Head porting and flow numbers

[Rabrooks]

I saw information concerning intake and exhaust flow from the stock head. But I can't find it now. Does anyone have any information on port flow. It seems I remember the intake was 257cfm but cant recall the exhaust

Also, If anyone has ported their heads and has flowed them, please share your findings please.

I have opened up my intake ports to 232 cc from 210 cc. Most all of that volume was in the bowl and throat area. I opened up the exhausts as well but I haven't cc'd them yet. I'm expecting about a 10% increase in volume in the exhaust ports.

Part of the reason for getting this information is so I can figure out if it would be worth regrinding my cams for extra lift. I think I can regrind the lobes moving the base circle toward the center of the cam shaft, shim the valves the amount the circle moved to gain .030 to .040" extra valve lift. But I really need to see flow numbers to help make that decision. There isn't anyone near me that has a flow bench.
Thanks

[Ultramaroon]

I've never done this kind of work but I'm super interested in the topic. I'll get the obvious question about Piper cams out of the way. Why not those?

[Rabrooks]

Originally Posted by Ultramaroon

I've never done this kind of work but I'm super interested in the topic. I'll get the obvious question about Piper cams out of the way. Why not those?

$1700. I dont expect much gain so I'm not willing to pay 1700 to find out. lol

[Ultramaroon]

Originally Posted by Rabrooks

$1700. I dont expect much gain so I'm not willing to pay 1700 to find out. lol

gangsta

[humfrz]

I thought "porting and polishing" went out back in the 50s. -

Maybe I went out back in the 50s -

[PulsarBeeerz]

Pulled from couple sources hope this helps.

Stock Exhaust Flow @ .500 lift = 170
FBM Stage 1 & 2 Exhaust Flow @ .500 = 220

Stock Intake Flow @ .500 lift = 280
FBM Stage 1 & 2 Intake Flow @ .500 = 305

[Grady]

If I was going to port the heads I would go with cams. I would think you will see gains since the heads are the restricted part of our intake system.

[Calum]

Where was a guy here years ago that flow benched his heads and was working on improving things. His claim was that the flow volume was high enough to support some crazy high power levels, but the flow rate was too slow. He was playing around with adding material in certain areas of the ports to increase flown rate. I have no idea what came of that.

[NoHaveMSG]

Originally Posted by Calum

Where was a guy here years ago that flow benched his heads and was working on improving things. His claim was that the flow volume was high enough to support some crazy high power levels, but the flow rate was too slow. He was playing around with adding material in certain areas of the ports to increase flown rate. I have no idea what came of that.

It is common for them to rework the throat of the port to change the downdraft angle if it doesn't blend well into the bowl. They usually do this by adding to the floor so maybe that was what he was trying to accomplish.

There is so much to porting including seat angle it is best just left to the pro's.

[Lantanafrs2]

Usually raise the floor to increase airspeed and make the short turn radius a little bigger.

[sato]

Well, I say go for it. And I mean it in the best way possible. Sub'd.

[Irace86.2.0]

I don’t know how much valve lift with duration is available before you get into interference issues with the head of the piston. From what I have read, there isn’t much material or thickness to the walls of the heads for porting. With that said, much of the gains are realized with a combination of parts. One of the critical bottlenecks are the valves. You might want to look into larger valves.

[NoHaveMSG]

Originally Posted by Irace86.2.0

I don’t know how much valve lift with duration is available before you get into interference issues with the head of the piston. From what I have read, there isn’t much material or thickness to the walls of the heads for porting. With that said, much of the gains are realized with a combination of parts. One of the critical bottlenecks are the valves. You might want to look into larger valves.

I would only be concerned with interference if you where running a lot of overlap. Porting doesn't always mean removing material. From what I have understood big valves are beneficial FI, not worth the cost/benefit NA.

[Irace86.2.0]

Originally Posted by NoHaveMSG

I would only be concerned with interference if you where running a lot of overlap. Porting doesn't always mean removing material. From what I have understood big valves are beneficial FI, not worth the cost/benefit NA.

Since the stock valve piston clearance is narrow, this camshaft kit was developed to be used with the capacity upgrade kit, and the piston recess was redesigned to enable a 0.7mm lift increase without replacing the springs.

The capacity kit is their stroker kit. I don’t think there is much room for more lift with equal duration on a NA build. With low compression pistons someone gains room for more lift for a FI build. The best gains would probably come from larger valves, assuming the reliefs in the piston can accommodate larger valves and there is room to machine them, but I don’t know if this is just for FI like you said.

https://86speed.com/hks-camshaft-fa2...CABEgL2YvD_BwE

Many may ask why don’t you port the intake ports fully? We don’t do this because almost 100% of the gain is realized by just fitting the larger intake valve and performing a bowl blend. (HP/value/compared to porting) On top of this the head retains 100% of it’s reliability due to how thin the cast walls are. It’s all too common to see highly stressed, high HP, road race engines blow through over ported head walls. The FA motors have nice and very large ports from the factory but extremely thin castings!

https://elementtuning.com/competitio...r-wrx-fa20dit/