Skip to content
View in the app

A better way to browse. Learn more.

Ultimate Subaru Message Board

A full-screen app on your home screen with push notifications, badges and more.

To install this app on iOS and iPadOS
  1. Tap the Share icon in Safari
  2. Scroll the menu and tap Add to Home Screen.
  3. Tap Add in the top-right corner.
To install this app on Android
  1. Tap the 3-dot menu (⋮) in the top-right corner of the browser.
  2. Tap Add to Home screen or Install app.
  3. Confirm by tapping Install.

2.5 phase 2 heads on 2.5 phase 1 block

Featured Replies

Has anyone tried this? putting 2000 phase 2 heads on 98 phase 1 block? Thanks

you would have some crazy high compression, if i remember right the phase one pistons come past the deck of the block just barely, but more then the phase 2 does. so the CCs in the combustion chamber is smaller in the phase 2 heads.

 

it's doable, but still the question is why, the DOHC heads aren't bad.

 

not unless it's the thing of "I have all these parts laying around lets see if I can make an engine"

It is an option. You should use the DOHC head gaskets to minimize any interference issues. I have a friend who is a subie mechanic and he has done it for one of his engines because he had the parts lying around and didn't want to buy another engine.

 

Good Luck

I know it works the other way around. If you go to the dealer and buy a new short block for a Phase 1 you get the same thing as used for the Phase 2.

  • Author

Yeah I have three good phase 1 2.5 lower ends and 2 good sets of heads off a phase 2 2.5. The pistons have the deep square recess so i think the compression ratio should work.

Please sign in to comment

You will be able to leave a comment after signing in

Sign In Now

Account

Navigation

Search

Search

Configure browser push notifications

Chrome (Android)
  1. Tap the lock icon next to the address bar.
  2. Tap Permissions → Notifications.
  3. Adjust your preference.
Chrome (Desktop)
  1. Click the padlock icon in the address bar.
  2. Select Site settings.
  3. Find Notifications and adjust your preference.