Rb20 Forward Facing Plenum?

[bubba]

OK, before anyone asks, YES I have searched but all I can find about this is that when people ask this question they get flooded with replies of WHY WOULD YOU WANT TO DO THAT? and THE STOCK SETUP IS GOOD FOR xxxRWKW oh and RB20 WILL LOSE POWER WITH FORWARD FACING PLENUM.

None of that please.

All I am after is some examples and experiences with the various (limited) RB20 forward facing plenums out there and any solutions to the lack of options..

The reason I am after an RB20 forward facing plenum is due to the fact I have an RB25DE head on my 30..

SO, examples, experiences and opinions (opinions on particular RB20 forward facing plenums, not opinions on whether a 20 will lose power with one or not!).

[GTR-32U]

funny you should bring this up but some time ago I was after one too, and I ran into all those arguments also.What people dont realise is that what happens on the dyno doesnt neccessarily happen on the street.I used to own an R32 GTS4 with aftermarket turbo.However RB20's are laggy.My theory was that putting the throttle body on the front in would allow the intercooler piping to be reduced by about a metre.So if you think about it thats one whole metre of pipe that doesnt need to be pressurised.So my theory was that response would pick up immensely,more noticable in the lower gears.First gear particularly.However as Dyno pulls are done in 4th Gear where lag and response isnt measured I felt I had a valid point.I have seen somebody who had the throttle body on the front edge of the factory manifold..( best of both worlds )..but I couldnt see that being cheap.

Anybody got any opinions ?

[bubba]

Yeah I'm not doing it for response reasons etc, it is purely a piping issue (twincam 30 in a 32 and putting a high mount 35r on) and having a nice flowing plenum will enable better gains in the future when I wind the boost right up

I won't be able to fit the high mount with my current piping arrangement and doing something like the 120deg inlet pipe is out of the question (already rubbing slightly on the timing belt cover so increased height there is a no-no).

A forward facing plenum would cure ALL of my pipework rubbing issues (it's even rubbing on the manifold slightly) and allow me room to high mount the 35R. A side benefit would be the reduced pipework and extra breathing capacity when I decide I want to push 400rwkw+

However, I am very sceptical of the limited ebay items and while the plazmaman item seems to be a proven design, the $1k price tag would be eating into the budget somewhere

[AntsRB25]

Yeah I'm not doing it for response reasons etc, it is purely a piping issue (twincam 30 in a 32 and putting a high mount 35r on) and having a nice flowing plenum will enable better gains in the future when I wind the boost right up

I won't be able to fit the high mount with my current piping arrangement and doing something like the 120deg inlet pipe is out of the question (already rubbing slightly on the timing belt cover so increased height there is a no-no).

A forward facing plenum would cure ALL of my pipework rubbing issues (it's even rubbing on the manifold slightly) and allow me room to high mount the 35R. A side benefit would be the reduced pipework and extra breathing capacity when I decide I want to push 400rwkw+

However, I am very sceptical of the limited ebay items and while the plazmaman item seems to be a proven design, the $1k price tag would be eating into the budget somewhere

Here is my modded factory plenum modded to front facing. It is on a 25 not a 20 but you get the idea. Hasnt made a huge deal of difference to drivability. I would say a fraction more responsive than the stock setup. Pretty easy to do and not that expesive!

[TTT]

Looks good.. I've seen ALOT dodgeyer versions..

I think the arguements of making the stock one Front facing is the fact that it is internally designed to have air coming in from the middle of the plenum.

having the air come in from the end there throws it all out..

have a look on the inside of the plenum and you'll see the little fins..

How do your spark plugs look?

1 thru to 6?

anyway, you didn't want any arguements so I'll leave it there..

it works for you.. all good.

[bubba]

Interested in how your plugs look too..

I was leaning away from modifying the stock plenum as it really isn't designed to flow from one end.

Might have to design my own O_o

[STATUS]

funny you should bring this up but some time ago I was after one too, and I ran into all those arguments also.What people dont realise is that what happens on the dyno doesnt neccessarily happen on the street.I used to own an R32 GTS4 with aftermarket turbo.However RB20's are laggy.My theory was that putting the throttle body on the front in would allow the intercooler piping to be reduced by about a metre.So if you think about it thats one whole metre of pipe that doesnt need to be pressurised.So my theory was that response would pick up immensely,more noticable in the lower gears.First gear particularly.However as Dyno pulls are done in 4th Gear where lag and response isnt measured I felt I had a valid point.I have seen somebody who had the throttle body on the front edge of the factory manifold..( best of both worlds )..but I couldnt see that being cheap.

Anybody got any opinions ?

you run into serious air distribution issues if you weld the throttle body to the front of a std manifold... we did the excersice 5-6 years ago on a flow bench and on a engine with 6 thermo couples... if you really must do at least change the whole top half.

[ix9]

Bubba - I think you saw my plenum, eBay job, works perfectly for me

[bubba]

Yeah I did mate, only problem is I have a 25DE head out of an R32.. same stud pattern as RB20. A 25DET plenum won't bolt up

It seems there are very limited solutions for RB20 style.. going to design my own in conjuction with another forum user and a couple of the mechanical engineers here at work. Afterall, that is what I do for a living.. (although I'm working in materials handling/mining & resources now as opposed to automotive R&D).

If I can come up with something that the engineers deem worthwhile, it should be able to be fabricated for half what a plazmaman plenum would cost and be a whole item instead of just the top half.

Definately still open to ideas though, proven real world experiences is where it's all at.. I'd rather use something that is proven than blow my engine up trying to develop my own

[jeffworld2]

i have a RIPS plenum for sale. pm if interested

[bubba]

Is it for an RB20? (your avatar shows a 33 )

[jeffworld2]

it is for an rb20, otherwise it would be on the r33

they are from the kiwi boys, and they get good results on stock motors. look up rotorua i think thats how its spelt

anyway its just sitting here. with piping and throttle cable and throttle body etc, everything really. but then i found it doesnt fit on rb25s due to the water lines etc beneath the plenum