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Old 03-21-2009, 09:57 PM   #1
pinoiboi13
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Cool are sti cams a good upgrade instead of using the wrx cams

hello i'm getting a block built with forged internals on a 2.0l since i spun a bearing. i have the option for swapping the wrx cams for sti cams for an extra $200. i wanted to know if its worth it. i heard i can get another 20-30 hp depending on the setup.what do you think guys. help me out. i was also thinking about getting the block pinned basically making it a semi-closed block like a version 7 engine but not the price. i need some feedback.
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Old 03-21-2009, 11:31 PM   #2
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If for $200 you'll get STI cams installed, I would do it. You'll get some more top end out of it.
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Old 03-22-2009, 03:14 AM   #3
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I'd beg to differ as the lift is not much more on those. The only reason to do this is to utilize AVCS but if you don't have the heads and ECU to support it, its a waste in my mind. If you do go down this route, make sure to plug up the oil holes for avcs if you can't control it. Honestly though, you'd be better off getting a set of cams made for the wrx...
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Old 03-22-2009, 08:59 AM   #4
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You can probably get another 2hp at the flywheel.... IIRC, theyre the same except for one more mm of lift on the exhaust side. = not worth $200.... I have a set of cams you might find useful - pm me if you want...
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Old 03-22-2009, 09:19 AM   #5
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They may net you only minimal gains to peak HP but your HP curve will definitely not drop as much up top as it does with WRX cams. For $200 installed and shimmed, I think its worth it considering if you want to go aftermarket cams you're looking 700-1000 bucks + necessary buckets + labor= way more money than you're probably willing to spend. Like said by others, duration is the same, lift is a little more I ran them before I got my Cosworths and they are better than the stockers.
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Old 03-22-2009, 09:26 AM   #6
pinoiboi13
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well thanks for the knowledge i'll probably stay with the stock cams. dont want to worry about other problems arising.
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Old 03-22-2009, 09:30 AM   #7
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STI cams have 10 degrees more duration on the exhaust than the WRX and I have seen decent gains over the entire rpm range with the swap.
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Old 03-22-2009, 09:52 AM   #8
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I put sti cams in and gained near 30 hp on the top end and the torque did not
drop near as fast..

Yes! they will help...
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Old 03-22-2009, 11:18 AM   #9
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Quote:
Originally Posted by scottD View Post
I put sti cams in and gained near 30 hp on the top end and the torque did not
drop near as fast..

Yes! they will help...

I stand corrected... Do you have dyno runs for this? Were the cams all that was changed?
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Old 03-22-2009, 11:26 AM   #10
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Might as well go with some BC's
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Old 03-22-2009, 12:40 PM   #11
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Quote:
Originally Posted by the real suby dude View Post
Might as well go with some BC's

If you can get some BC's installed for $200 I'm all for it but for the money his upgrade ain't to shabby.

Quote:
Originally Posted by andya View Post
STI cams have 10 degrees more duration on the exhaust than the WRX and I have seen decent gains over the entire rpm range with the swap.
What year and model STi where these out of? USDM STi cams are the same duration as USDM WRX cams ('04 at least)

Last edited by kellygnsd; 03-22-2009 at 12:46 PM.
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Old 03-22-2009, 12:46 PM   #12
autvincereautmori
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if you get the 06/07 sti cams they are hollow thus lighter weight.. i have a set of 07 cams in my car.. the top end doesn't drop off at all like the wrx cams did.. but i am not sure of the actual increase in power, i did a lot more all at once than just this mod
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Old 03-22-2009, 01:49 PM   #13
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Quote:
Originally Posted by kellygnsd View Post
If you can get some BC's installed for $200 I'm all for it but for the money his upgrade ain't to shabby.
What year and model STi where these out of? USDM STi cams are the same duration as USDM WRX cams ('04 at least)
Just to help you guys out a bit:

First, let's look at the part number history for the intake cam:
2.0L
02 WRX 13031AA101/102
03 wRX 13031AA390/391
04 WRX 13031AA391/392
04 WRX 13031AA490/492
05 WRX 13031AA490/492

2.5L
06 WRX 13031AA350/351/352
07 WRX 13031AA351/352
04 STI 13031AA350/351
05 STI 13031AA350/351
06 STI 13031AA350/351/352
07 STI 13031AA351/352

As you can see the 02-05 WRX cams are of course different from the corresponding year STI cams, but in 06 when the WRX went to the 2.5L motor it follows the same cam part numbers.

