trbob16a

After looking into having my b16 throttle body bored out I was disgusted with the pricing. I figured I could do it myself but was strongly advised against it. Used throttle bodies are cheap so I said what the heck, if I screw it up I'll get a new one. I reasoned that by closing the IACV valve completely, the difference in air going around the stock butterfly would suffice to idle my car at a reasonable (less than 1krpm) level.

Here is how to do it:
Go out and buy a dremel and 2 6 packs of the roller 150grit sand paper that goes on them. Remove the throttle body. This is self explanatory so no directions needed. Remove the two screws holding on the butterfly. Measure your intake manifold opening, for me it is 64.5mm. Using the dremel with sanding roller attachment, you can get all the way through the throttle body. Work from both ends, stopping every 15 minutes or so to measure the opening at 4 points on both ends. I slid the butterfly back in also every 15 and held it up to a light to make sure the opening I was creating was symmetrical. It does NOT have to be exactly perfect.

Repeat this process however many times until you have it opened to the size you want. Don't get too crazy and go through the side of the TB. Don't forget to put your gasket back on and open that up with the dremel also. At the end I went through the whole thing with 180 grit sandpaper and looked at it from a bunch of angles to see if everything looked good. In the end you will have a gap around the butterfly that will be noticeable just holding it but not too huge.

I reinstalled everything and fired her up. After warming up, it settled in at 1200rpm. Nothing major there, I had previously unscrewed my IACV some because I like the car to idle around 800. A couple of half turns in and she idled perfectly at 800. Just for kicks I screwed it in all the way and it sat between 550-600rpm. My guess is you could go up to 68mm on a b16 if possible and still have it idle under 1k.

Around town it is noticeably quicker to respond from off throttle to on. The car pulls a little better overall and top end seems stronger. This is nothing to call home about, but it IS noticably faster. My guess is a few whp, but under 15psi of boost I bet it will be worth ~10whp.

All in all I saved myself $250 and now I have a dremel to boot. I am not trying to **** people off, but I think that those of you who have paid to have this done were taken.

I wish I had pics but I don't have a digital. If I handed you my throttle body and one done by gude, rc eng, or someone else, you would not be able to tell the difference except for the butterfly. The car only has a AEM on the stock Si motor right now. I will try to post pics of the throttle body when the motor goes in here in a couple of weeks.

Edit: after seeing so many people doubting in the other post I will definitely try to post pictures. I am very tempted to go out tomorrow and open it up more just to see how big I can get it to still idle at...





[Modified by trbob16a, 2:23 AM 6/22/2002]

b18bvudoo

glad it worked out for ya

dustin

hehe

butt dynos are deceiving

rjardy

Im not trying to be rude here but really, i highley doubt that you are doing with a dremel tool what BBK and other manufacturers are doing with thousands of dollars or R&D and million dollar CNC machines..............just my two cents guy

Rob

dustin

dude give the guy a chance

I'm out in the garage right now welding myself up some new pistons

rjardy

Dustin, you are really welding on some pistons? what are you doing that for? Have you got a tig welder?
your right i should take it easier on the guy, but im a stickler for doing things right but for garage style r&d!!


Rob

dustin

yeah I welded myself a new block last night out of sheet aluminum

rjardy

oh now i get it!!!


Rob

trbob16a

About the butt dyno: I'm not claiming excessive horsepower, but I know that I didn't lose power.

I'd like to hear actual reasons why you all think this was stupid. Not just "oh its a bad idea, oh you're stupid." How about actual technical information as to why.

I'm excited that BBK has put thousands into research and hundreds of import enthusiasts are willing to pay $300 for 2-6whp, about the range I have seen on dyno's. I'm not one of those. My guess is, if a perfectly machined BBK throttle body makes 3.21whp, mine makes 3.01. The key is the size. Its just like a garden hose flowing water. A slightly larger hose with small imperfections will outflow a perfect smaller hose.

When Dan Paramore had my head we talked briefly a few times about head and intake manifold work. He actually told me that it wasn't too difficult but that over the years he had perfected it due to lots of experience. He actually said he thought most of his customers could do the work themselves with the help of a book from the library, a dremel, and a good polishing kit. Combustion chamber work is far more complicated, but still surprisingly simple. Boring out a throttle body is as easy as grinding down your block to make a turbo fit, you just need more patience. The number of technical reasons a 64mm BBK throttle body would outflow mine are few, and certaintly do not justify in my mind the difference in cost for the slight horsepower gain.

