Welcome to the North American Subaru Impreza Owners Club Thursday July 31, 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 Technical > Normally Aspirated with bolt-on Forced Induction Powertrain

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 11-16-2001, 08:32 PM   #1
bsquare
Scooby Specialist
 
Member#: 1911
Join Date: Jul 2000
Location: Seattle, WA, USA
Vehicle:
2000 Impreza 2.5RS
Silverthorn Metallic

Default Things to figure out before picking parts for your turbo project

Perhaps I am just a frustrated perfectionist, but I have been doing lots and lots of research and talked to many experienced people regarding what exactly works and doesn't work to get the performance from my car that I want. I notice that a lot of people asking about turbo kits or parts or projects in this forum don't seem to have a clear idea of what they want out of their car. To me, a plan is essential when embarking on something like this.

Here are a few questions you might consider in making your decisions (and I hope others with experience in this arena will contribute more):

What sort of performance do I want?
What sort of powerband?
Am I driving it primarily on the street?
Will I be drag racing?
What about autocrossing?
Road racing?

These questions allow you to focus in on what you need and don't need. For example, if you want a drag racing car, you can accept the trade of low end response for high end power. If you want the car for tooling around on the street, you probably want more low end. If you want to road race (that's on a track, not on public roads), you probably want a smooth transition to boost and a wider powerband.

Once you have figured out what it is you want, your goals, you probably want to figure out your budget. Remember, you are pushing your car outside of its intended limits, so things will likely break: DO NOT GO INTO DEBT FOR THIS!

How much am I willing to spend?
Am I ok with the project evolving over several months while I work out kinks?
Can I arrange to pay for some of the parts at a time while I work up to a full system?

Think about your own technical abilities and knowledge in this area.

Am I comfortable with assembling all the parts I'll need?
Am I comfortable with installing them myself?
Can I safely tune the car once it is together?

Some people are better off buying a pre-packaged kit, while others will enjoy hunting around junk yards for Legacy Turbo parts, and still others are stupid like me and will talk to local fabricators to have parts made to their own specifications.

Remember, there is more to installing a turbo, usually, than just the piping and the turbo itself. Be sure to consider any other upgrades that might be required to make your upgrades reliable, effective, and enjoyable.

Figure out how much fuel is needed for the power levels you want (there are lots of calculators for this, and other important metrics, at this site).

Similarly, figure out the required air flow (in CFM, m3/min, lb/min, etc). This is also very important for proper turbo selection, whether you are building your own kit or are just trying to compare existing kits.

Don't skimp on engine management! That's important, so I'll say it again all caps: DON'T SKIMP ON ENGINE MANAGEMENT! Many an otherwise perfectly good turbo install has led to blown engines and unhappy campers because they thought a Zener diode and a rising rate fuel pressure regulator would be fine running 15psi on an EJ25. I know it is hard to mentally justify early on, but engine management really can make your car faster!

All that extra power will probably require an upgraded clutch. There are sadly few choices out there, but more are on the horizon. Be sure to match your intended power levels with the holding power of the clutch. Think about whether you want the smoother engagement of an organic clutch or, if your power levels demand it, a metal button puck that is more like a light switch for engagement.

Transmission rebuilds and gearsets are not cheap, so if you need to upgrade them you should probably do it before you break your stock bits. Weigh the benefits of assembling a transmission that can take the stress of your intended use and driving style against using a clutch that will slip some and save the transmission from the full onslaught of your mighty turbo creation.
* Registered users of the site do not see these ads.

Last edited by bsquare; 11-17-2001 at 01:08 AM.
bsquare is offline   Reply With Quote
Old 11-16-2001, 08:44 PM   #2
Fusion
Scooby Specialist
 
Member#: 553
Join Date: Nov 1999
Location: In the trash can to which peop
Vehicle:
2000 2.5RS Coupe
Silverthorne Metallic

Thumbs up

Very nice! I like this!

Haig
Fusion is offline   Reply With Quote
Old 11-17-2001, 12:53 AM   #3
Rovah
Scooby Specialist
 
Member#: 1375
Join Date: Apr 2000
Location: Bangor, Maine
Vehicle:
2003 WRX Rally Car
Silver

Default

Ben,
Great idea and nice post! :-) Maybe this can evolve into a page describing various vendor turbo kits(and their applications and performance feedback) as well as real world systems put together by individuals.

