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turbogrill

N47 head - unshrouded from factory? Not much to do?

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Hi,

 

How are you guys unshrouding your N47 heads?

 

It doesn't seem to be much room to work on for on the intake? Exhaust seems to have a little more room.

 

Looks like they are already shrouded from factory?

 

Here is a picture with the gasket on, red arrow is intake and green is exhaust:

shroud.thumb.jpg.bc064b4c8b8458816a050bd095441e99.jpg

 

Here is a picture without the gasket:

20180423_234339.thumb.jpg.1fc1965dd2524b0df7c048ee90c4d3a2.jpg

 

 

 

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Posted (edited)
9 hours ago, madkaw said:

Okay - I can’t let you slide on this one.

you think you had to point out what was exhaust side and what was intake -lol

 

haha...I meant "look at he exhaust side! You have to be balsy to remove more material"

 

I did find a great picture in a thread.It's posted by BRAAP. I didn't realize that you also can remove so much stuff close to the sparkplugs. It's marked red in my picture below, he also smoothen the ridge around the valves (blue):

 

braap.thumb.jpg.07243c7875e69bc60febd2de56abb337.jpg

 

This is BRAAPs before:

N-47style.jpg.facbaf8aa36fd31e95e8884a1d025578.jpg

 

See how much material around the spark plug it is, the red area in my picture above.

 

After BRAAP:

portedchamber2.jpg.06da2a9edf47e80fe22e52831bfc7e82.jpg

 

Not a whole lot of material removed on the side of the vavles (where the red and green arrow is in the first post picture).  But plenty removed above the intake valve.

The ridge under the vavles (blue in the picture above) also seems like it's gone.

 

BRAAP also mention that on L heads the first thing he will do is to remove area around the vavle curtain area, I assume that is the blue line in the image above and also on the side of the vavles. Obviously on a race head he might do more but improving vavle curtain area seems to be the most important thing according to him. Not sure if it applies to all heads.

 

 

The thread can be found at:

 

However, whitehead performance seem to only remove material on the side, they ignore the ridge that BRAAP has removed: (http://atlanticz.ca/zclub/techtips/headporting/index.htm):

 

i-2_B_L.jpg.a9fc4930b531547bab6021bcd7e50edc.jpg

 

In BRAAPs head it seems like that ridge the arrow points to have been smoothen out. 

 

Edited by turbogrill

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I think your a little confused on what’s being done here. The valve likes to have room to breathe all the way around the valve. Obviously close to the cylinder wall side is where there’s not much room. So no it’s not ballsy to clearance close to the fire ring if done right. Your exhaust valve side needs work in the green arrow area of your first pic. I’d follow the radius of the valve all the way to the fire ring ( or very close). Make sure you have your head dowels in place holding the HG where it will sit when installed. Do not take any material away from other areas UNLESS you need to adjust your CR by gaining CC’s. That’s probably what Brapp was doing with a small chamber head. Smoothing edges is great but you don’t usually remove much material. 

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1 hour ago, madkaw said:

I think your a little confused on what’s being done here. The valve likes to have room to breathe all the way around the valve. Obviously close to the cylinder wall side is where there’s not much room. So no it’s not ballsy to clearance close to the fire ring if done right. Your exhaust valve side needs work in the green arrow area of your first pic. I’d follow the radius of the valve all the way to the fire ring ( or very close). Make sure you have your head dowels in place holding the HG where it will sit when installed. Do not take any material away from other areas UNLESS you need to adjust your CR by gaining CC’s. That’s probably what Brapp was doing with a small chamber head. Smoothing edges is great but you don’t usually remove much material. 

 

Aha that makes sense! Good thing I didnt start whacking up the head.

 

Thanks

 

Curious about that tiny ridge between the valves. I would think you want the air to follow a smoot bent surface. Like a sinus bent shape or something. Removing that ridge would cause and abrupt opening. (Lots of homemade theories being developed here...)

 

 

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