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Old 05-02-2006, 03:27 PM   #1
Token-Negro
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Question Valvetrain interchange?

So i got a set of STI heads for a good price, but they have the AVCS and i wont be using that on my WRX since i dont have a jdm ecu, or a Hydra. So in my quest for more power should i ditch the usdm cams and just upgrade them to something else? Like JDM v7 cams and valvetrain? Will the JDM valvetrain fit in the USDM heads?
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Old 05-02-2006, 06:10 PM   #2
bboy
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Ummm it's not that simple. The valve lash will change when you change the cams. Why would you give up AVCS if you don't have to. If you use the Hydra you don't have to, but you may end up with wiring isssues depending on the wiring harness you have. At worst you can set up your own hall effect camshaft sensor and run open loop AVCS. Ditching AVCS and upgrading the Cams would be the worst of all worlds for boost onset and spool up. Why do that if you can have AVCS at least, and better cams and AVCS at best?
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Old 05-02-2006, 06:46 PM   #3
Peeblesmx445
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Quote:
Originally Posted by Token-Negro
So i got a set of STI heads for a good price, but they have the AVCS and i wont be using that on my WRX since i dont have a jdm ecu, or a Hydra. So in my quest for more power should i ditch the usdm cams and just upgrade them to something else? Like JDM v7 cams and valvetrain? Will the JDM valvetrain fit in the USDM heads?
As you said, You dont have a Hydra or a JDM ECU and wiring harness. If you are not going to be using the AVCS then the JDM V7 cams by themselves are a hotter cam than the USDM STI ones and will yield more power. They will fit in your heads as long as you plan on using them as NON-AVCS cams. If you only plan on drag racing then AVCS is not nearly as important as everybody makes it out to be......

edit. ^ as bboy said. Your valve lash may change, but it may change no matter what cams you put in there other than the whats in there now (USDM STI). Valve lash is actually not a big deal to get right, just a little time consuming to get everything in spec. If you dont know what valve lash is. Its the space between the bottom of the cam lobe and the top of the valve bucket. You change the specs by changing different valve buckets.
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Old 05-03-2006, 12:16 PM   #4
Token-Negro
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Its simple tho for me i dont have a way to run the avcs at all, and im not really sure how to get avcs to funtion without buying a hydra, im really dont want to go that route. I would like to do some type of JDM ecu conversion and just make it work via wiring. But with the usdm avcs and the jdm avcs there might be some differences.
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Old 05-03-2006, 01:15 PM   #5
Peeblesmx445
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Quote:
Originally Posted by Token-Negro
Its simple tho for me i dont have a way to run the avcs at all, and im not really sure how to get avcs to funtion without buying a hydra, im really dont want to go that route. I would like to do some type of JDM ecu conversion and just make it work via wiring. But with the usdm avcs and the jdm avcs there might be some differences.
I believe...
USDM AVCS= STI ECU, STI UTEC, STI Wire harness/ or a HYDRA
JDM AVCS= JDM ECU, JDM UTEC, IAP wire harness..../ or HYDRA

NO AVCS= nothing
Hotter cams= hotter cams
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