GT-R R35 Plenum Test Fitment on my VQ37HR

TypeOne

Are you affiliated with any shop or garage in Germany?

Thanks for going for it... it really is great to see someone doing something new. Even if the results turn out to be not worth it, it's progression in at least one direction!

Good luck!

KaienZ34

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ChrisUR

well, what I can say for sure is that this uprade will help everybody who goes or went FI - for the NA guys (like myself currently) it will be a surprise if and how it improves or not.

All I can say is that you have very little room to play cause the position of the plenum is quite pre-defined by the valve covers, hood, oil cap, etc. - so the way we are building it is plus minus a few 0. inches the only possible solution.

We try to make the piping of the lower manifold as big as possible / as close to the GT-R runner diameter, so with FI you will absolutely see gains because of the higher volume and better flow.

The fuel rail issue I worked on today is really a PITA - we will see later on if keeping the stock rails really is the best solution or if it wouldn't be easier to design new fuel rails which also have a larger diameter - which also would help those with bigger injectors, etc.

But for the prototype I will constuct the adapter to use stock rails, so we can do the first test runs asap.

Chris

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'10Anamoly

Sub'd for results.

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edub370

(*everyone on forum scoots up to edge of seat)

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TypeOne

What type of tuning are you going to do with this setup when it is complete?

Did you dyno your car before this so you have something to base it on?

Doing all of this work to say, "it feels faster" doesn't really do anything.

cdoxp800

biting nails in anticipation

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2011 Brilliant Silver NISMO 370z. #: 0046.
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Jeffblue

what are the potential gains from this?

AlphaSnacks

Really depends on how much volume this adds to the collector.

ChrisUR

yes, I made some dyno runs before - stock car - only exhaust (Topspeed catback) - catback + stillen gen3

so I have a good idea if the manifold will gain or loose when we do another dyno with it installed.

the main region I hope to see gains for NA cars with this conversion is that our design combined with the excellent gtr mani has a greatly improved airflow as the runners are now round instead of square and the runners are longer and going independently into the tanks and there are no sharp edges inside the manifold like with the stock one.

I guess that is the reason why the M370 looses power in the high rpm range. My guess would be that they cut the runners inside going into the plenum to enlarge the volume but this sacrifice the airflow.

Haven't seen the M370 in person but after looking at the stock manifold that is about the only thing they really can do as this is a plastic piece and you cannot really enlarge or polish anything like you would do with a cast unit.

Chris

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phunk

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.

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phunk

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...!

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The Dimer

It sounds so easy when you say it like that.

bullitt5897

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...

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phunk

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

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