Rb25 Forward Facing Plenum

[joe blo]

ive got a cut and rewelded stock rb25 plenum on my rb25 motor. just wondering if there ok in terms of flowing evenly to all cylinders. just because i have recently done a compression test and the number 6 piston i think it is (closest to firewall) is down to 50 psi or so. the others have a fair bit of variance also.

i just wanna find out if people think thats what would have caused it or if it would have happened if it was normal style. coz ive got a rb30 twincam motor il be putting in soon but dont wanna put it in with that plenum if its gunna make the new motor do the same thing.

ive got a greedy copy plenum here also i could put in but im thinking il just use the standard one again for ease of installation coz i think the greedy one is sorta hard after looking at the guide. or is it really not that hard to put on in regards to changing a few pipes and throttle cable mounting and stuff and i should use the greedy copy one with 80mm throttle body?

this is the one in my car. would it flow evenly and stuff. the vl turbo guys have the same sorta ones and its very common for them to have it made like my one. one of the main shops even uses that sort on a 8 second drag car rb30. i think

also, will i have the problem with the bit hitting the bonnet with this current plenum since its different? cant remember where they hit the bonnet with rb30 bottomend with rb25 head.

[GTR_Legend]

my 2c.

i did read somewhere of another who done this. flow was reported to be not so good to 5 & 6.

[PM-R33]

Theres a lot of old threads dating back to the early years on these forums where people did it a lot due to there not being much available aftermarket wise. Have a bit of a search.

[brother_david]

Had a friend of mine do this, checked temp and flow, was bad on both 5th & 6th

[discopotato03]

You could have a look at a few factory 4 and 6 cylinder front fed manifolds to see what they did . An examnple may be a 2JZGTE one .

A .

[chubs]

first thing i would do is get it welded properly that looks like its got dog turds laying on it. so im gonna guess the welds wont be to great

[lachlanw]

f**k ive seen some mangare cut n shut jubs before but that takes the cake .

[joe blo]

first thing i would do is get it welded properly that looks like its got dog turds laying on it. so im gonna guess the welds wont be to great

yer they used dog turds when they welded it bro

[boostn0199]

abit of topic but is there any way of getting a forward facing plenum on a gtst being epa legal wiht a frontmount?

[8znR33]

i did this to my r33 and added a 90mm throttle body, i actually got an extra 13rwkws and now i upgraded my turbo to a t67-25g on stock internals running 304rwkw and its fine, it improved the response also. and doest hit my bonnet but mine is just a rb25 bottom, my throttle cable also reaches

[Simon-S14]

yer they used dog turds when they welded it bro

the look of the weld mainly determines the quality of the weld. In your case is slapped on there and that usually means a total lack of penetration. Sooo... it means it will crack or leak, neither of which you want to happen.

[PM-R33]

"You're lucky that hundred shot of NOS didn't blow the welds on the intake!"

Sorry, it had to be said.

Edited January 9, 2010 by PM-R33

[8znR33]

"You're lucky that hundred shot of NOS didn't blow the welds on the intake!"

Sorry, it had to be said.

Hahaha

[gmx]

Either way, isn't 50psi comp on #6 low anyway?

Edited January 10, 2010 by gmx

[JayTay]

Good call on the low comp. Sort the motor before messing with plenums.

Besides that, i dunno why you'd go to the trouble of welding it up for poor flow etc. when a greddy knockoff plus a little bit of work will only set you back a few hundred bucks.