Issues I'd like to see put in one central location:

Rising Rate Fuel Pressure Regulators-which one, what rate, sources?
Fuel Pumps: Which ones work, what part #s, sources?
Turbo sizing
Spark Plugs: Heat range information?
Engine Management systems: who likes what and why? Links to manufacturers and user feedback
Piggy Back units: the what and why?
Gauges: Where to mount the EGT probe?
Tranny upgrades(MT and AT): what works, who supplies it?

I know that ALL of these things have been covered in various posts, and I've searched and printed out nearly 100 pages of information just from the i-club and vendor sites!

BUT, it would be MUCH easier and less redundant to have a central location for all this information. There certainly is large enough body of info to support something like this.

I'd love to be able to check one site for the latest info and links!

Thanks again for the great post and good comments!

Cheers! John
Rovah is offline   Reply With Quote
Old 11-17-2001, 01:05 AM   #4
bsquare
Scooby Specialist
 
Member#: 1911
Join Date: Jul 2000
Location: Seattle, WA, USA
Vehicle:
2000 Impreza 2.5RS
Silverthorn Metallic

Default

Thanks for the good suggestions. What I'd like to end up with is not yet another thread for people to wade through, but a FAQ that is actually a distillitaion of what is said on this thread and a number of others.

As I've said before, I just want a FAQ so I can tell people to quit asking and go read it


Ben
bsquare is offline   Reply With Quote
Old 11-17-2001, 01:09 AM   #5
Rovah
Scooby Specialist
 
Member#: 1375
Join Date: Apr 2000
Location: Bangor, Maine
Vehicle:
2003 WRX Rally Car
Silver

Default

Ben,
Couldn't agree with you more. I'm tired of seeing people tell others to "do a search," and I'm tired of trying to remember which thread I got some key info from in the past.

How can we make this happen? I have some server space if someone wants to gather info and put it together...

Maybe we should start to post links to pages that we feel should be referenced?

John
Rovah is offline   Reply With Quote
Old 11-17-2001, 01:10 AM   #6
bsquare
Scooby Specialist
 
Member#: 1911
Join Date: Jul 2000
Location: Seattle, WA, USA
Vehicle:
2000 Impreza 2.5RS
Silverthorn Metallic

Default

You are posting on the server that I suspect will host the FAQ (that's one of the reasons for this site, right?).

Yes, definitely post links to your favorite sites on this topic!
bsquare is offline   Reply With Quote
Old 11-17-2001, 01:27 AM   #7
Rovah
Scooby Specialist
 
Member#: 1375
Join Date: Apr 2000
Location: Bangor, Maine
Vehicle:
2003 WRX Rally Car
Silver

Default

ECU/Engine Management Links:
http://www.motec.com/
http://www.haltech.com/
http://www.turbofast.com.au/autronic/smcecu.html
http://www.avoturbo.com/index800.html
http://www.airpowersystems.com.au/unichip/unichip.htm

Torque Converters
http://www.levelten.com
http://www.protorque.com

Injectors
http://www.grapeaperacing.com/GrapeA...linjectors.htm
http://www.rceng.com

RRFPR
vortechsuperchargers.com/

Vendors
I'll let someone else fill this in...maybe turbo kits, parts, fuel pumps, drain lines, etc?

Automotive math sites?

Personal Turbo Kit pages
http://www.uniquemotorsports.com/
http://www.nothingserious.net/

I know there are lots more-just too tired to keep looking! Come on folks-chime in with your favorite sites!

John
Rovah is offline   Reply With Quote
Old 11-17-2001, 01:43 AM   #8
bsquare
Scooby Specialist
 
Member#: 1911
Join Date: Jul 2000
Location: Seattle, WA, USA
Vehicle:
2000 Impreza 2.5RS
Silverthorn Metallic

Default

bsquare is offline   Reply With Quote
Old 11-17-2001, 06:55 AM   #9
WRSport
Scooby Specialist
 
Member#: 2060
Join Date: Aug 2000
Chapter/Region: BAIC
Location: Bay Area
Vehicle:
00 2.5RS Coupe
01 black boxster hardtop

Thumbs up

WRSport is offline   Reply With Quote
Old 11-17-2001, 08:48 AM   #10
Rovah
Scooby Specialist
 
Member#: 1375
Join Date: Apr 2000
Location: Bangor, Maine
Vehicle:
2003 WRX Rally Car
Silver

Default

Anyone have links for piggyback units? J+S, Apex-i, other units?

