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I was up late, and tried to find something specific to FI and large throttle body size over at Endyn.
This is as close as I could get.
http://ferrari.colowatch.com/php/sho...=&view=&sb=&o=
Unfortunately I couldn't get the specific link to the last linked archive to work --- just the general statement that "blowers don't like large throttle bodies"
My stock Si TB measures ~60mm at the exit and I have an overbored stock TB that has been punched out to 64mm that I am going to try. All measurements were done with a dial caliper accurate to .001". The inlet on the Si's intake manifold measured 62mm and the inlet on the Type R manifold measured 64mm, so there is a 2mm "step" there from the factory.
I plan on putting the 64mm TB on first and running it on the dyno. If there is enough time and if the motor is not too hot, I'll swap the stock one back in and do another pull.
I did have this 64mm TB on my mildly modified car in NA form and throttle response was noticeably enhanced. Did it enhance power? It was really hard to tell. With the stock TB, the car really "jumped" into VTEC. The larger TB really diminished this effect.
FYI: A buddy of mine did dyno test this same TB (the 64mm I currently have in my garage) before though. It was a B16A with CTR pistons, CTR cams, i/h/e, and cam gears. When he put the stock TB back on, he lost 10whp on top and about 5whp across the board.
Sonny
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Sonny Van Hook ([email protected])
2000 Supercharged Civic Si @ 6psi
1999 Tonykart/Honda 80cc Shifter
[This message has been edited by Sonnyballs (edited April 25, 2001).]
Ok. Let me get this straight. Most of us here run 3" intakes, right? All Honda TB's are considerably less than 3" in diameter. When the air flows from the 3" intake to the smaller diameter TB, isn't that essentially tapering the air flow path during WOT conditions? Then the air goes through the JR TB tube which tapers even more.
So what gives? All this tapering increases intake velocities. Where's the theory of having a constant diameter tube to slow down intake velocites across the TB. Now when I run a TB close to 3", many are saying it's not a good idea. Huh? Isn't the larger TB just continuing the 3" intake path to lower intake velocities across the TB region? Anybody care to explain?
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Mods
Hey Zip,
I'll try to explain what THE MAN is trying to say. It's all about fluid dynamics and airflow. Just imagine air as a liquid and it flowing through a water hose.
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>One more thing before I drop... The inside diameter on these tubes must be "large",especially near the TB. The increased diameter will help push the air into the TB at lower velocities (and higher pressure). Throttle bodies do not like to have high velocity air heading at them, so that rules out several of the tubes on the market.I wonder how making choices ever got to be so hard with these cars!
--
.....TheOldOne....<HR></BLOCKQUOTE>
If you use and adapter that tapers the 3" down to 2.25" before the throttle body's opening then the whole concept is fudged.
Thats why he has Thompson Engineering (Mr. Doug that's MIA for a long time now) design a $$$ MegaTube intake that gets the job done to their liking. Here is the link http://ferrari.colowatch.com/php/sho...e&Searchpage=0 &Limit=25&Old=allposts&Main=6465
on the ENDYN BBS that shows Frank's setup. You can see that its a snug fit around the outside diameter of the throttle body but that *special* adapterwill alow the intake to fit in there without it tapering it down. Hope this helps! http://www.hostboard.com/ubb/smile.gif
http://www.g-speed.com/eg2/new/TB_view.jpg
Thanks for the correct info Reddsol as I am backwards today.
[This message has been edited by 90teg (edited April 27, 2001).]
I thought I read something Larry said applying to this (maybe) while I was looking up that other stuff. (thanks to IE history links I found it again)
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"A rule of fluid dynamics and air flow is that as velocity increases, pressure decreases. It might seem backwards, but the wind blowing on your hand when it's out the window of your car isn't pressure, believe me.
Therefore, if you drop velocity, pressure increases and you can manipulate the air into providing greater pressure on the outer portion of the TB by making the area of the tube larger.
