Searching around it looks like one can assume that a .005 increase in the pills in the lines or in the nipples off the primary turbo results in approximately a 2 psi drop in boost(?)
I've given up trying to figure out WHY my '93 with supposedly stock original turbos has no pills in the lines, and have decided to concentrate on just drilling the nipples bigger.
I think I will simply use some precision check pins to see how big the stock restriction is, and then go about five thousandths larger, and do the wastegate line only.
My old engine was routinely hitting 12 psi + with the addition of downpipe, intake mod and RB dual catback. Until I can procure my PFS Purple ECU I just want to make sure my new engine will be protected.

 

Get a good boost controller, or at least a basic manual boost controller. Fooling with pill sizes is a pretty medieval approach.

I had boost spikes with just a downpipe and cat-back - that's IT. Boost controller solved that problem. The factory ECU's boost control map is pretty fixed, and it just doesn't allow for changes in VE.

Dale

 

A manual boost controller may not help, unless the nipples are opened up first. I agree with drilling the wastgate line to make it larger. You can always add a pill to the hose at a later date if you need to increase boost, or install a boost controller.

 

I was looking for a similar idea last year. IME, it was much larger than that - I needed to take an .075 holley carb jet and drill out a little more metal with a .063" drill. That brought my boost down from around 12 to 10.5.

If you're worried about overboost, just leave the pills out entirely and you should see 8psi across the board.

Dave

 

You see....THAT was the plan until I discovered that rather than having pills in the WG and PC lines that I COULD just leave out, I have the ones in the nipples off the primary turbo. Which leaves me with two choices to control the boost, either drill them out larger or get a PFS Purple ECU, which I haven't had much luck at yet (trying to find one is hard enough to begin with, trying to find one with the 'commander' unit AND the latest software upgrade has proven impossible so far).

 

Oh, yeah, duh, you said that.

Well you could drill them out completely and use the separate pills.

Dave

 

I wonder if the location of the restriction (nipple on the housing vs. pill in the line) makes any difference. If so, you might need pills that have a different size aperature compared to the nipples for the same boost effect.

Anyhow, after installing a Pettit downpipe on my stock 94, I got boost spikes at 5500 rpm that caused fuel cuts in cold weather. The stock wastegate pill is supposed to be .062, and I replaced it with a Holley carb jet, #122-064, (supplied by Pettit with the downpipe) which is supposed to be .064” in diameter. It made no difference. Then I tried a Holley 067 jet (also supplied by Pettit), which is actually .068" in diameter, and it didn't reduce the boost spike either. Neither jet affected overall boost levels measurably.

Finally, I bought and installed a # 72 Holley jet in place of the 067 jet, and it reduced the post-transition spike by 1 psi and moved it lower in the RPM range from 5500 to 5000 rpms, where the over-boost cut curve ceiling is almost 1 psi higher. But, even going from the stock .062 pill to the .072 jet (a change of .010") did not have a noticable impact on my overall primary or secondary boost levels.

So, your plan to reduce primary boost by 2 psi by increasing the wastegate pill by .005" would not have helped on my car. It took twice that much of an increase just to cut the post-transition spike, and even then it had no effect on overall boost levels.

Recently, I installed a RB catback and it increased the boost spike at 5000 rpm, so I will probably put in a bigger pill than .072 come spring.

 

I don't think the location makes any difference, especially since the line is so short. I would bet that the hole in the nipple is the same as the hole in the corresponding pill.

For what its worth, I swapped my wastegate pill into my prespool line not long ago. My boost pattern was 13-8-13. I wanted a smoother transition. 13-11-13 would have been ideal. By swapping the wastegate pill into the prespool line, I increased transition to 9 psi. A slight improvement, but not as much as I had hoped. The next time I have things apart, I will put in a pill with a slightly larger opening.

I am using a "Home Depot" needle valve controller on the wastegate line, and have been very happy with the way it works.

 

i dont have pills on my wg and precontrol actuators to remove or drill out...and im getting VERY bad primary spikes at low rpms...PFS is being used and it doesnt control the electric solenoids much at all

 

If you have a newer set of twins, the pills are built into the actuators.

Dale

 

Do you have nipple restrictors?

 

its a newr set of twin so they r built into the actuators i guess....how can i possibly run the boost at say 7psi wastegate spring?

 

Which turbos had the restrictors in the actuators?

There were the original pills in the lines, and then the newer sets had them in the nipple tree on the primary compressor housing. I've seen them in the nipple tree on both USDM and 99 RZ twins.

 

Just drill them out pretty wide. With no restriction in the wastgate line, you should have pretty low boost. You can always put a pill in the line later

 

<must resist...mind in gutter...>

 

Oh, you're a kinky bastard.

LOL

Dave

 

mmmm..i like

 

Just go to home depot and buy one of these.

http://www.rx7.org/Robinette/boost_controller.htm

Open it up all the way and slowly turn it in, 1/4 click at a time until you get the boost where you want it. Run your gas tank low and fill it with race fuel before you start on this adventure.

 

i already figured it out...the electric solenoids behind the pres chamber were venting too much air from the actuators which caused MAJOR spiking...removed the electrical connectors and ran from the pressure of the primary to the precontrol and wastegate actuators...7psi 6k prms and creep of only 2.5psi to 8000rpms!

so boost controller will do the job now!