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sperry · 2009-10-27, 08:31 AM

The only thing different between an '06 WRX block and an '04 STi block are the heads. The STi has better flowing AVCS heads, the WRX does not. In fact, the short block (bottom end) even share the same part numbers IIRC. Of course the ancillary bits on the STi motor are a bit different with the WRX having a smaller turbo, smaller injectors, smaller intercooler... but none of that stuff is essentially different from the STi stuff.

You could probably even keep the '04 STi ECU if you are able to re-tune it for the smaller turbo/intercooler/injectors on the WRX motor. What's hard to do is use a WRX ECU to run an STi motor... there's no way to control the AVCS, but the other way around shouldn't be hard.

I'm afraid to ask why someone wants to put a WRX motor in an STi... did someone blow up their STi and need a cheap replacement?

2009-10-27, 08:31 AM	#7
sperry The Doink Real Name: Scott Join Date: Nov 2002 Location: Portland, OR Posts: 20,335 Car: '09 OBXT, '02 WRX, '96 Miata Class: PDX/TT-6 The way out is through	The only thing different between an '06 WRX block and an '04 STi block are the heads. The STi has better flowing AVCS heads, the WRX does not. In fact, the short block (bottom end) even share the same part numbers IIRC. Of course the ancillary bits on the STi motor are a bit different with the WRX having a smaller turbo, smaller injectors, smaller intercooler... but none of that stuff is essentially different from the STi stuff. You could probably even keep the '04 STi ECU if you are able to re-tune it for the smaller turbo/intercooler/injectors on the WRX motor. What's hard to do is use a WRX ECU to run an STi motor... there's no way to control the AVCS, but the other way around shouldn't be hard. I'm afraid to ask why someone wants to put a WRX motor in an STi... did someone blow up their STi and need a cheap replacement? __________________ Is you is, or is you ain't, my con-stit-u-ints?