Looking at the specs:

04 WRX


04 STI


07 WRX


07 STI


From this, we get:

04 WRX
240 duration intake
240 duration exhaust
17 degrees overlap

04 STI
240 duration intake
240 duration exhaust
0 - 20 degrees overlap

07 WRX
240 duration intake
240 duration exhaust
0 - 40 degrees overlap

07 STI
240 duration intake
240 duration exhaust
0 - 30 degrees overlap (* note difference from above WRX. This is an ECU programming difference)


As you can see, the change from 04 STI to 07 STI is only in the amount of AVCS advance.. Not a physical thing but instead an ECU map change. However, note that the duration of the WRX and STI cams are the same. What is different however is the overlap. WRX cams have a fixed 17 degree overlap, while the STI cams can be changed from 0 to 40 degrees. (Lift is also different)

If you put STI cams in WRX heads, you will be running them with 0 advance, so the will be the 'max retard' values.

How does this effect power:

WRX cams in WRX heads will have greater power rolloff up top due to excessive overlap.
STI cams in WRX heads will have better top end power, but worse spoolup due to lack of overlap.
STI cams in STI heads will have the best of both world. Yummy.

This, btw, is part of the reason for the difficulty in tuning the hybrid 257+wrx head/cam engines.

Jeff Sponaugle

Last edited by sponaugle; 03-22-2009 at 02:01 PM.
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Old 03-22-2009, 01:55 PM   #14
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Quote:
Originally Posted by kellygnsd View Post
If you can get some BC's installed for $200 I'm all for it but for the money his upgrade ain't to shabby.



What year and model STi where these out of? USDM STi cams are the same duration as USDM WRX cams ('04 at least)
Correct up to 07. (08 STI is different)

Quote:
Originally Posted by andya View Post
STI cams have 10 degrees more duration on the exhaust than the WRX and I have seen decent gains over the entire rpm range with the swap.
Not in the 04-07 range.


Quote:
Originally Posted by kellygnsd View Post
Like said by others, duration is the same, lift is a little more I ran them before I got my Cosworths and they are better than the stockers.
Correct:

04 WRX Cam Lift
Intake 9.25
Exhaust 9.15

04 STI Cam Lift
Intake 9.55
Exhaust 9.75

STI Cams have a bit more lift, especially in the exhaust side.

Jeff
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Old 03-22-2009, 02:09 PM   #15
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If you got the money some Tomei 252s or Kelford 264s cams would be great. I hold 300whp until 7K RPM with Kelford 264/264 cams and I am only running 16PSI.
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Old 03-22-2009, 02:18 PM   #16
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Interesting... I will take another look at the service manual because I remember compairing the 03WRX to the 05STI exhaust profiles and came up with the 10 degree difference... I could be wrong but the swap made a great improvement after tuning vs a WRX cammed vehicle with similar mods.
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Old 03-22-2009, 03:18 PM   #17
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Quote:
Originally Posted by andya View Post
Interesting... I will take another look at the service manual because I remember compairing the 03WRX to the 05STI exhaust profiles and came up with the 10 degree difference... I could be wrong but the swap made a great improvement after tuning vs a WRX cammed vehicle with similar mods.

Those pictures I posted above are from the service manual. It is possible you noticed the difference in open or close angle, not duration.

