samcowrx

as title, just wondering if it is really worth it on a force fed engine?, has anyone got dyno proof (before and after) that it makes a lot of difference on its own? thanks

silent running

Some say it's pointless because the boost does the work. I'd say it's the opposite - it's even more crucial for everything to flow well because you've got that much more being forced through than on a NA engine. I'm sure others will have more conclusive results though.

Put it this way though, if it's done properly, it can't harm your performance can it?

doppelganger

well they do it at prodrive,unless its just to keep someone in a job

Slowboy Racing

If done right it no it can’t harm, but if ported wrong you can loose hp and possibly harm there is an art to this.

With that said every little bit counts, you probably wouldn’t notice much difference with a basic port and polished to the heads on a standard setup but then add the cams and so on and, it all adds up.

Some tuners claim +20% on porting and polishing N/A motors. I think It’s more down to cost verses gain on turbo cars, for what it would cost to have your heads worked the money could be spent elsewhere with better returns Unless however you are reaching the flow limits for the heads it’s a timely and costly process

Also Less of a polished more of a sanded finish is preferred theses days more so in turbo cars I am led to believe as it reduces the tumble affect of the air this then inhibits the ability of the air and petrol to mix as well before entering the chamber. I think in the carburetor setups’ polishing was more of an advantage due to the fuel being feed nearer the entrance of the carb thus giving time to mix so the following polished path was an advantage

samcowrx

thanks for all the replies, uni ink, you have confirmed what i thought, with turbo engines the job wont make much difference at all, but if you are going the whole hog for power, you would definately port and polish. I spoke to someone today and they said it could be better to have a "rougher" inlet to help mix up the mixture and to help the fuel burn correctly. Lots of views on this i am sure but in my experiences with throttle bodied vw golf engines port and polish was essential and it gave great gains with good cams.

jaytc2003

iTrader: (1)

there is a v good book on cylinder head modification by a guy called David Vizard, it explains the reasons for it, the theories and the practicalities etc. dont know if you can still get it but it is very good (it focus mainly on mini engines but the ideas can be transferred across to different engine which the book says)

Trout

iTrader: (1)

It depends what you want.

WRC heads have very small ports to get good gas speed and it helps give a lot of torque. I had my STi V heads ported and on the inlet side the improvement in flow was around 20% and on the exhaust side the improvement was over 30%.

With a relatively modest turbo it produced a lot of power (around 10% more than the turbo was rated for) even with modest cam profiles. The porting clearly made a huge difference to the ability of the engine to produce it's power.

If you want to speak to someone about porting talk to Mark at Lateral - he does not do it himself but has a great contact who's name escapes me at the moment!

R

Trout

iTrader: (1)

I remembered it was Steve Gearey at SMG. He has a flow bench at home and has done a lot of work on Scoob heads.

You can reach him via Mark or on here.