The V8 Owners Forum -

I am not going to go a big power 4.6 engine as it is going in a slow lumbering big 4wd so I have not looked at getting the inlet manifold deburred but the ports in the heads were a bit rough so I just had the dags taken out rather than a full on port and polish.

My local engine builder was able to do this so I would ask your local engine builder to do this and they should be able to do it. I would only go for a deburr rather than a full on job as in many cases a "port and polish" has been shown to be counter productive to mixing of the mixture.

Garry

I believe that's more for carburettor engines as the mixture goes all the way through the manifold. As mine is fuel injected the air doesn't see any fuel until it is pretty much in the head.

The airflow still need to be swirling when it picks up the fuel squirt from the injector to get a better mix of fuel air or else the rich mix of fuel created at the point of the squirt will carry into the combustion chamber - a swirling air flow will mix the fuel better.

In my view traditional porting and polishing is no longer a great move - but also heavy casting dags, while creating swirl are restrictive so the compromise is to have the dags removed but leaving the surface a bit rough. Of course if the inlet manifold/heads cannot breathe the air flow required, then making them larger will be needed.

Good luck with it.

Garry

I'm not sure what kind of finish afm leaves and if you can choose a finish. I'm not too worried about polishing the manifold just to open it out a bit as it does seem very restrictive

I've done a bit of googling, but I can't find anybody in the UK who offers AFM for the likes of us.......

Chris.

http://www.deburring.co.uk/our-services ... machining/

This is who I was gonna try.

I think I would much rather hand a part over to a man who has done the task before and knows what is required to achieve what you are looking for.

Here you go mate I have pumped some slurry through your manifold for you which just indiscriminately scrapes away as whatever we pump it through

You can create as much restriction to gas flow by taking material from the wrong place as you can by improving gas flow by taking material from the right place.

Unless proven in your specific application - leave it alone

Removing casting marks and flash from a manifold does very little - to get more power out you need to get more air in and more air requires material removal from the right places.

Tony22593 wrote:http://www.deburring.co.uk/our-services ... machining/

This is who I was gonna try.

I did look at them, but wasn't convinced that they did engine parts.

Chris.

Are there any alternative manifolds? Apart from the gems one? Does the gems one really lose that much torque?

There are plenty of options, from the Aftermarket to the bizarre....
http://www.mez.co.uk/ms12-new.html

Ok what is a good inlet manifold upgrade in my application for a Landrover discovery? Modify the original or upgrade. Like I said I don't want to spend money on updated heads if the inlet manifold is going to hold it back.

Have a look at this upgrade, which doesn't seem to need any machining/honing and can make a difference to the engine's performance....
http://www.tornadosystems.com/product/b ... or-engine/

Yeah I was aware of mark Adams/tornado systems. Was probably going to go down that road when it's completed anyway to ensure all feeling is right etc.
Am I better of spending money just increasing the capacity further? To 5 litres using striker crank? I have seen real steels 5.0 and it looks impressive

Last time I asked Real Steel did not have a complete stroker kit available. Their current online catalogue only shows a stroker crank.

I would start with the ECU if I were you. You are already doubting the intake tract for the 4.6's breathing, so going up to 5.0 will put a bigger load on the manifold.
Find out if Tornado's ECU is suitable for the 5.0 without serious modifying, and if so, then you could always go to 5.0 later, once you have had a chance to drive the car a bit to decide.