OBX ITB's

[Fox351]

I was looking at these itbs and thought it is strange that they placed the fuel injectors in front of the throttle butterflies. I was thinking to my self how would this idle and wouldn't it cause fuel to puddle on the butterflies causing extreme problems? I was hoping that someone could explain this to me. Maybe I am missing something about the butterflies or how you set them. If anyone can help I would greatly appreciate it.

[NEMO]

are you sure your not looking at the direct port nitrous

[Fox351]

http://i5.ebayimg.com/07/i/001/11/30...t_id=800005007

[RBS]

i have yet to receive mines for my B20Vtec, if you havent figured it out by the time i get mines ill be sure to PM you what i did

[Fox351]

Thanks a ton...I have been trying to look at other itbs and all of them place there injectors behind the butterflies which would be more logical due to the stock manifold's originals being in relatively the same place. I have been playing with the idea of making adabter plates to move the injectors to where they are behind the butterflies but its still on the drawing board.

[Vteckidd]

ITBs are worthless bling, especially OBX ones.

A manifold and tb will almost always make more power

[Fox351]

Why is that? I would think with a plenumless design there would be no ristriction on the air flow coming into the engine. If this is true then an ITB setup would make more power due to its inherent ability to supply each cylinder with the proper amount of air required to make the most power and bring up the VE of the engine given that all fuel metering and requirements are met. I may have my facts wrong. If so please explain your theory. I would agree that the OBX ITB setup is not the most optimal setup to purchase but I have seen people take them and make decent power numbers. My inquiry is over the choice of OBX to place the fuel injector in front of the throttle butterflies when almost all other ITB manufacturers place their fuel injectors after. I find this odd due to the fact that if the fuel hits the throttle plate it will liquidize and cause idle problems and poor fuel consumption. I can understand the setup with WOT but you don't drive the car this way all the time. So my main question really would be how would this work on a car that is at idle or at low throttle?

[Vteckidd]

It's a secondary injector setup they copied from jenvey and kinsler. The optimal spray pattern is above te throttle plate.

Itbs are the most overrated mod in my opinion. They are a pain to tune, you don't make 20whp like a bunch of people think, they do add good midrange power but the cost per hp is not for most people.

I made 230+ with a lightly ported $120 aebs manifold and 70mm tb.

Unless your making 240-250 , or a avid road racer, they are a waste of money

[Vteckidd]

FYI honda motors usually run above 100% ve With little to no mods. They are very efficient

[Fox351]

Understood. I haven't seen a "primary" injector on the obx itb. That seems to be the only one. I can't imagine that at idle and low throttle that would be the ideal spray pattern due to the interference with the butterflies. You have built more motors than I have so I will take your word for it. I was just wondering if that is the best spray pattern why would Jenvey, Kinsler, and TWM have them with the fuel injectors behind the butterflies? I can completely understand at WOT that with the injectors infront of the butterflies it would allow more time for atomization of the fuel and air mixture but at idle it leaves no room and puts a plate in front of it for the fuel to liquidize on. As far as dollar per horse power I would agree that they are expensive. I can't disagree with that. I was asking the question on a more engineering point of view instead of engine building advice.

[Vteckidd]

Understood. I haven't seen a "primary" injector on the obx itb. That seems to be the only one. I can't imagine that at idle and low throttle that would be the ideal spray pattern due to the interference with the butterflies. You have built more motors than I have so I will take your word for it. I was just wondering if that is the best spray pattern why would Jenvey, Kinsler, and TWM have them with the fuel injectors behind the butterflies? I can completely understand at WOT that with the injectors infront of the butterflies it would allow more time for atomization of the fuel and air mixture but at idle it leaves no room and puts a plate in front of it for the fuel to liquidize on. As far as dollar per horse power I would agree that they are expensive. I can't disagree with that. I was asking the question on a more engineering point of view instead of engine building advice.

gotcha, what they arent showing you is the injectors above the throttle plates are secondary meaning they are on a switch, they only turn on under WOT. you have another set of injectors (like normal) for idle and low rpm , closed throttle applications.

like so

[Vteckidd]

i assume you are talking about these



If you flip it over there SHOULD be spots for 4 more injectors like a factory setup, otherwise you are right the car wont run and most likely catch on fire haha

[94_teg_ls]

http://www.youtube.com/watch?v=OIxdRqcIEKY some info in here somewhere

[Fox351]

Great video and great info....thanks.