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Old 08-05-2008, 05:26 PM   #1
auslyle
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Default is 230 whp NA to much to ask for??

so I've been doing a lot or research and have came to the conclusion that if VW's can do it why cant we??

TechWorks Engineering (Calgary, Alberta, Canada) clames that there normally aspirated Subaru 2.5L Flat-4 makes a wapping 300 HP (235 WHP at 6450 RPM and 209 WTQ at 4600 RPM)...we typically see 233 WHP for a WRX STi, which is rated at 300 HP. if so I could have a NA that is a stock sti killer and also would be incredible in the auto-x

using 11.2:1 CR forged pistons, Stage II SOHC Street cams and headwork, complete built bottom end

whats everyones opinions?
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Old 08-05-2008, 05:56 PM   #2
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Its doable.
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Old 08-05-2008, 06:20 PM   #3
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I need it!
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Old 08-05-2008, 06:21 PM   #4
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Is it really a need? Or just a want?
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Old 08-05-2008, 06:24 PM   #5
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it's a need! no one believes it can be done around here
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Old 08-05-2008, 06:55 PM   #6
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I believe it can be done, its been done before.
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Old 08-06-2008, 03:52 AM   #7
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There are plenty of us that believe it can be done, but very few of us who have the money to blow on a race motor. (Which is exactly what you would end up with.)
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Old 08-06-2008, 02:19 PM   #8
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Be real careful that if you decide to do this, you go to a reputable engine builder.
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Old 08-06-2008, 05:43 PM   #9
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it can be done..stand alone, built heads to rev high and maybe race gas

if u want high NA hp go honda and take off everything on your car until it weighs nothing, lols
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Old 08-06-2008, 06:47 PM   #10
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you can save a lot of money and just buy a turbo lol
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Old 08-06-2008, 07:03 PM   #11
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You'll need a 2.8 liter stroked motor, with good heads, good intake, and good exhaust to make that much power NA. You're talking a race built motor, it'll probably end up costing about $12k. Then, you have to realize, you're just hitting STi stock territory... Then you will have to worry about your transmission, axles, brakes, etc. You could blow another $10k on transmission upgrades, and that puts you into used 2004 STi territory.

Do it if you really want to, but you'll probably need more than the following list of parts:

17" wheels
STi hubs, axles, brakes
STi transmission, rear diff, hydraulics, shifter, linkage, mounts
STi suspension
STi Shortblock overbored and sleeved
Stroker crank
Forged pistons (11:1 or higher) and connecting rods
TWE 2.5" exhaust, block to muffler tip
Fancy DOHC heads
Race cams
upgraded valvetrain, including valves, springs, bucket under shim conversion, etc.
Fancy intake
Fuel injectors, rails, and pump

Then you'll have to think about tuning. There are many options, but with a 2.5" exhaust, stage III cams, and a higher CR, you're going to need at least to shift your power band up, probably having a rev limit at 8,500 rpm. You'll need EM flexible enough to allow you to custom tune your entire setup.

That's a huge list just to get you reliably to 300 CHP. Good luck.

Alternatively, you could spend $1200 on a used STi shortblock, $2000-$3000 on heads, $100 on an XMember, $100 on a FSB, and however much an UP, turbo, and DP costs, $1500 on EM, and have a 300 CHP turbo subie. The powerband isn't INSANE like a 300 CHP NA beast, but it's better than 165 CHP.
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Old 08-06-2008, 07:16 PM   #12
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You guys should stop always trying to talk someone out of it with money, maybe he doesnt care, maybe he wants to be unique. If he's ever gonna actually do this, he'll do research, and find out how much it costs.
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Old 08-06-2008, 08:14 PM   #13
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Quote:
Originally Posted by mxpunk View Post
if u want high NA hp go honda.
+12345
why not stick with what subaru is good at; turbo motors.
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Old 08-06-2008, 10:52 PM   #14
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Quote:
Originally Posted by Chi_San View Post
The powerband isn't INSANE like a 300 CHP NA beast, but it's better than 165 CHP.
???

A 300chp turbo has a way better powerband than a 300chp small displacement NA
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Old 08-07-2008, 11:39 AM   #15
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To make high horsepower on a N/A motor, you only need 3 things.

1) high compression
2) big cams
3) high RPM

Obviously, you can't have a restrictive intake or exhaust. This is a case where I would go with a billet crank and titanium rods and spin it to 9,000+ rpm. I'd probably use adapters to fit ITB's as well.

