Flat Plane Crank LT5

[XfireZ51]

Originally Posted by tpepmeie

Dom,
Imagine the crank throws all on the same "plane", rather than at 90 degrees to each other. Usually it is "up, down, down, up" for the 4 rod journals. Still have a cylinder event every 90 degrees, but they alternate banks (Left, Right, Left, Right, ...). And all the firing intervals are evenly spaced on each bank. Helps exhaust tuning quite a bit, and all cylinders exhibit the same airflow performance. On a 90 degree V-8, certain cylinders can perform up to 8-10% worse than the best cylinder due to exhaust tuning (mainly the closely spaced (90 degrees apart in the firing sequence) cylinders on each side.).

The downside... a considerable secondary shake, in the side-to-side axis. Not as naturally well balanced as a 90-degree crank. And-you can't run a large stroke due to this vibration.

Todd,

Thanks. I thought the name denoted basically a 180 journal config.