IE Mihle piston package

[zaq123]

I'm in the process of stroking my M20 and these are pistons that some :devil:s here steered me towards.

Anyway...I'm installing/assembling them as we speak and would like to say WOW, thanks fellas. Very impressed with this piston package: top quality, weight difference is within 1g, rings are high quality and no gapping was needed as promised in the instruction package if your machinist follows P to W clearance specs closely (all gaps were verified for obvious reasons).
If you are looking for a quality piston set, do not overlook these. Price is a little higher that some out there but no hassle fitting and the top shelf Mahle quality is well worth it.... just wanted to share

[digger]

yes, the finish quality is superior to what you get from other aftermarket suppliers

[LateFan]

I've been trying to read up and learn the differences between the Alpina B3 2.7 M20, the IE stroker motors, and the Metric Mechanic stroker. There are differences in displacement and crank throw of course, but it seems like a lot of it is in the head development - all related to what piston you choose, or vice versa.

So which comes first? Do you pick a piston then shape the combustion chamber, or do you shape the combustion chamber and order a custom piston?

[zaq123]

I've been trying to read up and learn the differences between the Alpina B3 2.7 M20, the IE stroker motors, and the Metric Mechanic stroker. There are differences in displacement and crank throw of course, but it seems like a lot of it is in the head development - all related to what piston you choose, or vice versa.

So which comes first? Do you pick a piston then shape the combustion chamber, or do you shape the combustion chamber and order a custom piston?

MM and IE kits are designed around M20B25 885 head, no mods are needed to the chamber.

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[digger]

I've been trying to read up and learn the differences between the Alpina B3 2.7 M20, the IE stroker motors, and the Metric Mechanic stroker. There are differences in displacement and crank throw of course, but it seems like a lot of it is in the head development - all related to what piston you choose, or vice versa.

So which comes first? Do you pick a piston then shape the combustion chamber, or do you shape the combustion chamber and order a custom piston?

choose the cylinder head based on what sized ports you need, this dictates the combustion chamber then choose pistons crown style based on this. there is generally enough meat on the 731 and 885 to achieve the same results

[LateFan]

So, port / valve flow and velocity first?

I just started looking through your engine thread, wow...that's a lot to take in. A question on the head shaping - if you take out all of that radiused "shelf" or chamfer around the perimeter of the i combustion chamber, does that raise the volume way up and then require a much taller piston for high compression?

I've read a few things in Alfa Romeo circles where really high peaked pistons, which may show high compression numbers, aren't giving the performance they should. A result of just filling up the volume and guessing on shape?

<EDIT> From looking at some of your posted pics, it appears the crease line of that "shelf" has been eased or smoothed, but the shelf itself hasn't been removed.