A few pounds of weight, thats probably it.

As a builder of the occasional custom intake manifold (heres our DE model; pic), ive studied tons of OEM designs and racing designs of intake manifolds. The GTR plenum is one of the most basic and conservative designs found in OEM intake manifolds.

I have a GTR plenum sitting on my desk for the last year or so. Id save the work of building a way to put the GTR plenum on, and just build a new plenum all together designed around greater top end power production.

I have not done a displacement measurement of the GTR plenum versus the VHR one, but its going to be very close and I bet the VHR is larger. But before you go through all the work, thats one thing I would do.

The runner length appears longer also but may be very close, I havent bothered to measure because without the GTRs entire engine here I cannot measure it from the stack all the way to the back of the valves which is the information needed to say one way or the other. But by the time its resting on top of a VHR and clearing the valve covers I bet its going to be longer runners than stock.

Ultimately the GTR manifold looks like it was designed with low end torque in mind, most likely because of the rather low 9.0:1 compression ratio of the engine combined and auto trans... the manifold seems to accomodate that with a design to help increase throttle response and engine "motivation" in the lower RPM.

Its my personal belief its going to be a huge dissappointment. But I really cant wait for someone to finally do it and dyno it to settle that question.

If I were to go forward with putting the GTR plenum on the car... I would take the VHR lower runner section and have it 3d scanned into CAD. I would also scan the runner flange on the GTR plenum. Then in CAD, cut about an inch off the top of the stock VHR part, and CAD up an adapter to the GTR pattern. Make it as thick as required to clear the VHR plenum, integrate in the fuel rail mounts as required, then machine the adapter. Put the VHR runner section in the mill and take that inch off the top of it, then weld on the adapter flange and port match. Then you dyno test it...!

It sounds so easy when you say it like that.

The fuel rails are going to be a huge PITA! trust me GTM went through the same problems. They are waiting on my car to finish the testing and release of the kit...

ya luckily fuel rails are a pretty easy component to custom build.. the rails are pretty much the only thing making this any sort of chore

Well it will sure look cool at least :bowrofl:

Also very interested to see the dyno gains. Visually it looks badass. Im guessing that the stock strut tower brace would no longer fit, correct?

Subscribed .... Good luck

@phunk
I really appreciate your work (awesome manifold build) and your input - as said earlier it was just like "everybody talks about the GT-R manifold on our cars, but there is zero to none progress, so lets try".

I'm absolutely ready to accept if this conversion does not yield any performance gains on my NA car. But hey, at least I finally tried it so there is a definite answer to the question if and how it works for the VHR.

As for the low end torque design I wouldn't be too angry if it helps our cars in the low end region as this is were we are missing torque the most. As soon as the VVEL kicks in the characteristics of the engine changes completely but before it feels very weak, so any gain here would be appreciated.

My hope with this conversion on the NA car is that it will gain in the low and mid rpm range and still keep the stock manifold numbers in the high end range.

As for keeping the stock lower manifold and modify it thats no option for me as it has square runners while the gtr manifold has almost round runners. When I take the effort of mounting this thing on our car I want to have at least a design which looks like to be the optimum you can do - testing a combination of stock lower and gtr upper says nothing about the potential this conversion may have.

@Bullitt
as said I can't wait to see what GTM finally releases and how they worked around the issues I have found so far. It can't really hurt to have two separat approaches to the same problem and two independant testing results. My build is not intended to be a selling product in the first place, its more like a project I wanted to do - well, if everything is ready and somebody wants one, there's no worries ;)

@Perf.Des
indeed the stock strut brace is also an issue - we tried to sit the plenum as low as possible but because the R35 has no strut bar over the plenum they have not designed it to clear one. When you look at the stock plenum it has a special angle and some kind of notch where the strut bar runs across.

we will either work with spacers or design a new strut bar that goes in front of the new plenum.

Chris

Man, that engine is beautiful!!

If the numbers are there I'll be very interested in one. Keep up the hard work! And thank you for taking the time to do this.

Hey man, its worth a try, if nothing else, who else can say they did this? Fantastic work so far! Keep it up! Sub'd

I cant wait till this is complete and you have dyno results...if it works I will definately be ordering a conversion from you.

Hey guys,

sorry for the delay, during christmas and new year the development was suspended but now we have continued to work on the manifold adapter.

