Welcome to the North American Subaru Impreza Owners Club Wednesday April 16, 2014
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Here you can view your subscribed threads, work with private messages and edit your profile and preferences Home Registration is free! Visit the NASIOC Store NASIOC Rules Search Find other members Frequently Asked Questions Calendar Archive NASIOC Upgrade Garage Logout
Go Back   NASIOC > NASIOC General > Newbies & FAQs

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.
* Registered users of the site do not see these ads.
Reply
 
Thread Tools Display Modes
Old 01-29-2007, 09:30 PM   #1
Unabomber
Big Ron
Moderator
 
Member#: 18062
Join Date: Apr 2002
Chapter/Region: MAIC
Location: I can save you a ton of cash
Vehicle:
on car parts so PM
me b4 j00 buy

Exclamation Boost Control FAQ: Read if you are thinking of buying one!

Boost Control FAQ

The genesis behind this FAQ is mainly due to the rampant “monkey see-monkey do” approach due to the fairly recent introduction of aftermarket boost control solenoids. While they do play a role in the overall boost control world, the press they have received has gotten way out of hand, so this FAQ will discuss your boost control options.




What is the function of a boost control device? To control boost. While this seems to be an easy definition the reason behind boost control is lost to many people. A boost controller of any type is designed to limit boost. Yes, you read that right….limit boost. Without a boost controller of any kind, your turbo would spin up until it explodes and produces upwards of probably 50PSI. This seems to be the most unknown fact of boost controllers, that they limit boost. Now that you have your mind wrapped around the proper function of a boost control device, you can explore the rest of the story.

Do I need to consult with my tuner about boost control options? Yes. Items in your car that can be tuner specific: manual boost controllers, electronic boost controllers, upgraded wastegates, restrictor pills, wastegate helper springs, external wastegates (type/size/brand), spark plug types/brands/gaps, and injector types/brands/sizes. ALWAYS take your tuner's advice on these matters no matter what the internet tells you!

What controls boost on my stock turbocharged car? The two main components are the boost control solenoid located on the passenger side strut tower and the internal wastegate on the turbo itself.

What is an internal wastegate? A spring/diaphragm based mechanism which controls the movement of the wastegate valve. A turbo wastegate is normally closed, forced shut by a compressed spring inside the actuator canister. As pressure is applied to the nipple of the canister, the wastegate shaft moves away from the actuator, swinging open the wastegate valve. When the wastegate opens, this allows air to bypass the turbine inside the turbine housing. Less flow = slower spinning of the turbo, so you can grasp the concept of how this controls boost.

Can I adjust my internal wastegate? Pre-loading the wastegate actuator arm, also known as adjustment of the wastegate actuator rod (if the rod length is not fixed and adjustments can be made) will allow proper calibration and some additional tuning. All IHI turbochargers have a fixed wastegate actuator rod that cannot be adjusted, while all MHI turbochargers have an adjustable wastegate actuator rod. If the rod coming out of the wastegate actuator is shortened, it will pre-load the spring inside the wastegate actuator increasing the pressure level at which the actuator will allow the wastegate valve to open and the total boost pressure that the turbo can generate will increase (as long as the turbo is still within its efficiency range). This pre-load will also limit how far the wastegate valve can open. Pre-loading (shortening) the wastegate actuator rod too much can potentially create a mechanical boost creep issue that cannot be tuned out. If the wastegate actuator rod is lengthened, the actuator will decrease the load on the spring and decrease the pressure level at which the actuator will open and the total boost pressure the turbo can generate will decrease. If the wastegate actuator rod does not put enough pre-load on the wastegate valve, then you could see boost fluctuations of + or – 2psi even when the wastegate solenoid duty cycles are constant. Help to adjust it can be found HERE.

What about a helper spring? A helper spring is a clever, cheap, easy, and removable way of wastegate adjustment as well. Basically its a small spring that stretches from the wastegate door arm to the wastegate itself. This puts more tension on the wastegate flapper door so the actuator has to work harder to open the door. Installation and more helper spring advice can be found HERE.

