Im interested in a bit of info on cossie heads.

From what i seem to remember when i measured them stock cossie inlet ports are 24 x 48? mm at the gasket face.

What size would you expect to see on a head destined for a 5-600bhp car? Would the valves be increased in size?

 

25mm in 26mm out imo.

 

You will get the wrong answer asking that question its the biggest error that Tuners make getting port sizes wrong.
Best to say my valves are standard & port sizes not bigger than the ones quoted above & that made 838bhp so be warned go to someone who knows what its all about not the average punter on here.

 

I dont believe there is a right or wrong answer, it all depends on the rest of the spec.

As rod mentions, he is getting massively more power than that on what most people would consider a fairly small head, but then he has a MASSIVE turbo.

Trying to get 600bhp out of a 600bhp turbo will probably require bigger ports than trying to get 838bhp out of a 900bhp turbo etc.

I agree with Rod that its easy to get carried away though, especially when selling things to people as people want to "see" the difference when they buy a head.

 

i recall a post by Karl some time ago where he stated that his std 500bhp head had standard sized holes at the head faces

 

Thats interesting. I was looking at some er, interesting porting the other day and the ports were 30.5 mm at the gasket face!

 

Chip

Mad ades head size is the same as Rods and guess what it makes on a 600hp turbo.

Mark

 

What turbo is Mad Ade on then, I though it was a GT35R capable of well over 600bhp on the right application?

 

Yes it is and its well over 600hp so it shows the ports sizes are correct.

Mark