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RXF Dual plenum trunk mount manifold

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49K views 181 replies 36 participants last post by  SnowRocker88  
#1 · (Edited)
Well the past few weeks I've been building a few manifolds and decided to build another one for my car while I was building those. Its much easier to build several manifolds at once. When I have down time, and waiting on parts to come in for other projects I get time to work on my personal manifold and car. I've just about got it wrapped up and hope to have it down to the dyno for results ASAP. Of course I'll add it to the data I have already so it can be compared to the other manifolds I've built and others I have tested.

All in all, I hope the dual plenum works as it should. I will admit there is always room for improvement and, I'm sure I'll build another eventually pending the results of this one. The idea and purpose behind the dual plenum is even distribution to all runners at the expense of some air velocity. While I was researching the dual plenum, I came across a quote that seemed to sum the dual plenum up fairly well. "The dual plenum is like having ITBs for turbo cars" Just how accurate that is will be determined.

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#9 ·
Very nice! I like that throttle body in the background of the first picture :)

Can't wait to see what the results you get are!

From the pictures it looks like the plenum is basically all that changed between the manifolds? the runners look the same.
 
#13 ·
MR2 Josh said:
^runners look to be tapered on the new mani.

Looks great! You've made more styles of manifolds in the last year than there were even ever produced for the mr2. Hah
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Yes, old runners were tapered as well. The new manifold I tapered inside and outside to save a little more weight. All in all I think I've managed to drop a few pounds of weight in the new manifold.
 
#14 · (Edited)
Results

Well, I'd say that this is probably about as good as it gets for my personal manifolds. From all of the designs, I still managed to pick up 3 whp, 9 ft/lbs of torque and looks to be about 100 to 150 in spool. I reduced the plenum size back down to what I originally had and varied the runner diameter. Final result is 482whp, 383 ft/lbs or torque. Same psi setting as before at 18psi.

Turbo: GT3076r

New results with dual plenum intake manifold:

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Old V2 plenum results: (Link to V2 build:https://www.mr2oc.com/showthread.php?t=392163&page=1&pp=30&highlight=dyno+comparison)
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Pics of how the set up looks now:

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#18 ·
#25 ·
cbishop11 said:
Not much of a gain over the previous design - unless you think there is a lot of optimizing left to do.......
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I think it is more a case of making it as good as it will get. I mean look at the numbers, 480rwhp at 18psi on a GT3076, that is unheard of for an MR2!
 
C
#26 ·
Texas_Ace said:
I think it is more a case of making it as good as it will get. I mean look at the numbers, 480rwhp at 18psi on a GT3076, that is unheard of for an MR2!
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Possibly. How much more money would you spend on a manifold if you were only promised a few more HP? My previous comment really addresses the fact that unless an improvement could be made with an optimized design, the extra cost just doesnt seem to be justified.

I hope RacerX really decides to go further with this. I personally believe he could achieve 500whp, but it just comes down to how much more R&D he wants to commit to it.

Another thought is a retune - how did the AFR's look on this dyno run? Any possible improvements to the tune because of the manifold?
 
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