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Restrictor Pill Sizes for Bleed Type Boost Control


mickeyd2005
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For those of you who tune your own cars, I thought it would be nice to have a list of P/Ns for different restrictor pills. Cobb lists these values but do not include P/Ns.

 

Thanks to King of Parts for providing the list of part numbers. It was also important as a double check. For example, I thought that the 2006 and 2007 WRX had different pill sizes.

 

If anyone has any updates/corrections/additions, please let me know and I'll add it to the list. If anyone has a list of pill sizes for non-Subaru cars that will work, let me know too.

 

MIG welding tips also work, but for the low cost of a OEM pill, it's easier just to get an OEM one.

 

For all those noobies out there: Don't change your pill size unless you are getting a custom tune.

 

Values in italic are not confirmed.

761367395_pillsizes.JPG.aa80ec3035184790d8016c238577fe50.JPG

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They are in the Boost Control Section :)

 

Seriously, look for the welders and they are right there; they sell them in packs of 5 or 10 for a few dollars.

:lol::lol:

And if you don't find the size you want, the dremel micro drill bits are right behind you in the tool isle that can be used to drill out a smaller tip to the proper size.

ignore him, he'll go away.
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For $0.93, I'm going to save myself the trouble of drilling it out. :)

 

I tune very aggressively for 2nd, 3rd, and 4th gear. Based upon my logs, I think that a smaller pill will help spool in 2nd gear and it might help spool in 3rd gear a tiny bit more.

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It's not magic. That's just LBGT talking.

 

A smaller pill will help or a 3 port BCS will help. I'm sure you know what I'm talking about.

 

I'm going to try both (smaller pill with 2 port stock BCS and then later 3 port BCS). Just for fun.

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Here's a little tip...if you have the "stutter" on an otherwise stock Legacy GT, swap the factory pill with the pill for the 2004-2006 STi and your stutter will be gone...but you didn't hear that from me...
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  • 2 months later...

I tried tuning my car with a 1.0 mm pill. It works but the WGDC needed to hit target boost is too low for my taste (40 to 50%).

 

For anyone tuning their own car who wants an aggressive stage 2 tune, I recommend a 1.1 to 1.2 mm pill for VF40 2005-2006 cars.

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hey thanks for the chart. I just ordered 22326KA120 which according to cobb's chart is 0.028" but the link's chart shows that pn as a 0.0472. I don't know which one's right so I ordered both, they're only $3 each. ;)

 

 

For those of you who tune your own cars, I thought it would be nice to have a list of P/Ns for different restrictor pills. Cobb lists these values but do not include P/Ns.

 

Thanks to King of Parts for providing the list of part numbers. It was also important as a double check. For example, I thought that the 2006 and 2007 WRX had different pill sizes.

 

If anyone has any updates/corrections/additions, please let me know and I'll add it to the list. If anyone has a list of pill sizes for non-Subaru cars that will work, let me know too.

 

MIG welding tips also work, but for the low cost of a OEM pill, it's easier just to get an OEM one.

 

For all those noobies out there: Don't change your pill size unless you are getting a custom tune.

 

Values in italic are not confirmed.

Spec_b

 

Cobb Stage II @ 18.2psi, K&N Typhoon, Shifter Bushings, waiting to install Perrin TMIC, Hawk Street Pads

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but a smaller pill hits higher boost targets, so why'd you go larger?

 

I tried tuning my car with a 1.0 mm pill. It works but the WGDC needed to hit target boost is too low for my taste (40 to 50%).

 

For anyone tuning their own car who wants an aggressive stage 2 tune, I recommend a 1.1 to 1.2 mm pill for VF40 2005-2006 cars.

Spec_b

 

Cobb Stage II @ 18.2psi, K&N Typhoon, Shifter Bushings, waiting to install Perrin TMIC, Hawk Street Pads

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the pills are so cheap I don't know if it's worth drilling them, is it? Unless you're in a time crunch...

Spec_b

 

Cobb Stage II @ 18.2psi, K&N Typhoon, Shifter Bushings, waiting to install Perrin TMIC, Hawk Street Pads

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Spec_b, I strongly urge you not to swap out your restrictor pill. This is only for tuners. You need to be able to dial in your WGDC if you make a change to the restrictor pill.

