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DIY plenum porting

Old 05-12-2006, 09:04 AM
  #181  
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Originally Posted by bilinghm
I'm not sure that it will make any differece either. However...

It may provide extra voulme in a way completely different and more benficial than a spacer. The spacer provides headroom over the cramped spot above the two front runners. Shaving the two front runners does the exact same thing. Untapered spacers also multiply the effect of the slanted lid of the 350Z plenum. They provide more room over 1&2 where is is needed, and even more room over the other runners where it isn't actually required. We also know that too much headroom can upset the pressure balance, potentially altering the velocity of intake air and harming low end torque.

Opening up the bowls along with shaving the 1&2 port roofs might be a excellent compromise. More headroom for 1&2, and a volume incease that effects all runners equally.

I'm beginning to believe that a properly modifed lower plenum will make spacers obsolete. I think many of the dyno results that we are seeing on the Mrev+ are providing the evidence.

Have I got the solution? Who knows?
I say give it a try

I will have another plenum to mess around with once i put this one on my buddies car. I know its going to make more power than stock, just not sure how much. So with the second plenum i can take from what i have learned and hopefully improve apon it.

Later
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Old 05-12-2006, 10:05 AM
  #182  
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Here is a photo of where I plan to mill out the bottom of the "bowl" area. Inside the dotted line.
Attached Thumbnails DIY plenum porting-plenum-dotted-line.jpeg  
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Old 05-12-2006, 10:07 AM
  #183  
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OVER 10 HOURS OF CYLINDER HEAD & INTAKE MANIFOLD SECRETS

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Looks like these CD's would be very helpfull, and they are only $99 and it comes with a Vinyl Carrying Case ( very cool )

Later
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Old 05-12-2006, 10:20 AM
  #184  
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Originally Posted by bilinghm
Here is a photo of where I plan to mill out the bottom of the "bowl" area. Inside the dotted line.

So your going to add more material underneith and then mill it out??
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Old 05-12-2006, 10:26 AM
  #185  
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Originally Posted by aceman
So your going to add more material underneith and then mill it out??
That is exactly correct.
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Old 05-12-2006, 12:56 PM
  #186  
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^^very interested thought
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Old 05-12-2006, 04:38 PM
  #187  
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great idea, be careful
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Old 05-16-2006, 10:48 AM
  #188  
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bilinghm,

Any update or dynos?
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Old 05-16-2006, 11:39 AM
  #189  
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Default Plenum corner

I have heard some comments and speculation that rounding off the corner shown in the photo would be a worthwhile modification. I have my personal doubts. There are two of these corners, one "corner" on the the left front by runner 1 and on the right rear next to runner 6. These little corners were very deliberately designed into this casting and NOT a mistake or overlooked opportunity. They are obviously designed to create a low pressure area below the lip and probably induce a swirl or vortex as the air cascades off the edge. The face of the corner below the lip is even slightly concave, further strenghtening my belief that this is a purpose designed arodynamic feature, not a mistake. I think the mistake would be to grind this off.

Polishing this area would probably be O.K. but I believe the original contours should be maintained unless somebody has either flow bench information or computer simulations that show an improvement with this area removed.
Attached Thumbnails DIY plenum porting-plenum-corner.jpeg  
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Old 05-16-2006, 11:48 AM
  #190  
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Originally Posted by bilinghm
I have heard some comments and speculation that rounding off the corner shown in the photo would be a worthwhile modification. I have my personal doubts. There are two of these corners, one "corner" on the the left front by runner 1 and on the right rear next to runner 6. These little corners were very deliberately designed into this casting and NOT a mistake or overlooked opportunity. They are obviously designed to create a low pressure area below the lip and probably induce a swirl or vortex as the air cascades off the edge. The face of the corner below the lip is even slightly concave, further strenghtening my belief that this is a purpose designed arodynamic feature, not a mistake. I think the mistake would be to grind this off.

Polishing this area would probably be O.K. but I believe the original contours should be maintained unless somebody has either flow bench information or computer simulations that show an improvement with this area removed.

LOL woooooops, well i guess we will see if it was a mistake to grind that down some

Later
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Old 05-16-2006, 11:49 AM
  #191  
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Another photo of the corner.
Attached Thumbnails DIY plenum porting-plenum-detail-2.jpeg  
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Old 05-16-2006, 12:16 PM
  #192  
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I will see if i cant get some pics up tonight, when i get home from work.

Later
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Old 05-16-2006, 04:02 PM
  #193  
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Here are a few pics, still need to finish the polishing. But this is the basic port design i will be dynoing on a bone stock car. So i guess we will see how well this works out for me

Later
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Attached Thumbnails DIY plenum porting-dsc01137.jpg   DIY plenum porting-dsc01136.jpg   DIY plenum porting-dsc01138.jpg  
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Old 05-16-2006, 04:15 PM
  #194  
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Few more pics

Hope to have it all finished later this week.
Attached Thumbnails DIY plenum porting-dsc01146.jpg   DIY plenum porting-dsc01151.jpg   DIY plenum porting-dsc01152.jpg   DIY plenum porting-dsc01153.jpg  
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Old 05-16-2006, 05:01 PM
  #195  
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wow looks good, you really opened those up.
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Old 05-16-2006, 09:26 PM
  #196  
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aceman, that is either going to be really good, or really crappy. Looking forward to results either way.
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Old 05-16-2006, 11:11 PM
  #197  
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Originally Posted by bilinghm
Here is a photo of where I plan to mill out the bottom of the "bowl" area. Inside the dotted line.
Here is my bowl just polished..



Are there any downsides to this??


Last edited by OCG35Coupe; 05-16-2006 at 11:16 PM.
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Old 05-16-2006, 11:16 PM
  #198  
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Originally Posted by OCG35Coupe
Here is my bowl just polished..


Did you do that yourself?
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Old 05-16-2006, 11:22 PM
  #199  
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Originally Posted by taurran


Did you do that yourself?
No, took it to a polishing shop..Told them to add it to my dads next bill
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Old 05-17-2006, 12:10 AM
  #200  
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uh.. your dad's next bill? that's cute... hope you're kidding..

I don't really see a downside as it would reduce air friction, I'm assuming
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