For starters, please only comment if you have experience porting intake manifolds. I really need sound input here, not just speculation. I don't mean that to sound rude or anything, I have just seen so many tech threads gummed up with ill-informed comments.

ANY input by professional porters would be very, very much appriciated. Thanks to all of you in advance for your help with this.

So heres the sitch: I have done basic porting on nsx intakes several times and had good results with FI cars, but I have an NA motor going together soon and I really need to get serious about sorting this part of it out. Now that SoS is offering their stroker kits, aggressive nsx NA builds are getting much more popular. The general opinion on the motors built so far is that the stock intake design is a limiting factor. ITB's offer a big inprovement, but are pretty spendy.

So far, I have been basically cleaning up the runners, port matching them and putting a knife edge on the divider in the entrance. I also ditch the VVIS plate and replace it with a billet part that maintains the depth and volume of the plenum with all the butterlies and associate junk removed completely. Lastly, the TB is bored out and the inake entrance is bored to match.

I will probably move to a custom intake at some point (getting flanges made soon), but I need an option based on the stock intake in the mean time.

I have included several pictures of a completely stock intake below so that anyone wishing to comment can get a good idea of what we are starting with. I also have several specific questions.

1) Do you think I should continue to put a knife-edge on the divider at the entrance, or should I lose the divider completely? I am really tempted to do that and to also remove the divider 'wall' that continues the length of the plenum. I think that without the VVIS assembly, the divider is pointless.

2) I was also thinking of welding in some material to build a slight radiused lip (like a velocty stack) on the runner opening that faces the plenum. It would only be on the bottom half, but it might be better than the extremely tight radius there now.

3) There is room to make the plate that replaces the VVIS assembly a few millimeters deeper than it is now. This would increase the plenum volume slightly, but I am not sure if it is worth the hassle.

Anyway, on to the photos.

First, here are some pictures of the complete stock intake assembly with the VVIS plate and lower plenum.





Looking into the plenum entrance:


Plenum entrance from inside. This shows the divider pretty clearly. When the manifold is assembled, that divider rests up agains the VVIS plate.



So, you can all see how the stock system works, this is the VVIS assembly. Again, you can see where the internal divider matches up to it. The butterflies open at high rpm to increase plenum volume. I generally remove this whole assembly.



This is the inside of the intake manifold:



And a closer look at the runner entrance:





If any of you need to see a different angle to get a better idea of the mani's design, let me know and I will do my best to post up a better photo.

So, let's hear from the experts - what would you do if you were porting this thing?


Modified by Top Ramen at 11:41 PM 4/5/2007

 

if i were working on the manifold i would remove the buttfly plate as you mentioned you are already doing and i would add the largest throttle body i could fit...maybe a 74+ mm.
i would also remove as much of the dividing wall as posible
extrund hone the the runners... the only problem i see it the manifold runner entrance... if you could add meterial to the tops of the runner and port it out...
pretty mutch you would have to cut the manifold in half or find a flex swivel head on a die gringer and taper port the entrance of each runner... making the entrance as large as possible...
this is where i would start but i am no means a professional at this.


it looks like they designed that manifold to hide the power of the nsx engine

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by alterdcreations &raquo;</TD></TR><TR><TD CLASS="quote">i would add the largest throttle body i could fit...maybe a 74+ mm.</TD></TR></TABLE>

The stock TB won't quite go that big and I don't want to have to machine an adapter plate. If I do end up making a custom intake at some point, I think I will just flange it for one of the huge billet Mustang TBs.

Any other input guys?

 

David, have you thought about using the Infiniti Q45 throttle body?

IIRC, GT-Rom is using this setup.

 

Shawn, do you have any more info on this? What sort of adapter (if any) is needed?

 

Just looked at the Hogan's intakes - looks like it would be $2500 for one of theirs. Definitely not in the budget.

 

There's a couple of threads on Prime about the GT-ROM throttle body:

Here #1

Here #2

Here #3

...but I dunno if those are going to answer your questions.

 

Yeah, I read through those before. They chatter about it, but there is no real information. I may just get a Q45 TB gasket and see how well it matches up.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Top Ramen &raquo;</TD></TR><TR><TD CLASS="quote">They chatter about it, but there is no real information. I may just get a Q45 TB gasket and see how well it matches up.</TD></TR></TABLE>

Yeah, I was hesitent to suggest it when I read the first response to your thread but thought, "what the heck." ak may know more about it since he patrols the Japanese boards.

Took a look at some of the Hogan's (they're from my hometown come to find out) intake manifolds and they looked impressive (w/o knowing any of the specs).

There's another thread on Prime from member Hypertune that did a custom intake manifold.







Thread HERE.

 

wow the inside of that thing looks better than the outside!

 

Shawn, I found that thread as well. I e-mailed hm about it, specifically trying to find out if he could help me out with the flanges, but never got a response. That intake was designed for FI, but with the long runners, stacks and nice plenum, I think it would also work really well on a bigger NA motor like yours.

BTW, I will probably start the process for getting flanges made next week.

Here's a picture of the Hogan's intake on a car:




Modified by Top Ramen at 11:12 AM 4/8/2007

 

Well, if it can flow enough air for a 1000hp engine... Not too much a fan of Saruwaturi though, actually not at all.

Have you talked to Endyn about fab'ing a less expensive custom intake plenum? They're right in your neck of the woods.

 

I understand how you feel about Saruwaturi. I spoke to Adam a couple of times (was introduced to him by his sponsor) and he was a complete ***** both times.

If I go that route (custom intake), I would probably either have Larry do it or Tony (Tony1 on H-T). He's doing some work on my old silver turbo car right now. If I am feeling especially frisky, I may try it myself. Ross Machines has some oval runners and stacks that would match up to the nsx ports almost perfectly.


Modified by Top Ramen at 4:54 PM 4/8/2007

 

Any updates on this project?

 

It was 4 years ago... Why the hell woud you bring this back up top.

 

Maybe because I'm curious about any other data that was discovered?

Maybe because I now own an NSX and am looking for worthwhile projects?

 

Well then change your sig to say you own a cool car and not some lame toxic battery pack carrying car.

But on another note im sure if there was some new found info in these four years, it probably would have been posted by now