Jump to content
SAU Community

Question for all you Greddy/Trust plenum owners ?

B-Man

By B-Man,
in Engines & Forced Induction

 Share

Recommended Posts

B-Man Grand Master

B-Man

Posted
Posted

Hi Guys,

I just received my Greddy/Trust RB25 plenum kit from Japan.

I was sort of surprised to see how rough and daggy the inside of the plenum chamber and runners are.

Understanding that the thing is cast aluminum , I thought the factory would have smoothed / ported / polished the chamber and runners ??

Did you guys who fitted these plenums do any extrusion honing, porting, polishing before you put them on ??

Or did you simply remove the cast dags an bolt it up ??

Cheers,

grepin Experienced

grepin

Posted
Posted
Hi Guys,

 

I just received my Greddy/Trust RB25 plenum kit from Japan.

 

I was sort of surprised to see how rough and daggy the inside of the plenum chamber and runners are.

 

Understanding that the thing is cast aluminum , I thought the factory would have smoothed / ported / polished the chamber and runners ??

 

Did you guys who fitted these plenums do any extrusion honing, porting, polishing before you put them on ??

 

Or did you simply remove the cast dags an bolt it up ??

 

Cheers,

Just had it bolted on. Sort of considered cleaning it out. However maybe a little turbulance may keep things even within the plenum. I might be waffeling however.

Merli Grand Master

Merli

Posted
Posted
For a $1000 plenum i would expect the inside to be nicely ported and clean, especially something from japan

Why? $1000 is cheap as chips for a CAD designed plenum chamber...

If you want all that, step upto the $4000 JUN GT Surge Tank (Plenum Chamber), and pay for the man hours it takes to get that kind of loving :)

Brendan, sorry I can't help, my car came with a GReddy plenum, although I bought one for my silver GTS-t before someone prematurely ended that project. You're right... The insides are quite rough and don't look perfect for smooth airflow, but they're not THAT rough. When I looked inside the one that I bought, although it had a slightly rough finish, there weren't any protruding cast marks inside that would really disrupt the path air would take...

Also notice that the runners are tiny!! But with a lot of meat cast into the runners. I believe they've been cast small to promote faster air velocity, but give you the option of boreing them out more if you're running high boost and need more airflow...

B-Man Grand Master

B-Man

Posted
  • Author
Posted

Thanks Merli,

Don't get me wrong - the thing is a work of art ! When you look at all the angles etc - you can see that a lot of R&D went into this.

I guess to get the most out of it, a bit of machining / hand luving with a dremel tool (in the right hands) would be beneficial !

I'll see if I can take some pics for reference while it is off the car !

DoughBoy Veteran

DoughBoy

Posted
Posted

Have to disappoint you, but the Jun plenum for the RB26 isn't smoothed out as much as you think. The only part which has been finished after casting (besides the bolt holes) is the outside. Go Go rice factor!

After saying that, there is plenty of meat in the runners for them to be ported out. Jun may feel that anyone going to spend that kinds of dosh on a plenum will pay someone to matchport/ enlarge the runners anyway.

Merli Grand Master

Merli

Posted
Posted
Have to disappoint you, but the Jun plenum for the RB26 isn't smoothed out as much as you think. The only part which has been finished after casting (besides the bolt holes) is the outside. Go Go rice factor!

After saying that, there is plenty of meat in the runners for them to be ported out. Jun may feel that anyone going to spend that kinds of dosh on a plenum will pay someone to matchport/ enlarge the runners anyway.

I had a look inside Mario's JUN plenum chamber, and let me tell you, it's about 5 trillion times more advanced than the GReddy plenum.

The way the internal bellmouths have been crafted is just mindboggling, and just by looking inside it, you can tell how much care has been taken in it's design and fabrication.

It was flowtested to a 0.4% flow difference across all cylinders. If that's rice factor, then I think I need to find a new hobby :D

DoughBoy Veteran

DoughBoy

Posted
Posted

Gah, don't make me pull out the cam and start taking photo's again. Wasn't discussing the performance, design or flow characteristics of the Jun piece, just the fact that the internal parts of the manifold are not machined from factory, and that the only polished part is the external.

Sydneykid Grand Master

Sydneykid

Posted
Posted

Hi guys, good machinists in Japan charge like brain surgeons. So there is no way that you should expect any hand finishing of anything. If it comes off the cast that way, then that's the way you will get it.

