M20 2.7 Block With 2.5 Head Questions

[skitzvonbimmer]

i have an 87 ETA and i want to replace the head with a 2.5 i head, i was wondering if ill need anything other than the i cam and head, and what will i have to do computer wise. any other tips or comments would be greatly appreciated

[Slowered318]

have you priced out an "is" head?

[skitzvonbimmer]

Originally posted by Slowered318@Jan 10 2005, 07:27 PM
have you priced out an "is" head?

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i didnt know there was a difference, i thought the only difference between the i and is was the suspension set up

[Slowered318]

I personally haven't seen any difference.. but its a different part number. strange cause they are identical power 168hp.

[skitzvonbimmer]

well if you are wanting to sell one, i would be interested, how much are you looking to sell it for and what kind of condition is it in?

[MrM3]

you'll need to use mostly m20b25 parts including the ecu and intake manifold, and you will also need custom or superETA pistons.

[skitzvonbimmer]

Originally posted by MrM3@Jan 10 2005, 08:32 PM
you'll need to use mostly m20b25 parts including the ecu and intake manifold, and you will also need custom or superETA pistons.

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the manifold i can understand, will the ecu need any modification? also ive heard of the new head slagging compression but ive also heard of people using the stock pistons and having it work fine, im not really sure why this is

[Torque]

there is no difference between the engines in the E30 325i, E30 325is and the E34 525i up to 1990.

They all use the m20b25 engine that puts out 168 hp and 164 lb.ft torque.

[guywithblack88e30]

Originally posted by MrM3@Jan 10 2005, 04:32 PM
you'll need to use mostly m20b25 parts including the ecu and intake manifold, and you will also need custom or superETA pistons.

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DON"T USE SUPER ETA PISTONS THAT ENGINE WILL BLOW UP!!! the piston form is different from the i and e engine will blow have heard many storys of that happening. go with i pistons or custom fit

[MrM3]

Originally posted by guywithblack88e30+Jan 11 2005, 12:49 PM--><div class='quotetop'>QUOTE(guywithblack88e30 @ Jan 11 2005, 12:49 PM)</div><div class='quotemain'><!--QuoteBegin-MrM3@Jan 10 2005, 04:32 PM
you'll need to use mostly m20b25 parts including the ecu and intake manifold, and you will also need custom or superETA pistons.

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DON"T USE SUPER ETA PISTONS THAT ENGINE WILL BLOW UP!!! the piston form is different from the i and e engine will blow have heard many storys of that happening. go with i pistons or custom fit

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[/b][/quote]

yes the superETA pistons are cut differently at the top, but that allows for higher compression. without them, you would have a low compression 2.7i, around 7.8:1 i think, which most would consider to be too low. I have heard stories of the cast eta crank not being strong enough to handle the extra revs and maintain reliability, but never any stories of superETA pistons causing the engine to blow. i would like to hear one of your many stories of this happening.

[jze325i]

Just drop an E36 motor in that sucker!!

[guywithblack88e30]

Originally posted by MrM3+Jan 12 2005, 10:25 AM--><div class='quotetop'>QUOTE(MrM3 @ Jan 12 2005, 10:25 AM)</div><div class='quotemain'>

DON"T USE SUPER ETA PISTONS THAT ENGINE WILL BLOW UP!!! the piston form is different from the i and e engine will blow have heard many storys of that happening. go with i pistons or custom fit

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yes the superETA pistons are cut differently at the top, but that allows for higher compression. without them, you would have a low compression 2.7i, around 7.8:1 i think, which most would consider to be too low. I have heard stories of the cast eta crank not being strong enough to handle the extra revs and maintain reliability, but never any stories of superETA pistons causing the engine to blow. i would like to hear one of your many stories of this happening.

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[/b][/quote]

wiith super eta pistons the regular i head can't take that much and neither can a e bottom and what happens after you let go of a compressed spring

[Aether]

Uh.
The whole point of not just swapping the whole B25 is that the Eta bottom-end can handle more than the 325i. You may want a turbodiesel crank for anything beyond just the top-end conversion, or if you just aren't sure your old crank is up to it. It just doesn't make sense that you could even use 325i pistons, at all, for this project. The diffrence in displacement is because of the 325e's stroke, so the i pistons shouldn't even be long enough to get any kind of running compression.

I don't know what you can dig out of this information, but the B25s are hemispherical, and the Eta isn't. It's best to go ask JE for some nice, shiny new ones.

[detour54]

Lots of people performing this mod...

http://www.e30tech.com/forum/viewtopic.php?t=4304

Good useful info - http://www.e30tech.com/forum/viewforum.php?f=2

[mr_black_001]

I am midway through a transplant and build of a 2.7 engine and with a 325i head ported out with the larger eta intake manifold and eta block, custom 6 port exaust manifold and i have never heard anyone say that changing the pistons was a must from eta to i is this true?