Plenums On Rb25

[shonen]

As the title suggests im curious to know about peoples experiences and/or opinions on a forward feed plenum on the RB25s.

Either a custom made one or a greddy one or an RB26 one adapted to suit.

Are all 3 essentially the same and do the hinder performance or do you gain performance ?

Ive heard many different arguments for both sides and would just like to get the opinions of people on here.

Also im very interested in peoples expereiences with forward feed plenums on the NEO RB25DET. If you have one, what style did you go for?

I originally wanted a greddy one...but apparently they do not make one for the neo type and they would have to use an R33 one and drill new threads in the cylinder head to make it fit.

which brings me to my next question....is it BAD to drill new threads in the cylinder head ?

cause it certainly SOUNDS bad....

My next option short of a full custom job is to get one of them new adapater plates to make an RB26 plenum fit. If indeed this is truly a "bolt on" mod then would all the fittings and hoses etc fit on the rb26 plenum ?

Edited November 11, 2005 by shonen

[ISL33P]

i currenlty am in the process of doing some flow testing for a rb25 plenum comparing stock to mine style, which have a foward facing tb.

it all depends on what you want to do with the car.

one of my rb30 plenums just helped a car make 780rwhp !!!

[R31Nismoid]

hooray for the search

This is only a SMALL toe in the water with these threads

Draw your own conclusion, my feelings are in the below

http://www.skylinesaustralia.com/forums/in...89670&hl=plenum

http://www.skylinesaustralia.com/forums/in...68046&hl=plenum

http://www.skylinesaustralia.com/forums/in...25648&hl=plenum

[shonen]

haha thanks R31nismoid....

I DID do a search....but there were hardly any topics on it for the neo type...

unlike the non neo ones I have the TCS to worry about....

wanted to know peoples experiences in getting rid of the TCS through the use of an aftermarket plenum..

[R31Nismoid]

dont think many have done it

you is a pioneer

[Abo Bob]

I don't see how the TCS is the problem. You can remove it any old time. All that will happen is that your slip and TCS lights will always be on in your dash.

The issue is all about fitting of bits like injectors, fuel rail and water lines. If no one is making one now then I guess you have to get something that just goes on the top half of the plenum.

(I may be confused but would you call the bottom half of the plenum the inlet manifold and the top half just the plenum?)

Maybe that bottom half could be cut about 5cm out from the head and some new thing fabricated for it. Will it work properly though?

[ghostflame]

no real gains and not worth doing unless ur going over 300 rwkw

[shonen]

haha bob I think you left me with some more questions....

ghostflame:

Although I would not like to LOSE power....power gain or loss isnt really the issue here...im considering an aftermarket plenum due to clearance issues...ie high mount turbo.

[R31Nismoid]

high-mount should pose no problem to piping using a stock item by any means.

[shonen]

high-mount should pose no problem to piping using a stock item by any means.

<{POST_SNAPBACK}>

Glad you raised that point as I would like to know what people think of that setup.

Ive only ever seen it done 2 ways.

1. The piping comes back up the same side and goes around the turbo one way or another.

Like this

or this

2. Piping comes up from where battery is and goes behind fan and goes over the rocker covers and practically does a u turn to connect to the stock intake.

sorry couldnt find a pic :lol:

With option 1 personally I think the cooler pipes are too close to the turbo and cant be too good for cooling properties.

option 2, too many bends in the cooler piping and once again coming close to the turbo....assuming a high mount setup of course.

[Kaido_RR]

i like the rb26 plenum idea but the cost is about the same or more than the greddy plenum

GTR Plenum $200-$300

URAS or Blitz Plenum adoptor plate $600-$700

then you need to have an aftermarket ecu and a few more bits, i have alook for the website for you which tells u what needs to be done to get it to fit

[Abo Bob]

So there is an adapter for the NEO engine? Would you then need an R34 GTR plenum?

[shanef]

U thought about running the plenum cooloer pipe down the left side of the bay? As in coming out of plenum, 90 degree bend, runs parallel to turbo/motor, then 90 degree n goes across/inbetween front of motor n radiator.

Or there could be the option in sending it backwards straight of the plenum n down the left side, ledd bends that way

[shonen]

U thought about running the plenum cooloer pipe down the left side of the bay? As in coming out of plenum, 90 degree bend, runs parallel to turbo/motor, then 90 degree n goes across/inbetween front of motor n radiator.

Or there could be the option in sending it backwards straight of the plenum n down the left side, ledd bends that way

<{POST_SNAPBACK}>

that was option 2 I was talking about...just didnt have a pic !!!

as I said earlier.....too many bends for my liking and really cluters up the engine bay...also comes just as close to the turbo as the first option.

[shonen]

i like the rb26 plenum idea but the cost is about the same or more than the greddy plenum

GTR Plenum $200-$300

URAS or Blitz Plenum adoptor plate $600-$700

then you need to have an aftermarket ecu and a few more bits, i have alook for the website for you which tells u what needs to be done to get it to fit

<{POST_SNAPBACK}>

hmm does anyone know where to get them from ???

I saw the ad in the latest Hpi but cant find anymore info on them...

the autobarn website is practically useless....

I already have a PFC.....so including labour this option could be done for around $1500.....last I checked greddy plenum was around the 2K mark...fitted.

[Kaido_RR]

So there is an adapter for the NEO engine?  Would you then need an R34 GTR plenum?

<{POST_SNAPBACK}>

the adapter is to run a gtr plenum on an rb25

[Kaido_RR]

hmm does anyone know where to get them from ???

I saw the ad in the latest Hpi but cant find anymore info on them...

the autobarn website is practically useless....

I already have a PFC.....so including labour this option could be done for around $1500.....last I checked greddy plenum was around the 2K mark...fitted.

<{POST_SNAPBACK}>

so far i have only seen them sold on yahoo auction and jap website, i dont know anywhere in Australia that sells them you could try contacting nengun, im sure they can source it for you.

I was under the impression the greddy pleunm cost 1k or alittle be more for the kit (come with t.b and cable i think)

[paulr33]

i dont believe there are sufficient gains to warrant the cost and crap you have to deal with to have it changed. we have seen numerous times $xyz-person has a $random-manufacturer plenum and they had issues with response and didnt make any more power. the $1000 cost does not justify the gains, and thats if you make any gains, many don't.

i dont believe shortening the pipework (as covered in previous post) will make a noticable differen as well. certainly if the pipework (length + volume) is %35 more then yes it will be worse but if you are talking re: past radiator vs using stock pipework then there probably isnt sufficient gains to be had, or noticable difference. certainly doesnt justify $1000 on a front plenum.

not a negative nancy would just be happier spending $1000 on something that had a high gain per $ than the front plenum

[Kaido_RR]

i dont believe there are sufficient gains to warrant the cost and crap you have to deal with to have it changed. we have seen numerous times $xyz-person has a $random-manufacturer plenum and they had issues with response and didnt make any more power. the $1000 cost does not justify the gains, and thats if you make any gains, many don't.

<{POST_SNAPBACK}>

The reason for using a gtr plenum on the rb25, so to get more responsed (its not a power gain). Now i havnt seen anyone in australia uses the blitz/uras gtr/rb25 plenum adptor.

But somehow i think that there will be responsed gain or why else would Ken Nomura (R34 4dr d1 car) uses it, if it gave poor results compare to a stock plenum system?

just my 2cents

[paulr33]

because they believe marking crap or have money to burn?

there may be some gains by using individual throttle bodies but $1000+ worth? surely you can get more power gains overall by spending the $1000 better ways