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Old 02-10-2006, 02:34 PM   #1
Siper2
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Impreza GC8 Oh alright I'm curious, how much power should I make?

Boy that's a lousy subject line. Oh well, it's Friday, and I'm tech-support'ed out for the week. My brain's fried.

So I just picked up bisonjr's Stromung cat. pipe this week. (Thanks, dude!) I'll be hooking it up to my car hopefully next week, when Boxer4Racing should be delivering my MIL and hardware/bolt kit.

What have I got?

- PDM-Racing CAI
- K&N panel filter
- Stock headers
- Stromung 2.25" cat pipe
- Stromung 2.25" midpipe (no resonator)
- WRX axleback

I'm thinking something like 10-12chp. Boxer4 says the cat pipe yiedls "6-8hp" and my guess is that it will be the major power gain.

I've noticed a little freer flow/better throttle with the catback since I installed it last year. K&N went on shortly after I got the car, nearly six years ago. PDM has been on since 2003. I have an Exedy Sport clutch, but the OE flywheel.

No I haven't dyno'ed yet. Some day maybe. I'll be happy no matter what. Not expecting miracles, but for me this'll be fun. 165 stock horsies since 2000 will do that to a guy.

=S2=
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Old 02-10-2006, 05:19 PM   #2
Matt Monson
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Yeah,
You've for 175-180 with that setup...
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Old 02-10-2006, 05:23 PM   #3
Siper2
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180 you think?

I wonder how much the axleback is hindering me. I know the WRX axelback piping (this is a 2004 one I think) is like 2.1" internal or something, and the insides of the muffler are a maze (what with that thread in the Gallery about it).

I just know it's better than the one I had before. Bought the car with the Bosal/BroSpeed axleback. Stock pipe diameter, so it did nothing. Unless it was an efficient muffler...
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Old 02-10-2006, 06:08 PM   #4
Matt Monson
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Here's the deal, which is rarely discussed around here since so many guys have so much ego wrapped up in their HP numbers...

An intake and cat back should realistically give you 8-12whp. At the crank, that's roughly 10-15hp. And thus 175-180. The cat may give you a little more, but it'd pretty negligible. You probably know that different mods provide their peak gain at different rpms. You can't just add things on top of each other when you read a manufacturer's dyno details for a part. They generally dyno them as a single part changing, unless they are doing a package like Cobb does.

But here's where that ego thing comes in. You see guys saying they have 190 or more with bolt ons, and they are just doing that false math. Do a search for BSFC (Brake Specific Fuel Consumption). Realistically, we are limited to 185chp without major changes to the set up of the engine itself. You could put headers rated at 14hp and an intake rated at 10hp and a cat back rated at 5 hp, and still only be at that 185hp number. Until you open up the engine and make the engine itself more efficient you aren't going to go any further.

I would imagine that the difference between a complete Cobb stage II and a Ganzflow/borla/random tech/ghetto back is 2-3 with Cobb solidly at 185 hp and the other at like 182.

Sorry for the rambling, but I am just bored and tired this afternoon and felt like some mental mast-urbation. BTW, I am going to do a little experiment shortly. I have a complete Cobb stage II on my car while I rebuild my PnP'd heads. I just bought a set of Cobb headers and a JC sports intake for my gurl's otherwise stock car. I want to dyno both of them. I am guessing they will be within 5whp of each other. The real power on bolt on NA mods is headers and intake; at least that's what the published dyno numbers say for the individual parts...
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Old 02-10-2006, 11:55 PM   #5
Siper2
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Hey that's an interesting point. I never thought of it like that, that each part doesn't necessarily add to the total, rather than the equation...

Excellent. Well, I really could care less about total power, if that sort of thing bugged me I'd have somehow found a job that paid a ton, and bought a faster car. (Though lots of searching for such job hasn't yet yielded fantastic results. ) Hopefully I'll have fun with what I've got.

=S2=
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Old 02-10-2006, 11:58 PM   #6
LordBass
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Chris, I've got pretty much the same setup:

- NESIC hand-me-down homemade CAI
- Amsoil panel filter
- Stock header/cat
- Brullen dual-tip cat-back

A 10hp bump sounds reasonable. All have been on the car for quite a while, though the butt-dyno noticed more growl and shove with the panel filter than with the CAI. *shrug*
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Old 02-11-2006, 12:06 AM   #7
dromango
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raise teh boost level by 2 and u'll easly make that power

actually, if you add in a mix of e85 and have ur ecu reflashed.... currently testing the e85 and im pushing around 180hp bone stock easy

Last edited by dromango; 02-11-2006 at 12:27 AM.
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Old 02-11-2006, 01:25 AM   #8
Suburban
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Dunno about the ghetto back exhaust (I like that ), but my car is doing 126 hp, 126 lb-ft torque according to the G-Tech Pro. That's at the wheels with wind resistance.

I've got the same CAI tube, Kool Blue filter, and a pulley.

It's possible that you might be making less power since the engine might prefer the backpressure of the factory exhaust. Heck, even the CAI might not be doing us any favors either, I didn't test the factory intake.
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Old 02-11-2006, 03:57 PM   #9
Siper2
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Hmm, yeah that's not too encouraging. Guess I ought to get the thing dyno'ed. Not even sure what they cost, really.

ECU reflash I've considered. The i-Speed one I guess is pretty popular...
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