What is the benefit of individual throttle bodies on a turbocharged car and what kind of gains comes with them?

 

i dont think ive ever seen an ITB setup w/FI...

 

there was a thread about this about a month or 2 ago, i tried searching for it but i couldnt find it. maybe someone else has it bookmarked...

 

They were 929RR itb's that bolt on to the D-Series motor only with minor modification.

https://honda-tech.com/zerothread?id=473099

 

Will someone just tell me the advantages without going into other stuff?

JUN's WRX has itb's.

 

How do you use ITB if you are getting boost? Im confused....

 

WTF? itb's on a turbo? Why? You'll have to have a manifold somewhere in order to take the pressurized air from the single turbo outlet and convert it into four inlet pipes for your throttle bodies. What difference does it make if the manifold is pre or post throttle?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SuperStreetRX7 &raquo;</TD></TR><TR><TD CLASS="quote">Will someone just tell me the advantages without going into other stuff?

JUN's WRX has itb's.</TD></TR></TABLE>

Why dont you just ask JUN. Why would we know rather then them?

 

they are very beneficial. ACTUALLY y else would JUN use them. not many hondas use it though, but many jap. silvias and sr20s and such use them, i think a jap manufacture car actually comes stock with them and turbo...?

 

Efficiency, better fuel atomization, better throttle response and more power.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by boosted hybrid &raquo;</TD></TR><TR><TD CLASS="quote">Efficiency, better fuel atomization, better throttle response and more power.</TD></TR></TABLE>

 

If you have a big turbo such as I'm going to be using, then you use big piping that connects to a "manifold." The "manifold" is just a lightweight yet strong box that surrounds the itb's. Thats what I can think of from the few pics of cars that have it done. I think on JUN's WRX though, that it is like this...

turbo--&gt;piping--&gt;1-2 "splitter"--&gt;(2)1-2 "splitters"--&gt;then each tb has it's own piping.

What kind of gains could be expected using 50mm tb's?

Using im and 70mm tb = 17.5mm/cylinder

Using im/50mm itbs = 50mm/cylinder

Can anyone help? I jotted that down and I'm going over it in my head and I'm starting to feel like I missed two weeks of school and have to make up my work.

 

on the JUN one yes it is like a reverse collector...

you can gain a lot with really good tuning..if built properly, but id do it the way they did and use a collector type setup

 

The flow to each runner is roughly the same between the itb and single throttle body. The individual throttle bodies gives the illusion that each cylinder is getting the maximum amount of air per throttle position, but this is not true. The single throttle body is the restriction to the overall flow, whereas the individual throttle is the restriction to the overall flow. You gain the power, throttle response due to the each cylinder getting the air velocity somewhat laminar since it does not have time to become turbulent as in the situation with the a single throttle body with a plenum. The fuel becomes better atomized since there is less turbulence created.

The critical aspect of designing itb's for use with boost is a reverse merge collector that the jun among others does not use. The reverse merge collector allows for each cylinder to recieve the identical amount of airflow in the manner that it can be used most efficient. So #1 and #4 runners should be shorter than #2 and #3 since those cylinder fire first. The reverse merge collector will further help the overall individual throttle body system flow more laminar for better efficiency. Throttle response is also improved since the airflow to the cylinders is being utilized in the most efficienct manner possible.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by boosted hybrid &raquo;</TD></TR><TR><TD CLASS="quote">The flow to each runner is roughly the same between the itb and single throttle body. The individual throttle bodies gives the illusion that each cylinder is getting the maximum amount of air per throttle position, but this is not true. The single throttle body is the restriction to the overall flow, whereas the individual throttle is the restriction to the overall flow. You gain the power, throttle response due to the each cylinder getting the air velocity somewhat laminar since it does not have time to become turbulent as in the situation with the a single throttle body with a plenum. The fuel becomes better atomized since there is less turbulence created.

The critical aspect of designing itb's for use with boost is a reverse merge collector that the jun among others does not use. The reverse merge collector allows for each cylinder to recieve the identical amount of airflow in the manner that it can be used most efficient. So #1 and #4 runners should be shorter than #2 and #3 since those cylinder fire first. The reverse merge collector will further help the overall individual throttle body system flow more laminar for better efficiency. Throttle response is also improved since the airflow to the cylinders is being utilized in the most efficienct manner possible.</TD></TR></TABLE>

What about using a tubular intake manifold, with a reverse merge collector and an individual 80mm TB? Im in the process of making/designing one, Im just trying to decide if it will actually benefit over a plenum design. Kinda funny, but my #'s 1 and 4 runners will be shorter than #'s 2 or 3 by an inch or two...
Whats your take on the issue?

 

If you are going to design one you'll need to do alot of R&D before you'll get something that will work. The runner length/size is critical for flow at certain rpms. Its actually quite a large project, which is the reason that I have shied away from it this semester. It will take at least two-three weeks of intensive calculations and modeling to come up with a first draft that will preform respectable and not lose any power.

The #1 and #4 are going to have to be shorter than the rest of the runners since those intake ports will be using the air before #2 and #3. If you dont make the runners in that configuration it will be opposing the flow of the head, and you might actually loose some performance. You need to create the exact opposite of how your equal length manifolds are constructed in order to create the equal length design.

The 80mm throttle body is far to large for pretty much any size engine under 2.5 liters that is going to be driven on the street. Your partial throttle is going to suffer the greatest since you are going to be letting more air into the engine that can be used and creating a turbulent situation which will hurt performance. Its important to match the single throttle body system to the displacement and volumetric efficiency of the engine or performance will suffer, especially partial throttle.

 

doesn't a skyline have a stock individual throttle bodies?

 

Yes, among other factory forced induction cars.

 

Hmmm...well, Its almost done, so how about I butt-dyno it? I just threw out a number on the TB. Whatever the LS-1 is, thats what I will eventually be using(70mm?).
Im still thinking that the current design of my manifolds will work great for this, because the 1 and 4 runners ARE shorter than the 2 and 3 runners by 1.5-2 inches. I can easily vary the difference between the lengths of the runners too.

Picture my SST manifold upside down, with a 3" ID Elbow welded onto the collector, and a 6 inch-long 3"ID pipe extending the TB closer toward the stock location. This will give the manifold a "plenum" of sorts thatll be roughly 12 inches long. Im just trying to picture how this is going to work, if at all...hehe

I think we should turn this into another one of your really technical threads, and I will actually TRY to pay attention this time

 

try it out tinker, itll be cool no matter what

 

do all skylines have stock itb's or was it just the r34's??

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hybridvteceg &raquo;</TD></TR><TR><TD CLASS="quote">try it out tinker, itll be cool no matter what </TD></TR></TABLE>
I am...Ill post pics/buttometer results
Im not sure about the skylines either...

 

Only the r34, and the pulsar/sunny gti-r (20srdet) came with from the factory by nissan.

 

Are there any sites or books that could help me in designing a itb setup?

 

ttt