Gear ratio

[GregWeld]

Originally Posted by IndyNova

I've got a bone stock 4l80e trans, with a 275/45/18 rear tire. I haven't ordered a cam yet, but I've been given a few ideas on what I should order.

Your tire is 27.74 inch DIAMETER


Your 4L80 is a .75 overdrive (final drive ratio)


If you have a small block -- I'd try to keep the 70 mph cruise at around 2000 to 2200 rpms.... same with a big block


3:70 = 2350rpms

3:89 = 2450rpms

4:11 = 2600rpms


These give you a rough idea of what you're dealing with