Welcome to the North American Subaru Impreza Owners Club Sunday December 28, 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 06-09-2006, 02:21 AM   #1
Rally_wgn
Scooby Specialist
 
Member#: 62629
Join Date: May 2004
Chapter/Region: MAIC
Location: Richmond,VA
Vehicle:
1996 OBS in Green
2.5 N/A w/ full exhaust

Default N/A power white paper, long, please critique.

This is long you may want to print it out and read at your leisure. I will revise as new information is brought to my attention (note: red text is the revision)

August 07, 2006 Update: Rallitek Header + Exhaust Dyno

How to get power out of a N/A Subaru motor.

This information is based on a reasonably extensive search of this site and specifically the N/A forum. Thanks to Matt Monson, Patrick Olsen, SOLUTION, Slack and several others for there pioneering efforts.

Im sure many will chime in with corrections but here goes:

Cold Air Intake:

Cobb’s Intake is the consensus leader with clear HP gains in the 10 hp range.
Cobb sells the intake for $279 and they can be found used in the $100 range.

Injen makes an intake as well, they have models that fit 2.5L 98-05 RS’s
The only dyno I could find was for there WRX intake which gave +12 hp.
Prices are between $250 and $280 new and in the $150 range used

Ebay Intakes are cheap and have been dyno’d to be competitive with the Name Brand Intakes. http://forums.nasioc.com/forums/show...ay+intake+dyno
They generally require some minor corrective work to fit properly.

EXHAUST:
There are numerous exhaust and muffler combos out there. The general consensus is that the largest diameter you want to use is 2.25”. The typical power gain is in the 10hp range. The biggest Issue is really how loud a particular combo is.

The best bang for the buck is to find a reputable custom exhaust shop and work with them to build an exhaust to your specs. Quotes I have gotten are in the $300 range. Keep in mind this is a mild steel piped exhaust with a Magnaflow or similar muffler and hi flow cat.

Cobb / TWE and Rallitek along with several other suppliers offer Stainless Steel setups for $500 - $800 dollars new. The benefits are obvious. These setups can however be found used on NASIOC.COM and RS25.com fairly frequently so some patience will save you some money.

OBX on ebay, Sparktec is the store, sells a Cat Back exhaust for $275 + $75 shipping. IF it is built like their other products then it will likely need some work to get everything to fit. This post illustrates the possible issues.
http://forums.nasioc.com/forums/show...2&page=3&pp=25

HEADERS:
Headers are the next step in the exhaust / power upgrade ladder. There are two types generally. Unequal length headers, used on most N/A subarus until the ’06 model. These are attributed to giving the Subaru its distinctive “boxer rumble”. They are generally believed to be less useful for generating power.

Equal Length headers apparently improve exhaust pulses and significantly improve power. The loss or reduction of the boxer rumble has kept many Subaru owners away from EL Headers. Typically a good resonator in the midpipe will restore the “rumble”.

Borla sells both a single port and dual port unequal length header. The Borla header is renowned for its enhancement of the “rumble” that makes so many Subaru owners pants tight J . Early versions had some issues with cracked welds but newer generations have apparently solved this problem. The Borla header is available for around $300 new and $150 used.

COBB / Rallitek sell an EL header that appears to be of a similar design. Dyno results indicate an avg gain of 12 - 15 hp but gain results for bolt ons depend heavily on supporting mods, intake, exhaust, cams, etc. Both of these headers replace the stock cats with a new cat section as the routing of the pipes is changed significantly from stock. Cobb gives some dyno information here:
http://www.cobbtuning.com/impreza/im...rformance.html
Cobb’s EL Header runs $650 w/o a cat, add $100 for hi flow cat
Rallitek’s EL header costs $700 not sure on the cat status.
Used both can be found in the $400 -$500 range.
Picked up a COBB header w/ hi flow cat and thermal coating for $400 from RS25.com

Rallitek EL Header Dyno
http://www.rs25.com/forums/showthread.php?p=890856&posted=1#post890856

TWE sells a EL header designed to work with the stock exhaust routing which can be handy. Power gains appear to be on par with the competition. Cost of these headers new is listed at $950 plus $460 for a hiflow cat section if you want it. Used price is commonly around $750.

MRT also sells a EL header on there site. After doing the conversion it appears to be $440 US. I dont believe this includes shipping as you have to put in credit card info before that is calculated.

Patrick Olsen's MRT vs OBX dyno thread, good read.


ENGINE MANAGEMENT
EM comes in a couple of forms piggyback, standalone and air-fuel controller. Each provides diffirent benefits and different costs.

S-AFC is the most common air/fuel controller I see used. This device is relatively easy to install some splicing may be required and only controls the air / fuel ratio at given RPM levels. As Subaru’s apparently run pig rich this little device can yield gains and provides some level of engine safety by giving the user the tools necessary to avoid running to rich or too lean. Prices new run around $250 and used ones run in the $150 range.

Perfect Power Pro is the most widely mentioned piggyback system for N/A Subaru motors. The PPP allows the user to control a/f ratios, and timing to further optimize your Subaru’s power. The biggest benefit to the PPP IMHO is the ability to adjust the timing and a/f as you add mods to your motor. The PPP comes with software to use a laptop to adjust engine maps to meet new requirements. Also Rallitek will provide you with 2 maps if you provide your cars specs to them when ordering. The PPP costs $440 from Rallitek and this includes 2 maps and tuning software. It is generally believed that the PPP adds about 10 hp to your current setup. Warning: the following thread should be considered before purchasing / installing PPP.
http://forums.nasioc.com/forums/show...t=cracked+coil

One word of caution the PPP requires that you splice the piggyback into your ECU wiring harness. This may deter some from using it but I believe a competent shop or friend could help if this is the case. Rallitek does offer a PnP harness, this is only available for ’05 / ’06 models according to their site.

Standalone systems such as linx and hydra give the user full control over the engine. These essentially replace the stock ECU. These systems require a fair bit of user knowledge from what I can tell and are quite expensive, $2000 - $4000 depending on capability.

[color=red]For the those of us who like to tinker, there is the megasquirt system. Essentially a stand alone system that you can build from scratch to meet your exact needs. The basic kit starts around $250 and provides full control over a/f ratios, timing advance, IAC control etc. Check out http://www.megasquirt.info/ for more information.

I forgot the I-speedusa ECU reflash. This seems to be effective for many ppl. You give I-Speed your ECU and mods and they reflash the chip for additional power. As you add mods you will have to update the reflash. The initial license for N/A apps is $350 with the updates at $125.

New information is out on the COBB Accessport for NA cars. Se the following threads, we'll be watching. http://forums.nasioc.com/forums/show....php?t=1034195

On to bigger projects

CAMS
Cams provide more aggressive power curves by changing lift and duration of the valvetrain. They generally come in 3 flavors: Street/Stage 1, Spicy/Stage 2, Race/Stage 3. I will really only address the first two and the race versions tend to make the car less than streetable. Changing cams also requires a decent level of comfort with pulling your engine part. Generally it helps to remove the engine and partially disassemble the heads. Power gains are significant, 15 – 18 HP.

Where the gain is realized is determined by the “stage” of the cam. Street cams provide power in the mid and upper range of the redline. Spicy cams provide most of their gains after 4000 rpms and can benefit from raising the redline. This however requires additional upgrades such as stronger springs and EM. There is some debate about this however. I have not seen a definitive answer to this issue.

COBB and TWE both offer cams at both levels. Both require a core return. Your intial outlay will be $900 for the COBB cams, then a $400 refund when you return your old cams to COBB. TWE sells both levels for $540 for SOHC versions.

A common route for cams is to have them reground to specific lift and duration. Deltacams is the most common and trusted supplier of regrinds. Keep in mind this requires you send them your cams (engine no worky) and they send them back modified. The process requires they weld new material on to the existing cam and regrind the material into a new lobe. Delta carries two grinds last I checked that correspond with the “street” and “spicy” monikers. The beauty of the regrind is that it cost about $75 per cam. So a SOHC owner spends $150 for improved performance. An interesting thread on Delta's 220 grind

Labor for cam work can be expensive so search around a fellow NASIOC member in your area may be able to help.

PORT AND POLISHED HEADS

Port and polished heads provide better and greater airflow for the combustion process. This translates into more power. Coupled with a/f control, cams, intake and exhaust mods significant power gains are possible. Generally port and polish assumes a multi-angle valve job.

Again this procedure requires that you remove your engine from the car and take the heads completely off the motor and disassemble the heads completely. Then send the heads to folks like Crucial racing for the work.

This procedure follows the typical 3 stage format. As before Stage 3 is intended for the track and is likely to make the car difficult to use as a daily driver. It also is likely to significantly reduce low end power and require stand alone EM to be worthwhile.

COBB sells stage1 heads for $1375 assuming you send them your heads otherwise there is an $800 core charge.

TWE offers all 3 levels of head work. Stage 1 is $1500 and Stage 2 is $2000. The valve job is extra at $250.

Most other vendors charge between $1000 and $2000 for similar work. HP gains are highly dependent on supporting mods. EM is also very helpful as this work coupled with intake can begin to make Subaru’s running very lean (not good) at higher RPMs.

I have seen used heads with this work already done for sale but generally they are not any cheaper than having the work done to your existing heads. I have also pulled good heads from my local junk yard for $100, so you may be able to avoid having the car out of commission for extended periods.

One final note on this subject, I have spoken with ExtrudeHone about their process and its cost. They claim similar gains and charge $600 to ExtrudeHone a set of 4 cyl Subaru heads. I don’t have any information on power gains, anecdotal or otherwise.

INTAKE MANIFOLD

Swapping the intake manifold is another power gainer that is available to the owner willing to put in time to figure out how to do it. The consensus is that the ’04 and ’05 intake manifolds provide better air flow to the cylinders and therefore more power. Pricing on this is all over the board as these are OEM parts and also available from salvage yards.

The biggest hurdle appears to be the retro fitting of the newer intakes to older EJ25 motors. For the ’05 intake look here:
http://forums.nasioc.com/forums/showthread.php?t=976482

Extrudehone also works their process on intake manifolds. If you search COBB’s site you will see that their initial N/A build project car used an ExtrudeHoned Manifold. Again I don’t have any data on the benefits of this process. The pricing from ExtrudeHone was $300.

HIGH COMPRESSION PISTONS

This is the big dog of mods. Not necessarily because of power gains, of which there are good ones, but because of the work necessary to do this. The pistons raise the compression of the EJ25 from its decent 10:1 ratio to some where near 11.2:1 for street purposes. Anything beyond this requires high octane race gas to run correctly as well as standalone EM. At the 11.2:1 level the motor will require good quality premium all of the time. It has been brought to my attention that 12:1 compression may be the safe limit for 93 octane use. But a quality EM system is highly recommended, otherwise engine may BOOM!

This mod usually requires that the bottom end be beefed up. This means better main bearings, better rods and forged crankshaft for reliability. The pistons themselves cost around $700 -$800. TWE shows $719 on their site just for the pistons. The additional block work and parts will likely run another $700 - $800 assuming you do the assembly.
Additionally some owners are using the Sti’s EJ257 block as it has the necessary reinforcement already. New Sti Blocks cost about $1700 though used ones can be had for around $1000.


To be continued...
* Registered users of the site do not see these ads.

Last edited by Rally_wgn; 08-07-2006 at 10:34 AM.
Rally_wgn is offline   Reply With Quote
Old 06-09-2006, 02:22 AM   #2
Rally_wgn
Scooby Specialist
 
Member#: 62629
Join Date: May 2004
Chapter/Region: MAIC
Location: Richmond,VA
Vehicle:
1996 OBS in Green
2.5 N/A w/ full exhaust

Default

THE SMALL STUFF

PULLEYS AND LIGHTWEIGHT FLYWHEELS
There are other “power” mods that are popular that if anything improve the feel of the car. The lightweight pulley is generally considered a useful mod. It reduces the drag of rotational weight on the crankshaft “releasing” about 3-5hp worth of energy to the wheels. The biggest benefit being better throttle response and faster revving.

COBB sells their Power Pulley for $135, Rallitek sells Perrins Lightened Pulley for $130. Unorthodox Racing carries two types, one lightened and one lightened and underdriven. The Underdriven pulley has a smaller diameter than the stock pulley so it has even lower parasitic drag on the crankshaft. The down side is that is doesn’t drive accessories on the car as well as stock so there may be some loss of electrical power. Most vendors price the UR pulley at $150. Mr Josh sells a pulley for about $75.

Lightweight Flywheels provide the same type of gain as the pulley. It is generally recommended that you don’t do both the flywheel and the pulley as it may cause the car to idle poorly. Some owner report no problems but the recommendation is from knowledgeable sources.


GROUNDING KITS
Grounding kits provide better electrical grounding to the cars sensors and electrical system. The theory being less electrical interference provides the car’s ECU with better data and the car runs better and stronger. Most users seem to notice smoother idle and excelleration. Some dynos are available that suggest a small 2 – 4 hp gain. These kits can be found on EBAY and most aftermarket suppliers. Paranoid Fabrications sells a nice kit onfor between $35 and $50 depending on the level of wire and fabrication desired. He can be found on www.rs25.com . A DIY kit can be put together for about $10, instructions for this are all over the Web.

THROTTLE BODY SPACER
While not a new concept in N/A performance enhancement, suppliers for this part for the EJ25 seem to be just one. Area1320 sells a EJ25 TB spacer and has dynos on their site showing around 4hp gain. However most users have reported a significant gain in fuel mileage. Somewhere in the neighborhood of 4 mpg. At $150 this could pay for itself quickly. One caveat is that supplies seem to be pretty limited as the shop makes these on a part time basis. It is not their primary business.

THE GREAT DEBATE

In your searching (assuming you do any) you will find in every thread about N/A power at least one naysayer who calls you stupid for trying to make N/A power. Their solution is to always swap in a WRX motor or turbo your existing 2.5L motor. The argument being that it provides more power and is less expensive or a better value.

Here is my opinion on the issue. First lets address the cost issue. If you buy a USDM WRX motor you will generally spend $1500 -$3500 on the motor, this should include a wiring harness and ECU. This is money that is spent in one lump sum and is not always easy to do. These motors are almost always used so reliability is a concern. There are many threads of folks buying bad motors and having to chase down the seller to get their money back.

Additional associated with the swap include exhaust parts, uppipe, downpipe and turbo cross member. On top of that is the hours spent splicing the WRX wiring harness into your RS / L harness. For a first timer expect about 30 – 40 man hours. My time is worth about $40 an hour in my business that is an additional cost of $1200. So figure a full $4000 of real dollars as the swap cost. You may need driveline components as well.

With the swap you get a WRX engine that dynos at around 170whp. A stock EJ25 dynos at about 100whp. If you have an older Impreza your car is also lighter than current Impreza so power to weight becomes a factor as well. A 1996 – 2001 impreza only need about 150whp to equal the power to weight ratio of a bugeye WRX. I will illustrate.

A 1998 Impreza weighed about 2800 lbs ( the coupe and sedan less, the wagons more). Based on 100whp a GC style impreza has a p/w ratio of 28:1.

A 2002 WRX weighs about 3100lbs, with 170whp its p/w ratio is 18.24. To equal that p/w ratio the GC owner only needs 152hp at the wheels. This can be achieved with cams, intake, headerback and EM. New these parts would run about $2000. Do some smart shopping and your budget is closer to $1200. You also don’t have to spend the money all at once so you can use WAM (walking around money), those readers who are married know how important that can be. Keep in mind that these numbers assume the two vehicles are dyno on the SAME dyno under similar conditions. Dyno results varily widely from one dyno brand to another, one location to another and even the operator of the dyno can have and impact.

You also don’t have the down time of a swap. Parts can be bought and installed a little at a time, so the car is down for a weekend. Cams are the only parts that put you out for a week or so. The addition of heads can put the N/A owner close to WRX power levels. Coupled with the RS’s better gear ratios, a properly tuned RS can give even Stage 1 WRX’s a run for there money in most situations.

Auto-x favors the tuned N/A car. The WRX needs to spool out of every corner ( the ’06 model fixes this to some degree) unless left foot braking is well executed. The N/A motor sees good power from 2500 rpms to redline.

For the $4000 that a swap would cost a prudent N/A impreza owner should be able to reach the hi comp piston level of build, assuming the labor is DIY. This should give you at least 200hp at the wheels. Keep in mind that their only a handful of ppl attempting a build to this level and it can be time consuming. But a stock WRX needs a Stage 1 mod package to reach these levels, and at that the p/w ratio is still an issue.


Conclusion

N/A power is available for a reasonable cost, don’t let the boost fanboys tell you otherwise. But if you want 300hp in your current non-turbo impreza your money IS better spent on a swap. If you want WRX levels of power without dropping $3000-$5000 in one lump then consider the build instead.

P.S. for us 2.2L owners, add in an additional $500 to $1000 for a 2.5L motor to swap. Fortunately this is a plug and play procedure for the most part. So down time is at a minimum. Also you can do things like heads and cams before you drop the motor in saving you more time.

There is also the Frankenstein motor. This is a 2.5L block with 2.2L heads which bumps compression up to the 11.2:1 area. I haven’t seen any dynos but the math makes sense. A 2.5L block can be found for $250 - $500 and heads can come off your existing engine. You simply swap intake manifold and everything else over to the new longblock. I am considering doing the cams pre-install as I have a set of ’94 dual port heads (I can take advantage of the new EL header available) I picked up for $100 at my local u-pull-it junkyard. Power with Borla headers, intake is reported to be in the 150whp range. I’m interested to see what cams, EL headers and PPP6 do at the dyno and the strip. Hopefully I can have this done by the end of this year (’06)

For those interested their is good post here on 1/4 times. http://forums.nasioc.com/forums/showthread.php?t=886267

To see what is possible with enuf resources check zzyxx outhttp://zzyzxmotorsports.com/news/300hpnamods

Matt Monson's thread with dyno info
http://forums.nasioc.com/forums/showthread.php?t=595740

Last edited by Rally_wgn; 06-23-2006 at 01:07 AM.
Rally_wgn is offline   Reply With Quote
Old 06-09-2006, 09:19 AM   #3
reality1011
Scooby Newbie
 
Member#: 114475
Join Date: May 2006
Vehicle:
2000 Impreza RX
Silver

Default

good write up.... expecting others thoughts to come in ....

but this is a good arguement
reality1011 is offline   Reply With Quote
Old 06-09-2006, 12:30 PM   #4
JoshP
Scooby Specialist
 
Member#: 94350
Join Date: Aug 2005
Chapter/Region: NESIC
Location: S. Maine
Default

Great write up, I have to disagree about high compression motors though. You said that anything north of 11.2:1 will need race gase and engine mangement. While I agree that those things would be great with the high compression, some of the locals here run hybrid engines with 12:1 c/r on 93 ocatane with stock ecus. Those motors run great, and have lasted well. My build is going to be high compression on 93 octane, but I plan on using a s-afc or e-manage. Just my opinion though, great thread!
JoshP is offline   Reply With Quote
Old 06-09-2006, 12:41 PM   #5
Rally_wgn
Scooby Specialist
 
Member#: 62629
Join Date: May 2004
Chapter/Region: MAIC
Location: Richmond,VA
Vehicle:
1996 OBS in Green
2.5 N/A w/ full exhaust

Default

Tzedek thank you for both the compliment and the input. I have added additional info to the post based on your opinion.
Rally_wgn is offline   Reply With Quote
Old 06-09-2006, 05:34 PM   #6
bstarr
Scooby Newbie
 
Member#: 74827
Join Date: Nov 2004
Chapter/Region: MWSOC
Vehicle:
1999 impreza rs
rbp

Default

awesome write up, maybe even a sticky
bstarr is offline   Reply With Quote
Old 06-09-2006, 06:21 PM   #7
Diz
Scooby Specialist
 
Member#: 874
Join Date: Feb 2000
Chapter/Region: RMIC
Location: Colorado Mountains
Vehicle:
2004 Porsche 911
2004 Mazdaspeed MX-5

Default

In addition to Cobb & TWE, Delta cams offers cams for our cars.
Diz is offline   Reply With Quote
Old 06-09-2006, 06:23 PM   #8
vincent-h
Scooby Specialist
 
Member#: 59504
Join Date: Apr 2004
Location: Chestermere/Calgary AB
Vehicle:
2005 Impreza RS

Default

I'd bump this to a sticky i've done a ton of research on n/a and its very nicely compiled on here with very accurate dummy proof info.

If i dig up some more stuff i'll be sure to post it here for your review and editing... Also i'll be dynoing the injen intake at the end of june unfortunately i don't have a stock dyno but i will release the numbers i get with it installed.

on top of that i'll be dynoing a full twe exhaust system at the end of july which will also be added and posted here for yours and everyone elses review. hopefully we can see how nicely your numbers up there add up :P
vincent-h is offline   Reply With Quote
Old 06-09-2006, 06:40 PM   #9
DoinkMobb
Scooby Specialist
 
Member#: 3787
Join Date: Jan 2001
Chapter/Region: South East
Location: Lutz, FL...that's N. Tampa
Default

Excellent. I hope this writeup is around in a few years, because I have a project in mind someday: super lightweight FWD Impreza with a high rev NA EJ25.
DoinkMobb is offline   Reply With Quote
Old 06-09-2006, 06:48 PM   #10
Rally_wgn
Scooby Specialist
 
Member#: 62629
Join Date: May 2004
Chapter/Region: MAIC
Location: Richmond,VA
Vehicle:
1996 OBS in Green
2.5 N/A w/ full exhaust

Default

vincent i look forward to your contribution. I think it would great if this thread turned into a collection of solid N/A tuning info.
Rally_wgn is offline   Reply With Quote
Old 06-09-2006, 08:11 PM   #11
goNads
Scooby Newbie
 
Member#: 61888
Join Date: May 2004
Chapter/Region: SCIC
Location: San Gabriel, CA
Vehicle:
2003 Outback Sport
Midnight Black Pearl

Default

under EM: I-Speed N/A reflash
goNads is offline   Reply With Quote
Old 06-09-2006, 08:37 PM   #12
Rally_wgn
Scooby Specialist
 
Member#: 62629
Join Date: May 2004
Chapter/Region: MAIC
Location: Richmond,VA
Vehicle:
1996 OBS in Green
2.5 N/A w/ full exhaust

Default

Fixed for ya goNads. Thanks for the reminder Diz, I rechecked the doc and Delta is mentioned.
Rally_wgn is offline   Reply With Quote
Old 06-10-2006, 06:09 AM   #13
anonymous_wolf
Scooby Specialist
 
Member#: 57780
Join Date: Mar 2004
Chapter/Region: VIC
Location: Richmond B.C.
Vehicle:
2000 RS sedan, GC6
Blue Ridge Pearl

Default

brullen also makes equal length headers.
it's discountinued but used ones can be found in 400-500 range with a hi-flow cat depends on condition.

for the cobb intake used one cost from 150-200, it would be a STEAL to found a used cobb for 100.

for EM there's also e-manage (or something like that?)

also another common small stuff for power is upgraded spark plug and wire (ie, magnecore)
anonymous_wolf is offline   Reply With Quote
Old 06-10-2006, 11:11 AM   #14
cueball89
Scooby Specialist
 
Member#: 90513
Join Date: Jul 2005
Chapter/Region: Tri-State
Location: NY
Vehicle:
2003 wrx wagon
black

Default

for em, i think its a build your own stand alone.
http://www.megasquirt.info/
cueball89 is offline   Reply With Quote
Old 06-10-2006, 11:37 AM   #15
Rally_wgn
Scooby Specialist
 
Member#: 62629
Join Date: May 2004
Chapter/Region: MAIC
Location: Richmond,VA
Vehicle:
1996 OBS in Green
2.5 N/A w/ full exhaust

Default

thanks for the info wolf, I have purchased two COBB intakes used in the last couple of months for $90 each, you just have to be patient.

I didn't include the Brullen's because they are discontinued and I couldn't find enough examples of ppl use them to make a judgement on there effectiveness. But they are out there.

YOu are the second person to mention e-manage, so I'm researching that now.

From what I have seen upgrading plugs and wires doesnt seem to have any real effect on horsepower on our cars. Upgraded ignition systems seem to help but I havent found any real empirical data on the effect they have. If you have a post or article that has solid information I would really like to read it.
Rally_wgn is offline   Reply With Quote
Old 06-10-2006, 11:46 AM   #16
sryardsale
Scooby Newbie
 
Member#: 116045
Join Date: May 2006
Chapter/Region: NESIC
Location: Wethersfield, CT
Vehicle:
1998 2.5 RS
black

Default

awsome write up, lots of usefull information in there
sryardsale is offline   Reply With Quote
Old 06-10-2006, 12:06 PM   #17
GuyLR
Scooby Specialist
 
Member#: 21811
Join Date: Jul 2002
Chapter/Region: South East
Location: Atlanta, GA
Vehicle:
2003 WRX Wag/01 OBS
WRB and SM

Default

Your power to weight comparisons should also include the weight of the driver and a tank of fuel to be more accurate. This will negate some of the older GC/GM/GF cars weight advantage because you, the driver weighs the same in both cars and they have the same size fuel tank so the relative additional weight as a percentage of the total is smaller in the GD cars.
GuyLR is offline   Reply With Quote
Old 06-10-2006, 12:26 PM   #18
anonymous_wolf
Scooby Specialist
 
Member#: 57780
Join Date: Mar 2004
Chapter/Region: VIC
Location: Richmond B.C.
Vehicle:
2000 RS sedan, GC6
Blue Ridge Pearl

Default

Rally_wgn:

damn you are good at finding used part for cheap then.
i've been watching the classified field for quite a long time and the cheapest i've ever seen is 140 shipped and they sell pretty fast.

I have brullen headerback right now that I'm having a bit of mixed feeling to.
it surely sounds great but the power increase of header back vs. catback is really not much. I'm gonna do emission and change my exhaust back to stock on monday, maybe i'll have more insight after i review the feeling of stock exhaust

I too is very interested in how e-manage work and how effective it is.

IMHO both spark plug wire and the grouding mod are those things with too small of an effect to have any empirical data. some might feel a difference in throttle response and smoother acceleration, but some say it's just placebo effect~

btw, just noticed we both lived in Richmond, just different country and state...haha

anyways, very very nice write up, this should be sticky man!
anonymous_wolf is offline   Reply With Quote
Old 06-10-2006, 01:09 PM   #19
Rally_wgn
Scooby Specialist
 
Member#: 62629
Join Date: May 2004
Chapter/Region: MAIC
Location: Richmond,VA
Vehicle:
1996 OBS in Green
2.5 N/A w/ full exhaust

Default

how could I have forgotten megasquirt. Though it is not mentioned much on the N/A forum specifically it is a viable EM alternative.
Rally_wgn is offline   Reply With Quote
Old 06-10-2006, 01:11 PM   #20
Matt Monson
Scooby Guru
 
Member#: 832
Join Date: Jan 2000
Chapter/Region: RMIC
Location: Teh Ghetto Garage, CO
Vehicle:
99 2.5RS, '85 911
'73 914 and 2012 BRZ

Default

Quote:
Originally Posted by tzedek
Great write up, I have to disagree about high compression motors though. You said that anything north of 11.2:1 will need race gase and engine mangement. While I agree that those things would be great with the high compression, some of the locals here run hybrid engines with 12:1 c/r on 93 ocatane with stock ecus. Those motors run great, and have lasted well. My build is going to be high compression on 93 octane, but I plan on using a s-afc or e-manage. Just my opinion though, great thread!
Realistically, this is going to vary greatly by location. This is because both available local octane and altitude influence this. I consider 11.2-11.4 to be a good safe limit as a generalization. Beyond that, as he alluded to, running some sort of EM is the best approach. If one were to make the blanket statement that 12:1 CR was safe on pump gas, there would be guys out there who had engines go south on them because they were misadvised...

Rally_wgn,
Great compendium of info. Really my only suggestion would be to trying and get some clarity regarding dyno's. In your power to weight ratio section, you make reference to a certain WHP level that will be equal to a WRX. Without knowing both the stock NA and WRX power levels on that same dyno, it's a meaningless number. I make 150whp on our local Dyno Dynamics dyno, and more like 170+ on a Mustang. I was handing WRX's their arse back when I was in the 130's. The only point is that it's all relative, and like my CR comments, it something where making gross generalizations gets into questionable territory with respect to accuracy...
Matt Monson is offline   Reply With Quote
Old 06-10-2006, 01:43 PM   #21
Rally_wgn
Scooby Specialist
 
Member#: 62629
Join Date: May 2004
Chapter/Region: MAIC
Location: Richmond,VA
Vehicle:
1996 OBS in Green
2.5 N/A w/ full exhaust

Default

Hey Matt, thanks for the comments. You make a good point, I made the mistake of assuming the typical reader would know that dyno numbers are specific to that particular dyno and not neccesarily applicable to a dyno of a different make or in a different geograpic location, say 5000 ft above sea level
Rally_wgn is offline   Reply With Quote
Old 06-10-2006, 01:43 PM   #22
andys
Scooby Specialist
 
Member#: 53455
Join Date: Jan 2004
Location: vancouver
Vehicle:
2004 Forester XTI-RR
dark

Default

turbo ej20 motors are like 500$. Why get a WRX motor when you can get an old OBD1 closed deck JDM legacy EJ20G turbo motor? Mine was 750$ cdn with EVERYTHING and it hauls a$$.

Also you can get a turbo back straight exhaust for cheap and it's not really that loud because of the cats and turbo. NA makes no sense. Sorry
andys is offline   Reply With Quote
Old 06-10-2006, 01:59 PM   #23
Rally_wgn
Scooby Specialist
 
Member#: 62629
Join Date: May 2004
Chapter/Region: MAIC
Location: Richmond,VA
Vehicle:
1996 OBS in Green
2.5 N/A w/ full exhaust

Default

Quote:
Originally Posted by andys
turbo ej20 motors are like 500$. Why get a WRX motor when you can get an old OBD1 closed deck JDM legacy EJ20G turbo motor? Mine was 750$ cdn with EVERYTHING and it hauls a$$.

Also you can get a turbo back straight exhaust for cheap and it's not really that loud because of the cats and turbo. NA makes no sense. Sorry
Quote:
Originally Posted by rallywgn
In your searching (assuming you do any) you will find in every thread about N/A power at least one naysayer who calls you stupid for trying to make N/A power. Their solution is to always swap in a WRX motor or turbo your existing 2.5L motor. The argument being that it provides more power and is less expensive or a better value.
At least one always shows up, oh well its a free country and public site.

Perhaps in Canada turbo EJ20s are available a dime-a-dozen but they are rarely available and parts are even harder to find in the States.

In places like the Socialist Enviromentalist People's Total Eutopia of California OBD1 engines may not pass anti-smog laws so it may not be an option.

All other swap problems of rewiring etc. still stand and the car will still likely be slower and more fragile.
Rally_wgn is offline   Reply With Quote
Old 06-10-2006, 02:53 PM   #24
andys
Scooby Specialist
 
Member#: 53455
Join Date: Jan 2004
Location: vancouver
Vehicle:
2004 Forester XTI-RR
dark

Default

not slower - no way.

wiring - yes. PITA. but it's not that bad once you know what to do. You only really need to connect 6 or 7 wires to your original car harness.

availability - they are mostly in demand by the dune buggy people. If you sniff around a bit you can find all kinds. As for parts - well it's basically the same engine as the US ones (for the most part) and any part number I have taken to the dealer has resulted in me receiving the part in a couple of weeks. Even if it is a JDM part.

Like i said - I am not being an armchair theorist. I have one. I installed it. I've messed with my 2.5 NA. The turbo is not fragile - I have never DNFd in my rally car because of it. It hauls at 16 psi on a whimpy vf11. It cost so little that if I blow it I'll just by another one for 500USD and swap it out. there's no point even opening it up!!
andys is offline   Reply With Quote
Old 06-11-2006, 02:12 AM   #25
NekkedSquirrel
Scooby Newbie
 
Member#: 91360
Join Date: Jul 2005
Chapter/Region: Tri-State
Location: Between WB and Scranton....
Default

wow..... looks to be alot of great info here... gunna have to look into some of these to add to my N/A Suby! Keep the info coming!
NekkedSquirrel 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
Build-up plans, please critique bongchild Normally Aspirated Powertrain 11 09-27-2005 04:25 PM
OT: Please Critique my resume DrDRum Off-Topic 25 07-20-2005 05:48 PM
Please critique this computer... GarySheehan Off-Topic 67 09-13-2004 07:40 PM
OT please critique my resume suprsubepower Off-Topic 17 03-23-2004 05:15 PM
IT/Developers please critique my resume maaw Off-Topic 9 08-22-2003 04:16 PM


All times are GMT -4. The time now is 04:14 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.