As I mentioned above, the swap will net more lift as well as less overlap at higher rpm, which will net more power. So you are not wrong as to the gain. It is as would be expected given the differences.

Jeff
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Old 03-22-2009, 03:57 PM   #18
gto7419
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Quote:
Originally Posted by andya View Post
Interesting... I will take another look at the service manual because I remember compairing the 03WRX to the 05STI exhaust profiles and came up with the 10 degree difference... I could be wrong but the swap made a great improvement after tuning vs a WRX cammed vehicle with similar mods.
Im actually pretty sure I was right, that the sti cams only offer a mm of additional lift on the exhaust cam..
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Old 03-22-2009, 05:17 PM   #19
pinoiboi13
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Quote:
Originally Posted by scottD View Post
I put sti cams in and gained near 30 hp on the top end and the torque did not
drop near as fast..

Yes! they will help...

thats why i was thinking about putting them on. my machinist and tuner said it give me around 20-30 hp. thats the feedback i wanted to hear.
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Old 03-22-2009, 05:22 PM   #20
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so basically i could get some good topend gains uptop???
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Old 03-22-2009, 09:07 PM   #21
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Here is a dyno of a hybrid with 02 heads with stock 2.0 cams and sti cams. Not much of a change in peak power but area under the curve is way improved.

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Old 03-23-2009, 12:00 AM   #22
pinoiboi13
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i guess the sti cams aren't bolt on either. do i got to do something with the acvs. also am i gonna have to retune my car with the sti cams.
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Old 03-23-2009, 03:13 AM   #23
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Quote:
Originally Posted by pinoiboi13 View Post
i guess the sti cams aren't bolt on either. do i got to do something with the acvs. also am i gonna have to retune my car with the sti cams.
All you have to do to make the AVCS cams work is plug the oil feed passages by tapping and putting in an allen head set screw + loctite.

Of course you need a re-tune after upgrading cams. Cams are the heart of any motor. They orchestrate the whole combustion process and if you hadn't noticed, most anything you add to our cars would benefit from a re-tune.

What was all included in this $200 deal you talked about. I'm starting to think you may have misunderstood what you where getting for $200. If its STi cams installed, shimmed, and made ready for non-AVCS use its a steal. If its just $200 for the cams and the rest on you, expect to shell out a good bit more to get everything right and right is the only way to do it

Last edited by kellygnsd; 03-23-2009 at 03:19 AM.
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Old 03-24-2009, 01:20 AM   #24
pinoiboi13
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Quote:
Originally Posted by kellygnsd View Post
All you have to do to make the AVCS cams work is plug the oil feed passages by tapping and putting in an allen head set screw + loctite.

Of course you need a re-tune after upgrading cams. Cams are the heart of any motor. They orchestrate the whole combustion process and if you hadn't noticed, most anything you add to our cars would benefit from a re-tune.

What was all included in this $200 deal you talked about. I'm starting to think you may have misunderstood what you where getting for $200. If its STi cams installed, shimmed, and made ready for non-AVCS use its a steal. If its just $200 for the cams and the rest on you, expect to shell out a good bit more to get everything right and right is the only way to do it
actually ya its only $200 more. basically i paid for the labor already with the motor being built. he already has some sti cams already there that are plugged. so ya just $200 and he installs them and everything. i also heard he builds good engines.he only builds subaru race motors. keith from awdtuning.com reccomended him to me. he's a reputable tuner in texas.
i spun a bearing on mine so he's basically making mine like a version 7 motor. thats why i was thinkin about doing this upgrade. can i drive my car with the sti cams on and be ok till i get a tune 2-4 months from now??
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Old 03-24-2009, 02:23 AM   #25
kellygnsd
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So my question to you is why aren't they installed yet?

Don't half ass this build. Sell yourself on the corner or wait a few until you can raise $400 for a tune. You will possibly be in different load site throughout the rpm range and your timing will be off. You'll be risking you new motor and that's not worth $200 so do it right or don't do it.
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