Personally, I do want to keep the engine cover. In my eyes, the NSX is slowly becoming a classic car and I’d like to keep mine relatively stock looking.
If a new intake manifold is designed, I think it would be great if not only the plenum volume were optimized, but also the cross section and length of the runners. And it would be great if the runners were kept smooth – if no Z-shaped kinks or corners were introduced.
In a naturally aspirated application, FastraxTurbo did a dyno test with a stock intake manifold, with a ported intake manifold minus the VVIS plate, and with a ported intake manifold that had its center divider machined away and that had the outer walls of the gutted VVIS plate reinstalled (to maximize the volume of the plenum). Here were his results:
To visualize what those different intake manifold configurations look like, I sketched them based on one of Honda’s cutaway drawings.
For shits and giggles, I also sketched an OEM intake manifold with a one inch spacer between it and the cylinder heads and a correspondingly deeper plenum.
That looks like one big plenum! Since the mating surface of the intake manifold and cylinder heads is not at a right angle to the airflow, installing a spacer between the two unfortunately creates a Z-shaped kink in the runners. Depending on how thick the spacer is, the spray from the fuel injectors might start hitting the upper walls of the intake ports in the cylinder heads instead of shooting straight down the backs of the intake valves.
I wonder what intake manifold would be optimal for a turbo and what would be optimal for a naturally aspirated engine. If I remember correctly, turbo engines benefit from removing the VVIS system. Of the three configurations FastraxTurbo dyno tested in a naturally aspirated NSX, the one with the VVIS in place looks best overall. However, it would be great to have more n/a dyno measurements plus an understanding of why a certain design is best.
To those waiting last to produce one I'm not giving out the design secrets all at once. There will be some iterations in the future to keep it ahead of the curve haha.
You make me wish I wasn't SC'd.To all those interested in my versions of the manifold. I have finished the prototype and I should have a finalized version in a couple of weeks. I have calculated the finalized plenum volume to be very close to 7.2L with the engine cover (spaced 1/8 inch in front)give or take of course. It will support any type of NA application as long as you don't just run only the manifold. I am assuming everyone who buys this will have some supporting mods so my dyno testing will reflect that (ex. headers, exhaust, and some form of tuning). Since the parts I have produced for my NA1 have already depleted the fuel delivery system I suggest everyone who installs this to upgrade the fuel system including the injectors. This manifold size is enough to support an engine making almost 200 percent VE naturally aspirated. Since the C30 and C32 engines will never surpass that it will never be a restriction. Even at the engine's biggest displacement this manifold will only produce more power. It can cover just about every forced induction setup as well. I have built turbo setups on 4 cylinders with intake manifolds in the 5.5L range making close to 1000BHP so this manifold will more than suffice a FI application as well. On the NSXs with throttle cable it will accommodate a BLOX Honda 76MM throttle body and for the DBW guys there will be a throttle adapter flange to accommodate the factory throttle body. If anyone wants to run my AEM Infinity PNP setup I can handle the task of getting you a bigger DBW throttle body that will work too.
Despite the manifold having some versatility, I will still make a bigger volume version of this as well. It will accommodate only a 90MM throttle body( I have not chosen the type yet) and the plenum volume will be roughly 9L. This is for outright HP (more than 1000whp) and high rpm operation. I will start on this manifold after the smaller one is done and I am satisfied with it.
To those who know what they are looking at you will see some sneakiness in the design but I am trying not to go overboard until I test the first one
The manifold will be all aluminum, probably brushed and/or polished. I have tucked everything underneath it (sensors, throttle cable, vacuum ports) to make it the centerpiece of attention and most importantly clean. So far it only weighs in at 14lbs (stock with TB 34lbs) but I will weigh it in when it is done. I will post a teaser shot of the rough prototype if anyone is interested in seeing it at the early stages. I have so much more to tell but in due time. If anyone has any reasonable questions please don't hesitate to ask.
Kinsler not only allows you to choose the ITB sizes you can change runner lengths and inlet sizes as well. They also will CNC match your units to whatever cylinder port you have whether it be stock or modified. Very useful and somewhat versatile.
I personally like the look of machined aluminum versus cast so I don't see the need to make it look stock. If you have an oem throttle body that needs a throttle cable it will not work unless you make a custom cable bracket that can pull it in the right direction. The shape of the plenum simply won't allow the cable to be run like factory. I designed this manifold to run the throttle cable under the plenum hiding it and it works great with the Blox billet TB. I am a BLOX dealer and have used untold numbers of these TBs. Despite what you hear they work just fine. No such warpage from heat at all. If anyone is having idle issues with them then they do not have the throttle base/stop adjusted properly. If it is set too much toward the closed position then the plate will catch the inside of the body causing inconsistent returns, which in turn causes the inconsistent idle you are referring to. They put the adjustments there for that very reason. Just gotta know what you are doing
