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Top Mount Manifold

RBnub

By RBnub,
in Engines & Forced Induction

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RBnub Contributor

RBnub

Posted
Posted

hey guys and girls i own a HCR32 with the standard rb20det motor.

im planning a build on my rb20 looking at around the 260kw+ margin. i know the easier way would be to go with an rb25 but i like a challenge and i like the little rb20. just wondering if there is much to gain with a top mount manifold over a polished bottom mount? i presume that getting the top mount would cost extra as i would have to extend the turbo water/oil lines and make adjustments to the front pipe of the exhaust as well as the intake pipe and plumb back pipe from the BOV.. any tips are much appreciated :)

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GTScotT Grand Master

GTScotT

Posted
Posted

Roy has managed those results with a TD06 20g on an 8cm housing. The 8cm is only available in a 3 bolt housing and you will need a custom manifold for it.

An option I would explore is the 10cm T3 with a gate welded off the housing. I think this would get you the said 260kw without need of moving to a highmount manifold.

For that kind of power the high mount will sound nice but probably wont yield much of a gain.

R31Nismoid Grand Master

R31Nismoid

Posted
Posted

No specific gain performance wise. Just easier to work on really, and you need to deal with the heat - so perhaps a minor hinderance (that can be fixed).

It's here nor there really - Just custom everything made up to suit relocation which is $$$.

Nice to be persistent/challenge, but RB25 is a better option realistically dollar for dollar.

RBnub Contributor

RBnub

Posted
  • Author
Posted (edited)

at the moment its running a rebuilt and high-flowed r34 turbo but i am obviously looking to upgrade to something with a little more mid range response as the rb20 tends to get quite a bit of lag. only replacing the manifold because the previous owner has done some dodgy machining to the original one.

so by the sounds of it i think i will just hunt down a decent bottom mount manifold as a replacement and save the extra cash for something else.. anyone have any brands to recommend other then the ones sold on for next to nothing.

Edited by RBnub
RBnub Contributor

RBnub

Posted
  • Author
Posted

i never said i didn't like the lag i currently run 230kw in my r32 and its definitely a laggy setup. :). i don't mind sacrificing a little torque for power since the rb20 has next to no torque anyway. having quite a large rev range helps compensate a little.

simons987 Explorer

simons987

Posted
Posted

Stick with the stock manifold. Iron Cast is much better then these stainless steel pipes, they are much stronger and are far better handling heat. From personal experience I just got sick of having to repair my stainless steel manifolds so I went back to the iron cast and have not had a problem. The manifold will allow for way more then 260rwkw. If you really want want that extra 2hp you can always do some mold porting. There are tones of guides on here on how to do porting.

R31Nismoid Grand Master

R31Nismoid

Posted
Posted

i never said i didn't like the lag i currently run 230kw in my r32 and its definitely a laggy setup. :). i don't mind sacrificing a little torque for power since the rb20 has next to no torque anyway. having quite a large rev range helps compensate a little.

Wait till you get to 260rwkw+ then.

You need a tacho that starts @ 4000rpm :D

R31Nismoid Grand Master

R31Nismoid

Posted
Posted

Haha yeah I bet But I still can't shake the feeling when boost creeps up on you In a laggy set up :P. Previously owning an r33 the extra torque didn't really amuse me much on the street.

Well linear power can be deceptive, and on the street is generally faster.

Remember 200rwkw on a R32 will feel faster than 200rwkw in a R33, weight, peaky setup etc. So totally agree there. It would potentially be faster too all things being equal.

However @ the power range you are talking about. RB25/260-280rwkw, pit it against a RB20/260-280rwkw - in the same car. It'll be difference like night and day :)

You'd be talking 500-1000rpm of difference depending on turbo choices, on/off throttle performance would be huge as will the power delivery.

You get more area to the right of the dyno graph, and thats what really is more important on the street. Less peaky setup = less wheel turning and more forward action.

Don't get me wrong - I've had an RB20 before, but it's tough to justify spending 1500+ on exhaust manifolds, plenums etc. You'll never see that value against performance as it's capacity & the head holding things back.

RBnub Contributor

RBnub

Posted
  • Author
Posted

Yeah the head is the only thing holding me back on going through with anything on this car. Already having a Nismo high volume pump, gtr injectors, FMIC, Greddy type RS BOV, 3" exhaust, highflowed r34 turbo all working through a nistune might be easier to spend the money rebuilding a rb25 and whacking it In with a better ecu. From what your telling me an rb25 would see considerable improvement I'n my r32 then In a r33. I will have to look into what's involved In the conversion. Like a better gearbox for the extra torque ect.

  • 3 weeks later...
R##S@ Enthusiast

R##S@

Posted
Posted

if you want a safe/reliable engine that pulls 260kw at the wheels every day whether its on rb20/rb25

you will need the following

Turbo hks25/35

minimum 3 inch exhaust all the way thru

stage 1 tomei cams and they mak a hell of a diff ,you dont need cam gears as hks turbo come on strong and on low rev

gtr injectors/hi flow your ones alot of preformance work shops hi flow them 650 cc

walbro fuel pump

z32 air flow meter

obviousley a computer and intercooler

had a couple of skyline did a lot of mistakes but again up to you what you want to do

if you need help getting any of these parts let me know i wil try my best to help

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