Welcome to the North American Subaru Impreza Owners Club Saturday July 12, 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 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 01-17-2000, 06:04 PM   #1
shiv
Scooby Specialist
 
Member#: 607
Join Date: Dec 1999
Location: SF Bay Area, CA
Post Making 300hp. Full disclosure (very long)

I'm currently in the middle of writing an SCC Project Impreza installment covering all the work I've recently done to the turbocharged 2.5RS. I've been busy this past month testing different upgrades and trying to establish a safe and conservative upgrade path. That said, I'm very happy with the car's current configuration. It's running safely with an estimated 300 engine horsepower. That's a significant step up from the dyno-proven ~255hp (183 wheel hp) the car generated not too long ago.

How does 183 wheel horsepower equal 255 engine hp? Good question. I'm sure most of you know this already but I'll address this again before moving on...

Tested on UPRD's dyno a stock 2.5RS dyno'd at 95 wheel hp. A few weeks later, when tested with the as-is 7psi Minnam set up (with a 2.25" Stromung cat-back), the project car dyno'd at 183 wheel hp. All on 92 pump gas. From the looks of the monitoring equipment, that is as far as the stock fuel system would take it. But still, the Stage II offered a remarkable 88hp gain to the wheels. So conservatively, engine output is *at least* 165 plus 88 = 253hp. Of course, this assumes that the stock car really does make 165hp. That's the only big assumption I'm going to make here.

Now, a more optimistic tuner may say (and I WON'T agree with him)... "Wow, wheel output increased by 93%. That must mean that engine output is 93% greater. So, 165*1.93=318hp! Holy *****!"

Obviously, there is a problem with that tuner's calculation. He would be incorrectly assuming that drivetrain loss is proportional to engine output. Evidence (and a little common sense) suggests that this is not true. While engine ouput does influence drivetrain loss, my guess is that it does so to a small degree (esp. when talking about these non-obscene hp levels).

So let's go back and be grossly conservative. Meaning that engine ouput does NOT effect drivetrain loss. So, with this in mind, it's VERY safe to say that the stock Minnam Stage II system makes (at the least) a fuel-limited 253hp. Not coincidentally, the calculated safe and efficient limit (80% duty cycle) of four 320cc injectors is approximately 256hp. Also not a coincidence are the air flow meter readings from the AFC. Stock was 44% peak. The standard Minnam Stage II was 68% peak. That's a 50% increase in air flow. So, theoretically, that's a 50% increase in engine ouput. 165*1.55=255hp. We're right back to that magic number! Of course, there are other hp-influencing factors involved but I think their cumulative effects are minor and would likely come close to cancelling themselves out if factored in. Also, the math and physics behind it are beyond me so I'm just going to play dumb (well... it's not really playing, is it?) until someone beats me over the head with them.

But wait, we are still a healthy 45hp away from the big 300hp I'm claiming.

WHERE DID THE EXTRA HP COME FROM? The rest of this message will document the mods I believe necessary to make additional safe and reliable horsepower without resorting to a fully programmable EFI system (that comes later).

DISCLAIMOR #1: Given the user-dependant nature of performance tuning, nothing is guaranteed. If you make tuning error (and anyone can make them!), something nasty may happen to your engine. In other words, follow my advice at your own risk and discretion. Please note that this upgrade advice does not necessarily reflect the views/opinions of Minnam Racing, or anyone else other than myself. As always, be safe. Don't drive irresponsibly on public roads. Don't drink and drive. Wear your seat belts. Two hands on the steerig wheel at all times. Wear clean underwear. Don't shout at your mother. Help grannies cross the road.

DISCLAIMOR #2: The following advice applies specifically to my Minnam Stage II turbocharged MY99 2.5RS which includes (among other things) a T3/T04E turbo, external wastegate, GReddy Type S blow off valve, free flow cat, J&S Safegaurd (Absolutely necessary for anything over 6psi of boost!) and Field/S-AFC fuel controller (also to be considered manditory). Other cars with other systems will require different approaches. All testing was done using CA92 octane gasoline. Any lower and you are asking for trouble. AND MOST IMPORTANTLY, IF AT ANY TIME, YOU HEAR DETONATION (a.k.a., knocking, pinging, rattling, etc,.), GET OFF THE THROTTLE! Detonation, not sheer power output, is the cause for almost all catastrophic engine failures. Knock is bad. BAD BAD BAD. If you develope a healthy fear of (and good ear for) knock, your engine will thank you in the long run.