 

hey thanks for the chart. I just ordered 22326KA120 which according to cobb's chart is 0.028" but the link's chart shows that pn as a 0.0472. I don't know which one's right so I ordered both, they're only $3 each. ;)

 

What do you mean Cobb's chart. The 22326KA120 is listed in the catalog as a 1.2 mm pill. This is a confirmed size. Notice that the number is not italic. I have it and I can tell you that it is NOT 0.028.

 

but a smaller pill hits higher boost targets, so why'd you go larger?

 

I didn't go larger. The stock 2005-2006 pill is about 1.25 mm. I changed it to 1.0 mm. That means I went to a smaller size. The 2007+ has a different size.

 

The reason to change the pill is to change the WGDC necessary to hit boost target. My target boost hasn't changed at all. I dial in a different WGDC with the different pill size.

 

The reason I went to a smaller pill was that under some situations with all the compensations etc... etc..., I was bumping into the max WGDC. I wanted to lower my WGDC to hit target boost.

 

Is the idea simply to bring boost on earlier in the rpms (i.e. - increasing the boost AUC without increasing peak boost)?

 

Yes, for second gear, I want to hold a much higher WGDC than necessary to hit target boost during spool up. When it hits target boost, the WGDC drops to the necessary WGDC. I needed to lower the WGDC at target boost in order to do this.

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I went through all this last year, for the same reasons, and got the same results. It was a learning experience.

 

However, after installing my AVO FP, DW 740s, and Prodrive BCS, while still on the VF40, I found the Prodrive was the answer to boost control I had been looking for all the time. All the pills and drilling and fiddling with the WGDC tables was fine for learning the limits of the stock system. But in the end, even with the optimum pill for my setup, the stock system was still marginal and I finally just accepted it knowing I was moving on.

 

Once past the stock or mild Stage2 VF40 boost levels and requirements, the Prodrive BCS allows one to actually tune boost instead of working around limitations imposed by the bleed type BCS.

 

IMO, if one tunes their car, even the stock VF40, a Prodrive BCS or one like it should be regarded as a necessary mod. On a larger turbo it is mandatory.

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I went through all this last year, for the same reasons, and got the same results. It was a learning experience.

 

However, after installing my AVO FP, DW 740s, and Prodrive BCS, while still on the VF40, I found the Prodrive was the answer to boost control I had been looking for all the time. All the pills and drilling and fiddling with the WGDC tables was fine for learning the limits of the stock system. But in the end, even with the optimum pill for my setup, the stock system was still marginal and I finally just accepted it knowing I was moving on.

 

Once past the stock or mild Stage2 VF40 boost levels and requirements, the Prodrive BCS allows one to actually tune boost instead of working around limitations imposed by the bleed type BCS.

 

IMO, if one tunes their car, even the stock VF40, a Prodrive BCS or one like it should be regarded as a necessary mod. On a larger turbo it is mandatory.

 

Are you using a restrictor pill with your pro-drive and 380?

 

Here is the thread showing what happens with my pro-drive and 380 with and w/o a restrictor pill.

 

Pro-drive EBCS - w or w/o pill?

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Are you using a restrictor pill with your pro-drive and 380?

 

Here is the thread showing what happens with my pro-drive and 380 with and w/o a restrictor pill.

 

Pro-drive EBCS - w or w/o pill?

 

Not yet, although I intend to play with a pill soon after reading that thread.

 

I have a few days left before I can once again drop the hammer. I got my IPT 5EAT/TC back in Wednesday and have 200EASYmi on it. All is great and I should be able to resume tuning my AVO380 that was truncated over a month ago.

 

Nevertheless, there is no question about the Prodrive BCS although exactly the BEST setup with it may not as yet be known given your findings.

 

Im anxious to explore the results of a pill although it flies in the face of my thinking when I devised my BCS installation. I purposfully chose a larger hose from the compressor to the BCS so that there would be minimum supply resistance, and a smaller hose from the BCS to the WGA to minimize compression losses. Adding a pill INCREASES supply resistance. However, since my present BCS WGDC table's 'shape' is roughly similar to my smaller-pill WGDC table on the VF40, etc., I want to investigate further. I had found that while the smaller pill gave me the WGDC headroom I wanted on the VF40 it introduced some boost control problems I didn't like as well. That experimentation ended when I got the 380.

 

This should be interesting. Have you done any further testing? If so, what orifice did you use and what were the results.

 

One more thread that will be lost because We Don't Have a Tuning Forum :spin:. ........................

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