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Discussion Starter #1 (Edited)
Reduced price! $200 shipped to the contiguous 48 for the TB and manifold.

I modified an oem throttle body from a map based i4 betaII. The idea is to make it act like it had the acceleration pulley installed and flow a little more cfm. In other words, have a larger opening for airfow with a lesser percent open position as indicated by the tps. I think should have better throttle response like a bbtb.

UPDATE:
I still have the throttle body and decided to bore match an Intake manifold to go with it. So now it is being sold as an entire assembly. The set will include modified throttle body, fitted gasket, and p&p intake manifold.



$250.00+shipping

***I have not tested it and have no plans to. I did this set as a practice set to see if I had the tooling to do it and figure out what tooling needed to be bought or made. If they didn’t turn out, no biggie make a lamp or table legs or scrap pile since I made sure to get the parts on a deal. However, these ones turned out really nice (I think). So why not let someone benefit from a good deal on some custom parts? I have another set currently undergoing the same procedures that will be going on my car.
These are oem parts, so they still have oem fitment onto the engine and bracketry. They should just let air in better. Additionally, these are modified parts that are expected to be pushed to their limits and possibly abused (I don’t know your mechanical ability or ability to follow proper installation procedures) and therefore do not come with any warranties or guarantees. Use at your own risk.Race part, intended for off-road use only. ***

Here is a rundown of the features/work done.
1. Knife edged leading edge of the throttle body
2. Throttle shaft streamlined
3. Countersunk throttle plate screws
4. Throttle plate and TB bore smoothed and polished
5. TB exit taper, for venturi effect
6. Intake manifold bored to match the 58mm TB exit and smoothed
7. Gasket matched to TB and manifold
8. Intake runner entries smoothed
9. Entire runner length has been sanded some
10. Last 5-6 inches of each runner has been polished
11. Removed the least amount of material at runner exits to retain oem fitment to unported head.
12. Sand blasted and clear coated exterior for nice appearance.
13. Area for flow is nearly that of a 58mm BBTB

Manifold pics added further down.

Here is a bunch of pics, let me know if you have questions. Black is before and green would be after profile.























 

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Discussion Starter #2
Re: Modified Map based BetaII i4 OEM Throttle Body

Too high of an asking price? Guess I over value my time spent on it, open to offers...Or maybe just not a desired item?

Also, got curious to what it would take to put a little shine into it. So now it looks like this.






Light test:
 

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Re: Modified Map based BetaII i4 OEM Throttle Body

Hmm, while it looks good, the acceleration pulley is a larger diameter pulley for the throttle cable. It allows you to open the TB faster than the stock one with the same force from your foot and that's what accounts for the throttle response, not necessarily the work that you did, IMO.
I would expect that this TB would make the car respond better to the decel/accel conditions and of course flow better since I think you did bore and clean it some. For me, I know that my car doesn't like to decel right away.. I can let off the throttle in gear at about 2500 rpm and it'll be probably 2-3seconds before it decelerates. This TB would help fix that in my case.
 

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Discussion Starter #4
Re: Modified Map based BetaII i4 OEM Throttle Body

Yes, the acceleration pulley causes the throttle plate to move faster and thus the "open area" increases in size quicker. With the taper I machined in immediately after the throttle plate the "open area" increases quicker even though the throttle plate speed has not changed.

My thinking is that the "open area" and the rate at which it increases or decreases is what gives throttle response.
 

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Re: Modified Map based BetaII i4 OEM Throttle Body

i used to do these for the svt contour/cougar guys. nice work, the only thing i would've done to improve flow would be to either hour glass the rear shaft or shave it in half. all of what you did plus what i mentioned gained those cars 5 peak hp and 3 through the whole band. not bad for an essentially free mod.
 

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Discussion Starter #6
Re: Modified Map based BetaII i4 OEM Throttle Body

i used to do these for the svt contour/cougar guys. nice work, the only thing i would've done to improve flow would be to either hour glass the rear shaft or shave it in half. all of what you did plus what i mentioned gained those cars 5 peak hp and 3 through the whole band. not bad for an essentially free mod.
Thanks. I had seen other TB's having that done during my research, I initially opted not to for strength concerns. After having worked with it, its pretty tough. Perhaps I can go back and try yet since there hasn't been any interest yet. If it's around long enough I just might get around to making the adaptor plate needed to try it myself.
 