What is an external wastegate? External wastegates are used for two purposes:
a. To increase the flow when using high PSI
b. Required for larger turbos that have no internal wastegate

Using an external wastegate on an internally gated model will show benefits as it effectively reduces choking of the turbo. Choking is where the flow gets backed up due to the more restrictive internal wastegate. By replacing the internal with an external, this generally allows one to run more boost safely. While every turbo can benefit from an external unit, it really shines on larger turbos.

How can I run an external wastegate? You will need some custom fabrication and parts. Generally speaking you will need an uppipe fitted with a flange to run an external wastegate. Then you need a wastegate suited to your application. You also need to consider plumbing of the wastegate gasses.

External wastegate tuning tips can be found HERE

Where do I plumb my wastegate? Plumbing is the routing of wastegate gases. You can “vent to atmosphere” which is where the wastegate opens and air is directed straight to the outside air. Downsides to this are the need to route the venting so it won’t heat up anything in the engine bay and the increased noise. If noise is a factor, you might consider having a small motorcycle or 2 stroke muffler welded onto the end of your vent pipe, room permitting. The other, quieter option, is to plumb the external unit back into your downpipe. The key to successfully doing so is to ensure it is plumbed far away from the turbo (at least 18” past the downpipe to turbo flange, and hopefully beyond any catalytic converters in your system) and ensure the external piping is welded to the downpipe at a narrow angle to encourage aft flow vs. say a 90 degree entry that will encourage more back pressure into the exhaust. The downside to a “plumbed back” wastegate is even with a perfectly designed system, it is not as efficient as a vent to atmosphere system.

Which manufacturer of external wastegates is best? This topic is highly debated, but the general consensus is TiAL is the king of the hill.

Are there different sizes of external wastegates? Yes. 38 mm and 44 mm are the two most talked about and utilized sizes.

Which size is right for me? That is a question for your turbo vendor and tuner as sometimes their advice counters the external wastegate sizing theory. The theory is that a larger wastegate (44 mm) should be utilized on turbos using low boost vs. turbos that are running high boost which should run a smaller wastegate (38 mm). Where did this theory come from? Remember…a wastegate limits boost. If you want to run more boost, you don’t have to limit it as much. Running less boost means you have to limit it more. Think this premise through to get a good mental picture of it as this concept is terribly misunderstood.

Some also erroneously put credibility on the TiAL’s 44 mm model due to its superior V-Band clamp vs. the 38 mm models flat flange design as the decision maker. While the V-Band is an overall better design, the problem with TiAL’s 38 mm model is that it apparently ships with what many consider being a sub-standard gasket. Replacing this gasket to start with or after leaks occur generally solves the issue. Funny how a $3 gasket will convince some to spend $200 more on a 44 mm unit as well as encourage others to do so.

Useful thread that discusses TiAL pros/cons
* Registered users of the site do not see these ads.

Last edited by Unabomber; 12-14-2008 at 10:22 PM.
Unabomber is offline   Reply With Quote
Old 01-29-2007, 09:31 PM   #2
Unabomber
Big Ron
Moderator
 
Member#: 18062
Join Date: Apr 2002
Chapter/Region: MAIC
Location: I can save you a ton of cash
Vehicle:
on car parts so PM
me b4 j00 buy

Default

What about external or internal wastegate springs? Think back to the wastegate sizing question above. Once again, you have a theory that needs to be buttressed by the opinions of your turbo vendor and tuner. The theory is that if you want to run say 15PSI on your turbo, you want to run a spring that is 50% of that value or as close as you can get it for proper boost control.

How do I swap out wastegate springs External wastegates are serviceable by the end user, so refer to your external wastegate documentation for details as well as ordering information for new size springs. Generally speaking, most internal wastegates need to have the whole assembly swapped out as removing spring, finding the new correct spring, and replacing the spring is not able to be performed. There are a few sources of upgraded internal wastegate solenoids as Deadbolt, AVO, and others sell them.

What is a restrictor pill? This component limits the amount of pressurized air flowing from the turbo compressor housing. The restrictor pill restricts the air flow so the wastegate solenoid valve and wastegate actuator are not overdriven, which would force the wastegate valve to open prematurely.