DISCLAMOR #3: Before we begin this horsepower hunt, it is absolutely necessary to outfit the car will the following gauges: Exhaust gas temp (readable up to 1600F), fuel pressure (up to 90psi), boost/vacuum gauge (up to 15psi), and optional J&S dual monitor (a/f ratio and ignition retard). To make your life easier, go with an electric AutoMeter fuel pressure and EGT gauge. They are more expensive since they both require a sendor and an associated little electronic control module. However, both are very reliable, accurate, and most importantly, fast-reacting. I mounted the EGT sensor on the driver's side header (#2) just a few inches downstream of the exhaust port. At highway cruise, EGTs measure 1400 degrees. This should be a reference for all further temperature readings. In other words, if you mounted your sensor elsewhere (i.e. further downstream), your gauge will read lower under all conditions. Take this offset into consideration when looking at my temp readings.

DISCLAIMOR #4: Also, as with any turbo system, a non-restrictive exhaust is critical. Minnam Racing went to through great lengths to minimize hp-robbing and knock-inducing exhaust back-pressure by using a big turbine housing/wheel, an external wastegate, free flow cat, and fat exhaust tubing. It's completely counterproductive (and possibley unhealthy for the engine) to ruin this by using a small diameter cat-back designed for non-turbo cars (like the Stromung 2.25" cat-back I used during dyno testing). Currently, I'm using a Ralispec cat-back. It uses a wonderfully non-restrictive Apexi N1 canister with 2.5" inch stainless steel tubing throughout. It's loud and big-tipped, but it works better (for a turbo car, that is) than anything else I've tried so far.

Now that the disclaimors are out of the way, here goes...


PRELIMARY MOD #1: Blow off valve re-plumbing
--Vent blow off valve (BOV) to atmos and properly seal the discharge inlet. Don't use something filmsy to seal it off or it will eventually be sucked down by the turbo and cause a good deal of damage to the compressor wheel. This mod doesn't incease HP but it could very well prolong the life of the notoriously flimsy MY99 MAFs. Note that venting to atmos may require adjusting the BOV a little tighter so it won't leak under cruise and idle. Doing so will also insure a stable idle when cruising to a stop. Doing this, there should be no need to use the AFC's 'Decel' function. Besides, when the surge pressure is released into atmosphere, the car runs rich for a split second. This rich run condition can't hurt. In fact, it may even help and offset the temporary lean-run condition that can occur between full throttle, full boost shifts. It's also a good idea to mount a small K&N air filter on the BOV outlet since it does allow a small amount of unfiltered air to enter the system. Even more critical for those who go off roading.


PRELIMINARY MOD #2: Install a modified stock airbox.
-- This is yet another MY99 MAF reliability mod. This may require a little trimming of the blue Minnam intake tube. Once trimmed properly, use a 45 deg. 3" silicon elbow from Samco to conntect the box-mounted MAF to the blue minnam inlet pipe. This effectively isolates the MAF from engine-side vibrations. The stock panel air filter is restrictive. Dump it and install a K&N replacement. Now, the car will make full power/boost. Also, get rid of the inside-the-fender resonator system. Don't need it with a turbo. It's restrictive and unnecessary. Not to mentiont that the idea of the pastic snorkus/resonator ducting BACK INTO the hot engine bay is silly, to say the least. Instead, seal off that secondary hole with tape/pastic/whatever. This basically transform the intake box into a true cold air system that is fed air from the fender. The fender is fed air from the small vent next to the passenger side fog light. I can't imagine this setup could be improved upon. It's cold air and effectively non-restrictive. The mod only costs the price of your time and a K&N panel filter. Also, I'd bet that the MAF won't fail again.


Now, let's get down to business.


