ITB's

[79_rabbit]

ok what are the pros to having ITB's arron i know you have on your 2.0. i only ask because today in school. my friend was talking about putting ITB's on his on his b20 and asked me were there any benefits or y some one would do this. and i didnt know so i figured i would ask.

[JFryauff]

Since every runner has a throttle body, and there's no "log" that all the cylinders have to eat from, no restrictions. Much better performance once tuned right, but slow cruising is a bitch! It has a lot to do with the right sizing for your engine, and using a good fuel managment/timing set-up. A body too large for the motor is what causes the drivabilitiy problems. This happens anytime you use a throttle butterfly that's too large, wether ITBs or a plenum setup. The area of a circle (the throttle plate) increases exponentially (as opposed to linearly) with increase in diameter. So a relatively small increase in throttle bore makes a relatively large change in the amount of open area you get with the same amount of throttle input. Smaller bodies or a clever progressive throttle linkage would help. An 8v doesn't flow that much to begin with, so going huge on the intake doesn't make sense. If you have programmable EFI, it may be possible to make it feel smoother by underfueling at high vaccuum (nearly closed throttles) and eliminating accel enrichment, but hopefully there are better solutions.

[Fourt1thirty]

Josh pretty much covered it. The car is crazy fast, sounds awesome, but around town driving isn't the best. It's drivable with a careful touch, but I wouldn't want my girlfriend driving it around. Another issue is that since vacuum falls off so rapidly making a proper fuel map is pretty difficult. Some tuners say to use Alpha-N tuning, which is making the map based on RPM and TPS rather than RPM and MAP. This is a good option for this setup, but also leads to drivability problems since now the engine had no concept of load.

Really... this is one of those racecar mods and although I really enjoy driving the car if my girlfriend can't drive it to the store it kind of loses its purpose to me.

[vwmike]

Originally Posted by Fourt1thirty

Really... this is one of those racecar mods and although I really enjoy driving the car if my girlfriend can't drive it to the store it kind of loses its purpose to me.

She has her own car, stop whining.....If you're just trying to talk yourself into turbocharging it then why go to such lengths? Plus, remember how lonely the blue car looks sitting outside the shop. Blue rabbits need lovin' too.

[vwfreakDYC]

[detective]

Originally Posted by vwmike

She has her own car, stop whining.....If you're just trying to talk yourself into turbocharging it then why go to such lengths? Plus, remember how lonely the blue car looks sitting outside the shop. Blue rabbits need lovin' too.

You have to know aaron personally to get this. HIs syncro project has been on the back burner for a while now. when are we going to see you actually touch the car Aaron?!

[vwmike]

Originally Posted by detective

You have to know aaron personally to get this. HIs syncro project has been on the back burner for a while now. when are we going to see you actually touch the car Aaron?!

That core support has been sitting there - clamped onto the front of the car since last summer....make with the welding!!

[Fourt1thirty]

Don't make me lock this

[vwmike]

Originally Posted by Fourt1thirty

Don't make me lock this

Don't mess with me man....I'll cut you so bad....you'll wish I didn't cut you so bad

[diabolical1]

Originally Posted by JFryauff

Since every runner has a throttle body, and there's no "log" that all the cylinders have to eat from, no restrictions. Much better performance once tuned right, but slow cruising is a bitch! It has a lot to do with the right sizing for your engine, and using a good fuel managment/timing set-up. A body too large for the motor is what causes the drivabilitiy problems. This happens anytime you use a throttle butterfly that's too large, wether ITBs or a plenum setup. The area of a circle (the throttle plate) increases exponentially (as opposed to linearly) with increase in diameter. So a relatively small increase in throttle bore makes a relatively large change in the amount of open area you get with the same amount of throttle input. Smaller bodies or a clever progressive throttle linkage would help. An 8v doesn't flow that much to begin with, so going huge on the intake doesn't make sense. If you have programmable EFI, it may be possible to make it feel smoother by underfueling at high vaccuum (nearly closed throttles) and eliminating accel enrichment, but hopefully there are better solutions.

so far, this is probably the best response on independent throttle bodies i've ever read on ANY forum ...

[Fourt1thirty]

Originally Posted by diabolical1

so far, this is probably the best response on independent throttle bodies i've ever read on ANY forum ...

That's because Josh is a smooth pimp.

[diabolical1]

smooth pimp, eh?
well, i guess i need to take lessons ...