What to do with the throttle body?
 

I just can not decide what the best route to go is. The way I see it you have several options.

1)Modify the stock TB like BDC. It keeps the same size butterfly, and removes some of the obstructions.

2)Modify the stock TB like the Feed unit. Larger butterflys and I guess you could still do some porting work like BDC does.

3)Get the large single like Rotary works. The single TB has less surface area to slow down the velocity.

4)Leave the thing alone.

I personally do not know what the best method is, and I guess it might depend on how each car is modified, and what it is used for.

I have been bouncing back and forth between these four choices for a bout two months now.

I would assume they all should provide more power but what would you think is best?

I'm putting a 90mm TB soon..

why don't you spend that time and money on fixing up the interior or something? the factory throttlebody just isn't that big of a restriction

I have the FEED throttle body, cant say I noticed any difference.

Like they said, I cant see spending the $$$ on something that will yield minimal results(unless its a full track car), it can be better spent elsewhere.

^^^ +1, mods like this only make a difference if you do a whole bunch of them. They don't make much difference by themselves and often not worth the effort. In my MR2 I had enlarged throttle body, machined manifold, underdrive pulley, cams etc. (I tried to squeeze every little bit out of it) and only then I could feel a little difference compared to other MR2s but instead of spending time on these fiddly thing I could've gone on size bigger on the turbo and it'd make a bigger difference. So it all depends if you're willing and determined to do lots of little things to make a big difference or not.

I disagree with this if you mean any kind of throttle body mod as opposed to just machine work done on the throttle bore(s). While I don't claim to be perfect, the only perfect record I have when it comes to the work I've done for folks vs. the reactions I've received in response to that work would be my throttle body job. Out of all of the tuning, engines, da da da, the throttle mod I do has been the one that has produced both positive reactions and positive results from the owner consistently 100% of the time. It's always worked and has always produced an expected performance boost in a few areas. This also transcends the Mazda rotary stuff and goes into all of the other car makes/models I've done the same job on. But, not on a single one have I ever included machine work that replaces the butterfly with a larger diameter unit. My focus, instead of increasing overall internal size, centers more on two principles of fluid mechanics (as best as I understand them, at least) that aim towards reducing the velocity slow-down (pressure drop) that just about every factory throttle body has to some degree. Producing power is all about the velocity.

http://bdc.cyberosity.com/main.php?g2_itemId=7216

This part I agree with somewhat but from the perspective of analyzing car modifications as part of an entire system rather than throwing individual parts at it to try and "add power". When making any change to the setup, the entire thing has to be taken into account.

Here's my take on this from what my experience has taught me: while I'm not trying to promote my own work in this comment nor talk negatively about anybody else's, this is why I've got a beef with doing a larger throttle on a (mostly) stock car. Take the newly released, machined throttle that RotaryWorks provides. Without a doubt, it's a killer piece. Very high quality, exceptional machine work done to produce that, and worth the money in my opinion. However, that doesn't mean it's the best practical fit for every single car. The problem I have with it is it follows the common approach that "bigger is better". Again, not knocking the unit; it's very well made but "bigger ain't always better" as I explained to DoubleJ recently. In the case of something like a race car or a very high horsepower setup, where the throttle itself is truly a restriction, I can see a throttle body like this or any other that aims to increase bore size being efficacious. After all, only so much air can be pushed through a coffee straw, no matter how fast it goes. However, as can be the case with other intake mods and the like, going to a larger throttle bore on a stock and even modified car can be detrimental for power because of the change in charge velocity through it. When going to a larger bore, when the air enters the throttle from its inlet, it will slow down to try and fill that larger area. In practical terms, this can produce a more laggy throttle response and loss of low-end. If however at high RPM the engine is legitimately starving for air when the factory throttle is at WOT, then the larger bore body may help. But most of the time I would argue that it doesn't. Again, it's about velocity and not about size. For what most of us here do, I don't personally think the larger bore unit is worth it.

That's my 2 cents on it at least.

B

I once had a throttle body mod on my old 89 corolla gts with the 4AG motor. The only mods to the car were a k&N cone filter and an HKS cat back exhaust (with cat replacement pipe). I then had the stock tb bored out with a bigger flap. I felt more of a power increase with this modified tb than with the other 2 mods. Mind you this car had 114 stock hp. This was back in high school so I was pretty proud of the mods at the time......LMAO That's my 2 cents.

I would think this car would be coming stock with a much more restrictive tb than the FD so the mod will likely make a more noticable difference.

Very possible.

I ported mine along with the upper and lower intake, and I like it. I'd recommend it to anybody.
$.02

I have heard nothing but positive about your work too, and this isn't intended to be critical. But peoples reactions.... i.e. "butt dyno" are just too subjective. If I just spent a significant amount of money having you do that beautiful work on my stock T-body, or forked over $400 or so for a pretty new CNC machined T-body, I'd want to think it made a difference too.

I've seen somewhat controlled 'before and after dynos' on engine port work as well as a few aftermarket mods/parts. Maybe I've missed it, but I haven't seen similar objective 'controlled' dyno sheets on the T-body mods.

its only a matter of time (hopefully) before someone does a before and after dyno with that throttle body. I would think the shop selling them would provide that info as I have been told that they have a dyno in house.