Can I tune with this restrictor pill? A smaller diameter hole in the center of the brass restrictor pill will have a higher tendency to create boost spike in the system and require less wastegate duty cycle to run higher boost. The larger the diameter hole in the center of the restrictor pill, the less chance the boost control system will boost spike and greater wastegate duty cycle will need to run in order to produce higher boost. If you have installed a new turbocharger and you are using the stock boost control system to tune boost, please verify that the vacuum line coming off the turbo compressor housing (prior to the T-fitting) contains a restrictor pill with a hole machined in the center of the pill.

The stock boost control system most commonly uses a restrictor pill with a center hole size of 0.040”-0.048” +/- 0.001”

For larger-than-stock turbochargers or turbochargers with a stronger mechanical spring in the wastegate actuator you will need to use a restrictor with a larger center hole, something along 0.050”-0.055” +/- 0.001”

For similar-to-stock-sized turbochargers with a weaker mechanical spring in the wastegate actuator you will need to use a restrictor with a smaller center hole, something along 0.030”-0.040” +/- 0.001”. Be very careful when using a restrictor with a center hole of this size, there is a higher tendency for the system to boost spike and you will need less wastegate duty cycle to run higher boost.

Where do I get new restrictor pills? You can modify your OEM one via obtaining special small drill bits and a special small hand drill to drill it out. One can also obtain suitable sized nitrous jets and then file down the outside housing to fit inside the vacuum line. As well, many tuners have a collection of various sized restrictor pills.

What are aftermarket boost control solenoids? Perrin and Prodrive make purpose built Subaru unit, though the GM unit may be retrofitted as well. These units mimic the purpose and function of the OEM boost control solenoid.

What makes them so special? Nothing really. They serve the exact same purpose as the factory unit. Since they are slightly different in actuation values, they do require a custom tune. So what has appeared to happen is people with an off the shelf tune or no tune have purchased these. Then they get tuned with them. Then they attribute much of their gains, not on tuning, but on the boost control solenoid. While they can help, this is something to discuss with your tuner as one option for better boost control as 95% of the good/bad of this modification lies in the tuner’s skill vs. the boost control solenoid. The biggest difference in aftermarket units is that they are intercept style vs the OEM bleed style boost control. Intercept style allows for better boost response when compared to the OEM bleed style.

So how does a boost control solenoid work? It is opened via a pulsed duty cycle based on inputs from the ECU. While you are building boost, the BCS is not operating. This allows the wastegate to remain closed to built boost quickly. As target boost approaches, it ramps up quickly to control/limit the boost. At this point is where the BCS is working the hardest.

More BCS interaction help : Article 1, Article 2

Why is tuning needed on aftermarket ones? Port sizing and duty cycles can change with them which can lead to wild results. Even tiny changes in the turbo/wastegate associated hose length and diameter can cause drastic changes. Do not use a GM, Perrin, or Prodrive boost control solenoid until you are ready to be tuned.

What about a manual boost controller or electronic boost controller? With proper use and tuning they are other possibilities for controlling boost. These can be utilized as standalones for 02/03 WRX or STI models with judicious use and the proper knowledge. They may also be effective in conjunction with most engine management systems with proper tuning. These need to definately be discussed with your tuner prior to installation though.

Is there a simple, general guide to all these items? There is now:

Small boost change that require no tuning:

Pressure check your system for leaks. How to do so can be found HERE.

Small boost change that may require tuning:

Adjustment of internal wastegate. There are no hard and fast rules, but if you are only adjusting the wastegate for 1 PSI or so, you can probably safely get away with this. Anything over that and you want to strongly consider a tune.
Helper spring.

