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Discussion Starter · #1 ·
I don't know if I should cry or laugh (I think I'm just going to laugh) about what has happened a second ago. For the past few days I had been working on my upper plenum with dremel and removing some material which I taught wasn't necessary, I've also polished it inside and removed all the castings. I've not finished polishing it fully yet, i've only finished it up with 120grit sand paper and I was planning to finish it off with 400 or 600 grit.

Anyway, I need the car tomorrow, so I washed the plenum, I've made sure to remove all the aluminium dust from every nook, then I proceeded to install it on the car. Well I was tightening the bolts on top of the plenum and then the plenum has cracked :banghead: It's not hard to guess that I've removed way to much material in some places weakening the plenum. Right now I'm way to past to even look at what I've done, I might have some photos to follow later on.

Now how do I solve the problem of needing a car tomorrow when my car has cracked plenum. I wonder if any of you guys keeps around a spare plenum by any chance :)
 

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Discussion Starter · #3 ·
Well, It's nothing to do with polishing, what I did and I shouldn't have done is remove material around the posts, it's hard to judge the thickness there and I went overboard, if all you use is sand paper and don't touch any of the the high speed cutters you will not have any problems.

Crawford isn't an option, since I already have AAM spacer. All I want is a stock plenum and I want it fast, I don't even want to even imagine what my taxi bill will look like tomorrow.
 

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Sorry to hear about that nuff..... I got your PM and came straight into here.... I think Peter might be able to give you a hand sourcing down a plenum though... call him and see if he can help you out there!!!

So nuff, you have the AAM angled plenum spacer... so you reckon it is better than ME piece... why is that?

I thought with any thicker plenum (don't even need to be an angled piece) will directly improve the air flow to two front cylinders already... and what does it need to be angled? I just thought nissan made the plenum to have an angle is to pressurise the air going into the front 2 cylinerders just like the plenum on the GTR (the intake plenum gets narrower, even happens to the nismo product too)....

cheers,

richie
 

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Rich the AAM works better on the 206kw plenum because the front cylinders are starved for air and as such the airflow bw front and rear of the plenum is uneven. Being angled, the AAM allows for more additional airflow at the front than the rear to compensate and make airflow even front to back. There was a thread on here from a member who flow benched the 206kw plenum with the AAM and airflow was pretty much even

On the 222kw plenum, i rekon the MD would work better, as Nissan themselves improved the lower plenum to help even out the airflow, hence the smoother high rpm feel. I remember reading a thread on my350 from someone who flow benched the 222kw plenum and it was pretty much even front to back. If you were to fit the AAM angled spacer, you would probably make the airflow front to rear uneven again.....thereotical of course :shiftdrive:

In reality they probably do the same thing......or do i feel the third series of myth busters in the making
 

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Sam:

I will feel more comfortable going for ME though.... beacuse the larger the plenum, the better... Here is just my own believe: there is a reason to have an angle plenum (slop down)... because the front 2 cylinders are much further away from the throttle body... and if the plenum is "flatten" with no angle (therefore no pressure going towards the front 2 cylinders), I would think the air flow will still not be even...

This has been discussed many times as well and many dyno results show similar gain no matter it is on the 03 or 04 or even 05 anniversary engine... so I guess I will just go for the ME... since I will still retain the original plenum design which supposes to be angled there for some reasons... :)

cheers,

richie
 

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Discussion Starter · #7 ·
I'll call Peter tomorrow morning and see if he know of any plenums.

As for the angled vs straight spacer. There has been some people who have done flowbenches with the AAM spacers and it seems to get the air flow just about even. Take a look at this thread, the first post shows flowbench results for 2005 track lower plenum, the 16th post shows results with our lower plenum and AAM spacer. From the results I can see that the difference in flow between front and rear is about 20cfm for the 2005 track lower plenum and it's about 23cfm difference for our plenum when it's polished, my guess is it might be around 25-30cfm if it isn't polished.

