The head would flow better, but in your case that's not a good thing. The greddy kit is already choking at max rpm. Adding more would only make things worse. The exhaust flow is just too much for the 18g. You can get 300hp with meth, a single 70mm, and a good tune.

 

maybe some time in the future I will end doing head work.


The roots supercharger + a ported head would be an interesting combo.

 

Is there similarities between increased flow on both the exhaust and intake side with the head work? I know it's a lot more difficult to increase the intake side, but remember a few reads of people that had seen a minimal 5%, where as the exhaust side can see up to 15%.

Also after all the work is said and done, without milling the head, does the compression ratio drop dramatically or slightly?

 

Correct. The exhaust holds the most promise for gains. A 6 percent gain on the intake is good. On the exhaust I have seen up to 16.8 percent increases with most closer to 14%.

The final compression ratio depends on several different factors. We are referring to the combustion chamber volume. The factory is about 53.6cc. You could manipulate the final volume with dished valves or modified pistons. Most headword will make little difference to that volume. Final milling can impact it the most.

 

While the static compression ratio will largely remain the same.


Dynamic compression ration would change.


Dynamic compression ratio is what you should be looking at.


Exaggerated example but the engineering behind it is sound.
You can build a static 16:1 motor but with a specific selection of cam shaft profiles and overlap make the dynamic end up being 8.5:1

 

I have to ask...does a port / polish loose its gains over time, more so the polishing part? I only ask because I see carbon and what not build up in those areas...

 

No more than a stock head will loose some performance as carbon builds up.

A port and polish has evolved to a port and surface finish while retaining the original port and polish name. Very little to none is brightly polished.

 

Here's some pictures of my shade tree mechanicing port and polish job. I went with a built head, using supertech ss black nitride valves, dual valve springs and ti retainers. Im still building it , will post pictures when done. As for the port job, I knife edged the runners and removed all casting marks and deshrouded the valve seats. I didint do any signifigant bowl work, because thats where you can hurt flow the most if you do it wrong. Still needs some work, so far I have about 10 hours in to it. Not quite laskey quality, but the price is right.

 

 

Does anyone replace the valve seals I have never seen anyone talk about replacing them.