From: Jack Roberts [j.b.roberts@worldnet.att.net]
Sent: Dienstag, 18. August 1998 08:34
To: Horst Apfelthaler
Cc: BMW E21 Digest
Subject: Re: e to i conversion

Horst Apfelthaler asked:

>>>I want to convert my '85 EURO eta engine (CR 11:1, 2.7liter) with
some parts to i specifications.
Therefore I can use all parts from a '86 325i including all electronics
(ECU) for upgrade.  What of the following will give me the best
performance?<<<

> simply swap the heads (will the CR go down to 10:1?, I read something
of different combustion
   chambers 37cc for eta and 42cc for i)
> use the eta head and install the i cam and drill the necessary oil
holes for cam bearings?

With 11:1 pistons I would definitely go with the "i" head.  Yes it will
lower your compression to about 10:1 but it has larger valves and ports
that will more than offset the decrease in compression.  If you were
running 9:1 U.S. eta pistons I would not recommend the "i" head because
compression would fall to 8:1 which is too low for performance work
except turbocharging.

> which intake manifold should I use (eta for low rpm torque?)
> which injectors should I use (I think the eta injectors have more
flow rate)

Use the "i" intake, injectors, and computer.  The "i" has a more
performance oriented Motronic system than the "e" and the intake ports
will match up correctly.

> what hp can be expected from such an upgrade?

My guess is that this engine should produce around 185 horsepower. 
With a performance chip for the Motronic unit and an aftermarket cam
this can easily be increased beyond 200 hp.

Cheers,
Jack
81 323i with 2.7
78 Alpina B6