Engine Swap Forum

Hey guys,

   Hypothetically speaking, if someone was to go with 6 ITB's on a VQ would it be smart to make the ITB's diameter the same as the intake port?  I wonder if any stock TB is that size on any car, maybe a small little Geo motor or something?  I know some Toyota Avalon V6's come with two little tiny TB's (for traction control cars I think) mounted together, 3 of those could be used, maybe.

 

  Incase your wondering I've got a spare VQ35 with bent rods now to play with so I'm thinking about setting it up on a stand and slowly working on an "ultimate" intake manifold (but I can't toss streetability completely out the window).

Fred

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Instrument Cluster and Speedometer Repair

Cool pic of some Suzuki ITBs here:

http://www.honda-tech.com/zerothread/1191757

I wonder what kind of Suzuki they came off of, I have a motorcycle salvage yard a few minutes away from my house, they may be cheap..

 

Fred

 

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Instrument Cluster and Speedometer Repair

those look like gixxer throttle bodies

if you look around on ebay, you can find GSXR 750 or 1300 throttle bodies for less than $150

they use a 5 volt tps, and are pretty easy to adapt to different applications

there is a long thread on zilvia about a diy itb setup  - cool stuff (if you look on the photobucket link i posted up the other day, there are some tbs in the album)

they should be bigger than the port. pretty much any ITB from any motorcycle will be more than enough.

I'm wanting to make sure they aren't too big actually.  If you think about it, is a stock single TB's area the same or larger than the combined area of all six intake ports?  It's not, and even though all six cylinders don't intake at the same time at high RPM they may as well considering how rapidly the engine is going through it's 4 strokes.  So, I think for best drivability there's some debate there.

 

Fred

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Instrument Cluster and Speedometer Repair

Id say look at the diamiter of the RB26DETT stock ITB's. Then add some percentage, similar to the increase in displacement, and that would give a good ball park for response vs flow vs driveability. But then again I need to take a closer look at setups its been a while.

And for NA its where you want your power band.

~Alex

Good idea on the RB, I'll look into it.  I think the length of the runners is most critical to the powerband.

 

Fred

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Instrument Cluster and Speedometer Repair

    With a compromise in power/response and streetability, ITB's should be about 1.3x intake valve diameter. Race ITB's are about 1.5x intake valve diameter. I'm looking into options for this as well. I love the sound of those things!
    And you're right, the length of the ITB runner has a surprisingly large effect on the powerband, especially in NA engines. That is probably something you're just going to have to mess around with on a dyno or something.

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S13 Fastback...putting the chassis together.

Suspension before power!

Ya, I think I have an idea to make them easily length adjustable.  Also, did the skyline infact have ITB's from Nissan?  I can't find any pics of them, I know some SR20 motors did though, I've seen pics of those.

 

Fred

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Instrument Cluster and Speedometer Repair

Only on RB26DETTs. they are actually kinda small and hard to see I think, but look closely and you'll notice the individual throttles.

GTi-R SR20DET's came with ITBs as well.

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S13 Fastback...putting the chassis together.

Suspension before power!

mabey mail hks or top sectret about there kits? you might be able to get some information out of them.

Holy crap! Those are hot! I'm sure HKS did their research too!

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S13 Fastback...putting the chassis together.

Suspension before power!