John
Rovah is offline   Reply With Quote
Old 11-17-2001, 12:24 PM   #11
Andrew
Scooby Specialist
 
Member#: 1170
Join Date: Mar 2000
Chapter/Region: BAIC
Location: San Jose, CA
Vehicle:
2005 STi
White

Default

Quote:
Rising Rate Fuel Pressure Regulators-which one, what rate, sources?
I would suggest a Vortech FMU. It does the job decently. Now as for which plate to use that is up to you and your engine. You must, must, MUST, listen to your engine and see what it wants. You will have to watch the EGTs and A/F gauge to determine which will be the best. But I would put money down that you would end up using a 4:1 on a 98.


Also something else to consider...INJECTORS!

I would also like to suggest looking at the parallel fuel line mod. When doing this mod the stock FPR will need to be upgraded. I have had great success with an SX FPR. but you can also use an SVX's or XT6 FPR to bring it back to stock idle pressure.

Detecting ping on loud cars: Go to Home Depot or something and buy a copper pipe. Flatten one edge of the pipe. Drill a hole on the flattened side. Take a long hose (probably will be a radiator hose or some other large hose depending on your copper pipe) and go from the firewall to the engine and attach the pipe. Now stick the pipe on the engine somewhere. Now you have a choice. 1) Listen to the hose with one hand, or 2) rig the hose up in a set of headphones so that you can still use both hands to drive.



Last thing, DO NOT think that since Mr. Boost has X turbo kit and is pushing X psi with great EGTs that you will be able to do the same. EVERY ENGINE IS DIFFERENT. Like I said before listen to your engine, you will probably get close results to everyone else but there are so many variables that it would be a joke to expect the exact same performance as someone else.
Andrew is offline   Reply With Quote
Old 11-17-2001, 12:56 PM   #12
mastervic27
Scooby Newbie
 
Member#: 557
Join Date: Nov 1999
Location: Bellevue, WA
Vehicle:
1999 Impreza 2.5RS
Vishnu Turbo

Default

Ben, Awesome Post!

A few other things to consider:

- Gauges (Boost, EGT, A/F)
- Exhaust (Diameter of the piping)
- Brakes (More power => greater stopping power required) and don't forget the tires.

ACT Clutch:
http://www.advancedclutch.com/

MRT Performance:
http://www.mrtrally.com.au/

APEX-i
http://www.APEXi-usa.com/

Borla:
http://www.borla.com/

Autometer:
http://www.autometer.com/

Scoobysport:
http://www.scoobysport.co.uk/
mastervic27 is offline   Reply With Quote
Old 11-17-2001, 02:35 PM   #13
Rovah
Scooby Specialist
 
Member#: 1375
Join Date: Apr 2000
Location: Bangor, Maine
Vehicle:
2003 WRX Rally Car
Silver

Default

Andrew,
Great post. You made the comment that all engines are not the same. I think that it might be more correct to say that no two people putting forced induction on their cars take EXACTLY the same approach.

That said, I think that it is reasonable for someone to expect that if they duplicate the efforts of someone that's been successful in putting a kit on their car, then they CAN expect that things should run fine.

when I read your post, I see an appropriate and wise warning that proper research prior to getting under the hood and tuning after the fact are key in ANY install.

If you don't know what you're doing, or don't have the cash to fix it when you break it-don't do it. Success is not assured and end results may differ.

John
Rovah is offline   Reply With Quote
Old 11-17-2001, 11:37 PM   #14
Legacy GTR
Scooby Specialist
 
Member#: 9316
Join Date: Aug 2001
Location: Litchfield Park, AZ
Vehicle:
1997 Legacy GT
14.767@93.54

Default Wow

I wish this was all put together before I did my install.
What about intakes? I kinda forgot about mine and ended up getting some pipe, and cut it, then used aluminum shielding tape to seal it.
Vortech FMU
I'm using the 6:1 and only having it richen (via AFC) no more then 4%. That's going to change though once I get my exhaust made.

