Yeah, call me weird because I don't want to make a manual boost controller, but I'm currently running almost a 12-8-12 on the stock ECU since I added an RB dual cat-back. The low transition dip, naturally, is unrelated and should be fixed when I install new turbo control solenoids.

IIRC, the stock precontrol is .059 and the stock wastegate is .062.

Since Holley carb jets are $5/ea, can anyone suggest sizes to bring this back to a 10-8-10?

Dave

 

Dave, I thought you would know all this

As you know, many people have posted that the PC (pre-transition boost control) is extremely difficult to control with either different pill size or a needle-valve controller.

The WG can be controlled in this way for lower after-transition boost. However, I went with the dual ball-spring controllers (which work beautifully), and I'd just be guessing on how much larger the orifice should be.

 

I've heard about the PC being difficult, so I was expecting every .001 to be significant. I think those folks were talking about trouble drilling the stock pills, and even with a full set of drills the control isn't that fine. Maybe I can buy a bunch of Holleys and return the ones I didn't use. Either way, it would be good to have a guess at the appropriate sizes.

I may try the dual ball-spring setup, I guess, but I'm stubborn in that I like seeing the stock turbo system run the way it was designed :o). I'm an admitted glutton for punishment.

Dave

 

Dave, check here -

http://www.fd3s.net/turbos.html#PIL

You'll have to scroll down a bit through the pros/cons discussions of pill use. This is some old-school info that people don't mess with much any more .

Dale

 

Wire size drills do not come in .001 steps so drill and try is needed . I make pills from alum . rod and drill the size wanted . When my car was seq the transistion was so slight and fast that the boost gage only moved slightly and so fast you could not read the stroke . When the second turbo came on line the pull was very good with no hesitation at transistion . The drills in you range run .059=#53 ..063=#52 .067=#51 .070=#50 .073 =49 .076 =#49 .078 = #48 .081 = # 47 . You might try for a boost pattern of 10-9.5-10 . You will be spinning you tires in second gear when the second turbo comes on with WOT .

 

Dave,

IMO, the reason the PC is tougher to control with pill size is that you are still relying on the ECU to duty-control the balance between the pill orifice, and the effective duty-control orifice, and, thus, the motion of the PC actuator. This is still open-loop controlled, and so the direct control of boost is not possible. All you can do is bias the boost higher or lower, but, since the ECU duty control can't change its timing (which is critical to pre-spool AND to pre-transition boost level), all you can do is move the boost curve up or down. You really can't level it off at a desired boost psi.

 

PM moconnor

He has done some testing, and should be able to give a good recommendation for the WG pill. Do not change the pre spool pill. It is working fine.

 

They both work the same way, as far as i can tell: the duty control bleeds pressurized air, but in a cycle so fast that line pressure only drops a fraction of a psi at a time - the net effect on the pressure in the pc/wg actuator is a net pressure. It's just that the precontrol affects both primary peak pressure as well as secondary prespool - so tuning it is a balancing act I must be careful with. I expect that if I move up in size too much I'll get a nasty spike on transition and pop my motor. Fortunately I have Sunoco 94 octane, and I'll wait for a nice hot day to do my tuning.

Seeing as I'm only trying to decrease boost by 1-2psi, I think that a pill tweak should do just fine.

Since I see 12psi on the primary before transition, that I need to adjust both. Just for fun, I will tee a pressure gauge between the actuator and solenoid to see if I can observe the pills adjusting net pressure.

Dale, I always appreciate the link to the 'bible', naturally that was the background reading that led me to this. However, I did re-read it now, and I noticed Brad Barber suggested that 1psi of boost was a change of nos jets, and his sizes were .002 apart. So far that's the best answer to my original question.

The local speed shop has even # jets in stock (60 and up, $7/pair) and they'll let me return them since I'm using them for air bleed, not fuel. So I'll get a few pairs and see where it leads me.

 

Dave, that was my intended point - that although they work in the same manner, the PC is harder to control to get the correct compromise between boost level and spike. I guess I didn't say it very clearly.

 

Since the PC is harder to control, and it is already giving you the desired boost at transition, I strongly suggest that you leave it alone. All you need to do is change the WG pill to a larger size.

 

Strangely enough, I could not find any information about pill size and boost either so I did some experimentation. My stock car was boosting to 12.7 p.s.i. or so I ran through the following iteration of pills in my wastegate line. (Pills from the Holley box - about $50 at Summit). Slightly complicated by the fact that I added a K&N drop in in the middle of experimentation, but I got the answer I wanted in the end.

stock pill, .064": boost 12.7 p.s.i.
pill #69, .070": boost 12 p.s.i.
Installed K&N drop in.
pill #75, .084": boost 11 p.s.i.

By this time I had more or less figured out that a 0.008" increase in pill size would correspond to a reduction of 1 p.s.i. in boost. I was about to add a RE Amemiya open intake and assumed that it would add 1 p.s.i. to my maximum boost so I figured a .1" pill would bring my boost to 10 p.s.i. (.084" + .008" x 2). The nearest Holley size is .099", which is pill #84 so I tried that. With the intake installed, I nailed the maximum boost at 10 p.s.i.

So on my car at least, and increase in pill size of 0.008" corresponds to about 1 p.s.i. reduction in boost. I have no idea if this would be the same on other cars but I would bet that it would be close. (Since my car was completely stock and boosting to 12.7 p.s.i I am wondering if it may not be completely typical.)

