# S13 SOHC swap to DOHC Questions
**URL:** https://forums.speedlife.net/t/s13-sohc-swap-to-dohc-questions/111287
**Category:** SON240sx Automotive
**Created:** [November 23, 2007, 12:12pm UTC](https://forums.speedlife.net/t/s13-sohc-swap-to-dohc-questions/111287 "2007-11-23T12:12:38Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@240racer](https://forums.speedlife.net/u/240racer)
#### Post date: [November 23, 2007, 12:12pm UTC](https://forums.speedlife.net/t/s13-sohc-swap-to-dohc-questions/111287/1 "2007-11-23T12:12:38Z")
hey, Ive got a 91 2.4 DOHC car and i would like to swap in a SOHC possibly for the race track. I know the trannies are the same but what about the fly-wheel and such?? also does the whole wiring harness have to be changed?? or can i still use the SOHC…also ive heard theres two versions of the SOHC a 9:1 and a 8:6 compression ratio. How do i tell the difference?? I race a 240 at sunset speedway in the 4 cyl division and just looking for some information …any help would be aprecciated…thanks guys:😃
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### Author:  [@R33](https://forums.speedlife.net/u/R33)
#### Post date: [November 23, 2007, 12:42pm UTC](https://forums.speedlife.net/t/s13-sohc-swap-to-dohc-questions/111287/2 "2007-11-23T12:42:47Z")
buy my dohc t25 turbo kit.
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### Author:  [@tosh](https://forums.speedlife.net/u/tosh)
#### Post date: [November 23, 2007, 4:31pm UTC](https://forums.speedlife.net/t/s13-sohc-swap-to-dohc-questions/111287/3 "2007-11-23T16:31:54Z")
you will need the wiring harness, ecu, cluster, and a few other odds and ends. search this forum as well as a few others like [zilvia.net](http://zilvia.net) and nico. this is a topic that has been covered many times.
peace
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### Author:  [@simplemind7](https://forums.speedlife.net/u/simplemind7)
#### Post date: [November 23, 2007, 5:44pm UTC](https://forums.speedlife.net/t/s13-sohc-swap-to-dohc-questions/111287/4 "2007-11-23T17:44:40Z")
you need to swap the engine wiring harness and cut off the dash harness connector (cut and match wire colours), then you’ll need the ECU and gauge cluster and if you want your power steering to work, you’ll need the lines from the other motor… or modify your lines, but that doesn’t work for long usually.
clutch and flywheel are the same.