Jeff's MSP GTR Build

with a plenum it works fine. im almost done my new plenum, will post up pics when its done. its steel and when i am happy with the design i will have it welded up in aluminum like the runners/flange by someone with more skills than myself.
 
been watching this since i day one back when i owned a msp :(
in a b13 nissan sentra ser now
 
it is a new intake manifold that has 1 throttle plate for each cylinder located in the intake runner rather than just 1 throttle for all 4 on the plenum entrance. just google it if u still dont understand. common place on vehicles such as skyline, ae86, pulsar gtiR etc. mine are taken from a GSXR 750cc street bike.
 
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so you want me to write a essay because you dont wana type "itbs advantage" into google?

heres the short version. when done right you get increased mainly throttle response, altered powerband and peak power compared to the stock BP IM(well thats what I am shooting for anyways) . Also increased throttle plate area which is a plus if your current throttle plate is too small for the job etc.

there is quite a bit more to it than that which is why i suggested you google and have a read. as with any manifold, changing runner length, shape, adding trumpets etc. all causes changes in airflow. it is very easy to get wrong and have negative results which is why i have built 2 prototype manifolds before having this one made by someone else.
 
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BUILD THREAD??? no??? ask questions and comment! aj has been thro alot this week stop giving him stuff! he dont need more! and looks good, you have one of a kind msp!
 
Thanks rep, and Jeff for the explanation. I just was confused on the advantage as far as itbs with a plenum. But thank you I now understand.
 
no worries i was just kinda busy at work at the time i wrote that. multitasking ftl

what will be interesting to see is how the itbs will perform to a single throttle as I will be able to just remove the throttles altogether and replace with silicone couplings and then put on a single throttle whenever I want to switch the layout. this way I can get direct back to back comparsion with very little to do to swap back and forth.

as for the benefits, I am hoping to have increased throttle response, a larger powerband and a higher peak power number compared to the stock BP FWD IM *if* I did everything right. With itbs it is pretty easy to go two steps back with minor changes so I try to document everything along the way and build several protos to get things right. the biggest lesson I have learned so far is to keep the length of the runner from the itb to the flange as long as possible compared to the runner from the itb to the plenum. Seems to make even more of a difference than runner diameter changes with the GSXR itbs. My guess is that this is because the "outlet" of the itb is not perfectly round due to the integrated injector mounting, and the airflow needs more space to get back on track, where as the other end or the "inlet" has a perfectly round diameter. I think if I spent some time porting the ITBS to make the "outlet" more circular I could diminish or eliminate this effect, but thats out of the cards for now.
 
Hmmm. Well that covers all the bases. Do you have a cam in mind or are you gonna go with a custom grind. But I'm very interested to see how this turns out. Wicked awesome.
 
Good to know about the longer runners. If you're not going to use the stock ITB injector openings, you might be able to get them welded shut and then ground the outlet down to a true circular opening.
 
Good to know about the longer runners. If you're not going to use the stock ITB injector openings, you might be able to get them welded shut and then ground the outlet down to a true circular opening.

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My BP05 vs the VVT setup. For the VVT setup I am going to try and keep the injectors in the ITBs. For BP05 setup with the injectors in the stock location I had to have the different flange to clear the stock injectors.

but i could still do some porting if i find the time/patience.
 
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final plenum proto almost ready

almostITBS.jpg
 

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