Also in that thread you can see that the 2005 track lower plenum increases the flow, but it doesn't really fix the problem with the front and rear air distribution. Also the AAM spacer with it's angled design gets with in 5cfm for front and rear air distribution.

I also think that in the plenum you'll want to give each runner equal access to air and not more air for some (rear) and less for others (front). If you make the volume smaller you'll increase the air speed, but you'll also decrease the amount of air delivered. What you want to do, is achieve certain air speed at certain RPM to maximise production of power at that RPM. I could be wrong, but to my knowledge that's how it works. I think with your engine, you should strive to increase the volume as much as you can to make more power higher in the rev range. I think for that reason the AAM spacer is better then 1/4" MD, also if you later decide to get the 2005 lower plenum you might achieve perfect distribution of air to front and rear cylinders. Another option for you could be the 1/2" MD spacer, but you'll loose your strut bar, I think this one would be better for your engine then AAM. I think in your engine a lower plenum with shorter runners is a must to make more power, you might loose a bit of low end, but the gains in high end will compensate, you can either shorten the runners in our plenum or get teh 2005 track lower plenum.
 

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Good news and bad Nuff.

1. I have a spare plenum
2. I live in Perth

Let me know if you want to purchase and I can arrange shipping
 

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Thats the thread i was referring to Nuff

But he didnt flow bench the 05, if u scroll down i thought the same thing as u, and when asked he told me the 05 was a typo

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


so that should read 2003 for those figures not 2005

check out this thread for dyno/pics of an 05 lower plenum install. Some good info there, might be worth ur while Rich going for the 05 lower plenum with that MD spacer
 

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Discussion Starter · #10 ·
The first post has figures for 2005 lower plenum without the spacer, what I did is I've extrapolated the results from the 2003 lower plenum onto 2005 one. It's not accurate and very likely it's off, but that's the best we have at the moment.
 

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Nuff:

Thanks for the info mate! I think I MIGHT just go for the 1/4" MD one though... 1/2" is way too much and I would love to retain the strut brace as well as not using the bonnet spacers which are really ugly IMO... also AAM website is kinda crap because I don't even know where to start with the order and if they reply me back quickly enough, I might just buy their product.... hahahhaa...

cheers,

richie

cheers,

richie
 

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If you want a stock plenum, Crawford my very well be the answer. Before they started making their cast plenum, they were modifying stock plenums, and getting cores back from those that upgraded. He may have some left over, you never know. He would probably like to move them (if he has any left). Doug Stewart is a great guy, give him a call @ 615-327-4159. Can't hurt.

Lou
 

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Rich with ur higher rpm u should be fitting the 05 Ann lower plenum with a spacer (MD on the 05 id say)

The intake runners are much deeper, u can visually see the difference in pics, and that extra airflow will definitely help, not to mention smoother high rpms

03


05
 

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Discussion Starter · #15 ·
lowrider, thanks for the help, but I'm in Australia. I'm going to source it localy.

By the way, I went back to the scene of crime. Here's the photos, as you can see from the photos I've also started polishing the top of the plenum, I'm glad I didn't waste too much time on it.
 

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Discussion Starter · #18 ·
I'll check how much it weights tomorrow. I guess you want to practice polishing aluminium on it? :) I'll give you a hint while doing it, remove as little material as possible.

It also might be fixable if you have a MIG welder, few welds here and there and it should work fine, but it'll definitelly look ugly.

And here's the small crack (center rear bolt).
 

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Discussion Starter · #19 ·
I've forgot to mention that the lesson of today is that aluminium doesn't have great tensile stregth. Now is there any one who would make one out of Kevlar, it's 9times stronger the aluminium http://en.wikipedia.org/wiki/Tensile_strength
 

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Sam:

After a long talk on MSN with nuff... learnt heaps of things just then... I I guess I was wrong about one thing... with AAM spacer in place... the stock plenum is still at an angle (though it would have balanced it out and make it flat out totally)... which is what I need/after exactly... so might consider AAM now since you guys reckon that is a great choice for 03's design...

Nuff:

Hope your z will be running smoothly soon!!! keep us posted!

cheers,

richie
 
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