TO RUN 8 PSI (est. 270-280HP)===>

1) ADD HIGH FLOW FUEL PUMP
-- I installed a Mazda RX-7 twin turbo pump. Almost any high-flowing fuel pump will do. In fact, the pump flows so well that the tiny stock fuel pressure regulator proved to be a big restriction, making it impossible to get anything less than 40psi of fuel pressure. No big deal but it should be noted. This explains why the car would temporarily run rich (before the o2 feedback system would correct) during engine braking and coast down. With the pump, the ran richer and stronger at the top end. Appearantly, the stock pump was beginning to show its limitations at 8psi. How do I know? J&S monitor shows that maximum ignition retard went from 8-9 degrees to just 3-4 degrees. Less retard is more power. MY a/f ratiometer also shows that now the car can hold a nice rich mixture all the way to fuel cutoff instead of becoming ever-so-slighly lean (or actually, less rich) at max rpm. Also of interest is that peak EGTs dropped from 1650 to 1500. A nice change and no doubt a result of less ignition retard and more fuel. Double bonus. You may also want to take this opportunity to remove the tiny stock fuel pressure regulator and replace it with an aftermarket unit. I used the Weapon R regulator. It's pretty. I have it set to delivery stock pressure (43psi of fuel at atmos. pressure). Make sure to confirm fuel pressure with your autometer electic fuel gauge as I found the gauge that is mounted on Weapon R regulator to be inaccurate.

2) INSTALL APEXi ITC IGNITION CONTROLLER
-- As far as I know, this is the only unit of its type of the market. It is desinged to intercept the cam and crank signal, modify it, and effectively retard or advance (+/-15 degrees) ignition timing in 5 different rpm zones. But why do I need it if I already have a J&S Safegaurd unit? Well, theoretically, I shouldn't need it. But in application, the J&S has to be set very sensative to catch ALL the knocks. In essence can over-retards when you ask it to do too much (i.e. when you run too much boost). It's safe, but not optimal for performance. Ideally, the J&S unit should be used as a back up or fail-safe (hence, it's "Safegaurd" nomeclature). Used as a primary form of ignition retard in a higher boost system, it can get overenthusiastic. This can lead to too much retard, low power and high EGTs. Enter the ITC. To dial it in, I watched the J&S monitor and followed ignition retard activity. I noticed that retard was only necessary between 5000rpm and redline. So, I dialed back some timing in that rpm zone using the ITC. With a little trial and error, I retarded ignition by only 6 degrees in that range. The result? No J&S activity and less overall retard. A lot more power and even lower EGTs (now they rarely go over 1450 deg). Appearantly, it's more effective to prevent knock with the ITC than to react to it with the J&S. When both are used together, it's a killer package. Wonderful.

So why do I need the J&S? For added safety, that's way! If you are using an ITC, all that is needed for some engine damage to occur is an unexpected flurry of knocks/pings. This can be caused by fuel slosh, hot weather, a bad tank of gas, heat soak, etc,. In other words, unless you are always playing around with the ITC, constantly compensating for conditions beyond my control, you're in trouble. Of course, you can set it so conservatively, that knock is unlikey. But this sacrifices power. So instead, I let the J&S take care of these unexpected situations. In fact, I have tuned the system so I that I just *barely* see a little bit of J&S activity (by looking at the monitor). This assures me that the J&S is set sensative enough to take car of any knocks-- even the minor ones that usually go unnoticed by the ear. My healthy fear of detonation could explain why the car's cylinder compression is just as good as stock. But still, I know ***** happens so I will try not to get cocky. Really.


TO RUN 8 TO 10 PSI (est. 280-300HP)===>

1) INSTALL AUXILLARY RISING RATE FUEL PRESSURE REGULATOR
-- Now that I have both passive AND reactive ignition controls, half the battle is won. What still remains before I can run higher boost safely are the proper fuel controls. I need more fuel. Plain and simple. With fuel (and timing controls) I could raise boost levels without running lean, knocking, and blowing the engine. And now that the car has a real fuel pump capable of some serious flow, I can go to work. Since I'm using stock injectors (which max out at 8psi), I need to use some type of boost-referenced 5:1 rising rate fuel pressure regulator. Now, there is a problem with using these contraptions on a car that already seems to do quite well when it comes to compensating for boost (up to a point). Namely, at there will be a rich spot during transition or at least until 02 feedback dials back fuel-- and that's only if it stays closed loop. Either way, this is not good for driveability or power. Why increase fuel pressure under any amount of boost when the stock EFI system works just fine up to 8psi? Forget it.

