hw-itb
08-23-2004, 11:59 AM
#31
Guest
Join Date: Dec 2002
Posts: 1,463
Re:hw-itb
So back in the day....
When I dealt with N/A V8s, runner shape and length were pretty important.
I can see with singles and plenums, where you would want to shape things to ease the draw of air into the cylinders. The air is being drawn in by cylinder vacuum, so everything should be shaped accordingly to smooth the air path and allow as much air to be sucked in as possible..
The question is, does(should) this shape change when you convert to boost? The air is now being forced in, so would'nt you now focus on air velocity as opposed to air flow? Or is it the same thing in the end?
Of course if you put a plenum on the air intake side of the ITBs, full of a whole bunch of boost pressure, you could avoid some of the lag time that exists due the plenum and runners of a conventional intake. Instead of boost pressure building in front of the single TB, and then traveling through the plenum and runners to the cylinders, you'd then have boost building right next to the intake valves, just waiting behind each of the ITBs. Hmmm....
Your thoughts?
When I dealt with N/A V8s, runner shape and length were pretty important.
I can see with singles and plenums, where you would want to shape things to ease the draw of air into the cylinders. The air is being drawn in by cylinder vacuum, so everything should be shaped accordingly to smooth the air path and allow as much air to be sucked in as possible..
The question is, does(should) this shape change when you convert to boost? The air is now being forced in, so would'nt you now focus on air velocity as opposed to air flow? Or is it the same thing in the end?
Of course if you put a plenum on the air intake side of the ITBs, full of a whole bunch of boost pressure, you could avoid some of the lag time that exists due the plenum and runners of a conventional intake. Instead of boost pressure building in front of the single TB, and then traveling through the plenum and runners to the cylinders, you'd then have boost building right next to the intake valves, just waiting behind each of the ITBs. Hmmm....
Your thoughts?
08-23-2004, 12:23 PM
#32
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Join Date: Dec 2002
Posts: 2,949
Re:hw-itb
You also have to remember that the biggest mistake people make in an ITB setup (and many of you have in the past, including me) is they use the factory injector bongs on the intake manifold flange, this method is not the best in an ITB setup, since ITB's with proper runners give you a higher velocity of air going in to the engine, the fuel from the injectors off the stock intake manifold does not have alot of time to atomize with the air, therefore a poor mixture that will not burn to its fullest potential, this may be insignificant to you. but if you look at the molecule aspect of it, it makes a huge difference. When the injector is housed in the ITB injector bong, it is about 3 inches from the intake valve when the fuel sprays and mixes with the fast movind air, it has that extra 3 inches of travel through the runner where it atomizes better, which means more power, this brings me to the point where you guys say that runner angle and smoothness is important.
if the transition from the ITB to the intake runner is not smooth, then there will be some turbulance in the air as its hitting the intake valve, turbulance = BAD fuel atomization.
Hope i'm making sence.
if the transition from the ITB to the intake runner is not smooth, then there will be some turbulance in the air as its hitting the intake valve, turbulance = BAD fuel atomization.
Hope i'm making sence.
08-23-2004, 01:20 PM
#33
3.0 BAR
Join Date: Oct 2003
Posts: 3,254
Re:hw-itb
^^^ in response to that, the best bet you are going to have is using injector bungs in the stock location that they would be in w/ a conventional manifold. the atomization will not change for the worse there, the extra air velocity that you'll find with the ITB setup will only help to atomize that fuel. I'd think by using the injecter bungs on the TB's you'll get an adverse affect regarding fuel atomization because there is more room for the fuel to stick to the walls of the runners. fuel atomization should be happening within the intake ports on the head, not in the runners of the manifold. that is why the good od european CIS system sucked so horribly.
in response to craig, yeah, you would think that say a plenum ontop of the ITB's would be the way to go, because of time spent in vaccuum (especially for those of us with large turbos) however, the lack of an throttle body (in the conventional location, turns your whole charge pipe into one really big plenum. this way, one could use an equal length tubular intake manifold that connects on one side to the charge pipe, and on the other side just uses the TB's as an extension of its runners. that is basically my plan of action with my setup. I think there will be far sufficient plenum volume out of boost, there will not be the vaccuum problems generally associated w/ ITB's and there will be a substantial increase in air velocity by using that type of manifold on a forced induction setup. there are already setups sort of like this being used on E46 m3's and M3 csl's in europe, it is pretty much the only way to boost the stock ITB'ed motor in an M3 (besides the bastardized version of it that evosport is doing here in the states. by no means is this a new Idea, people have been doing this on sunny pulsar GTIR's, R34's, and TT supra's for quite a while. as far as I can tell there is not going to be a better system for iunduction on a car then this setup.
