? ultmitely i dont know what power im going for - not stupid amounts - but id like to add a good 100 bhp to the output in total over various stages. i dont want forced induction as yet (turbos are horridly expensive when theres 2 of everything) but its not impossible in the future. Certainly i want to bin the su carbs and change the exhaust - ive a total of 4 pairs of heads from v8s - which are best for breathing and/or modding? ive got ones from p6s, sd1s, and others of unknown origin. anyone help?

[100SRV]

Hi,
what is wrong with the SU carburetters? What about fitting a 3.9 engine or larger on EFi? The EFi manifolds and front system are certainly better for breathing than the standard 3.5 kit but I'm not sure of the installation in a P6.

100SRV

[v8 racing]

Pound per bhp, the first thing i would do is scan ebay for a 4.6 engine and webber 4 barrel carb, this will give you 225 ish bhp straight the way for around £1200, after that you can then do heads cam etc, there is nothing on your p6 that will be worth saving

[Lashout_UK]

The short-stroke 3.9's a good lump as well - revs much better than the 4.6 and I've seen real outputs of 270BHP from one with excellent heads, good pistons and a relatively standard bottom end. Runs high 12s at the pod without gas

Realistically, about 200BHP without forced induction or gas, is the limit for the 3.5. After that you start getting into serious development (like Nic Mann, anyone ).

[SplatSpeed]

drop a small block chevy in there

no replacement for displacement

[paolow]

thanks for all the pointers guys. in response:

id be looking to bin the su carbs because theyre rubbish
im reluctant to swap blocks though recognise the restrictions the 3.5 now has.
would there be any mileage in just working the top end of the unit for power gains or is this really a waste of time?
The only reason is that the engine currently in there is in excellent condition and is at least a known quantity. if i start messing around swapping blocks im going to have spent hundreds before i even get it started!

[Chassis 33]

IIRC SD1 heads flow better than P6 heads, mainly due to larger port sizes.

To install hotwire EFi you need a power supply for 3 wires, the rest is self contained, flapper EFi needs a couple more wires to be plumbed in however it has the advantage that 3.5l flapper ECUs are more common than 3.5l hotwire ECUs. Also for any EFi conversion you need a high pressure fuel supply not the 5pis or so that the SU's work on, and a fuel return to the tank.

Regards
Iain

[Church of Noise]

Check out what Peter Burgess ( offers in terms of porting/polishing/... : http://www.peter-burgess.com/page18.html
I just bought a set of his modified heads and am eagerly waiting to install them.
He did the work on 2 MGB cylinder heads for me before and I was very impressed on both occasions.

[Lashout_UK]

If you fit EFi, you'll have to fit EFi heads, or notch the existing inlet ports on the cylinder heads you have.

The EFi heads have a notch to clear the injector's spray pattern and without the notch you can loose a fair bit of performance and efficiency.