drivemusicnow
15+ Year Contributor
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- 30
- Nov 15, 2004
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Germany,
Europe
Okay, So this is pretty much just something that I was thinking about and not something I'm actually working on. That said, I would like to hear hard tech and not comments like "well nobody has done it before which obviously means there is no benefit from it" etc comments.
A lot of people are starting to use much larger throttlebodies recently, including the newly hyped Q45 TB. The first gen TB stock is 60mm, and the "larger" options seem to be the 75mm mustang TB, the 90mm Q45 TB, an overbored 1g TB (63mm). After working this over in my head, the increased TB size really will not increase horsepower or torque in any way whatsoever. The butt dyno will probably think that it "increases throttle response" just because with the TPS reading 35% a larger TB will flow much more than a smaller one, however at 100$, they'll pretty much flow exactly the same. The "rule of thumb" is to go with the smallest TB that will flow the volume of air you need, while keeping the velocity of said air flow under 300ft/sec.
What I am thinking about, is completely seperating the intake plenums, starting with a dual throttle body. A donor vehicle that comes to mind (and why I originally started thinking about it) is the Subaru SVX, which uses dual 63mm throttle bodies. (almost exactly 2.5 inches) My idea would be to run 2.5 inch intake pipeing to a Y pipe, into the throttlebodies, and then each throttle body would have it's own intake plenum, and two cylinders. This is sort of "halfway" in between individual throttle bodies, and the single larger throttle body. They have a normal "slip" fitting that would accept a 2.5 inch silicone coupler to make intake piping easy.
I would think that the benefit in seperating the intake pulses between the cylinders would be at least noteworthy. I would expect that you would see an increase in power and torque.
There are two reasons why I think this. First, by seperating the "back flow" you decrease turbulance in the plenum(s) which would result in smoother, and therefor faster flow, and second, it would increase the absolute pressure at the intake valve when it is opening. If you have the cylinders that are 180* opposite each other sharing a plenum, I would THINK that you would see a pulse that increases the pressure at the valve to a value greater than your MAP. I am not sure about this, nor am I sure how you would be able to "tune" the plenums to be able to do this.
I'm mostly just curious to see what some of the other ME types think about this idea. Whether you would see the benefits I would expect, or whether it is worth trying. It would be a PITA to do, but in the end it would be pretty cheap if you can do sheetmetal work yourself. I would expect to pay less than 75$ for an SVX throttle body, and the sheet metal work, while time consuming, would be relatively inexpensive.
A lot of people are starting to use much larger throttlebodies recently, including the newly hyped Q45 TB. The first gen TB stock is 60mm, and the "larger" options seem to be the 75mm mustang TB, the 90mm Q45 TB, an overbored 1g TB (63mm). After working this over in my head, the increased TB size really will not increase horsepower or torque in any way whatsoever. The butt dyno will probably think that it "increases throttle response" just because with the TPS reading 35% a larger TB will flow much more than a smaller one, however at 100$, they'll pretty much flow exactly the same. The "rule of thumb" is to go with the smallest TB that will flow the volume of air you need, while keeping the velocity of said air flow under 300ft/sec.
What I am thinking about, is completely seperating the intake plenums, starting with a dual throttle body. A donor vehicle that comes to mind (and why I originally started thinking about it) is the Subaru SVX, which uses dual 63mm throttle bodies. (almost exactly 2.5 inches) My idea would be to run 2.5 inch intake pipeing to a Y pipe, into the throttlebodies, and then each throttle body would have it's own intake plenum, and two cylinders. This is sort of "halfway" in between individual throttle bodies, and the single larger throttle body. They have a normal "slip" fitting that would accept a 2.5 inch silicone coupler to make intake piping easy.
I would think that the benefit in seperating the intake pulses between the cylinders would be at least noteworthy. I would expect that you would see an increase in power and torque.
There are two reasons why I think this. First, by seperating the "back flow" you decrease turbulance in the plenum(s) which would result in smoother, and therefor faster flow, and second, it would increase the absolute pressure at the intake valve when it is opening. If you have the cylinders that are 180* opposite each other sharing a plenum, I would THINK that you would see a pulse that increases the pressure at the valve to a value greater than your MAP. I am not sure about this, nor am I sure how you would be able to "tune" the plenums to be able to do this.
I'm mostly just curious to see what some of the other ME types think about this idea. Whether you would see the benefits I would expect, or whether it is worth trying. It would be a PITA to do, but in the end it would be pretty cheap if you can do sheetmetal work yourself. I would expect to pay less than 75$ for an SVX throttle body, and the sheet metal work, while time consuming, would be relatively inexpensive.