In order to make everything fit more easily and to have an extra option for the FI guys we decided to go with new custom made fuel rails. The rails will have a larger diameter and can be used with stock injectors or aftermarket injectors. You can run the rails in stock configuration as a returnless system or easily convert to a dual feed return system.

here are the newest prototype pictures - remember this is work in progress, the final product will look much nicer !

Chris

In for results.

Subscribed. Great thread!

When do you think testing will start?

in for results.

IIRC, GTM managed to reduce the installation height. It might be possible to fit the stock strut bar. If not, I'd love to see a CF strut bar like the GT-R.

I really hope GTM will reveal their solution as I'm curious how they overcome certain issues I discovered while working on this.

For for installation height there are some key aspects you normally cannot change:
- the manifold cannot sit lower than the stock manifold as the "air boxes" touch the valve covers. Even if you simply place the manifold on top of the engine as I did on one of the above pictures, means in the most lower position you can get with no space between mani and valvecovers the strut bar will not fit.
--> that is the reason why the flange for the GTR plenum needs to be at least 2cm / 0.787" higher to make the mani clear the valve covers

Nissan has designed the stock mani in a special way to fit the strut bar. If you put the stock mani on a table and have the lower flange (which connects to the lower manifold) in a horizontal orientation you will find that the top of the plenum has an angle which makes it lower in the front section. The GTR plenum doesnt have that as it was not designed to work with a strutbar going over it.

We have tried to make the plenum sit as low as technically possible so you might be able to put some thin spacers under the strut bar and make it fit but that has to be tested.

Chris

@370Z JT
the whole CAD development is now at about 80% ready - we hope to finish the design by end of this week so the production of the flanges etc. can start next week. My personal goal was to have the prototype ready and installed for testing before end of January.

amazing...

:iagree:

are you using solidworks or inventer for the 3D rendering on this?

the program I'm using is called "CATIA" - check this video !

sub

nice!

hah ironic, i get on here to take a break from my cadd job, get on here to talk about cadd

let me know how you like this !

GT-R plenum adapter, completely designed and made in Germany - prototype will be CNC machined on a 5-axis mill - custom -6AN 12mm fuel rails for stock or aftermarket injectors - easy upgrade to a dual feed return system if needed.

http://fbcdn-sphotos-a.akamaihd.net/...14692887_n.jpg

https://fbcdn-sphotos-a.akamaihd.net...59867434_n.jpg

we are almost finished - just waiting for the fuel rails to come in so the production of the prototype can start. Looking forward to the dyno results !

Chris

Sick!!! :rock::rock::rock:

sound like it starting to get fun
sub

Sweet! Awesome CAD work, you ever use Solidworks?

Wow very impressive.. Cant wait to see the final product! Irregardless of dyno numbers that is some great work!

Very excited to see what the results of this project are. Hopefully your hard work is rewarded with favorable dyno numbers.

thank you - its really motivation to move on ! I have invested about $700 so far plus about 40 hours of work in total. I assume it will be another 30-50 hours before everything is completely ready and about additional $1500-2000+ just to have the prototype on my car fitted and dyno tested so your appreciation keeps me going.

we are using CATIA as this software is normally used to develop aircraft parts for planes like interior, turbines, gear, etc. - you cannot get much better even though solidworks or inventer are great tools too.

Just so you know we are not simply design something that will fit / allow you to mount the GT-R plenum but also have software to virtually calculate the flow and dyno the part before actually building it. From what we found so far there is a real chance that this modification will yield HP and torque even on a NA car. But only real world testing will show if the theoretical work will pay off so I keep silent until the prototype has been installed on my car - every result will be documented and posted regardless if the result is good or bad.

What I can say so far is that our design should be lightyears better than the cost effective solution Nissan has developed. They use square runners while we use round/elliptic runners perfectly matching both the head ports and the GT-R plenum ports. The flow velocity should be far better than with the stock part which hopefully will help to increase performance - believe me I'm more excited about what we can achive than anybody else !

next step is to actually build this thing - will keep you posted !

Chris

^:tup:

I'm in.

The Z is also in.

Very nice. Catia rocks (its sister is Solidworks, both are developed by Dasult).

Im kinda bummed I went a different direction now. This looks like it has a lot of potential, if not the super cool factor.

sub'd.

Looking forward to those dyno #'s for both n/a and FI, also would love to know if there is any weight penalty by switching to the GTR plenum.

Hmmmm........sub'd now!

subscribed..