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DIY plenum porting

Old 05-08-2006, 05:38 AM
  #141  
bilinghm
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Hey everyone, Kevin (ATL_Red_G35) droppped by my house over the weekend. We had a good time examining my modified plenum, comparing our cars, listening to exhaust systems, etc. He's a great guy.

One issue that came up that I hope Hydrazine might be willing to cast some light upon is the strange groove in the two rear-most ports. Hydrazine, can you tell us what they do? Why would they only be on the rear runners? I'm sure everyone following this thread would be intrested to know. Thanks!

Bill
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Old 05-08-2006, 06:08 AM
  #142  
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I believe its for channeling oil from the PCV. The groove gives it a defined place to flow rather than making a mess over a large area.

Why just the back? runners 5 & 6? I don't really know. Maybey they designed 5 & 6 to be the low spot for the oil to run down to.
Or maybe for some reason the oil tends to flow towards the back due to air flow pushing it that direction.
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Old 05-08-2006, 06:41 AM
  #143  
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Originally Posted by Hydrazine
I believe its for channeling oil from the PCV. The groove gives it a defined place to flow rather than making a mess over a large area.

Why just the back? runners 5 & 6? I don't really know. Maybey they designed 5 & 6 to be the low spot for the oil to run down to.
Or maybe for some reason the oil tends to flow towards the back due to air flow pushing it that direction.
Here is a picture of that groove. So there is so much oil getting into the plenum that a special channel is required to channel that oil? I thought the central valley chamber with the small individual drilled holes in each runner would have dealt with the PVC oil. So much leaks ou that it needs a channel? I'm surprised. Maybe the dilled PVC holes need to be opened up some?
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Old 05-08-2006, 08:34 AM
  #144  
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It would be so cool if we had a real nissan engineer on the boards so we can ask him these things. These engineers are pretty damn smart when it comes to building these parts for a specific usage. I say lets port the hell outta whatever we want! Power to the people!
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Old 05-08-2006, 09:15 AM
  #145  
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Originally Posted by bilinghm
Here is a picture of that groove. So there is so much oil getting into the plenum that a special channel is required to channel that oil? I thought the central valley chamber with the small individual drilled holes in each runner would have dealt with the PVC oil. So much leaks ou that it needs a channel? I'm surprised. Maybe the dilled PVC holes need to be opened up some?
I was thinking the same thing. Makes me want to run out and install an oil catch ASAP.
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Old 05-08-2006, 09:31 AM
  #146  
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Actually, how much PVC oil loss could there be? How much oil in the manifold would have to be present to require an "oil channel"? If you lost a table spoon full each day, you would loose a quart in about 64 days. If that was the case, wouldn't everyone be complaining about excessive oil consumption? My car doesn't seem to use a measurable amount between changes.

sorry, only 2 table spoons in an ounce, so it would only take about 30 days to loose a quart.

Last edited by bilinghm; 05-08-2006 at 09:34 AM.
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Old 05-08-2006, 09:34 AM
  #147  
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Dont we have 2 hoses that are for the pcv? One being in the front of the manifold and one on the intake piping?
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Old 05-08-2006, 10:38 AM
  #148  
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Hey guys,
I've been searching but can't find this info...what's the pressure drop in our plenums with respect to RPM at WOT? Anyone know the actual pressure readings or ranges? (I assume that the pressure will continue to drop as RPM's increase, [WOT is constant throughout RPM range])

If this is true, I might try to make a sealed cylinder with a movable end attached to a rod that would be connected to the metal plate over each intake runner...as the pressure would drop, the rod attached to the clyinder would be pushed out and could move the metal plate over the intake runner....so at low RPMs, the intake runner length would be OE (or slightly longer) and at higher RPMs, the intake runner could be shorter.

I just bought a upper/lower plenum and will get a better idea of how fesible this could be.

-Peter
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Old 05-08-2006, 11:09 AM
  #149  
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I guess what we all want is access to flow bench information. There are several DIY flow benches on the web, how about ANOTHER project!!?
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Old 05-08-2006, 01:25 PM
  #150  
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Started porting and polishing my lower plenum this past weekend. I will say it is time consuming But i am enjoying it. Here is a pic of the tool and attactment i am using. Pics to follow once it looks pretty

Later
Aceman
Attached Thumbnails DIY plenum porting-rotary-tool.jpg   DIY plenum porting-dremel-kit.jpg  

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Old 05-08-2006, 01:35 PM
  #151  
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Originally Posted by aceman
Started porting and polishing my lower plenum this past weekend. I will say it is time consuming But i am enjoying it. Here is a pic of the tool and attactment i am using. Pics to follow once it looks pretty

Later
Aceman
I used to port and polish my old 110cc minibike and I gotta tell you its very difficult with a dremel. Those tools they have are useless because they break and wear out too quickly on metals. By the time you finish porting a little off your manifold your dremel will be so hot plus your tools will be melted off.