Big boost changes that require tuning:

Aftermarket boost control solenoids
Manual/electronic boost controllers
Upgraded internal wastegate actuator
Going to external wastegate
Changing springs inside the external wastegate
Restrictor pill swaps

So what do I need to assist controlling my boost? More than likely, nothing. Tuning is what ultimately controls your boost using the wastegate and BCS. If tuning doesn’t cure your ills, listen to your tuner’s advice as to what steps to proceed with. Do not surprise your tuner on the day of the tune with an aftermarket boost control solenoid or other fix because Tim in Kansas had “great results” with his. Tuning the boost control system is the hardest and most time consuming thing a tuner can do. You might have the latest “fad” boost control solution on the market, but will it be worth it when you put on a $175 wastegate actuator and it takes you tuner 1 extra hour of his and dyno time to the tune of $300? Consider he might be able to do the same thing in no extra time with a 10 minute swap out of a $2 restrictor pill.

And remember...if you are currently have boost control issues, you should fix them first rather than trying one of the methods described above to band aid fix the issue. For example, if you are only seeing 7 PSI, adding a spring to your wastegate to bring it back up to the normal 14.7 PSI is not the correct way to fix the problem. Troubeshoot and fix the main issue vs. performing a work around.

Where do I buy aftermarket boost control devices? Many NASIOC Vendors offer them.

How hard is it to install aftermarket boost control devices? Most are fairly simple to install and many come with directions that should be referred to and followed.

GM install instructions are HERE, though they would help with Perrin and Prodrive as well.
Another useful BCS install thread can be found via this link.

Editors Note

My thanks to Christian of www.cobbtuning.com for his assistance that provided a lot of the information contained within this FAQ. Another wonderfully informative boost control read that is authored by him can be found HERE.

This post was created because I wasn't able to find a good boost control FAQ. I came up with the text based on LOTS of searching here. Upon reading this you should have an idea of whether a boost control solution best suits your needs. The type/manufacturer is up to you.

If you find an error in this FAQ, please PM me with factual details and I will update this post. Responses such as, "I have XXX's BCS and it's great!" or "XXX's wastegate broke after 1 month" are not appreciated here, that is what the Car Parts Review Forum is for.

Last edited by Unabomber; 08-30-2008 at 09:07 AM.
Unabomber is offline   Reply With Quote
Old 01-29-2007, 09:31 PM   #3
Unabomber
Big Ron
Moderator
 
Member#: 18062
Join Date: Apr 2002
Chapter/Region: MAIC
Location: I can save you a ton of cash
Vehicle:
on car parts so PM
me b4 j00 buy

Default

C A U T I O N, this is not finished yet, I just wanted to get it online and off of 3 different computers in 9 formats to edit later. It's like 90% there though.
Unabomber is offline   Reply With Quote
Old 01-29-2007, 09:36 PM   #4
modaddict
Scooby Guru
 
Member#: 95840
Join Date: Sep 2005
Chapter/Region: NWIC
Location: Pasco, WA
Vehicle:
sold to a good bud
awaiting next car

Default

first
modaddict is offline   Reply With Quote
Old 01-29-2007, 10:16 PM   #5
nxttruck2002
Scooby Specialist
 
Member#: 90879
Join Date: Jul 2005
Chapter/Region: TXIC
Location: Houston, Texas
Default

dayum
nxttruck2002 is offline   Reply With Quote
Old 01-29-2007, 10:42 PM   #6
turbo_h4
Scooby Newbie
 
Member#: 112433
Join Date: Apr 2006
Chapter/Region: E. Canada
Location: Toronto
Vehicle:
06 WRX.stage2
OBP

Default

wow, i was just gonna buy one too!
turbo_h4 is offline   Reply With Quote
Old 01-29-2007, 10:58 PM   #7
STirocket
Scooby Specialist
 
Member#: 84006
Join Date: Mar 2005
Chapter/Region: NWIC
Location: Auburn, WA
Vehicle:
2005 Impreza WRX STi
WRB with Goldies

Default

typically excellent FAQ Ron... Tks...
STirocket is offline   Reply With Quote
Old 01-30-2007, 04:06 AM   #8
BugeyedMonster
Scooby Newbie
 
Member#: 137689
Join Date: Jan 2007
Chapter/Region: SCIC
Location: Long Beach, CA
Vehicle:
2002 WRX Sedan
MBP

Default

And una does it again. I was just thinking earlier this afternoon about wastegates in general and how very little i know about them. The man must be psychic. We know your game Ron, you can stop hiding it now
BugeyedMonster is offline   Reply With Quote
Old 01-30-2007, 11:11 PM   #9
RiftsWRX
Scooby Guru
 
Member#: 6124
Join Date: Apr 2001
Chapter/Region: MWSOC
Location: Glendale Hts, IL, USA
Vehicle:
2000 NFR AP1 S2000
'07 Honda FIT sport (5MT)

Default

Couple of things Ron.