One thing you may want to put in about Legacy Turbo crossmembers. The stock (on a 97 Legacy GT) front sway bar WILL NOT BOLT ON. The mount to the crossmember is too small(the crossmember side's too small). So right now i'm driving without one. (any help on this???)
I used many of the sites posted.
www.howstuffworks.com may not be a bad site to add, never been to it, but heard good things.
www.ezfindparts.com
Here's the J&S page-not too helpful to me though
http://safeguard.20m.com/index.html

A Transmission Company
http://protechtransmissions.com/about.html

Let me know if I can help more. In a few days i'll pull my plugs and see if 2 stages cooler was the correct choice for me.
Also, oil, and trans fluid info wouldn't be a bad idea.
And I printed out(and saved also) a 6 page explination about double-clutching, revmatching, and other manuel shifting techniques. It's THE best write-up i've seen on just about anything. Includes practicing drills. It's awesome.
Mike
Legacy GTR is offline   Reply With Quote
Old 11-18-2001, 12:47 AM   #15
Andrew
Scooby Specialist
 
Member#: 1170
Join Date: Mar 2000
Chapter/Region: BAIC
Location: San Jose, CA
Vehicle:
2005 STi
White

Default

Also here is a site I have found pretty useful for the misc parts (adapters, hoses, etc):
http://www.bakerprecision.com/
Andrew is offline   Reply With Quote
Old 11-18-2001, 11:38 AM   #16
Bahumut
Scooby Newbie
 
Member#: 460
Join Date: Oct 1999
Location: Overland Park, KS, USA
Vehicle:
1995 Impreza Wagon
Brilliant Red/Slade

Default

keep them coming guys. make sure someone lets a mod know about this post so they can make it a permanent faq for us tiring of hunting for this info all the time!
Bahumut is offline   Reply With Quote
Old 11-18-2001, 03:05 PM   #17
kaos200
Scooby Guru
 
Member#: 2692
Join Date: Oct 2000
Chapter/Region: SCIC
Location: SoCal
Default

how about places to get headwork done?
other than Cobb (I know they're great, but choices are nice, no?)
also where can we get valves, springs, retainers?
kaos200 is offline   Reply With Quote
Old 11-18-2001, 03:34 PM   #18
bsquare
Scooby Specialist
 
Member#: 1911
Join Date: Jul 2000
Location: Seattle, WA, USA
Vehicle:
2000 Impreza 2.5RS
Silverthorn Metallic

Default

Cobb sells springs and titanium retainers, which I assume are from Crower, since that is who makes their rodds, as well. Good stuff, certainly good past 8000rpm.

I'd be interested in other, higher strength spring options (titanium?), so if anyone finds some, definitely post about it.


Ben
bsquare is offline   Reply With Quote
Old 11-18-2001, 05:00 PM   #19
kaos200
Scooby Guru
 
Member#: 2692
Join Date: Oct 2000
Chapter/Region: SCIC
Location: SoCal
Default

Quote:
Originally posted by bsquare
Cobb sells springs and titanium retainers, which I assume are from Crower, since that is who makes their rodds, as well. Good stuff, certainly good past 8000rpm.

I'd be interested in other, higher strength spring options (titanium?), so if anyone finds some, definitely post about it.


Ben
I know they have them, and Cobb is great. But I am on a budget, and their stuff isnt exactly *cheap*.

Last edited by kaos200; 11-18-2001 at 05:22 PM.
kaos200 is offline   Reply With Quote
Old 11-18-2001, 08:38 PM   #20
FuJi K
Scooby Guru
 
Member#: 3687
Join Date: Jan 2001
Chapter/Region: MWSOC
Location: St. Paul, MN
Vehicle:
MY99 GF4 JDM 6spd
NF Performance

Default

well said....

another site if acceptable.

Turn Fast-Road Racing Resource


FuJi
FuJi K is offline   Reply With Quote
Old 11-19-2001, 12:58 AM   #21
Andrew
Scooby Specialist
 
Member#: 1170
Join Date: Mar 2000
Chapter/Region: BAIC
Location: San Jose, CA
Vehicle:
2005 STi
White

Default

If someone is a newbie turbo person and is putting together their own kit, then this info might help.