Another possibility would be to use a less aggressive 2:1 fuel pressure regulator like the one Adam is using. It's conservative enough that it won't throw the stock EFI system into a rich-running fit at moderate boost levels. However, I think it's too conservative. 2:1 means that for every pound of extra manifold pressure (boost), fuel pressure is increased by 2psi. At 8psi, max fuel pressure is 43 (stock@0psi of boost)+(2*8)=59psi. That's only 8psi more than what the stock 1:1 fpr would provide. This is a negligable increase of actual fuel injector flow. Even if the unit offers adjustable offset/preload (y-intercept for those who think in algebra), the slope-- 2:1, rise over run -- is fixed and your still left with the problem of not getting enough fuel under boost levels greater than 8psi. Need something else. Something that will provide a healthy 5:1 fuel rise while not making the car run rich at low boost. So, in other words, we need a fuel pressure regulator that starts "kicking in" when the car starts to run lean (at 7-8psi).

Hmmm... the only unit I know of that does this is offered by Bell Engineering (San Antonio, TX). They make a number of FPRs-- all designed to work differently. The one that I'm using on my car has no spring pre-load and is designed for modified OEM turbo cars. Suprisingly, it's not a big seller because not many people know about it. I should have kept it to myself But the unit works wonderfully because it is designed to become active only at 8psi and above. Below that boost threshold, it is just sitting pretty, letting the very effective S-AFC do all the fuel-related work. In other words, it doesn't screw anything up. This is good. But as soon as the injectors begin to max out at 8psi, it "jumps in" and raises fuel pressure agressively (5:1). To make things easier to visualize, here's a little chart of turbo boost and its associated fuel pressure.

Boost(psi) Fuel Pressure (psi)
0 43
2 45
4 47
6 49
8 60 <--injectors are maxed out and S-AFC becomes useless]
10 70
12* 80 <--RX-7 fuel pump is maxed out]

*too much boost

2) RE-GAP SPARK PLUGS
Even if you are using a colder spark plug, it may be a good idea to gap them smaller than stock at this stage. My RS came with plugs gapped at 0.042". I reduced them to 0.035". This improved power by eliminating the subtle misfire I would notice at high rpm during full boost runs. However, the elimination of misfire also made the car run marginally leaner which I took care of with AFC/FPR tuning. As with any modification, care should be taken to make sure the car still runs safely. At the end, peak EGTs should still be in the 1400-1450F range with ITC retarding 5-7 degrees between 5000rpm and redline.


TO RUN OVER 10 PSI (est 300+HP)===>

-- Don't do it. You will need a programmable EFI system to do this safely. While running 10+psi on the stock-ecu'd system is possible, it's bad bad bad. I've done it briefly and I'm ashamed. I did not inhale. Even though the car didn't ping or exhibit any obvious sings of running lean, there are several reasons why these boost/power levels are dangerous. First of all, almost every Japanese fuel pump is unable to reliably support the fuel pressure necessary (80+psi) to run high levels of boost with stock fuel injectors. Second, fuel injectors loose some mechanical efficiency when forced to operate at such unusually high pressures. Third, the "LEGO method" of EFI modifications that we have been following (stock ECU with lots of add-on fuel regulators and electronic gizmos) has its limitations when it comes to tunability, built-in safety margin, and response time. So basically, I feel that running over 10psi will require FULL and COMPLETE programmable control of ignition and fuel maps-- That only comes with the use of a programmable ecu (Haltec, TEC-II, MoTeC, etc,.) While the J&S Safegaurd is a wonderful safety device and has saved my a$$ more than once, even it has its limitations. Keep in mind that sh&t can happen quickly when you are right at the hairy edge between safety and complete engine failure.


IN SUMMARY===>

When in doubt, be conservative. Conservatism is the difference between a good tuner and a bad one. It's easy to make a car fast. It takes a lot more skill to make it driveable and reliable as well. Personally, a powerful car is only fun to drive when you aren't constantly worrying about detonation, overheating, lean-run, misfire, etc,. Be picky. Don't get accustomed to bad tuning. The ending to that story is always unhappy (and expensive). Also, when upgrading your car, take your time and do one upgrade at a time. Doing more than that will make the tuning and troubleshoorting process much more difficult. Also, going from 165hp to 300hp in just one week may not be a great idea if you are unfamiliar with peformance tuning and the associated inevitable glitches that comes along with it. Please note that this post does not go into the in-depth tuning issues. That's impossible given the fact that every car is different. Instead, it just offers a broad perspective, requiring that you apply your own discretion and knowledge every step of the way.

