Port and Polish?

[Dimman]

Originally Posted by oldeskewltoy

Oh... let see how many smart people are looking at this thread.... Can anyone tell me why the "dirty" port in my first graph flowed better then the cleaned port up to .25" lift?


Hint: the valves used were the same - clean and smooth in both test

Carbon buildup smoothed out some transitions?

[arghx7]

Some variability in the equipment can be expected as well.

[JDKane527]

Originally Posted by oldeskewltoy

Oh... let see how many smart people are looking at this thread.... Can anyone tell me why the "dirty" port in my first graph flowed better then the cleaned port up to .25" lift?


Hint: the valves used were the same - clean and smooth in both test

Did the dirty port act similarly to dimples on a golf ball to minimize the boundary layer? Less separation so the cross section of air moving is larger than if it was smoothed out, but only up to a certain velocity. Above that velocity, a smoothed out port would move more air.

For clarification, is lift correlated to air velocity? At higher lift (>0.25"), the air is traveling at higher velocity where the clean port shows a improvement as the air pressure moving it is all turbulent.

Trying to pull from memory about my Fluid Dynamics course.

[Hawk77FT]

So, is it worth it? I would love to have the time and do it myself before i go down the supercharger route!

[Turdinator]

Originally Posted by oldeskewltoy

I've adjusted lighting and size of most of these so they are a bit clearer

Wow, the exhaust port on the right isn't pretty. For reference, which port is closest to the fire wall?

[Mikem53]

Originally Posted by NomoreNA

Every cylinder head I have seen has always had tons of room for improvement. I don't see why the FA20 would be any different.

Maybe on V8's or 6's.. These small 4 bangers reaching 100hp per L are already pretty well thought out and optimized from the factory. Machining is taken to a whole new level on these Japanese 4cyl engines.
There was a write up on a scion xD that some engine builder used in his shop for errands and such. They removed the head on the 1.8L Toyota engine to see if they could improve flow and power. They didn't see anything they could do to improve flow thru the heads, valves.. Etc..(within reason). They remarked how well finished and thought out the design already was from the factory. The head already looked custom as it was..
In the old days.. There was always room to improve by cleaning things up or milling something... Not so much anymore..

[oldeskewltoy]

The best answer....

Originally Posted by Dimman

Carbon buildup smoothed out some transitions?

The carbon laid down smoothed the passages of the significant edy points. @ .25" lift the carbon became a restriction and so the flow was shut down quickly.

Briefly on laminar flow, and golf balls, and why they don't really translate well to automotive porting..... in essence the different is laminar flow and golf ball flight is something measured over longer periods of time.

Any golfers here?? Ever hit a golf ball "knuckle ball" a duff... how far does a duff usually go? A golf ball when properly struck rotates between 2000 and 4000 rpm... the dimples "carve" away at the air, and move it to the side.... golf ball analogy and head port flow just have no qualifier.


At 7000 rpm the intake valve opens and closes 29+ times a SECOND! Between acceleration, deceleration, the shape of an engine port, and our period of time... laminar flow doesn't exist!


This last bit is part of why you can't always trust a flow bench either.... the flow bench is running, testing over a much greater time period then an operating engine.


A flowbench is just a tool. It is the operator of that tool, and the other tools in head porting, that must process the information, and work accordingly.

[oldeskewltoy]

Originally Posted by Turdinator

Wow, the exhaust port on the right isn't pretty. For reference, which port is closest to the fire wall?

from this thread - http://www.ft86club.com/forums/showthread.php?p=828393

[oldeskewltoy]

Originally Posted by oldeskewltoy

A lot can be done inside the port.... without hogging anything

exhaust

Let me show you a typical (for me) 4AGE exhaust port from originally cast... to 90+% finished(port on left). For a finished port look to the port on the right in the bottom view. Exhaust ports should be as smooth as glass... the smoother the better.

[wparsons]

Originally Posted by oldeskewltoy

Briefly on laminar flow, and golf balls, and why they don't really translate well to automotive porting..... in essence the different is laminar flow and golf ball flight is something measured over longer periods of time.

Any golfers here?? Ever hit a golf ball "knuckle ball" a duff... how far does a duff usually go? A golf ball when properly struck rotates between 2000 and 4000 rpm... the dimples "carve" away at the air, and move it to the side.... golf ball analogy and head port flow just have no qualifier.

Another reason other than time is that the dimples reduce the boundary layer creating less of a low pressure area behind the ball (and therefore reducing drag). In a head there is no similar surface where a low pressure zone would be created.

[boxer 2.5]

Wow, so much info in this thread! If the heads were to be port matched, would it affect the afr enough to require a tune? That was the case in my buddy's 2006 gti

[Ozzman]

Originally Posted by oldeskewltoy

Oh... let see how many smart people are looking at this thread.... Can anyone tell me why the "dirty" port in my first graph flowed better then the cleaned port up to .25" lift?


Hint: the valves used were the same - clean and smooth in both test

Carbon built up where there was stagnant air in the port. With carbon now taking up that space the air flowed at a higher velocity. Thus letting more air in the cylinder at a lower lift. I personally would like to see how much material could be "added" in the ports in the proper places without dropping cfm.

[oldeskewltoy]

Originally Posted by boxer 2.5

Wow, so much info in this thread! If the heads were to be port matched, would it affect the afr enough to require a tune? That was the case in my buddy's 2006 gti

Require a tune.... maybe.... but that would be pushing an extreme...

Originally Posted by Ozzman

I personally would like to see how much material could be "added" in the ports in the proper places without dropping cfm.

[Lonewolf]

@oldeskewltoy

So, were you ever able to get a hold of a FA20 to work your magic?