GTR intake plenum on RB25

[N I B]

GTR manifolds do flow uneven this is why most good tuners use fuel trims on the rear cylinder.

[N I B]

The front runner even has a lot more reversion than the other 6 runners.

[aybee]

i dont anything about this, but i think its logical to say that if aftermarket brands make a different plenum for the 25 and 26, then it would mean that they require different plenums.

[DETurbine]

The main reason they make different plenums is becuase the bolt pattern is different from the two. For the runners flowing differently, what would stop some one from port matching them and smoothing them out?

[discopotato03]

I still think the complete 26 top end is the go . If you look at RB20/25/26 heads on the inlet side you'll find numerous detail changes to suit their application . I believe the bolt patterns are different because of access to the fasteners to assemble it all .

As for inlet system development I'll bet any money that Nissan put more into developing the RB26 inlet (as a package) than GReady ever could .

Cheers A .

[sweetr33]

im sure alot of research did go into the gtr plenum, im going to stick with it for the moment and see how it goes, then i can tell u of the results that i have seen ok steve and others. I would like to get the greddy one but already have the gtr one so im going to see what i can make outta it.

[lukevl]

Agree with discoepotato. Very good statement about Nissan. So true as well. A lot of people think that aftermarket stuff is the be-all and end-all of car developement. None of these guys would have any idea what its like behind the doors of an OEM facility.

[sweetr33]

we are more than likely going to weld the adaptor plate to the manifold and port match it to the head. I think this is going to turn out alrite.

[JasonO]

Agree with discoepotato. Very good statement about Nissan. So true as well. A lot of people think that aftermarket stuff is the be-all and end-all of car developement. None of these guys would have any idea what its like behind the doors of an OEM facility.

Don't be dumb !!

When Nissan were developing the GTR plenum, they had the same restrictions as they have with everything else they look into when developing a car......Accountants not being the least of their problems, they have to optimise design parameters to suit broad conditions of use. An aftermarket developer, like GReddy, doesn't have to comply with emissions design criteria, and their targeted performance parameters are a heck of a lot narrower than Nissan's ever were.

It's common knowledge that the GTR plenum has a flow problems with Nº1 & 6 cylinders, but I'd love to see evidence of the flow test results you claim to have heard.

[Sydneykid]

Don't be dumb !!

When Nissan were developing the GTR plenum, they had the same restrictions as they have with everything else they look into when developing a car......Accountants not being the least of their problems, they have to optimise design parameters to suit broad conditions of use. An aftermarket developer, like GReddy, doesn't have to comply with emissions design criteria, and their targeted performance parameters are a heck of a lot narrower than Nissan's ever were.

It's common knowledge that the GTR plenum has a flow problems with Nº1 & 6 cylinders, but I'd love to see evidence of the flow test results you claim to have heard.

I have done the flow tests, what would you like to know? Let me start the ball rolling, we saw none, zero, zilch, not one cracker, nothing, SFA improvement from testing the GReddy plenum on a GTR inlet and cylinder head at airflows equivalent to 750 bhp.

So if you spend your $1500 on a Greddy plenum and I spend my $1500 on something else, my car will be faster until we get to 750 bhp. And even over that the difference is nowhere near as significant as $1500 worth of other stuff.

Put it simply, personally I have demonstrably better ways to spend my money.

[BBQ]

I have done the flow tests, what would you like to know?  Let me start the ball rolling, we saw none, zero, zilch, not one cracker, nothing, SFA improvement from testing the GReddy plenum on a GTR inlet and cylinder head at airflows equivalent to 750 bhp.

So if you spend your $1500 on a Greddy plenum and I spend my $1500 on something else, my car will be faster until we get to 750 bhp.  And even over that the difference is nowhere near as significant as $1500 worth of other stuff.

Put it simply, personally I have demonstrably better ways to spend my money.

Sk,

The original post was about putting a GTR Plenum on a RB25 ? Not a GTR? what are your thoughts on that ?