I am going to be adding a downpipe, y-pipe, and exhaust in the next few weeks and assume that these will add ~3 p.s.i. to my maximum boost so I will add .024" (0.008" x 3) to my current pill size to further verify that my figures are correct. At that point I will have reached the maximum pill size in my Holley box.

Perhaps I am missing something, but I am not seeing the need for a boost controller given how well the pills work for me. Obviously, an MBC would be an equally cheap option, but I do not like the idea of an uncalibrated twist dial sitting in my engine bay.

 

Moconnor, thanks very much. It appears to be very much a YMMV situation. I'm running very similar mods: K&N in an uncut stock airbox, downpipe, Efini y-pipe, and RB dual cat-back.

You mention your boost level as one number - I assume that is in parallel mode (4500rpm+). What did your boost level look like before transition in those runs?

Dave

 

The recommended interval of .002" makes sense from a safety standpoint when you're trying to increase boost by pill tuning, but if you want to cut your boost by 2 lbs or so to compensate for flow increases, increase the WG pill orifice by .005".

 

I was quoting maximum boost in parallel mode. I didn't pay much attention to the transition boost - I think it was 8 p.s.i. for everything. I will be doing some testing this weekend before installing the downpipe and will verify this.

So you got a 2 p.s.i. increase with just the RB exhaust?

BTW, the discussion at the link quoted earlier makes the very ambiguous assertion that "Adjustments are made in .002" to .003" increments". Nowhere does it say that these increments correspond to 1 p.s.i. as people are assuming (and that I assumed initially). Also, the disadvantages of using pills to control boost listed in the discussion on this page refer only to using pills to increase boost and do not apply when they are being used to decrease boost.

 

Yes. I had y-pipe, stock cat, Pettit dp, stock ECU+fuel system, stock IC, and K&N in a stock airbox this fall. It was running 10-6-10, (low transition I'm guessing is due to a tired turbo control solenoid).

I installed a RB dual this winter, and noticed I was getting 12-7ish-12. I honestly don't remember the transition b/c I was too shocked at seeing the 12s. Even when it hit 80deg this spring, I tested it and still 12psi peak. So it wasn't just a cool weather thing. I may wait until some real hot weather and try to get just a little under 10psi max to restore that margin.

Because the wastegate is essentially inactive until 4500rpm, it's safe to say it will operate the same until transition. So I expect that adjustment of the wg will give 12-8-10.

The rough number .002"/psi is according to Brad Barber's post on that page, which says
"I made a set of tuning pills from NOS jets in the following sizes: .061", .059", .057", .055". I only change the wastegate line and get about 1psi boost per step LOWER in orifice size. " You're right - it's not necessarily true that his experience in increasing boost will match what happens when reducing boost.

I'm hoping a tweak of the pc will give more of a 10-9.5-10, or a 11-9-10 pattern. The speed shop has #60 and #62 jets in stock (.060 and .061") - I'll start with the #60.

Dave

 

Perhaps I am misunderstanding you, but that was definitely not my experience. Changing the wastegate pill size had the exact same effect on the primary as the secondary in terms of maximum boost. If I had 11-8-11 before installing a 0.008" larger pill, I had 10-8-10 after it.

 

That should be the case with any boost controller. If it were not, we would need separate controllers for both the primary and secondary boost.

 

Yup.

 

My understanding is that the stock ECU only duty-controls the wastegate after 4500rpm, and the precontrol duty controls up to 4500rpm. I don't see how what is in the wastegate line would affect primary function.

I'm pretty sure that I tested that behavior once by teeing into the wastegate and precontrol output lines. I'll do it again since my memory is fuzzy.

Are you running a PFC? If so, maybe the PFC controls them differently?

 

I have an M2 stage 3 ECU.
I believe that moconnor has a stock ECU.

The pill (or other boost controller) in the wastegate line definitely controls primary and secondary boost, and should keep them at the same level.

 

I'll take ya'lls word for it

But either way I was planning to get the wastegate set first - so we'll see pretty quickly.

Dave

 

I think you will have good success by increasing the size of the wastegate pill. Please let us know the results ................ and don't mess with the prespool pill

 

You might also look into an electronic solution. I've been meaning to test this myself, and am mostly curious as to how it effects the transition.


http://www.mantissaconsulting.com/et...ion_switch.htm
^^ I believe this is Gene Felber's site?


-s-


[edit: double-checked the site, and it says it's disabling the wastegate solenoid completely, so you'll see less than 10 lbs. Oops!]

 

Adam, I re-read the literature and finally it sank in: 95% wastegate duty doesn't mean it's inactive - it appears to regulate primary boost to 10psi. The problem is I still don't understand WHY, but that's my issue to deal with. The FSM and Service Highlights Manual don't say this conclusively one way or the other.

According to Vanditmars, the prespool adjusts flow to the primary according to throttle level, but at WOT the wastegate will also open as required to keep 10psi at the peak. I recall running a test on my car where I tee'd into the line between the wastegate solenoid and actuator, and I thought I saw 0psi all the way through 4500rpm. However, I will run the test again when I get my car back on the road (injector cleaning, solenoid and turbo replacement, but no time to work on it ).


Dave