What is the down side of installing a larger throttle body?
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What is the down side of installing a larger throttle body?
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http://www.groupbuycenter.com/
Causes uncontrolable wheelspin at throttle tip-in. http://www.hostboard.com/ubb/smile.gif
Does it reduce low end torque?
Do you have to get a larger than 3 inch intake?
I'm sure you have to port match the JR intake neck (no biggy)
The Civic already has a small TB, but the GS-R is a bit larger too.
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The downside would be less control over throttle modulation: 1/2 throttle becomes 3/5 throttle, etc. etc. and its harder to hit lower throttle levels.
Do you guys think an overbore TB is neccesary on a JRSC Integra and have any of you actually seen WOT gains with this? I don't mean feel, because the above paragraph is gonna make it feel like its gained power no matter what. I'd like some numbers.
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by lundgren:
Does it reduce low end torque?
Do you have to get a larger than 3 inch intake?
I'm sure you have to port match the JR intake neck (no biggy)
The Civic already has a small TB, but the GS-R is a bit larger too.
<HR></BLOCKQUOTE>
The Si's TB is about that same size as the TypeR's TB, ~61-62mm. The Holley TB I'm using is 68mm which will do until I receive the 70mm BBK TB from Summit. I had the JR TB tube ported to 70mm. The intial tip-in surge of power is just tremendous. Coupled w/ the roots blower's ability to make boost at low rpms masks the low end torque loss due to slow intake velocities apparent in NA setups. Of course, you'll need a 3" intake w/ the larger TB.
http://www.hostboard.com/ubb/Forum40/HTML/006754.html
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Mods
[This message has been edited by zip (edited April 23, 2001).]
OE throttle body sizes:
'92+ Civic = 58mm
GSR/'99+ Si = 62mm
Type "R" = 64mm
I believe that a larger T/B would benefit a JRSC car with 8+ psi of boost... I have one for my Blackbird.
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'93 Civic Si H/B with B18C1, JRSC @ 8psi
Best 1320: 12.68 at 110 mph
I'd say, do some searches over on the Endyn forum
Here's one post Larry addresses bored vs tapered.
"Most engines don't need a bored out throttle body. Boring the throttle body is an easy way to pick up some flow, but the reason most people like them is that they make the cars "feel" more powerful, as they provide greater opening area per degree of throttle opening, due to the larger diameter.
Doing the taper bore is like porting an intake port. You can go for bulk flow numbers by making the port big all the way through (over-bored TB), vs going for high quality flow with only mildly increased flow numbers (tapered TB).
I'm sure I don't need to tell you which is more important....quality wins out every time.
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.....The Old One....
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by reddelsol:
I'd say, do some searches over on the Endyn forum
Here's one post Larry addresses bored vs tapered.
"Most engines don't need a bored out throttle body. Boring the throttle body is an easy way to pick up some flow, but the reason most people like them is that they make the cars "feel" more powerful, as they provide greater opening area per degree of throttle opening, due to the larger diameter.
Doing the taper bore is like porting an intake port. You can go for bulk flow numbers by making the port big all the way through (over-bored TB), vs going for high quality flow with only mildly increased flow numbers (tapered TB).
I'm sure I don't need to tell you which is more important....quality wins out every time.
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.....The Old One....<HR></BLOCKQUOTE>
Is the quote directed to NA or FI setups? You forgot to mention that. TOO will be contradicting himself if he says tapered TB's are the way to go on JRSCs. Since he's a large proponent to slowing intake velocities across the TB on a roots SC setup.
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Mods
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>On a JRSC equiped 00SI would replaceing the throttle body with one like BBKs make any difference? How about on a stock engine? There seems to be another made by Holly as well. I think the 2 are 62mm & 64mm respectively. Thanx for any input.
...Steven<HR></BLOCKQUOTE>
In reply to that question.....
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>The larger TB on a JRSC just makes th flow characteristics of the TB to blower adapter worse yet. If the larger TB makes the engine produce less usable power, it's your call. Larger doesn't always mean better.