B-Man Grand Master

B-Man

Posted
  • Author
Posted

Hi Guys,

Well I've had a bit of a better look at the plenum/intake and I did imagine that the finish internal to the unit would be better - maybe I got a newby casting engineer or something - I got BIG dags there..... Nothing that can't be fixed mind you ....

SK - I do understand that manual labour in Japan is expensive - but when I looked at the Greddy plenum/intake, I thought to myself - yup, designed in japan, made in China or Korea....... I expected better.

OK nuff said on the afformentioned problem.... what am I gonna do to fix it ??

Well I had a crack at removing some dags and gave up - this is a job for the pros -

Since I paid good dolllar for the unit (more than $1000) I've decided to spend and extra 200-300 to get it extrusion honed, ported and polished. Mirror finish on the inside (used to know a girl like that once..... he he)

Here's some before pics.... (i'll post after pics too)

greddy51.jpg

greddy51.jpg

greddy53.jpg

greddy54.jpg

greddy55.jpg

greddy57.jpg

greddy58.jpg

mambastu Collaborator

mambastu

Posted
Posted

I got my GReddy plenum a few months ago and mine hasn't got the casting marks yours has in picture 3 and 4 but it has the casting marks in the runner side walls. Must admit I was a bit surprised it wasn't smooth inside.

I also bought the GReddy throttle body adaptor and when I bolted it onto the plenum I found it wasn't aligned very well either so port matched the plenum to the TB adaptor plate and matched the runners to the manifold gasket and smoothed the runners as far up as I could go with the porting tool.

The plenum water ways were much worse than yours so I smoothed those out as well.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • MBS206
      NC MX5

      By MBS206 · Posted

      My guesstimate, with no real numbers to back it up, is it won't effect it greatly at all.its not a huge change in position, and I can't see the air flow changing from in turbulence that much based on distance, and what's in front of it. Johnny and Brad may have some more numbers to share from experience though.
    • dbm7
      Automatic Power Button Light Flashing

      By dbm7 · Posted

      Which solenoid? Why was it changed? Again, why was this done? ...well, these wear..but ultimately, why was it changed? Did you reset the idle voltage level after fitment? I'm just a tad confused ~ the flash code doesn't allude to these items being faulty, so in my mind the only reason to change these things, would be some drive-ability issue....and if that's the case, what was the problem? Those questions aside, check if the dropping resistor is OK ...should be 11~14 ohms (TCU doesn't throw a flash code for this) ~ also, these TCU designs have full time power (to keep fault code RAM alive), and I think that'll throw a logic code (as opposed to the 10 hardware codes), if that power is missing (or the ram has gone bad in the TCU, which you can check..but that's another story here perhaps).
    • The Bogan
      NC MX5

      By The Bogan · Posted

      Question for people who "know stuff" I am looking at doing the new intake like the one in the picture (the pictured is designed for the OEM TB and intake plenum), this design has the filter behind the front bar, but, the filter sits where the OEM duct heads into the front bar, and the standard aperture when the OEM ducting is removed allows the filter to pulled back out of the front bar into the engine bay for servicing, a simple blanking plate is used to seal the aperture behind the filter This will require a 45° silicone hose from the TB, like the alloy pipe that is currently there, to another 45° silicone hose to get a straight run to the aperture in the front bar Question: how will it effect the tune if I move the MAF about 100-150mm forward, the red is around where my MAF is currently, and the green would be where it would end up Like this This is the hole the filter goes through  Ends up like this LOL..Cheers    
    • Duncan
      R34 Plug Identification

      By Duncan · Posted

      Despite the level up question, actually I do know what that is....it is a pressure sender wire.  So check out around the oil filter for an oil pressure sender, or maybe fuel pressure near the filter or on the engine. Possibly but less likely coolant pressure sensor because they tend to be combined temp/pressure senders if you have one. Could also be brake pressure (in a brake line somewhere pre ABS) but maybe I'm the only one that has that on a skyline.
    • joshuaho96
      Automatic Power Button Light Flashing

      By joshuaho96 · Posted

      Pull codes via the self-diagnosis procedure. As far as I can tell this is just a sign of transmission issues but not a code unto itself.
×
×
  • Create New...