Hi Jim,

While I'm not intending to come off as argumentative, I can tell you with great certainty that this does work. I've been doing them for 8 years. I don't know how many I've done but I bet it's close to or over 100 by now. They all produce the exact same results as I've already listed and even so on different makes and models of cars. It's pretty predictable. I've not had a single person tell me that it didn't do anything positive.

The subjectivism you've mentioned about people "wanting to feel" a positive difference is certainly for real and probably more prevalent with younger folks. After all, if I spent money to have someone do something on my car that's meant to be a performance boost, I'd want that to actually be the end result when I get back in the car and drive it. While it might be possible that that's a factor, I don't think that it honestly is given the number of these things I've done plus over the amount of time I've done them. It's been way, way too long for folks to give me negative feedback on this mod yet I've never received such. On the contrary, on the one and only dyno test I have seen as a true before and after (a '79 Triumph Spitfire w/ the change of TB plus a difference from 3000 to 7500miles or so of engine time) showed that the same setup hit its target of 400rwhp a full 1000rpm earlier and it clearly illustrates the larger benefit that I've claimed that it yields on turbocharged cars; that being a more aggressive boost response.

The way I sell this mod doesn't follow the typical "bolt this on and you'll gain x horsepower!" advertisement that's not only normally fallacious but also litters car magazines everywhere. Truly, it's a mild to moderate modification (depending upon the car and setup) that's meant to compliment other modifications as part of the overall system. It's not meant to "add x power" or even add peak power so I don't advertise it as such.

A throttle body like the well-made one Rotaryworks.com provides would be more about total peak power on vastly higher power setups where the use of the factory throttle (in terms of the diameters of the three throats) proves to be plain just too skinny in that its disallowing the total mass air flow that the engine can demand for achieving said high power. After all, like I've said, you can only breathe so much air through a coffee straw so on a high power setup where the TB might be a true restriction in the system then a larger body like theirs is efficacious and worthwhile. However, the idea behind the way I do mine is about reducing the pressure drop points within the body to allow it to be a lesser restriction as the air from the inlet transitions into the three throats while it passes through. It's about trying to keep velocity high and banking on the speed of air vs. time factor instead of overall area and diameter. At some point, no matter the porting and gee-whiz polishing work done on a factory TB, is going to be a true mass-air restriction in the system but I suspect that it's not the case for a great number of us. For those that are perhaps aiming for ~500rwhp and above then it may be worth looking into a larger bored body.

It works. If it didn't, I wouldn't still be spending time trying to perfect it even 8 years later.

Hope that helps,

B

Only had one person do one on one of my 2nd gen units and it was several years ago. GoodfellaFD3S is/was/will/he'd better do a before/after of my 3rd gen one on his FD sometime, some day, some way... :)

B

I had someone bore out the stock throttle body with a new flapper on my 89 corolla gts (stock hp 114). Car only had HKS exhaust and k&N filter with no airbox. Yeah, weak mods, I was in high school......hahah Anyways, the tb made the most noticeable seat of the pants hp increase.

im not too up to date on my TB mods, lookign into it. regardless of Ho and everything else, if you have the equipment and like me would do it just for the sake of having something to do, then go for it. I like the idea of not having new buttereflies though. looking into BDC TB mod now.


just seen it, $150 doesnt seem like much of a bill... I think its a safe bet.

just get the RW TB so we can all stop guessing on the benefits...........hahah Be the first to get it and tell us how it is :)

Got my Throttle Body back from Brian at BDC, it looks great

I would personally upgrade the whole upper intake assembly with the FreeLance Motorsports UIM & 90mm throttle body combo. I wish the people that had them would post about them and not keep the secret...

Another back from da dead thread!! :D

^Ok so post up some pics and provide a link bro!

Regards,
crispy

I agree. I did a few searches and couldn't find any "Freelance Motorsports". I an very interested to see what they have.

Funny,,I sold Double J a 90mm TB from R-W last year..so I think that is what he is using now.

Lots of people are making lots of power on stock throttle bodies.
Single bore throttle bodies like the RW unit fail to account for the chambered design of the stock UIM.

IYAMO, the JDM overbore units, and BDC style units look the best.

They're a rotary cult so you'll never find information on them lol. No, in reality they don't mass produce engines or parts. I was told that in 2012 they might migrate into a vendor on here as they're getting more organized.

As for the intake manifold I was not allowed to take a picture as they're very protective of it. I'm sure I won't get into trouble for telling small details so here's what I can say.

The manifold weighs less then 4 pounds! I didn't believe it myself so I asked to see it on their scale and it read 3.95lbs. The 90mm throttle body weights 2.5lbs so the combined weight is around 6.5lbs. Lance said it was possible to take more weight off but that it wouldn't be cost effective as nobody would pay the price.

I bug Lance to post something but he says he respects the forum vendor policy and will only let owners of the manifold post information until vendor status is approved. A little birdy also told me that there's one being shipped off to New Zealand for a 99spec Type R FD :drool: I'll try to get their forum name to sent them a PM and post information.