I love technical discussions, and I'd like to see this one become one.

I expected these kinds of responses over on clubsi, but on honda-tech I'm kind of disappointed...


[Modified by trbob16a, 4:44 AM 6/22/2002]

9integra2

How does opening up your throttle body, without changing the size of the throttle plate, help? A chain is only as strong as your weakest link and the weak link is still there...the restriction caused by the plate. Now, if you open up the bores around the plate and install a new plate to match, then I can see how it can increase airflow.

Brian*

but the plate is now smaller than the bore of the tb, how is something with less diameter causing more restriction when it essentially lays flat at wide open throttle....

Brian

rjardy

lemme straighten on thing out, about the head work, i believe your refering to a port and polish job of the intake and exhasut tract. You keep calling it the cumbustion chamber, the combustion chamber is the place where the explosion takes place not where the fuel or spent exhaust fumes will enter or exit when the valves are open. Intake runner,tract call them what you will just not combustion chamber. The simple fact is, that you didnt increase the size of the butterfly therefor you didnt increase the mass amount of air that the throttle body is letting in. I believe myself to be correct but like you i allso love a tech conversation, so if you know something i dont please let me know

respectfully, Rob

rjardy

exactly

Rob

earl

Man, I guess pigs can fly..

Brian*

nathan knows what the combustion chamber is..

but i still dont see your point about the throttle plate. its not like he tapers the bore of the tb down to fit the throttle plate. if overall bore is increased, overall flow increases, no?

Brian

rjardy

no because the restricting factor is the throttle plate, and the diameter of the hole,evan if you open it up before the butterfly and after it you still have a point where the air is restricted down to the stock airflow (at the butterfly) you see?

Rob


[Modified by rjardy, 1:33 PM 6/22/2002]

Brian*

no, i dont

Brian

rjardy

well i dont know what else to say to help you understand other than that the air is going to be restricted back down it the un-worked are, that is the area that was not machined down (not really machined but you know) but hell who knows i am certainly no scientist so screw it it may be the best thing in way of DIY...


Rob

H22coupe

He apparently worked the entire area of the throttle body, thus he has a 1 or 2 mm gap around the butterfly when it's closed.

Brian*

correct, he has a gap btw the throttle plate and tb bore

Brian

rjardy

WHAT is this true? And it idles good? Idles at all? wow im baffeld


Rob

rjardy

Holly Molly dude you HAVE to post up some pics of this!!!!!!!
**** ill send you my camera if you dont have one, I wana see


Rob

trbob16a

I know what the combustion chamber is. I was referring to the combustion chamber. I also know that most top tuners do not polish the intake or exhaust tracts because air flows faster over a slightly rough surface. But I assume you knew this. The reasoning for this is slightly unknown, and even NASA has released in white papers that the air will flow faster over a slightly rough surface, but only offers vague answers as to why. Perhaps you can enlighten us.

About the butterfly, I suggest you take apart a throttle body and reconsider your post. Or perhaps you can read Black99Si's posts and figure it out yourself.

Yes, there is a gap around the butterfly. That is why I was originally worried about idle because the air would flow around the butterfly when it was fully shut. My thought was that by closing the IACV down I could just use the air around the butterfly as my idle control. A lot of domestics run a hole in the butterfly for idle control using a similar concept. Well, it worked, my idle remains at a stock level and I have a bigger bore throttle body.


[Modified by trbob16a, 3:04 PM 6/22/2002]

rjardy

hey guy no need for all the scarcasm. Im no ricer boy for one. And as for the "top runners" as you so elequently put it, do you know anything about a step job? in addition to a port and polish? it is designed to atomize the fuel and air mixture into evan smaller particals. i know of many nine second hondas that run a full port and polish with a step. But any ways this is not going to turn into a debate about who knows more and who tears there **** up with a dremel tool. If you like what you have done to your TB than thats good man, its just that i wouldnt do it. If i did anything i would turn it in the lathe and fabricate a new throttle plate. but thats just me. AND YES I UNDERSTOOD ALL THE BIG WORDS YOU USED but lets cut it out before we get pissed at each other....

Rob

Smashback

Do you realize that the IAC valve also compensates for engine load, like AC and lights, so your idle won't hose up when you turn these things on? If you disable the IACV, you are killing this function. Just another .02 for ya.