What do you think of this 16V head?

I know, I shall phone and have myself commited
Edited by: Golden

 

Just to throw things a bit further....

I have been told by a friend well into his Cossies, and does a lot of work with a local FI specialist that a rougher finish is far more desirable on a charged application. Even the satin finish we NA boys have is a little too smooth for FI...

Opinions?

 

one for the tramp that tubs

 

The reason for not having a smooth finish is to create turbulence at the boundary layer.

When air travels down a pipe its at its fastest at the centre of the pipe, getting slower and slower towards the sides. The point where the air meets the sides is called the boundary layer. Here the air starts to stall dropping to virtually zero speed.

On an old carb engine where the fuel/air mix goes all the way down the inlet, where the mixture met the sidewall and the air stalled the fuel would drop out of the air. This then collects as a liquid film on the manifold/head, running into the cylinder as neat, unmixed fuel.

The idea of a rough finish is to create a small amount of turbulence where the mixture meets the manifold/head surface to keep the fuel suspended in the air, if you like throwing it back into the main airflow.

On an injection car this only applies on areas after the injector as before then there is only neat air.

 

Hope that's not too geeky

 

I understand what you are saying Golden - i knew that already

I'm just asking if a far rougher and un-even finish (like the one at the start of the thread) is more desireable on an FI car (like he is gonna be building) than going for a standard/flowed NA 16v head.

 

Sorry, I think I missunderstood, by FI do you mean fuel injection or forced induction? I now suspect you mean forced induction. If so excatly the same applies.
Edited by: Golden

 

Forced induction - yes.

I know the same applies - but would it be more desireable to have a rougher finish than that we NA lovers want...?

 

Been using a sandblaster in work on alloy heads for ages, no ill effects and not too heash. All depends on how course the grit is you use.
Our finish comes out like that above, nice and smooth with a slight texture.

 

Fairynuff... can't argue with that

 

yep. rough as a dogs arse. sorry mate.

however, if it goes well, it might not be as bad as it looks.

 

Off the top of my head Tubs I can't think of any reason why a rougher surface would be benificial on a pressure charged engine.