As for needing $10,000 for drivetrain mods for a 300hp motor, that's just silly. MFactory gears would probably be a good match for the powerband, though.
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Old 08-07-2008, 02:04 PM   #16
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If power is all your looking for then yeah its do-able but Id also suggest wieght reduction to get a better track time and quarter mile
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Old 08-07-2008, 02:43 PM   #17
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Ok first off there is no price on labor since my buddy and i can manage that part, everyone thinks it's impossible to crack open a case and get building... second is im not worried on price, and its not a daily driver and its going into a fully striped GC8... my daily driver is my wagon that is getting a complete sti swap with a 18G on meth... but anyways I have cases laying around my house and why not play around with them? make some crazy numbers with a NA put it in a GC8 shell and tell people you just got smoked by an NA!!! that sounds like fun to me... turbos are fun but everyones got one and what determines your sti is faster than the others is how big you turbo is. so the build is starting soon, two swaps at once is going to be fun... and again my house is going to look like a chop shop...
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Old 08-07-2008, 03:01 PM   #18
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Quote:
Originally Posted by Splinter View Post
???

A 300chp turbo has a way better powerband than a 300chp small displacement NA
I'd beg to differ in a huge way.... NA will have a much flatter tq curve unless you progressively increase boost pressure.
Case and point Vern's (at All Aspects and awesome!!) NA project...
new sti 2.5 short block
all parts are thru twe
wiesco 12.1
stage 3 cams springs and such
4-2-1 twe race header
hydra management

also...
05 NA intake manifold, powersteering and AC delete but am not sure it that was for this graph...?


Needs a bigger cam, more headwork and rpm to make 230 though


It can be done and I'm not sure that a 2.8L ginormous engine would be the ticket as isn't going to breath all too well at 8500rpm nor be very happy with harmonics...

I'll take a 2.4L at 9500rpm over 2.8L at 7500rpm all day

I'd do a 2.55 or my long rod 2.4L with STi heads, custom cams and a well designed/sized intake manifold to make high rpm NA power.

A NA subie is something I've wanted to do for a while...but bigger power got me first
Maybe once I move onto my next shortblock I'll get some high CR pistons for my current block and give it a whirl.

I need more time and spending money

Last edited by Homemade WRX; 08-07-2008 at 03:22 PM.
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Old 08-07-2008, 03:26 PM   #19
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Old 08-07-2008, 04:11 PM   #20
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Quote:
Originally Posted by Splinter View Post
???

A 300chp turbo has a way better powerband than a 300chp small displacement NA
I don't remember if it was TWE, COBB, or another company, but 300 chp on a 2.8 makes roughly 280 chp at 2,000 rpm, and just under 290 ctq at the same RPM. The two lines go up slightly, then start dropping around 8,000 rpm. A 300 chp turbo motor of the same displacement will make significantly less hp and torque at 2,000 rpm.
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Old 08-07-2008, 04:23 PM   #21
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Quote:
Originally Posted by Chi_San View Post
I don't remember if it was TWE, COBB, or another company, but 300 chp on a 2.8 makes roughly 280 chp at 2,000 rpm, and just under 290 ctq at the same RPM. The two lines go up slightly, then start dropping around 8,000 rpm. A 300 chp turbo motor of the same displacement will make significantly less hp and torque at 2,000 rpm.
that's mathematically not possible (that whole crossing at 5252 rpm thing)...but I think you are thinking of zzyzx's auto-x car anyhow
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Old 08-07-2008, 05:43 PM   #22
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wait... turbo cars can have good tq curves and make power too.

Good luck with your NA project, its a really cool idea. But in the end I think you will have a ton of money invested in it and still not be happy.

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Old 08-07-2008, 08:07 PM   #23
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if you got the time and $$..why not go h6???
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Old 08-07-2008, 08:45 PM   #24
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Quote:
Originally Posted by Badazzcr View Post
wait... turbo cars can have good tq curves and make power too.
Yes doug, I know they can but about 99% of NA cars will have a better torque curve than turbo set ups and you know that
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Old 08-08-2008, 01:07 AM   #25
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I hate to add on to a thread with something not completely relevant, but this is the the closest thread to what I was looking for i could find with the search. . .That being said, how much power/rpm do you think a stock EJ25 SOHC (EJ251) block crank and rods could handle with the 11.2:1 CR pistons? how about the STI stock block crank and rods? would the CR make a difference other than having to handle the increased power?
hopefully this is not too off topic
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