Try to get the BOV as close as possible to the throttle body. Get it welded onto the IC for best results.
Andrew is offline   Reply With Quote
Old 11-19-2001, 01:09 AM   #22
bsquare
Scooby Specialist
 
Member#: 1911
Join Date: Jul 2000
Location: Seattle, WA, USA
Vehicle:
2000 Impreza 2.5RS
Silverthorn Metallic

Default

Andrew: It'd be good to explain exactly why, perhaps by detailing what a BOV does and how proximity to the throttle body enhances its performance...newbies won't know what compressor surge is, usually, even if they've heard of a BOV.
bsquare is offline   Reply With Quote
Old 11-19-2001, 01:29 AM   #23
Andrew
Scooby Specialist
 
Member#: 1170
Join Date: Mar 2000
Chapter/Region: BAIC
Location: San Jose, CA
Vehicle:
2005 STi
White

Default

oh so since i brought this up I have to explain it?


anyways ill do my best explaining it... here goes...

What a Blow off Valve (BOV) does is vents the air coming from the turbo to the engine. The reason it does this is becuase once you let off the gas (close the throttle plate) the air that was on its way to the engine hits the plate and goes BACK to the turbo. this causes major strain on the turbo and is known as compressor surge. (I believe, if i remember correctly, its a fluttering/pigeon/butterfly type sound). You can avoid this by putting your BOV closest to the throttle plate as possible (hence the idea of putting it on the intercooler itself). Some things you need to watch for, you need to have the proper spring inside the BOV or else it might not vent the built up pressure properly.


Hey ben, how was that?
Andrew is offline   Reply With Quote
Old 11-19-2001, 02:10 AM   #24
bsquare
Scooby Specialist
 
Member#: 1911
Join Date: Jul 2000
Location: Seattle, WA, USA
Vehicle:
2000 Impreza 2.5RS
Silverthorn Metallic

Default

Yes, you bring it up, you explain it

Let me see if I can expand on this a bit to explain why things work the way they do.

The reason the BOV is most effective near the throttle body is because that is where the compression wave is initiated when the throttle snaps shut when the driver lets off the gas to shift. By placing the BOV near the throttle body, the purpose of which is to release that excess pressure of the compression wave, the excess pressure is ejected as early as possible.

The reason proper spring tension in the BOV is important is that the spring tension determines the pressure at which the BOV begins ejecting air from the intake tract. If the spring pressure is too high, the BOV will fail to open, or fail to open enough, and compressor surge will continue on its way back to the compressor wheel in the turbo.

Now, what's so bad about compressor surge? If your turbo has a 360 degree thrust bearing, nothing, according to a certain UK rally driver and mechanic. However, most turbos do not have that feature, so the compressor surge can unbalance the compressor wheel, potentially overloading the shaft. Snap the shaft, dead turbo.

There are 2 primary types of BOVs: atmospheric (also called dump valves) and recirculating. An atmospheric BOV vents the air directly out (making that "pfffffttt!" sound that some people love so much). A recirculating BOV has a tube running from it to a point on the intake tract _before_ the turbo. A recirculating BOV is significantly less noisy than an atmospheric valve and injecting the excess air back into the intake tract can improve performance in cars with certain air flow sensors (MAS? MAF? help me out?).


Ben
bsquare is offline   Reply With Quote
Old 11-19-2001, 02:15 AM   #25
Andrew
Scooby Specialist
 
Member#: 1170
Join Date: Mar 2000
Chapter/Region: BAIC
Location: San Jose, CA
Vehicle:
2005 STi
White

Default

yeah what he said...i just um...forgot about it...
Andrew 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
About to pick up V7 STi Trans, any thing to look out for? cdnsigop Transmission (AT/MT) & Driveline 7 02-03-2010 04:46 AM
Things to do in Kmart while waiting for your wife nepawrx Off-Topic 19 01-17-2008 04:14 PM
Strategies to figure out your gifts from your SO.... MidnightSti05 Off-Topic 24 12-10-2007 03:54 PM
Trying to figure out the best route for camber adjustment ButtDyno Brakes, Steering & Suspension 7 08-06-2004 02:25 AM


All times are GMT -4. The time now is 12:32 PM.


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.