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.....The Old One..... <HR></BLOCKQUOTE>
Also I remember when Larry said he used a larger than stock throttle body on his civic and said it made more power on the dyno up top but was less drivable. It was a post started by Larry but it is not coming up in the search engine??? Must have been deleted????? He also mentioned that some of the larger throttle bodies from Honda were too large for the motor they put them on???? I am not taking any sides on this but just trying to show what ENDYN believes is better for your JRSC motor. http://www.hostboard.com/ubb/smile.gif
Sorry, I think that was for n/a Zip. Though I know he recommends 3" intakes for BOTH n/a and FI for what that's worth.
While I was looking around though, found this interesting post
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If you want to know the truth......you have to cut and try. There are certain flow relationships that can be made, but arbitrarily using a TB butterfly diameter and assuming that flow increases with size won't cut it.
Most of our tesing has shown conclusively that an increase in TB size for an engine with headers and an exhaust might fool the driver into thinking the engine's more powerful, due to the availability of more air flow at lower throttle angles, but in an properly accelerated dyno run, or a trip down the quarter in the real world the joy will be short lived and the realization that you wasted a lot of money will get you looking for a "sucker" pretty quick. "Almost new throttle body for great price, anyone!"
I think that if you really increase the rpm range the engine runs in, a bigger TB is going to be necessary, but how much larger is something you'll have to experiment with.
Most of you don't realize it, but Honda uses a larger TB on production engines than's necessary for peak performnance. Why? Because the larger TB fools the driver into perceiving "more". This is an old trick in the industry. Similar tricks can be played with variable ratio throttle activation. Manufacturers have been building small engined cars with "cam-style" throttles for years. The first third of the pedal travel brings in 3/4 full throttle and the car seems to be real "peppy". It might move fast at the start, but there's not much left when you've pulled out and the traffic is on your ass.
I'll wind it up with this... if anyone can tell you what TB to buy for a certain application and guarantee that it'll work, buy it.
Don't forget the relationship between TB size and plenum volume either. We've discussed this before here, so you might want to search around for it before you leap for a larger TB.
LW
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!
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.....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
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by zip:
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
<HR></BLOCKQUOTE>
What about comparing the throttle body size used for a 16psi JR Endyn modded blower?
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by reddelsol:
What about comparing the throttle body size used for a 16psi JR Endyn modded blower?<HR></BLOCKQUOTE>
http://www.hostboard.com/ubb/confused.gif Who's running that setup? You guys are getting off-topic throwing in Endyn modified products. I know Steven is running under 12psi at the moment. And only a couple of members actually have Endyn work.
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Mods
11psiGSR has that mod.
He posts on here on and off.
Please re-read my statement about trial&error for "YOUR" specific B16A JRSC application. You are missing my point. I am not directly comparing your setup to Larry's just trying to rationalize an educated guess on were you can start doing your own testing on what will give you the most power without too much compromise. http://www.hostboard.com/ubb/smile.gif Are you trying to peice together a "system" or just following what other Civic SI JRSC people have done? I respect you all the way Zip and I want to help you out anyway I can. By the way would anybody have an exact replica of every single modification/part/tunning that you have made on your civic?? So how can you compare your setup to anybody elses? I seriously believe that the throttle body bore size is not universal as every motor is different JRSC'd or not. http://www.hostboard.com/ubb/wink.gif Not to mention atmospheric conditions/elevation too.....
<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."
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.
<HR></BLOCKQUOTE>
They've also got plenty in common. For one thing, in both cases more air = more power. The statement regarding energy and inertia translating to better cylinder filling could also apply to the blower, as in "more energy and inertia translate to better blower filling", which ultimately translates to better cylinder filling.
I'm about to install a 67mm JG tb in my gsr. I'm presently running the aem cai. I know, I need to switch to something short and 3". Which one?
Thanks.
I hate to bring up old posts, but someone mentioned a trial and error process for an oversized throttle body.
Has anyone actually done some trial and error with this question? If so what did they come up with for a JRSC application??
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ive got a 3" throttle body and 12 psi JRSC and it all works together "great".
got any other ???
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12.4 @ 110mph
listen to jeff and zip. they know what they say. Liar larry doesn't know anything about honda engines or supposedly air flow. All engines are alike on air. They need air to make power,so the bigger the door is that lets the air in, the more power it'll make.
Jeff can explain it scientificaly. Just ask on ImportBuilders.
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