I'll keep you guys posted on my progress, I have an ebay auction ending soon that is going to fund the endeavor.
I'll dyno it too, just to show results (I'm specifically interested in seeing the changes in placement and duration of the powerband)
yee hoo, for a fun, technical post.
in response to craig, yeah, you would think that say a plenum ontop of the ITB's would be the way to go, because of time spent in vaccuum (especially for those of us with large turbos) however, the lack of an throttle body (in the conventional location, turns your whole charge pipe into one really big plenum. this way, one could use an equal length tubular intake manifold that connects on one side to the charge pipe, and on the other side just uses the TB's as an extension of its runners. that is basically my plan of action with my setup. I think there will be far sufficient plenum volume out of boost, there will not be the vaccuum problems generally associated w/ ITB's and there will be a substantial increase in air velocity by using that type of manifold on a forced induction setup. there are already setups sort of like this being used on E46 m3's and M3 csl's in europe, it is pretty much the only way to boost the stock ITB'ed motor in an M3 (besides the bastardized version of it that evosport is doing here in the states. by no means is this a new Idea, people have been doing this on sunny pulsar GTIR's, R34's, and TT supra's for quite a while. as far as I can tell there is not going to be a better system for iunduction on a car then this setup.
I'll keep you guys posted on my progress, I have an ebay auction ending soon that is going to fund the endeavor.
I'll dyno it too, just to show results (I'm specifically interested in seeing the changes in placement and duration of the powerband)
yee hoo, for a fun, technical post.
08-23-2004, 05:43 PM
#34
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Join Date: Dec 2002
Posts: 1,463
Re:hw-itb
This is a fun discussion!
Originally Posted by bambooseven
...turns your whole charge pipe into one really big plenum.
Of course then it would also be true that air velocity would build more slowy in a large plenum system vs a large one....
08-23-2004, 06:24 PM
#36
3.0 BAR
Join Date: Oct 2003
Posts: 3,254
Re:hw-itb
yeah, but I like to ---- around with fun stuff, and I don't have money or resources to build the ---- that I would build if I did have the money and resources.
Craig, think about the difference in an a6 manifold and a Y8 manifold, that small of a change in plenum size makes a difference (well, the runner lengths make more of a difference, but it is still noticeable).
Craig, think about the difference in an a6 manifold and a Y8 manifold, that small of a change in plenum size makes a difference (well, the runner lengths make more of a difference, but it is still noticeable).
08-23-2004, 06:43 PM
#37
Administrator
Join Date: Dec 2002
Posts: 13,991
Re:hw-itb
After you do your own ITB project you will find out for yourself.. 
All they do is make noise and your car doesnt go anywhere until about 7-9000rpms. Why dont you try something different like a set of ITB's with a huge box welded around it (like a plenum) and boost it, haha.. It would just be like a Skyline RB26DETT
Corolla w/ ITB's and Turbo.. I should of done that, it would have probably been funnier.
Jeff
All they do is make noise and your car doesnt go anywhere until about 7-9000rpms. Why dont you try something different like a set of ITB's with a huge box welded around it (like a plenum) and boost it, haha.. It would just be like a Skyline RB26DETT
Corolla w/ ITB's and Turbo.. I should of done that, it would have probably been funnier.
Jeff
08-23-2004, 07:19 PM
#38
0.0 BAR
Join Date: Apr 2004
Posts: 0
Re:hw-itb
jeff, those were my plans....but had to sell the ----.
I thought of it like hitting 4 beer bongs at one time, instead of just 1.
i would love to see it done, and it could be done really cheap to. (a few extra hundred dollars)
and about the injectors, I JB welded the holes shut on the ITB's and was gonna use the injector holes on the hacked manifold. -on the B16 one i helped with, we just enlarged the holes on the ITB's to accomidate the stock B16 injectors.
I thought of it like hitting 4 beer bongs at one time, instead of just 1.
i would love to see it done, and it could be done really cheap to. (a few extra hundred dollars)
and about the injectors, I JB welded the holes shut on the ITB's and was gonna use the injector holes on the hacked manifold. -on the B16 one i helped with, we just enlarged the holes on the ITB's to accomidate the stock B16 injectors.
