Port and Polish?
 

Hi all,

I was thinking the other day about getting the cylinder head, intake manifold, exhaust manifold (if not going to the aftermarket header route) and throttle body ported and polished?

This will free up some ponies for sure!!!

Has any one done it?

Subscribed for results. If you go ahead with this could you get them flowed befor and after?

The intake manifold is plastic so good luck with that one. :)

There are two heads, I don't doubt it will help but is best done when building the rest of the engine unless you like removing the engine.

I don't think anyone has done it yet.

It hasn't been done and for the work your going to do id just wait and get cams/valve-train goodies at the same time.

Still if you do try and get flow bench data of the before and after.

Several rs25.com members have done it in their cars... but tbh, you'll won't see much as you think you'll get... but I'm looking from EJ engine & not FA engine, so I could be wrong on this one.

If you gonna do it, I would recommend get some cams too. That's where you'll see more result w p&p

The throttle body on the FA20 is already pretty large. I doubt you will see much gains staying N/A.

You will probably need a tune to make the most of any head work also.

How about doing just the ports? cyl head - intake and exhaust, and intake manifold, and exhaust. The intake is plastic? WTF?

No doubt!

I guess if you do JUST that the gains will not be as significant as if you do the whole thing:
1. Exhaust - port and polish ports, header back system
2. intake - port and polish ports and full intake system.

No point in doing just one bit if you dont go all the way. My .2 cents. Just like the exhaust - what is the point in having a high flow axle back if the rest of the exhaust is 1.5 inch (not that it is but you get my point;)). Yes, it will free up some power but not a great deal of it. Same with the intake. Yes, the throttle body might be big enough although Greedy is making one with a bigger diameter...so more air in the intake plenum will need to go somewhere with the same proportional flow. But than again a true free flow system would include cyl head - back in both intake and exhaust!

And if we go into the cyl head..than I agree with @dabocx by waiting for cams/valve goodies to get it done properly.

And it is quite obvious that such mod will need a tune.

I read that the top end would become quite crazy...not as much as the bottom end and who knows maybe that 4000rpm dip would disappear FOREVER!
https://encrypted-tbn0.gstatic.com/i...q6stJbTPrX7eV5

Resurrecting this semi-old thread...

Has anyone given the porting/polishing idea a try? Any results?

I know there have been some gains shown on late model Chevy's with the plastic intakes. Seems like it would be easier to work with the plastic than the metal.

FBM and others are working on beefing up the heads(CNC, Valvetrain, Cams)

The TB is 70mm, more than enough for high horsepower.

JDL is making a billet intake manifold after they popped the top of their motor.

Thats all I know of as of right now.

I used to do custom head work on Ford and Chevy small blocks back in the day. Those old factory heads were built by cavemen when compared to the R&D and engineering that goes into heads these days. I don't think there would be much to gain from this work unless you were building a full-on race long block with cams, stroker rods and pistons, the works.

Also there are some big misconceptions when it comes to port polishing. You really don't want to make the runners "perfect" and smooth. The small casting bumps and imperfections aid in turbulence which helps keep the fuel-air mixture from separating.

If it were me, I would like to set the heads up on a flow bench to see where the restrictions are (if any). Its never a good idea to start grinding unless you are doing it with a specific purpose, otherwise you are just working "blind".

Scott

+1. A flow bench is critical. I think the heads are pretty decent on these cars in terms of flow, the cams will give the most gain in terms of beefing up the heads.