I think the best porting tools are the air powered ones, they have a lot more power plus the accessories are for heavy duty use. The dremel is for light duty around the house/garage.

Good luck though.
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Old 05-08-2006, 01:46 PM
  #152  
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Originally Posted by 97supratt
I used to port and polish my old 110cc minibike and I gotta tell you its very difficult with a dremel. Those tools they have are useless because they break and wear out too quickly on metals. By the time you finish porting a little off your manifold your dremel will be so hot plus your tools will be melted off.

I think the best porting tools are the air powered ones, they have a lot more power plus the accessories are for heavy duty use. The dremel is for light duty around the house/garage.

Good luck though.
I agree, but it is what i have Got the Tool for Christmas. Its not the small dremel. Its the All in One Craftsman rotary tool. Alot bigger, plus 2 speeds. So far its going pretty good. I have 3 of the 6 done and ready to polish. Going to start working on the other side maybe tomorrow.

Later
Aceman
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Old 05-08-2006, 03:47 PM
  #153  
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so if not the dremel ($90ish) then what? for the same price. i was actually going to buy one for this project, plus other things...
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Old 05-08-2006, 07:59 PM
  #154  
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Originally Posted by aleok
so if not the dremel ($90ish) then what? for the same price. i was actually going to buy one for this project, plus other things...

For the price? I would go with hand tools, files and such things. Its cheaper but it requires a lot of labor. Are you up for the challenge?
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Old 05-08-2006, 10:31 PM
  #155  
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^ of course. but i also want to polish the entire "inside" and "outside". i also wanted a dremel but if ur saying that its going to break or overheat all the time then i guess it not worth it?
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Old 05-09-2006, 01:13 AM
  #156  
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Originally Posted by aceman
I agree, but it is what i have Got the Tool for Christmas. Its not the small dremel. Its the All in One Craftsman rotary tool. Alot bigger, plus 2 speeds. So far its going pretty good. I have 3 of the 6 done and ready to polish. Going to start working on the other side maybe tomorrow.

Later
Aceman
Actually, Dremel does make the Craftsman rotary tools. They're just a different color and have the Craftsman logo on them, and they also come with the lifetime warranty.

I've got the top end Craftsman rotary with the variable speeds, works great!
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Old 05-09-2006, 11:43 AM
  #157  
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Originally Posted by taurran
Actually, Dremel does make the Craftsman rotary tools. They're just a different color and have the Craftsman logo on them, and they also come with the lifetime warranty.

I've got the top end Craftsman rotary with the variable speeds, works great!
I could not do the work with just the Rotary tool. The Craftsman Flexible Shaft Attachment is a must to get into the tight places and ease of use.

Later
Aceman
Attached Thumbnails DIY plenum porting-flex-shaft.jpg  
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Old 05-09-2006, 04:02 PM
  #158  
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Originally Posted by bilinghm
Here is a picture of that groove. So there is so much oil getting into the plenum that a special channel is required to channel that oil? I thought the central valley chamber with the small individual drilled holes in each runner would have dealt with the PVC oil. So much leaks ou that it needs a channel? I'm surprised. Maybe the dilled PVC holes need to be opened up some?
I doubt it has anything to do with channeling the oil. It is more likely to change the airflow or velocity.

I did airflow testing on the old and new lolwer plenum. The new lower plenum does flow 10% more volume, but due to velocity changes you give p torque. I also found that it did nothing to balance the airflow front to rear.

By simply sanding the bowl area down to a smooth finish (600 grit) you can pick up 10% airflow without the drop in torque from the newer version of the lower plenum. I also verified that a spacer does balance the airflow from the front ports to the rear.
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Old 05-09-2006, 04:10 PM
  #159  
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Originally Posted by z327
I doubt it has anything to do with channeling the oil. It is more likely to change the airflow or velocity.

I did airflow testing on the old and new lolwer plenum. The new lower plenum does flow 10% more volume, but due to velocity changes you give p torque. I also found that it did nothing to balance the airflow front to rear.

By simply sanding the bowl area down to a smooth finish (600 grit) you can pick up 10% airflow without the drop in torque from the newer version of the lower plenum. I also verified that a spacer does balance the airflow from the front ports to the rear.
Where is "the bowl area"
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Old 05-09-2006, 04:52 PM
  #160  
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Originally Posted by OCG35Coupe
Where is "the bowl area"
The large open area in front of the three runners on each side of the plenum.
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