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