1: What controls boost on my stock turbocharged car? - I'd also mention just how important the restrictor is while using the factory narrow range solenoid. Without it, you simply will not be able to bleed enough signal to do any more then a few PSI worth of increase.

2: What about a helper spring? - I STRONGLY encourage a sense of caution here. TOO many times have I had blown motors come in from people who read about how using helper springs are OK, and they've been running around with 2, 3, 4, hell even 5 helper springs on their VF39 on their STI's, or VF30's on 2.0's. I just had this conversation in factory 2.0 last night.

There's a big difference between being able to help a weak actuator spring, and forcing a door closed on a turbo with a EP/BP that's through the roof. Let's be honest... most people have no clue what I'm talking about, or the ramifications of what they're forcing the car to do.

3: Which size is right for me? - I fully agree, but also think that for full disclosure you should add that the major benefit of a 44MM really lies in the servicability of the unit. V-bands really are the cats ass when you have inches to work with, and nothing more then a token amount of tools at your place.

4: What makes them so special? - Technically, there are two things you need to inform people of. The differences between boost control strategies (which you don't mention IIRC); intercept and bleed style boost control, and how wide range solenoids are capable of an intercept style of control, where the factory, or another narrow range unit can't. Intercept style, in and of itself can dramatically improve boost response, even over the same solenoid being run in bleed mode.

5: What about a manual boost controller or electronic boost controller? - Any open loop boost controller WILL NOT DELIVER CONSISTENT PERFORMANCE AND IS SUBJECT TO ENGINE LOAD IN A PROFOUND WAY!!!!! I have to beat this point into my customers heads sometimes. Simply put... set a MBC to X PSI in 3rd, it'll be X+something in 4th and X+something more in 5th.... While doing it in 5th results in X-something in 4th and X-why bother in 3rd.

A closed loop electronic boost control is the proper answer, but people need to really understand that the term MANUAL boost controller is not there to look pretty. It takes discipline, a discriminating user, and common sense to use right.

Other then those points, looks great man!

Jorge (RiftsWRX)
www.ProjectWRX.com
RiftsWRX is offline   Reply With Quote
Old 01-30-2007, 11:14 PM   #10
nhluhr
John Wayne Toilet Paper
Moderator
 
Member#: 7327
Join Date: Jun 2001
Chapter/Region: NWIC
Location: Seattle, WA
Vehicle:
2008 Mazdaspeed3
2006 Wrangler Sport

Default

^^ I agree with Jorge's points fully.
nhluhr is offline   Reply With Quote
Old 01-31-2007, 07:50 AM   #11
Unabomber
Big Ron
Moderator
 
Member#: 18062
Join Date: Apr 2002
Chapter/Region: MAIC
Location: I can save you a ton of cash
Vehicle:
on car parts so PM
me b4 j00 buy

Default

1. Yeah, I keep forgetting how people love to swap turbos and remove the pill or people love to swap lines for no reason, I'll add your caution.

2. I agree with your point, but 5 helper springs?? I'm sorry, but if I saw someone bring their car into my shop with 5 springs, I'd kick them in the stones and send them on their way. Springs have a purpose, but anything over one is called hillbilly engineering.

3. Noted. I didn't think of it from that angle, great viewpoint. Not sure if it's worth the price difference, but I'll mention it.

4. Crap. Your knowledge>mine. I'll have to research this and update it when I get my dork on. If not, I'll have to have you 'splain to me this stuff.