Lastly, don't get swayed by the claims of others (including myself, of course!). That is, if someone is claiming, say 500+hp streetable hp on a small displacment engine running pump gas, so what? Chances are, they are either grossly optimistic or budding supertuner destined for international fame. The nice advantage that come with learning about the tuning process is being able to seperate the fact from the fiction.

And remember, 300hp is plenty. And if done correctly, it's safe as well. Keep in mind that our cars are very unique. It's EXTREMELY rare that one can add a turbo to a non-turbo, high-compression car, nearly double engine ouput with simple bolt-ons, still run pump gas, sacrifice no driveability, and still (presumably) provide years of reliable trouble-free service. Feel lucky.

--
Shiv Pathak

[This message has been edited by shiv (edited January 17, 2000).]
shiv is offline   Reply With Quote
Old 01-17-2000, 06:21 PM   #2
Revision
Scooby Guru
 
Member#: 242
Join Date: Sep 1999
Chapter/Region: MWSOC
Location: Carol Stream, IL USA
Vehicle:
MY05 PSM GGA !STOCK
MY99 RS-RIP / MY95 MX-5

Thumbs up

I think we need to change Shiv's status...
from anything other than scooby newbie...

[This message has been edited by Revision (edited January 17, 2000).]
Revision is offline   Reply With Quote
Old 01-17-2000, 06:23 PM   #3
TR
Scooby Newbie
 
Member#: 28
Join Date: Jun 1999
Location: now w/100% less turbo
Vehicle:
1997 M3 Sedan
Blue

Post

Shiv, THANK YOU!
I know that last few steps to make my car safe and fast (relatively).
fuel pump and J&S are the last 2 steps.
TR is offline   Reply With Quote
Old 01-17-2000, 06:30 PM   #4
rao
Scooby Specialist
 
Member#: 52
Join Date: Jun 1999
Location: Naperville, IL
Vehicle:
2005 Legacy GT
98 BMW 540i LS2/T56

Post

Thanks Shiv . I can't wait to read the whole writeup in SCC and see the pictures!
rao is offline   Reply With Quote
Old 01-17-2000, 06:37 PM   #5
STi Sev
Scooby Specialist
 
Member#: 2876
Join Date: Nov 2000
Location: South San Francisco, CA.
Vehicle:
99 Impreza
Rally Blue Pearl

Thumbs up

Shiv Thank you for everything..
Im definately in range of turbocharging in a couple of months (gotta get that Athlon 900mhz Afterburner first ;-) and no I will not run more than 5lbs, hehe I swear!
How is the ACT clutch holding up?

Last question and hardest one (only the future can tell) How long will your car last at say 7 pounds of boost?

[This message has been edited by STi Sev (edited January 17, 2000).]
STi Sev is offline   Reply With Quote
Old 01-17-2000, 06:59 PM   #6
mastervic27
Scooby Newbie
 
Member#: 557
Join Date: Nov 1999
Location: Bellevue, WA
Vehicle:
1999 Impreza 2.5RS
Vishnu Turbo

Post

Thanks Shiv! Can't wait for the SCC article.
mastervic27 is offline   Reply With Quote
Old 01-17-2000, 07:05 PM   #7
Impy
Scooby Newbie
 
Member#: 489
Join Date: Nov 1999
Location: Toronto, ON, Canada
Post

Haha... THANX TOO!! I can't wait to do ALL those things!!
Impy is offline   Reply With Quote
Old 01-17-2000, 07:23 PM   #8
adam99rs
Scooby Specialist
 
Member#: 20
Join Date: Jun 1999
Location: New York
Post

Very well said Shiv - could not have said it better myself - especially about the 10 psi thing. I think that while the car will run at the 12 or 13 psi you and I have tried, and the car damn fast, it probably won't last, unless yu feel like switching injectors. I am going to try that route with the stock ecu - I have had good uck on other cars doing this in the past, though I am unsure if the AFC will allow enough changes to make it run as seamless as it does now. Anyway, any lans on playing around with head/cam work/cam timing? This is also a future step for me. I do have the TEC2 ready to go, but with so many other proects of mine going on, I do't want to put the car outof serice for a week or 2 to install it (nightimes, after work). Anyway, good article......now how bout those ITC install instructions!!!
adam99rs is offline   Reply With Quote
Old 01-17-2000, 08:34 PM   #9
edekker
Scooby Newbie
 
