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Skyline Gtt Plenum

rice boy

By rice boy,
in Western Australia

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SKY 34 Mentor

SKY 34

Posted
Posted

plenum looks cool ~~..I reckon if it's going to cost $600 get the Greddy ones, the Stock TB is not going to fit into the plenum unless you have them custom made....either get an adapter plate or change the TB.

If you do change the TB, the traction control will be removed. You notice that The Gtts have longer TB than normal...hence replacing the TB will require some custom pipe to be made to replace that length...

with the Greddy ones I think you'll need top feed injectors and fuel rails

rice boy Collaborator

rice boy

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  • Author
Posted
but dont u HAVE a r34 GT-T????

why would u want another plenum for when u already got one of them on ur car

unless its a aftermarket front throttle body opening one that ur talking about

Yes, I want the after market one.

less piping and cooler induction.

rice boy Collaborator

rice boy

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the aftermarket plenums are forward facing , so you cut out all the cross over the engine part of the piping

but the stock plenum is good for lots of HP and flows very well , not really a worth it just to cut a foot and half of piping out

well actually for me it at less 3 foots.

the way I see it .....less volume=easier compression=less stress on the turbo..

=cooler air= better preformance.

32vspecII Mentor

32vspecII

Posted
Posted

3 foot is still nothing

your theory is correct but in practise there will be virtually no benefit

also lots of the aftermarket (cheaper) plenums are poorly designed , dont flow as well and tend to have uneven air distribution across all the cylinders casing some of them to run rich or lean

apart from the visual appearance no benefit has been covered many times in the forced induction section if you want to search

rev210 Grand Master

rev210

Posted
Posted

The stock plenum is better than a crap el'cheapo one.

However a well made unit is another story. The plazmaman plenums increase power over a stock plenum as a bolt on ($1,100 no crap required unlike the Greddy) not to mention the benifit from reduced piping volume, length and very restrictive bends.

The stock plenum might be good for 500hp. A good aftermarket one will get 500hp with less effort.

The cheapo units however are not worth bothering with. $1,100 for a good bolt on one is value.

SKY 34 Mentor

SKY 34

Posted
Posted
i agree. the stock plenum is good for close to 500hp so unless your shooting for big numbers or have a space issue then i would put the dollars into something worth wild

are you sure? I think they'll only last to abt 350-400hp

and you can use the Greeddy r33 gtst ones to suit r34...I got them off Nengun for $1020

these units are direct bolt on as well...at least that's what I was told...haven't fit them yet

rice boy Collaborator

rice boy

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well over 350hp

350rwkw easy on the stock plenum , apart from the annoying cross over i/c piping its a a very good intake

to be honest, it hard to judge unless there someone actually done some experiment on it.

theory is all good and I do appreciate everyone opinions.

by the way had anyone read about it or had converted the standard 25det plenum or any cross over plenum to non cross over?

I, myself witness my mate did it to his Mk3 Supra but he also did few other mods as well so we couldn’t really judge if the cross over had makes any difference.

But I think I can work it out if we will pull all the paper works out and investigate. it that is if he still got all of the paper work.

32vspecII Mentor

32vspecII

Posted
Posted (edited)

there is lots and lots of evidence , pre and post dyno runs in the forced induction forum , search

its been pretty well gone over now , no flow increase for the aftermarket plenums at this power level

you can convert stock to fwd facing but you have the same problem with uneven air distribution

get the proper greddy one if you want to do it , not that expensive and they work properly . just no flow gain.

look good though

Edited by arkon
rev210 Grand Master

rev210

Posted
Posted

Honestly the fact that the plenum allows 350rwkw worth of air through it means very little. Air flow restrictions to an extent can be overcome by working the 'air pump' (engine) harder.

The good thing about the factory plenum is that it had long runners for better off boost performance and is pretty good at evenly distributing the air going into it at moderate power levels. It has a fairly low volume plenum chamber for suited to the airflow needs of the factory engine, helping with low end rpm response.

The bad things are that , the plenum chamber volume is a tad small for bigger power levels requiring bigger airflow and cylinder fill rates. It will be well down on power compared to a good aftermarket unit with the same equipment. At 500hp I'd say there would be a significant difference indeed. It faces in such a direction as to cause restriction and dull response when coupled to a FMIC (not an issue with the factory side mount though).

As for modification of the factory plenum, Grandenko did this to his RB25det and reported no ill effects and increased response. As to whether the cylinders fill evenly I'd say there may be an issue as the stock plenum isn't tapered to suit the front feed airflow bias to the rear cylinders.

  • 2 weeks later...

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