The tiny CNC tool ridge can be hand polished [or machine] to perfection for another $5,000 say 2 hours x $100 x 24 ports. If every single HP counts. Probably 6-12 HP left on table to save money.

Winning NASCAR HEADS cost $30-50,000 a set - they use a microscope.

 

The even grooves made by the CNC program will help with the boundry layer of air that is created by them. Essentially this air stands still and lubricates the incoming air increasing velocity.

 

There is an ongoing debate between smooth port finish, and the CNC style finish. Advocates of both positions bring up very good points. I have spoken to many head builders that opine that a rougher finish actually improves velocity and flow, as the ridges serve to minimize air to wall contact. Think of a golf ball....lots of dimpels for improved flight and distance, and better travel through the air. Others claim that a smooth port is better. Honestly, I have no opinion on the matter either way. A properly engineered and designed head will perform. Sure, customers like the shiny smooth ports...probably sells more heads. If smooth is the best solution, why dont some head designers finish the ports with a super high polish...bling bling. Just some food for thought.

Mista...best of luck with the buildup..looks great.

Also, if anyone is interested, we are WD with Cosworth.

 

Thanks Sharif!

I agree with Sharif about the rough finish. The polished finish is much easier to do than creating these patterns on the runner walls. As much as I know, the smoother finish is better for NA cars and rough is better for FI.

 

Many years back I was an advocate of the super polished heads on big block v8's but I'm recently done more research on flow designs that are rougher. It deals with the laminar flow. If the air is too smooth its fine when there is a perfectly flat surface the air will flow just fine. Once there is a discontinuity there is no boundry layer of air. It swirls arround and becomes extremely turbulant. This creats a pocket behind the bend and the air wants to suck to the walls creating friction slowing the flow over all.

You add little pockets that scavange some of the air from the outside with little roughness and the little pockets of trapped air act like roller bearings. That will guide the air arround bends and openings. You will actualy flow more than the minute amount of volume of air that was scavanged from the main flow. This is the boundry layer of air mentioned earlier. Only draw back you have to have the air moving faster to keep this effect up. There is more of a definitive layer at higher speeds. So from what I've seen in flow charts and diffrent tests this method is extremely effective.

There is a fine line between a rougher surface and a **** head job (so to speak) too rough and the discontinuity acts like a boulder in a river. Too smooth and you get the "sticky" air flow. Think of the rough surface as the surface of teflon, keeping the pocket of air in there keeps the air moving.

 

I love these technical debates.

 

+1^^ Hell yeah Im learning more and more by the post...

 

yeah...thats right....

 

nice explanation

 

Being a Mechanical Engineer, and studying fluid flow characteristics, a turbulent flow is better than a laminar one, for this application.

For example, golf ***** have dimples to create a turbulent boundary layer so that the ball "cuts" through the air. Fish have scales and sharks have dimples to make them "slip" through the water.

 

For those who are not grasping the golph ball comparison: http://www.howstuffworks.com/question37.htm

 

Yes you're all good, a lots of finishing needed for smooth flow.

 

By no means what do these heads look totaly finished there seems have too many real hight ridges. I dont know the actual depth of these grooves but it looks to me that .5 mm and under would give the desired effect fot the boundry layer. At that depth it looks more scuffed than the ridges pictured.

Many people still are adiment about the super polish finish because they go for the static volume, which with the chamber being polished you get the optmal volume. But this does not take into account the fluid dynamics for air with higher velicities.

If you take that into account then read the golf ball URL i posted.

So basicly to put it out in the open the 2 main schools of head work are:

1) Static Chamber Volume

2) Dynamic Fluid Flow.

 

Man those sure are pretty. The patterning on the runners is great for better fuel mixing and the porting looks great. I would love to see a before and after dyno graph and a flow bench comparison to the stock head!

 

Status of the install?

 

I've received the L19s from Sharif yesterday,
waiting for new buckets, forge actutators, total seal rings and PE bearings from UK and Japan right now. Prolly the install will be complete sometime next week. Scott Stg2 cams are also going in. I'll post the during the install with pics.


BTW Thanks to Sharif for the ultra quick service (I've received the L19s from him in 3 days and that's an international shipping )