5. You caught me with my pants down as I just brushed this issue with no research. Once again, I'll try to reword that.

C/Ns: I'll update this later with your excellent points and/or contact you if I need more help. Thanks a ton!
Unabomber is offline   Reply With Quote
Old 02-05-2007, 09:49 PM   #12
lancelucas
Scooby Specialist
 
Member#: 124282
Join Date: Aug 2006
Chapter/Region: NWIC
Location: 30000 ft
Vehicle:
04 WRX Wagon PSM
13 STI Sedan SWP

Default

Quote:
Originally Posted by Unabomber View Post
So how does a boost control solenoid work? It is opened via a pulsed duty cycle based on inputs from the ECU. While you are building boost, the BCS is not operating. This allows the wastegate to remain closed to built boost quickly. As target boost approaches, it ramps up quickly to control/limit the boost. At this point is where the BCS is working the hardest.

Please clarify this.

The BCS sure is "operating" during spool...it's open It vents to reduce the pressure presented to the wastegate.

And it doesn't "ramp up" to control boost, WGDC goes down = BCS vents less.

And feel free to flame on if I'm wrong.
lancelucas is offline   Reply With Quote
Old 02-05-2007, 09:58 PM   #13
nhluhr
John Wayne Toilet Paper
Moderator
 
Member#: 7327
Join Date: Jun 2001
Chapter/Region: NWIC
Location: Seattle, WA
Vehicle:
2008 Mazdaspeed3
2006 Wrangler Sport

Default

Right. The higher the WGDC, the higher the boost (or faster the spool). As boost target is reached, the WGDC should lower slightly to maintain target boost.
nhluhr is offline   Reply With Quote
Old 02-21-2007, 10:44 PM   #14
WRX Shenanigans
Scooby Specialist
 
Member#: 101378
Join Date: Nov 2005
Chapter/Region: MAIC
Location: VA
Vehicle:
2011 Sonata
Harbor Gray Metallic

Default

Thanks for all the faq's unabomber!!

But I thought this to be relevant:
http://forums.nasioc.com/forums/show....php?t=1204830
WRX Shenanigans is offline   Reply With Quote
Old 03-01-2007, 03:36 PM   #15
mickeyd2005
Scooby Newbie
 
Member#: 122595
Join Date: Aug 2006
Chapter/Region: NWIC
Vehicle:
2005 LGT Wagon
ABP

Default

I think I understand how a stock 2 port system works with the restrictor pill. When using a 3 port system, I was told that we can eliminate the restrictor pill.

However, one of the moderators on www.legacygt.com recommends using a restrictor pill and he has the Prodrive BCS. See post #93 below.

http://www.legacygt.com/forums/showt...t=55151&page=7

In fact, he not only uses a restrictor pill, but he reduced it to 0.025.

Why would a system with a Prodrive BCS benefit from a restrictor pill? Am I misunderstanding how a 3 port system works?
mickeyd2005 is offline   Reply With Quote
Old 03-01-2007, 09:40 PM   #16
4wdrift
Scooby Guru
 
Member#: 1403
Join Date: May 2000
Chapter/Region: TXIC
Location: In a warm dry place
Vehicle:
99 RBP GC8 Impreza

Default

Once again Ron, this is good information and nice useable data. I can't help
but think that a published limited run, compilation of your FAQ's would have
netted a reasonable profit for tunning and playing, Much like the Subaru
Impreza Turbo publication by Chris Rees, (Haynes). But hey, thanks...and
another job well done.
4wdrift is offline   Reply With Quote
Old 04-04-2007, 09:40 PM   #17
GHOST R1DER
Scooby Newbie
 
Member#: 144390
Join Date: Mar 2007
Chapter/Region: South East
Location: South Florida
Vehicle:
2002 WRX
PLATINUM SILVER

Default

i know this might be a little out of context but i dont think anyone stated what the factory boost setting is or should be before making any modifications and i know this might be a touchy subject but also what is the maximum recomended boost on a factory set up for both the 2.0 and the 2.5 . im sure the info is out there, it just really kicks a$$ how you guys can answer it all in 1 thread props to Ron and Jorge !!
GHOST R1DER is offline   Reply With Quote
Old 04-04-2007, 09:55 PM   #18
GHOST R1DER
Scooby Newbie
 
