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Nissan Throttlebody Sizes - Suitable For 33 Rb25det .

discopotato03
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discopotato03 Grand Master

discopotato03

Posted
Posted

I'm looking to get heaps done in the near future to my GTS25T and a GReady manifold may be on the cards .

I did speak to SK ages ago about larger throttlebodies and he didn't think there was much it it even for a Modified RB25DET .

I'm just thinking that a larger throttle wide open may do something for an RB25 to get from the pre to the post boost state .

I don't know what the std TB size is on an RB25 or VH45 though I believe its 80 or 90mm .

Out of curiosity is there anything suitable in between the RB25 and VH45 throttlebodies ?

Also where do you get raped least buying the GReady manifold , hint 2nd hand ok too if clean ...

I guess this may mean the 90mm MAF as well .

Cheers Adrian DP03 .

N I B Grand Master

N I B

Posted
Posted

We use the Stock Throttlebody On the RB25 Powered 180SX Sportsedan I work on and never had trouble making 600+rwhp.

All you get from a large throttlebody is poor throttle control, I did a Power run on another Skyline Racecar with 90mm Throttlebody, at 20% throttle

the car made 440rwhp, This car was very hard to drive on the track so we went back to Stock 25 Throttlebody, No powerloss at all but Lap times were faster and more consistent.

scotty nm35 Grand Master

scotty nm35

Posted
Posted

I ripped out the electronic 72mm in mine and replaced it with a 65mm bore Ford throttle. I gained power right through the rev range so I dont think it will help anywhere but up top if at all.

Go too big and you will loose the low throttle resolution and it will "feel" quicker but only because for the same throttle input there is more airflow. In my opinion, most important is to keep the laminar flow through it by matching the throttle bore to the piping and manifold .

wlspn Proficient

wlspn

Posted
Posted

Saw an article in Autosalon magazine where they had a mildly modified (under 200kw from memory) R33 GTST with I think a Plazmaman plenum among other small mods. They dyno'd it, then fit a bigger t/b (again Plazmaman I think) & picked up something like 20-30rwkw throughout the rev-range... Been a long time, maybe even a few years since I read it so sorry I can't be more specific...

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N I B Grand Master

N I B

Posted
Posted

NA cars gain but Not Turbo cars until you are chasing massive power.

This car is a lap record holder and runs a 55mm throttlebody. IP cars are restricted requiring massive low rev boost so throttle control is vital.

http://www.barnettmotorsport.com.au/index.htm

StealthX Veteran

StealthX

Posted
Posted (edited)

I did the same things as Scott (m35 stag) on my X-Trail and ripped out my electronic TB and replaced it with a 65mm SR20 TB...

It's hard to tell if it made any more/less power, cos i had a shat turbo and an eff off exhaust leak a the same time, but unless your shooting for 600whp+, a few mm in throttle bore wont make a huge difference.

As NIB said, it can become hard to drive, the throttle becomes more of an 'on' 'off' switch rather than a progressive increase of flow. throttle sizes are matched with different air flows, because consider: 20% opening on a 70mm throttle = 'x' amount of air, then consider 20% opening on a 90mm TB = alot more than 'x' amount of air... Thu it becomes harder to regulate the amount of air going into the engine.

None of this directly leads to more power, cos there is no more or less overall air that's entering the engine.

Edited by turbo x-trail
discopotato03 Grand Master

discopotato03

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  • Author
Posted

Yeah fair enough , just thought I'd ask .

Nissan really screwed us RB25 owners over with the different manifold pattern to RB26's .

I got interested in RIPS RB25 to ITB 26 adapters but I don't want to lose the idle air control or cold start bypass .

I'm also finding that GReady manifolds are serious money nowdays like probably enough to make some sort of 25/26 hybrid work if RIPS was asked for it .

I think we all know what the preferable system is , ITB's .

Cheers A .

chuckie Mentor

chuckie

Posted
Posted
I'm looking to get heaps done in the near future to my GTS25T and a GReady manifold may be on the cards .

I did speak to SK ages ago about larger throttlebodies and he didn't think there was much it it even for a Modified RB25DET .

I'm just thinking that a larger throttle wide open may do something for an RB25 to get from the pre to the post boost state .

I don't know what the std TB size is on an RB25 or VH45 though I believe its 80 or 90mm .

Out of curiosity is there anything suitable in between the RB25 and VH45 throttlebodies ?

Also where do you get raped least buying the GReady manifold , hint 2nd hand ok too if clean ...

I guess this may mean the 90mm MAF as well .

Cheers Adrian DP03 .

VH45 is 83 mm,

cheer`s Chuckie.

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