Member#: 143
Join Date: Aug 1999
Location: Kanata, ON, Canada
Vehicle:
1999 Impreza 2.5RS
Supercharged - and STOLEN

Post

Thanks for the exhaustive info Shiv. We have a whole lot of learning ahead of us.
Ed.
---------
'99 Rally Blue 2.5RS - Mods - My Site
edekker is offline   Reply With Quote
Old 01-17-2000, 09:59 PM   #10
RalliSpec
Former Vendor
 
Member#: 39
Join Date: Jun 1999
Location: Hainesport, NJ, USA
Vehicle:
98 Prodrive WRC

Post

Shiv,

Very nice job...hopefully that will clear up some issues here.

One thing that i didn't see mentioned that some people may be confused on(including some of these forced-induction kit companies)...

a rising rate FPR is useless with the stock Subaru RS fuel pump at ANY significant boost levels. It simply will not produce enough fuel pressure.

BTW we can supply motorsport-grade intank fuel pumps capable of upwards of 140psi. They are custom made to order by our supplier and are not cheap. Just another option.
RalliSpec is offline   Reply With Quote
Old 01-17-2000, 10:10 PM   #11
beachbum
NASIOC Supporter
 
Member#: 457
Join Date: Oct 1999
Chapter/Region: MWSOC
Post

One word: WOW!

Boy, I've got a long way to go. Hopefully some day I'll get to the point where I can use all this. Thanks a bunch, Shiv.

------------
Josh Beach
<a href="http://members.tripod.com/~jabeach">World's Slowest Impreza Project</a>
beachbum is offline   Reply With Quote
Old 01-17-2000, 10:44 PM   #12
rsquire
Scooby Specialist
 
Member#: 265
Join Date: Sep 1999
Location: Kirkland, WA
Vehicle:
1998 22B Blue
1986 Ford RS200 White

Post

Excellent post Shiv. Just as all your articles are. This should be cross posted to the UK board as several of those guys are currently suffering dead STI / 22B syndrome mainly caused by re-mapping their ECU.

Interestingly, when I recently met some of the UK guys they also felt that they were "pushing the bleeding edge". Maybe there's an opportunity for SCC in the UK?

I'll let you know how the Possum-Link system works out with the Minnam stage 2

Richard

rsquire is offline   Reply With Quote
Old 01-17-2000, 11:39 PM   #13
Imprezer
Dynamic Uno
 
Member#: 1
Join Date: Jun 1999
Chapter/Region: BAIC
Location: Alameda, CA
Vehicle:
2011 Impreza WRX STi
Black

Lightbulb

Great job, Shiv. Your post cleared up a lot of things that everyone (including me) assumed we knew.

Shiv was only 3 posts away from becoming a Specialist, but I have promoted Shiv even higher, to Scooby Expert. Hehe. I know it's nothing, but it's the least I can do.

Here is something I want to add to clarify things out even more. Shiv, Adam and anyone else feel free to correct me, since I can't be 100% right on these things.

What can cause an engine to "blow"?

1. High EGT's will literally cause engine internal to melt. I think the magic number not to go above on pump gas are 900C and 1650F.

2. Detonation (ping, knock) will destroy the pistons, bent conrods and amage the valves due to the extereme stress caused by the self-igntiting a/f mixture happening anywhere in the cylinder.

3. Too much boost with high compression will cause head gasgets and rings to blow due to the extreme cylinder pressure.

4. Increased power output will put excessive stress on engine's internals and destroying them.

5. Inefficient engine cooling and lubrication will also do dramatic damage to the engine.

6. Donuts sucked into the blow-off valve will also do... I am way off this time, hehe.

Is this it? Did I forget anything or mention something wrong here?
Imprezer is offline   Reply With Quote
Old 01-18-2000, 12:23 AM   #14
shiv
Scooby Specialist
 
Member#: 607
Join Date: Dec 1999
Location: SF Bay Area, CA
Post

Imprezer writes:

"1. High EGT's will literally cause engine internal to melt. I think the magic number not to go above on pump gas are 900C and 1650F."

