2.7eta engine conversion

[MikeF]

To whoever can help me! I been offered a 2.7 eta bottom end from a E30 525e, I would like to build the engine to the more common type higher revving conversion that everyone does. The engine is a complete block consisting of the block, crank, pistons and rods . Now I heard you need the 325i head and psitons to do the conversion. I am currently running a 325i with a schrick 288 cam, 6 branch, chip, modded throttle body and LSD. good for doughnuts but I want more!!! this will all go into the build, can anyone help Thanks Mike.

[Ant]

Hi Mike, this is a topic we've covered a few times, may I suggest a search would provide 99% of the answers you are looking for.

I'm going to move this thread to Tech help also, get better exposure there dude

and Welcome to E30Zone.

feel free to post up if you cannot find the info you are looking for, its there for the finding

[Andy_magic]

As you've already got some nice bits there I owuld recommend fitting the ETA crank into the 325i block.

To do this you need to deck the block to get the compression ratio right.

Its an engine rebuild job but will be well worth it, I think you'd be looking in the 200-210 bhp range with a good hike in torque output.

[MikeF]

How does this work? as the crank is a longer stroke, also what rods do I use. thanks

[Andy_magic]

The ETA engine and the 325i share the same bore size, the extra 200cc is gained from a longer ste crank.

The ETA engine has different profile pistons so you need to use the 325i pistons but the block is too tall for the combination to work. I think you have to use 320/323 rods too.

If you do a search for 2.7 convertions it will probably shed much more light on it.

I did mine the cheap way!

[chu346]

I did mine the cheap way!

Same here (Ԛ£1200).

[MikeF]

So the low down is use 2.7 ETA crank, 325i block, 325i pistons, 325i head 325i inlet system and 320i conrods. but does this all just fit together or is there any machining required if so what and why.
Please let me know Thanks.

[M5pilot]

Its not as simple as that. You need to use the early 325i pistons to get the compression nce and high. However then youll need to do some maching work otherwise the pistins skirts will come into contact with the crank.

A bit of maching and the correct measurements make all the difference in a 2.7 conversion.

Bexleys offer a service - take block head and one early piston stil in block to them. They will do the measurements and tell you how much to shave off where to give the required compression ratio.

Your aim is to get over 10.0:1.

Quaser (another member) is using the exact same formula as this and his engine last made 204 bhp with MAF conversion. CAT was still in place and he only used an Alpina 268 cam.

Its all about the machining and the CR.

Oh, porting the head will add some horses aswell and costs Ԛ£350.

Sal

[MikeF]

Hi, thanks for the info, what year of car would the 2.5 pistons be out of, or what years am i aiming to look for.

[M5pilot]

85-87

You could just an early block.