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Poopra King
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Discussion Starter · #1 ·
Hey what's up guys.....loooooong time since I've been on here to help out the QR peeps....but I have some interesting info. One of my buddies down here is almost done making a badass ITB kit including the manifold. I've seen a lot of his work on Hondas, EVO's, Ducati's, and more. All I can say is this kit is going to make POWER!!! I'm helping him with all of my QR knowledge and some spare parts I still have laying around. There will be a few versions, one for use of the stock MAF, one for boosted engines, and one for standalones. As usual I will be doing the install on who ever we can get to be our guinie pig. I saw the almost completed kit last night....people will be drooling!!!

- Armin
 

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Just curious, tell us noobs to engine modification how this helps? Haha.
 

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Poopra King
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Discussion Starter · #3 ·
Power....power....power. That's what we want right...power? :D It will also help the motor rev much quicker...kinda like a formula car....especially if you already have the BSR kit, light weight pulley, and aluminum flywheel. Will it make the power my Supra makes....no. Will it make a surprising amount of power....well....lets just say yes :p

I know that when I was porting just the lower half of the intake manifolds I was seeing 10whp gained at 5300 rpms and about 4-5whp at the rev limiter. These make much bigger gains than that!

I don't remember who I did the upper and lower ported intake for for the life of me...but I would love for him to chime in with his results
 

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JDM swapped shortbus
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I've got an unlocked factory ECU (UpRev Osiris pro-tuner version) I can tune like a standalone (I can even permanently drop out any codes that would pop up), and unlimited access to a dyno.
 

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JDM swapped shortbus
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(Here you go Sammy)

It's all about pumping losses and flow potential.

A motor doesn't suck in air, air is pushed in due to the vacuum created in the cylinder, from the area of high pressure to the area of low pressure.

Flow potential is all about the size of the hole between to bodies (containers), and the amount of pressure difference that exists between them. To get more flow into the motor, you can make the differential larger (like what a turbo does) or you can make the passage larger, or stay open longer (i.e. camshafts). The other factor that affects flow potential is the length of the passage something has to flow through. The shorter of two pipes of the same diameter will flow more with less pressure.

If you look at intake manifold design, and a little physics, and apply some practical examples you can get a good idea.

Air that is rushing into the intake and towards the valves can be moving pretty quick. Once it is moving it doesn't want to stop (an object in motion wants to stay in motion), when the intake valve closes the air slams into the back of the valve and compresses, so it bounces off of the valve like a spring or ball back down the intake runner to the plenum, where it bounces again where some of that energy is bounced back down the runner towards the valve. IF the intake valve can be open when this compressed bundle of air reaches it, it will force more air into the cylinder than it could get w/o that advantage of more dense air. That only happens when the events are perfectly timed to the valve opening. There is a certain speed where the time it takes to bounce improves air flow into the cylinder via "inertial supercharging". The reason the QR intake (and a lot of other manifold designs have secondary runners etc.) is to be able to change the frequency of the air pulses in the intake manifold. Think of a flute or other wind instrument, when you block a hole or let off of one the note changes which is the frequency of the reverberation of the air column.

So how do ITB's work? In an intake manifold there are pulses from other cylinders interacting with each other. The other part is that an area of low pressure (vacuum) exists in virtually every point of the manifold after the throttle body. With an ITB, the throttle plate is only a few inches (5-8") from the back of the intake valve and high pressure exists at the front of the throttle plate. When I built an intake manifold for a QR, the runners were 15" long, not including the length of the runner in the cylinder head. So the air column was having to travel close to 20" to reach the valve vs 5-8" w/ an ITB. SO what about inertial supercharging? Doesn't matter, the air that bounces off the back of the valve bounces back and since there is no plenum involved the energy is just dissipated back into the atmosphere and atmospheric pressure air (14.7 psi) fills the small volume of the ITB runner up quicker than any reflected air pules could do, so over more of the running range of the motor more air enters the motor.

I've tested ported QR heads and flowed close to 250cfm, but as soon as the intake manifold gets bolted on the number goes down to about 210-215cfm or so. Since length is part of calculating the flow potential of a passage, an ITB is going to win every time. In a 4 cylinder engine, 1cfm = about 1hp. Do the math and where most people top out about 185-190whp, and when you figure in drive train loses to calculate crank HP, they just about = cylinder head flow.



A motor like a QR will really respond to ITB's.
 