--Corect, very high exhaust gas temps are not good. Not only can they damage engine internals (usually exhaust valves) and turbos, they can also trigger serious detonation which, of course, is the end to any engine. Hot exhaust gas temps can also fool you (and your a/f ratiometer) into believing that the car is running richer than it really is. This is why an EGT gauge is so critical with high output forced induction engines.

"2. Detonation (ping, knock) will destroy the pistons, bent conrods and amage the valves due to the extereme stress caused by the self-igntiting a/f mixture happening anywhere in the cylinder."

-- Yes. This is what likely happened in the case of those dead STi/22B motors. They knocked themselves to death. Terrible way to go. The owners must have heard it and ignored it. Afterall, most people don't expect a stock turbo car to ping. Also, ping can be quiet and hard to hear-- especially when the car is revving at 8500rpm.

"3. Too much boost with high compression will cause head gasgets and rings to blow due to the extreme cylinder pressure."

-- This, I'm not to sure about. Although some will swear that combustion pressures brought about by "extreme" power outputs have caused their engine to fail, I'm more willing to believe that knock was the true underlying culprit. Detonation is an order of magnitude more stressful to a engine than any normal combustion. Temps and pressures sky-rocket instantly. Literally, it's an explosion. This is why everything all comes back to guarding against detonation above anything else.

4. Increased power output will put excessive stress on engine's internals and destroying them.

-- In most situations, this is not true. Power loads aren't very stressful in the big scheme of things. In fact, the load a rod goes through just after TDC is far more stressful than the load caused by engine output. This is why raising maximum engine speeds can be far more stressful to an engine than introducing boost. Rule of thumb: You can add boost but leave the redline where it is.

But like everything else in life, there are no absolutes. So take everything with a grain of salt...

shiv
shiv is offline   Reply With Quote
Old 01-18-2000, 02:05 AM   #15
rrsettgast
Scooby Newbie
 
Member#: 104
Join Date: Jul 1999
Chapter/Region: BAIC
Location: Pleasanton, Ca
Vehicle:
2009 WRX Wagon
White

Question

Shiv, I posted this question on the mlist also in response to your post. Didn't see your post here until after i posted:

Shiv Just a couple of silly questions:
1) I assume you are venting the BOV to atmosphere to prevent a pressure wave from hitting the MAF. Instead of venting to atmosphere, have you thought of putting some sort of an air box between the bov and the discharge inlet? This might dampen out any high pressure waves from the bov. Also if you aligned the discharge inlet so that the pressure wave travels away from the MAF (point the inlet almost parallel to the intake piping, pointed away from the MAF), you probably could isolate the MAF further.

2) So if you were to run 7psi, would you not need to worry about the stock fuel pump pressure/flow? All you really should worry about would be the ITS, J&S safegaurd, and the mentioned gauges? (in addition to the AFC, AVC, turbo timer..etc.)

3) REALLY stupid question - What is the cause of your perpetual check engine light? Although your nifty black tape fix works great :-), is there a better way to get rid of it?

Thanks
Randy
rrsettgast is offline   Reply With Quote
Old 01-18-2000, 03:12 AM   #16
Shik
NASIOC Supporter
 
Member#: 132
Join Date: Jul 1999
Chapter/Region: Tri-State
Location: Central PA
Vehicle:
1997 LGT wagon
2015 WRX on order

Post

Fantastic job Shiv. I think I speak for most when I say I feel pretty fortunate that we have a bunch of very knowledgable guys turbo'ing the Imprezas. Ones that seem to "look befor you leap" . Now, instead of rumors that the NA subaru motors can't handle being turbocharged because of people just throwing turbos on and blowing them up, we have fact that when done correctly, the NA motors(specifically the 2.5) can handle a streetable and reliable 300hp. To me that is simply amazing! Again, to Shiv and the rest of the guys, fantastic job.
Shik is offline   Reply With Quote
Old 01-18-2000, 04:18 AM   #17
Marquis
Scooby Newbie
 
Member#: 64
Join Date: Jul 1999
Location: Lansing, MI
Vehicle:
1999 Impreza 2.5RS
Rally Blue Pearl

Post

All I have to say is, "We're not worthy..."