Now, we're going to get into what your hand feels out the window.....force or energy. If the throttle body is too large, the air entering the plenum won't have as much energy. You want energy and inertia at this point, as it ultimately transfers to better cylinder filling."
By the way Zip,
You and many of the other posters on this board probably know at least twice the amount of stuff that I do on engines-- just that when the subject was brought up I remembered stuff from reading on Endyn's board so I thought I'd look it up again. Don't mean to be an upstart or anything as this is definitely not my knowledge.
I found the mini article that Larry posted in the test archives http://www.hostboard.com/ubb/wink.gif
http://ferrari.colowatch.com/php/sho...=&view=&sb=&o=
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by reddelsol:
By the way Zip,
You and many of the other posters on this board probably know at least twice the amount of stuff that I do on engines-- just that when the subject was brought up I remembered stuff from reading on Endyn's board so I thought I'd look it up again. Don't mean to be an upstart or anything as this is definitely not my knowledge.<HR></BLOCKQUOTE>
I'm not jumping on you reddelsol, I just wanted to provoke a meaningful discussion to clear this theory. Yeah, I've been aware of the Thompson tube setup for quite a while. What I'm concerned is the size of the TB compared to the intake size specifically on FI setups. Is there a definite relationship between those two factors and the amount of boost the engine is going to run on a roots type blower setup?
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>"If the throttle body is too large, the air entering the plenum won't have as much energy. You want energy and inertia at this point, as it ultimately transfers to better cylinder filling."<HR></BLOCKQUOTE>
Well this comment is kind of null on our setups since we have a two rotors in front of the incoming air path. And since the air will be under pressure, cylinder filling wouldn't be a factor except during the transition to boost (which is almost instant on a roots blower).
Yes, Frank runs the thompson tube but he isn't using forced induction. Frank is all NA. All of the Endyn links provided on this post all pertain to NA setups. I've read Larry's posts enough to understand that applications on NA and FI are nothing alike.
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Mods
I see what you mean Zip, I am not trying to rub any info on you just letting everyone see some of the info that Larry put out that is even close to your question. From this standpoint it is pretty much trial&error or "cut&paste" for a intake/throttlebody that will be optimized for your JRSC setup on a B16A. If Larry's civic can make soo much power from the stock throttle body out of a 1.55liter d16 on 22psi, It does not seem that the stock bore Honda throttle body is any kind of bottle neck. From the mini article (apple and ornges) you can see that the stock throttle body is pretty sufficient for the size of your motor. Another factor would be personal preference, do you need so much torque available at idle - 2000rpm? and if your new throttle body helps your et's at the drag strip and makes the car feel stronger on the street then more power to you? Good ol "There's more than one way to skin a cat" http://www.hostboard.com/ubb/smile.gifIMO
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by 90teg:
I see what you mean Zip, I am not trying to rub any info on you just letting everyone see some of the info that Larry put out that is even close to your question. From this standpoint it is pretty much trial&error or "cut&paste" for a intake/throttlebody that will be optimized for your JRSC setup on a B16A. If Larry's civic can make soo much power from the stock throttle body out of a 1.55liter d16 on 22psi, It does not seem that the stock bore Honda throttle body is any kind of bottle neck. From the mini article (apple and ornges) you can see that the stock throttle body is pretty sufficient for the size of your motor. Another factor would be personal preference, do you need so much torque available at idle - 2000rpm? and if your new throttle body helps your et's at the drag strip and makes the car feel stronger on the street then more power to you? Good ol "There's more than one way to skin a cat" http://www.hostboard.com/ubb/smile.gifIMO <HR></BLOCKQUOTE>
You can't compare Larry's civic to our JRSC setups since there totally different species. We have to compare to what we run, which is the JRSC TB manifold + stock Eaton M62 SC + JR manifold. Nothing endyn associated about it. http://www.hostboard.com/ubb/wink.gif
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Mods