Yeah. I finished the HEMI prototype. I just gave it a quick run with 2 lego air tanks, to see if it's ok. Seems fine. Tomorow morning i'll give it the first test run to see how it goes.
Why HEMI? The original engine has hemispherical combustion chambers. Well... in lego we don't have combustion chambers, but the switches have a bionicle ball joint attached to them, and thus, the name HEMI is fully justified :)