Itb's

[Siege911]

So I've heard much about individual throttle bodies for N/A cars, and I was wondering exactly what they do... I figured they give more air to the engine, and allow more adjustability in the amount of air allowed in, but other than that I have no clue. Also, they seem damn expensive ($700+), can anyone confirm this? I'm just trying to find some information, b/c I haven't heard much about them.

[NstyGrnHatch]

try like TVM's they go for about 1400-1800, yes they are for n/a vehicles but HEAVILY modified engines. If you have a stock engine ITB's are basically gonna do you no good, you need alot of valvetrain work to actually benefit from them. Honda motorcycles also use ITB.s and will also work on some B series heads.

[Calesta]

Originally posted by siege911@Sep 17 2005, 12:47 AM
So I've heard much about individual throttle bodies for N/A cars, and I was wondering exactly what they do... I figured they give more air to the engine, and allow more adjustability in the amount of air allowed in, but other than that I have no clue.* Also, they seem damn expensive ($700+), can anyone confirm this?* I'm just trying to find some information, b/c I haven't heard much about them.

Just like the name says- Individual Throttle Bodies put one throttle in front of each cylinder. Most of the really high performance cars are set up this way- Ferrari, Lamborghini, F1 race cars, even some BMWs (but they've gone to something even better).

The main advantage is better control over the amount of air going into each cylinder. With one throttle body and an intake manifold, it's difficult to guarantee that each cylinder will receive the exact same airflow. You have to design the intake manifold in such a way that the air mass going into the engine has enough volume to satisfy the needs of each cylinder. Think of it this way- your engine takes "bites" from the air in the intake mainfold. If you're lucky, the last cylinder (farthest from throttle body) has enough air available to it to take a full sized "bite" from the air mass. Even if your manifold is set up to flow enough air to all cylinders, other losses such as friction, changes in air density and velocity from flow restriction and friction through a funny shaped box will cause each cylinder to see something slightly different. Using ITBs lets you put the exact same thing in front of each cylinder- the same velocity stack, the same throttle body, the same flow characteristics (as much as possible anyway)- so you can have more even power production. You get the ability to control the fuel more precisely (the best engine management systems will allow you to set fueling up for EACH cylinder separately), so you make more power.

Needless to say- most people leave ITBs as an "ok, I've done everything else, let's go to the last step" type of mod. They aren't the easiest to tune, you have to come up with a solution for filtering your intake air, and buying/building them is expensive.

[dubcac]

Not only do you make more power, but you have increased throttle response. The air has a much shorter distance to travel before going into the cylinders. Are they worth the money? That's debatable. On a built motor that already cost a few grand, whats another grand? On a stock motor, I wouldn't bother.

[Siege911]

Yeah, i wasn't even considering buying them, but I just wanted to know how they were used... I kinda figured they were for extreme engines, but thanks for the info. They sound very expensive, and actually I think I just read a DIY on making your own itb's (on homemadeturbo.com maybe?), but I don't know about that. Cool, if I ever plan to swap in a DOHC block in for my SOHC, I might possibly consider looking into thinking about asking about purchasing them (lol).

[cynosurecivic]

the skunk 2 9 second rsx has ITB with a huge air tunnel connected to the front bumper to direct airflow directly to them.

[TERROR]

Have you pics of the RSX system?

[steronz]

ITBs are for race cars and show cars only. they're basically just like the ultimate race intake manifold... everyone has known for years that increasing plenum size and decreasing runner length will allow better breathing at high RPMs while sacrificing low-end power and driveability. people often LOSE power going from a stock intake manifold to an aftermarket race manifold on a street car. well, what are ITBs if not intake manifolds with super short runners and a plenum the size of earth's atmosphere? most people who put them on street cars lose power at all RPMs below 8500. they're really for people with 11000+ RPM redlines. not to mention the huge hassle of figuring out how to get your engine to idle, hooking up vacuum lines for sensors, etc.