Member#: 144390
Join Date: Mar 2007
Chapter/Region: South East
Location: South Florida
Vehicle:
2002 WRX
PLATINUM SILVER

Default

also is there a way to guage the standard setting for the internal wastegate actuator rod to see if it has been tampered with ?

so you can get an idea why im so interested in the factory settings is because i just got an 02 wrx and its at 10psi. i cant figure out why or how the previouse owner got it up there so i want to know if its worth leaving it as is, or should it be returned to factory settings ? im always a real knit pick when it comes to other peoples craftsmanship its kind of like that saying "inocent untill proven guilty" but mines is "you suck untill you prove otherwise" <-- not directed towards anyone here, you guys know your ***** !!
GHOST R1DER is offline   Reply With Quote
Old 07-26-2007, 09:06 PM   #19
puma815
Scooby Newbie
 
Member#: 155022
Join Date: Jul 2007
Default

How much boost can a stock WRX turbo take with out causing damage to the turbo assembly?
puma815 is offline   Reply With Quote
Old 07-31-2007, 02:09 PM   #20
Cody
Scooby Newbie
 
Member#: 42048
Join Date: Aug 2003
Chapter/Region: BAIC
Location: Sonoma County
Vehicle:
03 WRX Wagon
Sonic Yellow

Default

Quote:
Originally Posted by RiftsWRX View Post
5: What about a manual boost controller or electronic boost controller? - Any open loop boost controller WILL NOT DELIVER CONSISTENT PERFORMANCE AND IS SUBJECT TO ENGINE LOAD IN A PROFOUND WAY!!!!! I have to beat this point into my customers heads sometimes. Simply put... set a MBC to X PSI in 3rd, it'll be X+something in 4th and X+something more in 5th.... While doing it in 5th results in X-something in 4th and X-why bother in 3rd.

A closed loop electronic boost control is the proper answer, but people need to really understand that the term MANUAL boost controller is not there to look pretty. It takes discipline, a discriminating user, and common sense to use right.

Other then those points, looks great man!

Jorge (RiftsWRX)
www.ProjectWRX.com
I have used a MBC for over a year now and am very happy with it. My tuner has checked my logs and I have an EGT gauge and everything is perfectly fine. Its major benfit is boost response, especially in the lower gears (RE: AutoX).

For my particular MBC (Hallman Pro RX) I do see about 1psi higher on a 5th gear pull than 2nd gear, but who does 5th gear pulls? The difference in peak boost in 3rd and 4th is negligible (RE: <0.5psi). Elevation changes are equally miniscule: going from 5K feet to sea level adds about 0.5 psi of boost which I can adjust out in 5 seconds if I want.

On the stock tuning, I saw roughly equal "inconsistent performance".

I realize this MBC on the stock turbo is not the same as X MBC on Y Turbo, but just thought I'd share my experience since it seemed a little contrary to the quote above.

As always, thanks for the FAQ Unabomber.

Last edited by Cody; 07-31-2007 at 02:20 PM.
Cody is offline   Reply With Quote
Old 07-31-2007, 02:23 PM   #21
Cody
Scooby Newbie
 
Member#: 42048
Join Date: Aug 2003
Chapter/Region: BAIC
Location: Sonoma County
Vehicle:
03 WRX Wagon
Sonic Yellow

Default

Quote:
Originally Posted by puma815 View Post
How much boost can a stock WRX turbo take with out causing damage to the turbo assembly?
Anything beyond 17.5 PSI will really start to accelerate turbo wear. That's the threshold I decided on anyway. I could make more power at 19psi, but that's pretty hard on the stocker, especially at this elevation (5K feet).
Cody is offline   Reply With Quote
Old 08-07-2007, 02:09 PM   #22
richde
Scooby Specialist
 
Member#: 79498
Join Date: Jan 2005
Chapter/Region: SWIC
Location: SCIC's trashy neighbor
Vehicle:
2013 XV Silver Slug
'84 Porsche 911-sorta red

Default

Quote:
Originally Posted by Cody View Post
I have used a MBC for over a year now and am very happy with it. My tuner has checked my logs and I have an EGT gauge and everything is perfectly fine. Its major benfit is boost response, especially in the lower gears (RE: AutoX).

