Just got the engine out of my hill climber and looking for something to do while the engine is 'done' at API.
Putting the head/manifold gasket on the headers, the difference in diameters is a huge 5 mm. It is realy worth all the effort to grind them to match the gasket diameter?
911

 

911,
The answer to that is yes in a turbo you want to have the least restrictions to the exhaust gasses as you said earlier there is a 5mm step from the heads to the manifold I ground my manifolds back to suit the gaskets seemed to improve things but until next time I put the car on a r/road I woulnt know how much of a differance it has made there will have been people who have and will have the r/road results on here.Hope that is of some help.

 

API do this to motors that are being repaired as well if you ask.

 

911, said it yourself really ..... 5mm step between manifold/head. If the manifolds already off, and you've access to the right tools ( air driven die grinder and 13mm tungsten carbide cutter, latter from RS Components ) you're only looking at an hours work! To be fair, think this works best in conjunction with other exhaust based mods, but if it's in bits anyway......

 

911,

Some pics here of before and after

http://www.zen24039.zen.co.uk/Scooby...20WRX/Headers/

 

Thanks for all that guys. I can get the cutter from RS, and the air drill from work, looks like i may as well do it while the engines away.
I was just so surprised to see such a large step. Bit crude !
911

 

My 93 wrx was the same ported them out to match gaskets , used to get full boost at 3500 rpm now get it at 3000 rpm . Cheap and worth while .

Mark

 

AND at such reasonable cost.

 

Oh no! Not MORE API extras!
Even I can port these, but on a Porsche they all line up!

That should get APIDavid going (again).........

Such an improvement on spool-up is well worth it.
Hope you have all the gaskets David.

911

 

is it possible to use a electric drill to cut the headers?

or maybe a dremmel or sumthing? (no air tools here)

 

Yes but it will take a lot longer as they do not spin as fast.

Mark

 

welloilbefooked thought you werent ment to wrap standard headers

 

[QUOTE=911 Even I can port these, but on a Porsche they all line up!

That should get APIDavid going (again)......... 911[/QUOTE]

I shan't rise to it, I shan't, I shan't, ......But Porsches cost lots more than Subaru - Dammit! No self control you see !!