Really, though, you've done a remarkable service to the community both in what you've done and the full disclosure of details. I applaud your efforts and most certainly look forward to reading all the future articles in SCC.
Marquis is offline   Reply With Quote
Old 01-18-2000, 05:38 AM   #18
Leonardo
Consigliere
Super Moderator
 
Member#: 185
Join Date: Aug 1999
Chapter/Region: South East
Location: Orlando, Fl
Vehicle:
2009 Civic EX
Silver

Question

shiv, How could you describe the difference between 7 and 10 Psi?

Will a Supra Twin-Turbo in-tank fuel pump do? I have a spare lying arround.

What is the address of "readers rides" for your mag?

Leonardo is offline   Reply With Quote
Old 01-18-2000, 05:53 AM   #19
imprezive
Scooby Specialist
 
Member#: 746
Join Date: Jan 2000
Chapter/Region: South East
Location: FL
Question

Hey shiv, Thanx and
Does SCC sell the cars when they are done with them *wink wink*
hahaha
imprezive is offline   Reply With Quote
Old 01-20-2000, 12:44 AM   #20
Andre Vandenberg
Scooby Specialist
 
Member#: 501
Join Date: Nov 1999
Chapter/Region: International
Location: Krum TEXAS
Vehicle:
1998 2.? RS Turbo ;)
RBP

Thumbs up

Thanks for all the research Shiv it sure helps us other WRX & 22B whanna-be's.
Maybe we'll turn the 2.5 RS into a 25 WRX-A. The baddest road going Subys on the planet.....

Andre
Andre Vandenberg is offline   Reply With Quote
Old 01-19-2000, 04:55 PM   #21
SKiDaZZLe
Scooby Newbie
 
Member#: 19
Join Date: Jun 1999
Location: Dallas, TX
Question

Quote:
Originally posted by shiv:

TO RUN 8 TO 10 PSI (est. 280-300HP)===>

1) INSTALL AUXILLARY RISING RATE FUEL PRESSURE REGULATOR

Hmmm... the only unit I know of that does this is offered by Bell Engineering (San Antonio, TX). They make a number of FPRs-- all designed to work differently. The one that I'm using on my car has no spring pre-load and is designed for modified OEM turbo cars. Suprisingly, it's not a big seller because not many people know about it. I should have kept it to myself But the unit works wonderfully because it is designed to become active only at 8psi and above. Below that boost threshold, it is just sitting pretty, letting the very effective S-AFC do all the fuel-related work. In other words, it doesn't screw anything up. This is good. But as soon as the injectors begin to max out at 8psi, it "jumps in" and raises fuel pressure agressively (5:1). To make things easier to visualize, here's a little chart of turbo boost and its associated fuel pressure.

--
Shiv Pathak


Shiv, can you explain how you hook up 2 FPRs? (if that is what you did) And how they work with each other?

Also do you have a part number for that Bell FPR?

TIA

Michael
SKiDaZZLe is offline   Reply With Quote
Old 02-06-2000, 08:02 PM   #22
Mark C. Ritter
Scooby Newbie
 
Member#: 860
Join Date: Feb 2000
Location: Marietta GA, USA
Thumbs up

Shiv,

Thanks much for the article. As a potential RS owner later this year your article was inspiring. Glad to hear that your kind of expertise is out when for when I start to spend $$ and turn wrenches.

Mark C. Ritter is offline   Reply With Quote
Old 02-07-2000, 07:32 AM   #23
nativo
Scooby Specialist
 
Member#: 157
Join Date: Aug 1999
Location: Coamo, Puerto Rico
Vehicle:
1998 JDM STIv8 6sp
Rally Blue Pearl

Question

Señor Shiv:
¡¡¡Muchas Gracias!!! Now can you explain if there would be much diferences if we have a '98RS??

Gracias,
Nativo
nativo 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
Full Disclosure? Transparency in Government? Not with the $700B bailout plan L Bo Political Playground 2 10-19-2008 11:20 AM
How to Drive Fast on Drugs... (warning, very long) Pyr0 Off-Topic 41 07-30-2007 09:12 PM
('93-'01) Rally of Canberra: Lots of Problems...(Warning: Very Long) BigElm Impreza Forum 0 05-08-2001 08:46 AM
Making 300hp. Full disclosure (very long) shiv Technical Forum Archive 23 12-12-2000 08:24 AM
I'm a lawbreaker! (OT & very long) Opie General Forum Archive 23 09-27-2000 07:18 AM


All times are GMT -4. The time now is 06:30 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.