For my particular MBC (Hallman Pro RX) I do see about 1psi higher on a 5th gear pull than 2nd gear, but who does 5th gear pulls? The difference in peak boost in 3rd and 4th is negligible (RE: <0.5psi). Elevation changes are equally miniscule: going from 5K feet to sea level adds about 0.5 psi of boost which I can adjust out in 5 seconds if I want.

On the stock tuning, I saw roughly equal "inconsistent performance".

I realize this MBC on the stock turbo is not the same as X MBC on Y Turbo, but just thought I'd share my experience since it seemed a little contrary to the quote above.

As always, thanks for the FAQ Unabomber.
Maybe he's looking at it from the perspective of his car, and not how differently the 02-03 ecu's respond to modifications.

More info on the aftermarket BCS's would be appreciated, there seems to be WAY too much conflicting information around concerning them.
richde is offline   Reply With Quote
Old 08-07-2007, 02:21 PM   #23
RiftsWRX
Scooby Guru
 
Member#: 6124
Join Date: Apr 2001
Chapter/Region: MWSOC
Location: Glendale Hts, IL, USA
Vehicle:
2000 NFR AP1 S2000
'07 Honda FIT sport (5MT)

Default

In short, the VAST majority of MBC's are inconsistent, especially since it's greatly related on engine load, and transmissions with huge differences across gears will suffer from this. (4EAT, 6MT, etc).

Jorge (RiftsWRX)
www.ProjectWRX.com
RiftsWRX is offline   Reply With Quote
Old 08-07-2007, 08:58 PM   #24
JETS02WRX
Scooby Newbie
 
Member#: 67386
Join Date: Aug 2004
Chapter/Region: Tri-State
Location: West Chester, Pa
Vehicle:
2002 WRX Wagon -16G
MBP

Default

Quote:
Originally Posted by mickeyd2005 View Post
I think I understand how a stock 2 port system works with the restrictor pill. When using a 3 port system, I was told that we can eliminate the restrictor pill.

However, one of the moderators on www.legacygt.com recommends using a restrictor pill and he has the Prodrive BCS. See post #93 below.

http://www.legacygt.com/forums/showt...t=55151&page=7

In fact, he not only uses a restrictor pill, but he reduced it to 0.025.

Why would a system with a Prodrive BCS benefit from a restrictor pill? Am I misunderstanding how a 3 port system works?
Bump for an answer this question...I was wondering the same thing.
JETS02WRX is offline   Reply With Quote
Old 08-08-2007, 08:22 AM   #25
richde
Scooby Specialist
 
Member#: 79498
Join Date: Jan 2005
Chapter/Region: SWIC
Location: SCIC's trashy neighbor
Vehicle:
2013 XV Silver Slug
'84 Porsche 911-sorta red

Default

Quote:
Originally Posted by JETS02WRX View Post
Bump for an answer this question...I was wondering the same thing.
He must be using it in the stock like "bleed" configuration, instead of "interrupt" like Perrin and Prodrive suggest for a performance benefit.

I just ran a log this morning for something unrelated and noticed that it takes 1.5 seconds for the signal to the (stock) BCS to go from 0% to whatever% that mine is maxed at. If I read correctly, the Prodrive or Perrin would close the ms that it didn't receive a full open command, but that makes me confused about part throttle/partial boost situations....
richde is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Uppipe FAQ: Read if you are thinking of buying one! Unabomber Newbies & FAQs 342 04-10-2014 03:59 PM
Exhaust FAQ: Read if you are thinking of buying one! Unabomber Newbies & FAQs 274 02-03-2014 11:38 AM
Pulley FAQ: Read if you are thinking of buying one! Unabomber Newbies & FAQs 108 01-25-2014 01:28 AM
Downpipe FAQ: Read if you are thinking of buying one! Unabomber Newbies & FAQs 305 08-07-2013 04:06 PM


All times are GMT -4. The time now is 09:55 AM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2014 Axivo Inc.
Copyright ©1999 - 2014, North American Subaru Impreza Owners Club, Inc.