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Rb20de Itb Build

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screamin' Collaborator

screamin'

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It's been while coming, but I have started work on the engine build for my rallycar.

The car is an R32 GTS Coupe. I run an RB20DE in stack form with some basic breathing mods.

Now the time has come to start building the head I want to use to extract power from the 2ltr block.

Due to the car having to fit into a class based on engine capacity, I want to keep the motor below 2000cc and non-turbo.

On the weekend we stripped the head and prepared it for porting and cam work. Also, the bottom section of the factory intake plenuim was cut from the rest to be used in the build. The idea of this was to allow us to us the factory injector position and to match the intake runners to the new ports.

itbs005uv6.jpg

These are the throttle bodies I'm planning on using. They are off a 20 valve 4age and I have modded the linkage to allow me to run 6 in-line. These will be mounted to a common flange and bolted to the fabricated intake runners.

itbs001al2.jpg

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screamin'
screamin'

It's been while coming, but I have started work on the engine build for my rallycar. The car is an R32 GTS Coupe. I run an RB20DE in stack form with some basic breathing mods. Now the time has come

Cheddle Enthusiast

Cheddle

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nice, cant wait to see it all done, should help the little rb20 to rev like its bore/stroke should let it!. what RPM are you planning on having peak power at?

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screamin' Collaborator

screamin'

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nice, cant wait to see it all done, should help the little rb20 to rev like its bore/stroke should let it!. what RPM are you planning on having peak power at?

No problem with rev's as it is. With basic breathing mods the lil thing revs to 9,000rpm on occasion.

By matching intake runner length, cams and head work I'm looking for a strong usable midrange and good throttle response. But yeah, looks like it'll be happy to rev it's nuts off still.

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Eug Grand Master

Eug

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No problem with rev's as it is. With basic breathing mods the lil thing revs to 9,000rpm on occasion.

By matching intake runner length, cams and head work I'm looking for a strong usable midrange and good throttle response. But yeah, looks like it'll be happy to rev it's nuts off still.

9000rpm?? have you done any block work/balancing?

excellent thread - will be keeping a close eye on this

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GTS4WD Grand Master

GTS4WD

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was that for me? have i missed something????

lol.. not everything is about you eugene :)

I asked where he got the ITB's.. then i read the thread :)

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screamin' Collaborator

screamin'

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lol, yeah, they smelly old Toyota itb's, $300 for two sets :P

The bottom end is stock on the current motor, done 210,000km and is untouched. It was well thrashed before I got it and has a lightened flywheel, so I'm guessing thats why it's happy to rev hard.

When I do get around to building up the other block I have, I'll do a bit of balancing work, just to make sure it'll last.

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screamin' Collaborator

screamin'

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Would be good to do this on a larger capacity motor, but I need to stick to below 2000cc.

The runner length was calculated by the specialist at the cam/head shop. He has ground a cam and ported the head specifically for the diameter itb's I have and through this calculated the runner length required.

Generally the length is way longer than what I have seen discussed on here and it's measured from the seat of the valve to the edge of the bell on the trumpet.

The calculation includes volumes, diameter, length, air speed, air flow. Seems to be quite involved.

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UNR33L Grand Master

UNR33L

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theres a nice video of a na 32 on youtube, it was white from memory with a asian woman owner going around a track with something similar to what your doing and it sounds mean!!!!!

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AnthonyRB20 Newbie

AnthonyRB20

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It's been while coming, but I have started work on the engine build for my rallycar.

The car is an R32 GTS Coupe. I run an RB20DE in stack form with some basic breathing mods.

Now the time has come to start building the head I want to use to extract power from the 2ltr block.

Due to the car having to fit into a class based on engine capacity, I want to keep the motor below 2000cc and non-turbo.

On the weekend we stripped the head and prepared it for porting and cam work. Also, the bottom section of the factory intake plenuim was cut from the rest to be used in the build. The idea of this was to allow us to us the factory injector position and to match the intake runners to the new ports.

itbs005uv6.jpg

These are the throttle bodies I'm planning on using. They are off a 20 valve 4age and I have modded the linkage to allow me to run 6 in-line. These will be mounted to a common flange and bolted to the fabricated intake runners.

itbs001al2.jpg

Nice job, will be sweet, i am doing a similar sort of thing to my GTS but just not for a rally application, i am getting bigger injectors at the moment, will they need any extra modification or will thay just slot straight in?

Cheers, and keep up the good work.

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GTR-32U Mentor

GTR-32U

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which version of the 4age are the throttle bodies from ? Later black top are actually larger throttle bodies than the silver top....Just out of curiosity what comp you running the motor at ?

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GTS_Retro Enthusiast

GTS_Retro

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There would be some serios number crunching to determine runner lenght then, if they are tuned specificaly to head setup. Definatly a job for profesionals.

Ive seen the video mentioned white 32 in japan. girl tuner, she used http://www.twminduction.com/ThrottleBody/2000_inst.html

ITB's adapted to her RB24de. runner lenght looked really short in the video, might be because of the adaption she made, however from memory it only liked revs above 5000 from memory.

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screamin' Collaborator

screamin'

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Hey screamin.. would you be interested in doing a second set?..

Or sending dimentions?

Or is it intelectual property?

I'm gonna have to find out if the first set will work first!

For your application all dimensions and cam timing/duration will be different because of the bigger motor.

If I'm going to do a second set it'll be for my GenIII SS :P

Anthony- As far as injectors go, I'm going to start with the stock ones, but if I have to upgrade to GTS-t or 13B ones I can just slip them in I beleive.

GTR-32U- I don't know what 4age the itb's are off, but they are 42mm butterfly diameter. Comp. will be the highest I can run pump gas on, as Av-gas is being outlawed by Motorsport NZ.

GTS Retro- For a track application and 2.5ltr the short runners would be fine, but for the 2ltr I need instant throttle responce and reasonable torque, hence the length.

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