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Discussion Starter #1
I have completed the flow testing on the 2005 Lower Plenum that is changed and a part of the additional 13 horsepower for 2005 models.

There is still a big difference between the airflow at the front of the intake where it is squeezed down by the upper intake and the back of the intake.
The front flowed 226 CFM @ 28" H2O
The back flowed 247.5 CFM @ 28" H2O

I then removed all the rough casting from the bottom side of the upper plenum and the inside of the lower plenum. I sanded it down from 120 grit to 600 grit. I also did a little port work on the inlet and the front runners (where there is less flow).

The front now flows 248.5 CFM @ 28" H2O
The back now flows 269.5 CFM @ 28" H2O

I have a dyno scheduled for Monday to see how much horsepower I picked up and what happened to the torque.

This is the upper pleunum before polishing.
 

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Discussion Starter #2
This is the upper pleunum after polishing.
 

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Discussion Starter #3
This is the lower plenum before polishing
 

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Discussion Starter #4
This is the lower plenum after polishing
 

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Discussion Starter #5
A side view...
 

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So Warren, Do you think one of the new Plenum Spacers and a 05 lower Plenum would be a good Set up? Let me know and I'll order one of the spacers.

Steve Called me the other day to tell me that mine came in. Want to polish and port mine For me :) Or is it to big of a PITA.
 

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Discussion Starter #7
I will also be getting my original 2003 upper and lower plenum flow tested next week to see how they compare to the 2005.
 

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Discussion Starter #8
[/quote]

Now that I have all the right tools for the job it only takes a few hours to do. Polishing the top side for show is the most time consuming.

I'm going to consider a spacer after I see the difference between the 2003 and 2005 versions. We could polish yours and then flow test it with a spacer. I can probably get it tested for $30.
 

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Discussion Starter #11
[/quote]

No we are going on vacation that same week.

Which spacer are your going to get?
 

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Discussion Starter #13
[/quote]

Great....we should try to work on it the weekend of the 21st...
 

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[/quote]

Great....we should try to work on it the weekend of the 21st...
<div align="right">[snapback]98421[/snapback]
[/quote]


The weekend of the 21st is when we'll be in Branson, Leaving thurs the 19th and will be home Sun the 22nd :doh:
 

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Discussion Starter #15
[/quote]

Dyno is done.
I picked up 6.6 HP but its all up over 6,200 RPM. Keep in mind I have an automatic so I loose a lot compared to the manuals.
You have to ignor the peak torque number as it is an error at the start of the run. The loss at 4800 RPM is around 8 ft/lbs.

I'll try and get my original 2003 plenum airflow tested next and then it will be on to Chazz's 2005 plenum with spacer.
 

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Discussion Starter #16
Originally posted by z327@Apr 29 2005, 08:51 PM
I have completed the flow testing on the 2005 Lower Plenum that is changed and a part of the additional 13 horsepower for 2005 models.

There is still a big difference between the airflow at the front of the intake where it is squeezed down by the upper intake and the back of the intake.
2005 stock lower plenum
The front flowed 226 CFM @ 28" H2O
The back flowed 247.5 CFM @ 28" H2O

I then removed all the rough casting from the bottom side of the upper plenum and the inside of the lower plenum. I sanded it down from 120 grit to 600 grit. I also did a little port work on the inlet and the front runners (where there is less flow).
2005 polished lower plenum
The front now flows 248.5 CFM @ 28" H2O
The back now flows 269.5 CFM @ 28" H2O

[snapback]98282[/snapback]​


I have now flow tested my original 2003 lower plenum. One note is I did polish the inside to remove major casting roughness, but did no porting. So the total airflow is probably up 10 to 15 CFM. I wanted to test the AAM spacer so could not justify the expensive of doing three more runs.
2003 polished lower plenum
The front flowed 232 CFM @ 28" H2O
The back flowed 255 CFM @ 28" H2O

Bottom line is you can take a 2003 lower plenum and polish it and the upper and get just about the same airflow as a stock 2005 lower plenum.

Now for the spacer results.
2003 polished lower plenum with AAM angled spacer
The front flowed 250 CFM @ 28" H2O
The back flowed 255 CFM @ 28" H2O

AS you can see it does a great job of balancing the front to rear airflow. The interesting thing is it did nothing for the back airflow even though it raises the back a little also. Makes me wonder if having it angled is important or not.

If you get the AAM I recommend you buy some extra bolts. They only supply new bolts for the front of the plenum where it is raised the most and do nothing with the studs (they say to leave the nuts off since they don't reach and not to worry about it). The bolts in the back have very little bite and are really too short IMHO. Buy 11 stainless or grade 8 M6 x 35mm bolts and you will be better off. I would also remove the two studs and put the 35mm bolts in their place (need 11 if you do this).
 

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i also installed my lower plenum from the track model i felt a big change maybe cause i am boosted i dunno :dunno:
 

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z327 can u tell me what tools u used and how u went about polishing the top of the plenum and inside

thanks :cheers:

now onto the results, im not sure if im following this correctly

but it looks like u gained only marginally better flow up front by putting the spacer on the 05 plenum, but lost more at the rear

2005 polished lower plenum
The front now flows 248.5 CFM @ 28" H2O
The back now flows 269.5 CFM @ 28" H2O

2005 polished lower plenum with AAM angled spacer
The front flowed 250 CFM @ 28" H2O
The back flowed 255 CFM @ 28" H2O

so the spacer is a waste of time then? Would the same be true for the Motordyne?
 

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Discussion Starter #19
Originally posted by TPIACE@Jun 14 2005, 12:49 AM
z327 can u tell me what tools u used and how u went about polishing the top of the plenum and inside

thanks  :cheers:

now onto the results, im not sure if im following this correctly

but it looks like u gained only marginally better flow up front by putting the spacer on the 05 plenum, but lost more at the rear

2005 polished lower plenum
The front now flows 248.5 CFM @ 28" H2O
The back now flows 269.5 CFM @ 28" H2O

2005 polished lower plenum with AAM angled spacer
The front flowed 250 CFM @ 28" H2O
The back flowed 255 CFM @ 28" H2O

so the spacer is a waste of time then? Would the same be true for the Motordyne?
[snapback]113795[/snapback]​


Sorry had a typo. I only tested the AAM spacer on a 2003 polished lower plenum.
 

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Thanks for posting the info. Been considering changing to the new Track lower plenum...among other things.
 
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