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DIY plenum porting

Old 05-09-2006, 05:04 PM
  #161  
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Originally Posted by aceman
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
Umm.. yep. I've got that too. I was just noting that Dremel makes all the Craftsman stuff. Perhaps I should give this a shot, too, seeing as I have the appropriate tools... I'd like to see some results of those who already have their manifold open, however.
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Old 05-09-2006, 05:26 PM
  #162  
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Originally Posted by taurran
Umm.. yep. I've got that too. I was just noting that Dremel makes all the Craftsman stuff. Perhaps I should give this a shot, too, seeing as I have the appropriate tools... I'd like to see some results of those who already have their manifold open, however.
Does that flex-shaft come with the original dremel too? its like the same price at the craftsman. so the craftsman is better? the dremel looks so much COOLER!! haha
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Old 05-09-2006, 05:40 PM
  #163  
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Originally Posted by OCG35Coupe
Where is "the bowl area"
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.





This is extremely interesting. I too was very skeptical about the groove being an oil channel. I would think that with the extensive scientific testing that Motordyne does would have revealed exactly what's going on. Of course that assumes that they do extensive testing and not just trial and error.

So you polish the depressed area in front of the runner openings? That's an easy improvement! Have you flow tested the modification to the front two ports?

Last edited by bilinghm; 05-09-2006 at 05:42 PM.
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Old 05-09-2006, 05:51 PM
  #164  
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Originally Posted by z327
The large open area in front of the three runners on each side of the plenum.

oh ok. I sent my MREV2 to get polished everywhere that its alluminum. I told them i didnt want a mirror finish. Just wanted it smooth.

Now im reading about oxidiation concerns. Should i be concerned? Maybe i should use some type of coating to help prevent oxidation and keep things even cooler.
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Old 05-09-2006, 05:58 PM
  #165  
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Naw, oxidation on non clearcoated wheels is a problem because of the conditions wheels face. Polished aluminum under the hood will stay nice for a very long time. If it gets a little fingerprinted, buff it up with Mothers.
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Old 05-09-2006, 06:15 PM
  #166  
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^ same for if i polish the outside plenum?
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Old 05-09-2006, 09:45 PM
  #167  
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I wish nissan would have used the type of Intake manifold they put on the 00-01 maxima.
Think about this the 95-99 vq30de had a 5600 rpm peak HP .then nissan changes the vq 30 intake manifold for 00 keep in mind nothing else in the engine changed. now the vq30dek has a 6500rpm peak HP and more power everywhere in the powerband . That IM is perfect.
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Old 05-09-2006, 09:51 PM
  #168  
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the kinetix ssv is loosely based on the stock maxima vq30de plenum..its not bad. only thing that sucks is that w a v shaped engine, the air charge makes a 90 degree turn not soon after entering the mid plenum.
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Old 05-11-2006, 07:26 AM
  #169  
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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.
Please tell us more about how you do your airflow testing.
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Old 05-11-2006, 08:05 AM
  #170  
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How is the angled-runner mod coming along?
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Old 05-11-2006, 08:55 AM
  #171  
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Originally Posted by 97supratt
Try looking into the Acura CL Type-S manifolds. I used to own one and they had a valve that would open at high rpm because it would pressurize the air at low rpm and increase torque.

The F/I guys always kept it open though.
The 2000-2001 Maxima VQ had this type of intake manifold as well.

Btw, Subscribed!
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Old 05-11-2006, 11:00 AM
  #172  
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Originally Posted by Wired 24/7
How is the angled-runner mod coming along?
Pretty slow, all my evenings have been taken up. No time for makin' chips lately.
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Old 05-12-2006, 06:45 AM
  #173  
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Hey guys, I think I am going to try a different tactic on my plenum. I think I will deepen the "bowl area" in front of the runner inlet openings. The material is quite thin in this area, probably less than 1/4 ", so I will weld aluminum plates on the underside of each bowl. Then I can deepen and polish the bowls. I figure that I should be able to go fullt 1/4" deeper and create a more rounded bowl area than the current more flattened area on the stock plenum. This concept will incease the plenum volume by a signicant amount, but should run no risk of decreasing the velocity of the airflow.

What do you guys think?
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Old 05-12-2006, 06:46 AM
  #174  
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Worked on porting and polishing the plenum alittle lastnight. Getting close to done. Next week i plan on doing a before and after on a bone stock 350z. My friend wants to get a baseline on his car before he starts modding it, so this should be a perfect time to kill 2 birds with one stone.

But i will say it has been fun, time consuming but fun porting out the lower plenum.

Later
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Old 05-12-2006, 06:52 AM
  #175  
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Originally Posted by aceman
Worked on porting and polishing the plenum alittle lastnight. Getting close to done. Next week i plan on doing a before and after on a bone stock 350z. My friend wants to get a baseline on his car before he starts modding it, so this should be a perfect time to kill 2 birds with one stone.

But i will say it has been fun, time consuming but fun porting out the lower plenum.

Later
Aceman
Pictures please
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Old 05-12-2006, 06:55 AM
  #176  
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Originally Posted by bilinghm
Hey guys, I think I am going to try a different tactic on my plenum. I think I will deepen the "bowl area" in front of the runner inlet openings. The material is quite thin in this area, probably less than 1/4 ", so I will weld aluminum plates on the underside of each bowl. Then I can deepen and polish the bowls. I figure that I should be able to go fullt 1/4" deeper and create a more rounded bowl area than the current more flattened area on the stock plenum. This concept will incease the plenum volume by a signicant amount, but should run no risk of decreasing the velocity of the airflow.

What do you guys think?
Im not sure if this would make in differnce over getting plenum spacer. I could be wrong, you are changing the plenum in a different location in front of the runners. Might work might not But would it work better than the spacer for the time envolved. I dont know

But i would say i have not seen anyone else try this

Later
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Old 05-12-2006, 06:57 AM
  #177  
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Originally Posted by bilinghm
Pictures please

I have been taking pics, so once im done they will be posted. I hope to finish it up this weekend.

And it will be soooo pretty when im done. And smooth like my wife's bottom

Later
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Old 05-12-2006, 07:03 AM
  #178  
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Also if my porting of the lower plenum produces good gains, i might dyno the difference between the ported lower plenum and my Kinnetix SSV plenum for chits and giggles

Later
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Old 05-12-2006, 07:45 AM
  #179  
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Originally Posted by aceman
Im not sure if this would make in differnce over getting plenum spacer. I could be wrong, you are changing the plenum in a different location in front of the runners. Might work might not But would it work better than the spacer for the time envolved. I dont know

But i would say i have not seen anyone else try this

Later
Aceman
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?
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Old 05-12-2006, 08:23 AM
  #180  
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Originally Posted by bilinghm
Hey guys, I think I am going to try a different tactic on my plenum. I think I will deepen the "bowl area" in front of the runner inlet openings. The material is quite thin in this area, probably less than 1/4 ", so I will weld aluminum plates on the underside of each bowl. Then I can deepen and polish the bowls. I figure that I should be able to go fullt 1/4" deeper and create a more rounded bowl area than the current more flattened area on the stock plenum. This concept will incease the plenum volume by a signicant amount, but should run no risk of decreasing the velocity of the airflow.

What do you guys think?
I would rather see the angled cut approach and then if you want to increase volume, try a spacer. Hell you can even use the gasket trick where you stack like 20 gaskets to make a ghetto spacer.
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