[Flieger]

Originally Posted by TCracingCA

Personally I think a magnesium case is not a good idea period, unless low hp! But I do think it can be built to stand up to 2.8 (with the tricks!), but Porsche themselves at the 2.8 point, switched again to the aluminum going to the 3.0.

On the shifting, I have always set the shift light at Peak hp, because by the time the slow human being completes the motion, you are at least the better part of 600-800 rpms past that with a quick revving engine. My rule on setting up the gearing is so as to not fall out of the power band on a shift, but if racing you would want to minimize the drop off of rpms! But I am taking in what was said!

Also Porsches racing 2.5's were done with the 70.4 crank and was closer to the class maximum is what I have read! Thus there are too ways to build a 2.5!

They started with the long stroke, then once Nikasil cylinders became available (from the 917 project) they went back to the short stroke, big bore since it was more reliable. But they couldn't get the 90mm bore with the Biral construction. The Ni-Si-C coating allowed thin aluminum walls to be hard enough to run piston rings on.