[JasonO]

SK,

I don't doubt for a second that the GReddy Plenum, in either RB25 or RB26 applications, only comes into it's own after a certain level of airflow is required, nor do I doubt that the OEM designs are good ones, but I'd still love to see the figures so as to appreciate just how futile the whole argument really is.

Like BBQ though, I'd like to know your POV regards the RB26 plenum on an RB25.......

[N I B]

Why not tell us who you are SK so we can see if you are what you claim to be as you have posted a few Facts that have been anything but so i feal its time you name your self.

[carlo]

*mod hat on* Keep it clean guys... *mod hat off*

I did some research on the greddy plennums and found that stock RB25 unit was good up to 250rwkw.. I was going to buy a greddy unit but found my self wondering why none of the worked GTST and GTT's at tokyo autosalon had them.

The stock unit is under appreciated.

[GTS-t VSPEC]

While I agree the stock unit is more than capable of supporting decent horsepower, I think the main difference is how it makes the horsepower. Ever since I've had my Greddy manifold on my midrange power has dramatically increased, and I'm yet to even see other cars match my dyno graph for average power.

[discopotato03]

Tell me if I'm wrong but is someone trying to cut and shut RB25 manifolds with GTR plenums ?

[Sydneykid]

Why not tell us who you are SK so we can see if you are what you claim to be as you have posted a few Facts that have been anything but so i feal its time you name your self.

Steve the people that I want to know, know. The problem is if I tell EVERYONE, I will get hundreds of retail calls. As you know, I am not in the retail business, I help some people out, particularly when they have an interesting problem, but that's it. I already get 30+ PM's per week and I reply to every single one. I don't make any money out of it, I don't charge anything, I don't have anything to sell.

I made the mistake about 3 years ago on another forum, one that I have lots of experience in, more than Skylines in fact. But I got pestered so much I had to change my phone number. I no longer contribute to that forum. I don't want the same to happen here.

I promise you this, next time I am in Perth with the race team, I will drop in and pay you a visit. I know where you are in Welshpool, just up from the Leach Highway. Will I need to bring a body guard? :uhh:

[Sydneykid]

While I agree the stock unit is more than capable of supporting decent horsepower, I think the main difference is how it makes the horsepower. Ever since I've had my Greddy manifold on my midrange power has dramatically increased, and I'm yet to even see other cars match my dyno graph for average power.

Let me apologise for this post before I start, but regular readers will know why....

Paul where did you get the term "average power"? From ME, that's where you got it from, I introduced that terminology to this forum. Before I explained it, you didn't even know what it was. You didn't even know why it was important, much the less how to calculate it. Don't bother, I have the posts to prove it.

So don't try the

"I'm yet to even see other cars match my dyno graph for average power"

, without even trying I found 20 on here that shoot on it from a great height.

Let's get down to facts.....

Ever since I've had my Greddy manifold on my midrange power has dramatically increased,

I simply don't believe you, show me the before and after dyno graphs and prove that the ONLY change was that from the standard manifold to the Greddy. You and I both know you can't make that claim, you changed lots of things, not to mention tune at the same time. Maybe Steve's brilliant tuning gave the increase in midrange and it would have been even greater with the standard inlet manifold.

Time to apologise again for this post, but sometimes ya just gotta say it. :fart:

[Blitz]

Sydneykid & Steve SST - how old are you both? Its clear you have differing opinions on various issues but your constant arguements and bickering is getting a little old now.

How about giving it a rest and concentrating on continuing to offer the fantastic tech info that both of you have been providing to SAU?

[Sydneykid]

Sydneykid & Steve SST - how old are you both? Its clear you have differing opinions on various issues but your constant arguements and bickering is getting a little old now.

How about giving it a rest and concentrating on continuing to offer the fantastic tech info that both of you have been providing to SAU?

Hi Blitz, I am sorry if you are offended by reasoned discussion, well at least my half of it is. I know from experience that you can put two circuit race engineers in a room and they will both have differing opinions on many subjects. I had 2 of them in heated argument last weekend over whether Penske or Ohlins were better.

What am I supposed to do? If I stay silent, it is taken as agreement, if I put forward a rational argument , I am accused of bickering. :freak: