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Old 02-11-2009, 07:33 PM   #1
Imprezed04
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Rally Stuff Stick with Stock Compression??

I've ordered various parts for increasing the performance of my 2004 WRX, however, I've always known that to get more boost out of a forced induction engine, you need to make sure you have a low compression. Currently I'm running a Stock internal 2.0L, however, I'm planning on ordering a solid set of forged internals and dont know specifically where to go to look for them. Should I order pistons with the same specs just forged, or go with a lower compression piston/head combo to increase boost? I've ordered a 18G turbo, front mount intercooler, Turbo XS Type H BOV, and my car already has the typical bolt-on's such as turbo back exhaust, intake, turbo manifold/header as well. My goal is to get somewhere between 450-500 whp. I also know that I need to change some things in the tranny due to the fact that an increase of that amount of horsepower isn't really allowed in the tranny without breaking stuff...

Thank you in advance for all the advice.
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Old 02-11-2009, 07:52 PM   #2
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you could run meth injection and bump up the compression a little.
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Old 02-11-2009, 08:08 PM   #3
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Whats a meth kit cost? Where to get one? and would it be smart to run that on the streets here in Alaska?
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Old 02-11-2009, 08:15 PM   #4
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18g will not be anywhere close to 450-500. More like 275, 300 tops. You're looking @ a 35r at least for that man. You will need a lot more but probably also need a sleeved block to get there safely, and probably a 2.5. Time for more research.
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Old 02-11-2009, 08:19 PM   #5
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Nah I've crunched numbers, the 18g will give me approx 60-75 more hp, the front mount intercooler is going to allow more air, which we all know = more hp. I'm running 650 injectors, Perrin Intake, Full Turbo Back exhaust, no cat, aftermarket up and down pipe. The exhaust system is a full 3". I'm also looking at getting 272 or 280 cams when I order the new heads and forged internals. With these parts, I SHOULD be between 450 and 500.
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Old 02-11-2009, 08:20 PM   #6
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I'll also obviously be reflashing the ECU when the install is done to max hp, and allow for more boost safely.
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Old 02-11-2009, 08:29 PM   #7
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Quote:
Originally Posted by Imprezed04 View Post
With these parts, I SHOULD be between 450 and 500.


I only stopped by in this forum to read an N/A oriented post, but i gotta say...

not a chance. I don't know much about the turbo motors, but i do know 300+ whp takes some serious work, and 400+ is getting away from streetability.

Can 650 cc injectors even support 450 whp?


EDIT: by the way, those injectors don't come close to supporting 450 chp, let alone whp.
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Old 02-11-2009, 08:44 PM   #8
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On what dyno? Sorry man. I doubt you will even hit 350whp. Unless maybe you run race gas and 40lbs of boost.
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Old 02-11-2009, 09:08 PM   #9
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the only way your hitting 450-500 WHP on a 18g is with a 150 shot. just say no
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Old 02-11-2009, 09:39 PM   #10
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you're going to need a bigger turbo..an 18g wont flow enough air to make that on most dynos.

You could hit 10's w/ an 18g if you gut the car enough.

If I was going for big whp out of a 2.0/2.2 L engine I would get forged pistons, rods, and build the bottom end & the heads to withstain 8500 rpm blasts.

HP goals are kind of lame and vague..you'd have better luck saying you want to build a car that will run 12's,11's or trap @ X mph

For example..I am building a 2.2L engine for my wrx and I plan on using a big16g. My goal is to trap between 110-120 mph.
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Old 02-11-2009, 11:20 PM   #11
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I'm shooting for 11.5-12.0 I know its gonna take work, and seeing as I know muscle cars more than anything, I'm here asking for advice. However, to answer your question as to what dyno I used...it was a computer program called AutoCAD, might look into it and see what its capable of.
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Old 02-12-2009, 07:49 AM   #12
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AutoCAD can't do analysis of any sort, as far as i know. To be honest its hayday was a decade ago. EDIT: well, there are some packages available now for it - which one did you use?

Maybe, *maybe*, flowworks could help, but probably not.

There are some quick ways to estimate your power (pick up "maximum boost" by corky bell), but not very accurate ones and even so your estimates are still way, way off.


EDIT: and by the way, we know you screwed your math up because your injector size is wrong. There ARE simple calculations for how much power an injector can support, and those 650's are about 2/3 the size you need.

Last edited by sniper1rfa; 02-12-2009 at 08:21 AM.
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Old 02-12-2009, 08:20 AM   #13
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Quote:
Originally Posted by Imprezed04 View Post
I'm shooting for 11.5-12.0 I know its gonna take work, and seeing as I know muscle cars more than anything, I'm here asking for advice. However, to answer your question as to what dyno I used...it was a computer program called AutoCAD, might look into it and see what its capable of.

You can get into the high 11's pretty easily. I'm there now on stock internals and 50/50 meth. Definitely don't need 450WHP. Remember this is a 3000# car, not a 5000# boat like the muscle cars you're used to. As for your earlier question, plenty of people use a meth mix on daily driver cars. The kits are cheap, and it's like having permanent race gas. Best mod I've done.
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Old 02-12-2009, 09:33 AM   #14
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who told you a 18G can make 450 WHP?????????
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Old 02-12-2009, 12:29 PM   #15
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Quote:
Originally Posted by Imprezed04 View Post
Nah I've crunched numbers, the 18g will give me approx 60-75 more hp, the front mount intercooler is going to allow more air, which we all know = more hp. I'm running 650 injectors, Perrin Intake, Full Turbo Back exhaust, no cat, aftermarket up and down pipe. The exhaust system is a full 3". I'm also looking at getting 272 or 280 cams when I order the new heads and forged internals. With these parts, I SHOULD be between 450 and 500.
No, you really won't be at those power levels at the ground....those cams will also probably leave you wanting more turbo. I'll say 350whp max.

I will however suggest throwing some compression back into the motor for various reasons.

And did you just say you used AUTOCAD to prove that you can make 450whp?!!



Now all joking aside, your goals are reachable but you'll need to change a few things in your plans. You asked the questions on the forum, now stop arguing and open up your ears.
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Old 02-12-2009, 12:32 PM   #16
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are you going to upgradeing the heads at all????
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Old 02-12-2009, 01:18 PM   #17
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Oh boy!

If you really want 450-500 whp forget the 18G (compressor flow limit) and forget the EJ205 block (open deck). Neither will get you there reliably.

Get yourself a 2.5 STi short-block and a set of forged pistons (hone block to fit of course). With your WRX heads you'll be at about 9:1 compression which is nice as long as you know what you're doing tuning wise. You'll need to add cams and valve springs to the WRX heads to make the combo work well.

To hit those numbers you'll need a big turbocharger like our bolt-on GT65 or a 35R. Because of these large turbochargers the high compression and the 2.5 displacement will still allow the car to have a decent powerband.
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Old 02-12-2009, 01:19 PM   #18
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Let's assume the turbo will fit your application. Those injectors will not flow enough. You need at least something in the high 700's if not 800's. A Meth kit is one of the safest ways to add power. It's safe to run on the roads. Use a 70/30 split. The biggest thing the 2.0 is missing is real torque. It's a world of difference between the 2.0 to the 2.5 and you might want to rethink the whole horsepower figure you have in your head and think of ways to increase torque and make that car streetable.
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Old 02-12-2009, 01:28 PM   #19
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Just so you understand, your oem wrx puts ~150-60 to the ground so you're trying to triple that. Do you want a drag car? Sounds like it. You might want to consider a 2.0 for revving.
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Old 02-12-2009, 01:46 PM   #20
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Here's the plan. I have a 2004 WRX with Stage 3 parts in it. I bought it for the most part this way, however, while it is quick, I KNOW that I will get dusted by an STi or an EVO. The plan I have for this is 1, not get waxed at the track, hence the 11~12 sec mark. 2, Mod it so that it makes power efficiently through from low to high rpm's. 3, increase handling for AutoX and what not. Also, I would like to show it a bit this summer at the various events here around Anchorage.

Yes, I plan on porting and polishing the heads, changing valves (given), as well as picking up a set of forged internals. As far as switching blocks, etc. I hadn't exactly planned on it, due to the fact that IF I managed to get a 2.5L block from the STi, I definately know I would want the 6 speed as well. And doing a conversion for that requires other parts and time.

Seeing as I am military, and live on post, I dont exactly have a garage to put the car in and work on it periodically...I'd have to do the work, and be done in a day ish at the Car Care Center.

I know that ya'll know more about this car than I do, however, everyone keeps referring to my WRX as OEM...which it isnt.

I know what parts have been put in the car, just dont know specifics about them. All I can do is take the advice (without being chastized on the forums) and order the parts that get me to my goal accordingly.
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Old 02-12-2009, 01:47 PM   #21
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Quote:
Originally Posted by Imprezed04 View Post
Nah I've crunched numbers, the 18g will give me approx 60-75 more hp, the front mount intercooler is going to allow more air, which we all know = more hp. I'm running 650 injectors, Perrin Intake, Full Turbo Back exhaust, no cat, aftermarket up and down pipe. The exhaust system is a full 3". I'm also looking at getting 272 or 280 cams when I order the new heads and forged internals. With these parts, I SHOULD be between 450 and 500.
Do you live on the planet earth? That turbo can NOT physically flow enough air for anywhere NEAR 500. I done care if you have 361/361 cams, they only allow the air pushed BY THE TURBO to enter, they dont PRODUCE any more airflow.
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Old 02-12-2009, 02:28 PM   #22
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You're asking for a lot here and I would suggest some balance and compromise. A few rules of thumb:

1) The larger HP #'s you shoot for, the more you will lose bottom end power as you will have to get a bigger turbo. Unless you supplement with anti-lag (kinda risky + pricey), this rule will always hold true. E.G. (all examples on pump gas only with the 2.5 on 2.0 heads with cams, valvetrain and headwork)- a 35r will get you to ~450 but you won't see spool in 3rd gear below 4.2K. Lucky by 4K in 4th. A 20g will get you ~330-350 but you will see full boost by 3.4K in 3rd and low 3s in fourth. This is coming from my personal experience. A Dom3 is right in the middle there as reference.

2) Many folks have suggested you lightening the car and you can lose ~300#lbs without going super crazy. This will give you both better pick-up and handling. Try to lose more weight up front as our cars are front heavy (58/42) so it would help with track balance. Many folks have put the battery in the trunk to help this as well.

3) Cams will have a similar effect of #1. You will breath better up top but lose some low end torque.

4) If you lower compression to take higher boost (25 psi+), you will lose off boost power/torque as well. How big is this 'track' of yours that you run on? You keep mentioning 'track' but then quote 1/4 times so I think you are referring to a 'strip'?

5) Doing mods to support higher revving will give you better drag times too = less shifting. I rev my motor to 7750K when I had the 35r but now I'm on the 20g and rarely see over 7.2 b/c its just pointless.

Good luck and you got a lot of research ahead of you man. Look her and otehr places for real world experience and when possible, ride in other folks cars to see how it REALLY feels and if its too big/too laggy or not. The key is to build something you're happy with that will allow you the flexibility to go smaller or larger at safety thresholds only you will agree to yourself man.

Last edited by Fongers; 02-12-2009 at 02:33 PM.
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Old 02-12-2009, 02:50 PM   #23
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By "track" I'm referring to the 1/4 mile track in the area. I also drive the car around town. It's not some trailer queen lol. I want it to look nice, sound nice, and perform well. Meaning I dont feel like blowing rods through the motor every time I decide to punch it on the high way for one reason or another. I've looked into the meth injection kits, and while it sounds easy enough...I'm afraid of chewing up gaskets etc. I guess I could nix the 18g and look for a better performing/ efficient one to create more hp, however, I'm trying to keep the lag down a bit at lower rpm's. This is going to be a project that I'll most likely be working on through the next couple years etc. And I dont mind that. I've build various other Muscle Cars before this, but just kinda new to the turbo and what all goes with it. On a Muscle Car, for added power at all times, just add a supercharger, tune the motor, and make sure it breathes and gets fuel, and for the most part your good to go. As far as turbo goes, you gotta worry about compression, cams, internals, boost, etc. If you add too much boost, you blow out the bottom end, if not the intake. Ya'll know what I'm getting at. I'm sure that all of you out there know ALOT more about these pocket rockets, than I do, hence asking for advice and guidance etc.
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Old 02-12-2009, 03:14 PM   #24
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Bottom line: for 500whp you will have to have a 35r (or equivalent) and race gas to hit those numbers.

You are asking a 2.5 liter motor to make what the LS7 7.0 liter motor makes.
You are going to have lag and plenty of it. You are also going to need a built tranny, upgraded clutch, upgraded diffs and stand-alone engine management to run the injectors.

650's will not come anywhere NEAR enough fuel for 500whp. 880's would be more like it PLUS probably dual walbros or a weldon.

a 500whp 4 cyl is just not going to be very street friendly. The high lift cams will idle like crap, the large injectors will be sluggish at low rpms. And the turbo is gonna be like an on-off switch. LOL

Get with guys like Homade WRX on here as they know much more than me about specifics. I am more a toyota specialist LOL.
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Old 02-12-2009, 03:17 PM   #25
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find the 2.0 section for a while. your driving a stock wrx(even though you dont wanna hear that) so even a basic vf39 or 16g is a huge upgrade for you. start small and work your way up the modding ladder.

and btw a RELIABLE 400-500 whp wrx will cost you in the neighborhood of 10k. start saving.
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