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Poopra King
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Discussion Starter · #9 ·
We're looking for someone local. The car will need to have a throttle cable too, so even though your ecu is unlocked...I don't think you can get around the throttle-by-wire.
 

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(Here you go Sammy)

It's all about pumping losses and flow potential.

A motor doesn't suck in air, air is pushed in due to the vacuum created in the cylinder, from the area of high pressure to the area of low pressure.

Flow potential is all about the size of the hole between to bodies (containers), and the amount of pressure difference that exists between them. To get more flow into the motor, you can make the differential larger (like what a turbo does) or you can make the passage larger, or stay open longer (i.e. camshafts). The other factor that affects flow potential is the length of the passage something has to flow through. The shorter of two pipes of the same diameter will flow more with less pressure.

If you look at intake manifold design, and a little physics, and apply some practical examples you can get a good idea.

Air that is rushing into the intake and towards the valves can be moving pretty quick. Once it is moving it doesn't want to stop (an object in motion wants to stay in motion), when the intake valve closes the air slams into the back of the valve and compresses, so it bounces off of the valve like a spring or ball back down the intake runner to the plenum, where it bounces again where some of that energy is bounced back down the runner towards the valve. IF the intake valve can be open when this compressed bundle of air reaches it, it will force more air into the cylinder than it could get w/o that advantage of more dense air. That only happens when the events are perfectly timed to the valve opening. There is a certain speed where the time it takes to bounce improves air flow into the cylinder via "inertial supercharging". The reason the QR intake (and a lot of other manifold designs have secondary runners etc.) is to be able to change the frequency of the air pulses in the intake manifold. Think of a flute or other wind instrument, when you block a hole or let off of one the note changes which is the frequency of the reverberation of the air column.

So how do ITB's work? In an intake manifold there are pulses from other cylinders interacting with each other. The other part is that an area of low pressure (vacuum) exists in virtually every point of the manifold after the throttle body. With an ITB, the throttle plate is only a few inches (5-8") from the back of the intake valve and high pressure exists at the front of the throttle plate. When I built an intake manifold for a QR, the runners were 15" long, not including the length of the runner in the cylinder head. So the air column was having to travel close to 20" to reach the valve vs 5-8" w/ an ITB. SO what about inertial supercharging? Doesn't matter, the air that bounces off the back of the valve bounces back and since there is no plenum involved the energy is just dissipated back into the atmosphere and atmospheric pressure air (14.7 psi) fills the small volume of the ITB runner up quicker than any reflected air pules could do, so over more of the running range of the motor more air enters the motor.

I've tested ported QR heads and flowed close to 250cfm, but as soon as the intake manifold gets bolted on the number goes down to about 210-215cfm or so. Since length is part of calculating the flow potential of a passage, an ITB is going to win every time. In a 4 cylinder engine, 1cfm = about 1hp. Do the math and where most people top out about 185-190whp, and when you figure in drive train loses to calculate crank HP, they just about = cylinder head flow.



A motor like a QR will really respond to ITB's.

So a QR head that flows at about 250cfm would possibly be good for 250hp before drivetrain losses? But due to the IM, it's being brought down... And this will help bring the flow a little higher than the 210-215cfm it's being constricted too?

There's lots of other stuff, but this is the main concept I'm grasping (I think). Lol

Interesting read. Good stuff to learn. Thanks Justin.
 

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Poopra King
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14,929 Posts
Discussion Starter · #15 ·
Here's a vid of the ITB's with a similar set up to what we're doing....this way you see what they kinda look like :p The ones for the Nissan would be way shorter though.

 

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Poopra King
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14,929 Posts
Discussion Starter · #17 ·
first off im a complete noob about itb's, among other things. my question is how would itb's work with our maf sensor? =/
For those that would use a standalone you wouldn't need to worry about the MAF. For those NOT going with a standalone we have a plenum that boxes in the ITB's and has an inlet that the MAF would bolt to....so we got you covered (no pun intended) either way you decide to go. The plenum for the NA motors will be either thermo-plastic or carbon fiber. The plenum for boosted engines is aluminum and is good for up to 120psi (not that any gas motor would boost that high but he makes them for diesels as well).
 

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Poopra King
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14,929 Posts
Discussion Starter · #18 ·
Ok I was instructed to post this....this is Kevin K's VQ35 Sentra that we did some ITB's on....enjoy :)









And here's a vid.


This motor made 280whp before the ITB's and 305whp after the ITB's :)
 
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