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Discussion Starter #7
Re: Modified Map based BetaII i4 OEM Throttle Body

So, I decided to try machining some of the thickness from the back half of the shaft since I had a bit of time after work. I only took a third of the thickness off, about 1.5mm. This is the last of the mods for this TB. The plate screws have been loctited and staked, so it's not coming apart again. Now to duplicate these processes on the one I'm going to be using.

I have even more time into it, but I'll let the price stand at my original asking price. I think this would be a good item for someone with a 2003 NA BetaII that has I/H/E.





 

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Re: Modified Map based BetaII i4 OEM Throttle Body

dont know how i missed it, but i also countersunk the screws so the head wasn't visible from the side and the back end was flush with the bar, all minor details but just things i noticed that someone else could possibly do if they bought it. nice work btw. the rear shafts are strong even shaved. i bet i sold well over 40 and never had a problem. tell you what, $100 shipped you might have deal.
 

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Discussion Starter #9
Re: Modified Map based BetaII i4 OEM Throttle Body

Thanks again. Yeah that first pic in my last post I was sizing up what the profile would look like. The screws were then ground flush with the back, I was focused on reassembly and forgot to stop and take a pic. I had actually tried to find some metric flat head screws, but kinda gave up after a couple times just missing fastenal before they closed so I settled for the original oval head screws. They are countersunk into the plate and slightly into the shaft.

I would do 100 shipped to the 48 and would work something out for other locations.

I think maybe for the next one I'll try to get some flat heads yet and work on a setup to make a new plate with a bit more angle.


 

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Re: Modified Map based BetaII i4 OEM Throttle Body

knife edge the lip of the housing as well,helps reduce turbulence.
I think i'll take it
 

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Discussion Starter #11 (Edited)
Re: Modified Map based BetaII i4 OEM Throttle Body

knife edge the lip of the housing as well,helps reduce turbulence.
I think i'll take it
I'll see what I can get done this week. I did machine the leading edge a little already, but didn't take it to a knife edge for not wanting it to be too thin and crack or deform when the hose clamp/T-bolt clamp is tightened. I took a comparison pic...I can try to take it farther, just going to need some time to get it done.
 

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Discussion Starter #12
Re: Modified Map based BetaII i4 OEM Throttle Body

Ok. Machining is done and front lip is knife edged. That took a bit, had to make an adaptor plate to bolt it to so it could be chucked up as the taper behind the throttle plate was no longer going to hold up to any kind of chip load. All that is left to do is re-loctite the screws into place. Any more time on this one and I may have to ask a little more for it.
 

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Discussion Starter #13
Re: Modified Map based BetaII i4 OEM Throttle Body

I was curious and wanted a way to compare to a 58mm bored version of this style TB so I did some quick area calculations to include the subtraction of frontal area for the shaft and TB plate at WOT. Calcs do not make allowance for any part of the screws that would protrude into the air stream.

area for flow 53mm stock TB shaft and plate=2.5630in^2
area for flow 53mm mod TB shaft and plate=3.0505in^2
area for flow 58mm BBTB with stock shaft and plate=3.1568in^2
 

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Discussion Starter #15

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Discussion Starter #16
Re: Modified Map based BetaII i4 OEM Throttle Body

Happened to make it to the fastener store for another project and also picked up some flat head machine screws for the TB.



 

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Discussion Starter #18
Re: Modified Map based BetaII i4 OEM Throttle Body

so what are you at for a price? have you tested it for idle quality?
I guess I can still do 100 shipped, the screws and counter sinking wasn't too bad for time.

I have not tested it and it may be awhile before I am ready and able to. I have a maf betaII and will need to change the manifold before I can bolt it up to my engine. However I'm not quite ready to do that yet.
 

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Discussion Starter #19
Re: Modified Map based BetaII i4 OEM Throttle Body

I was getting the tb I'm actually going to run cleaned and ready to machine and decided what the hey, I'll clean this one too. So I cleaned it up and a light coat of clear to keep it clean and painted the cams black.





 

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Discussion Starter #20
Re: Modified Map based BetaII i4 OEM Throttle Body

Bump, still available.
 
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