Need some input from the board. I have '86 272LS with 365hp small blocks running 64mph @ 5000rpm in flat water. Drives are alphas (1.5 ratio) spinning 21p Turbo stainless props. Both drives are righthand turning with simrek showers. Would installing a port LH lower give me some more top end? Looking to get a little closer to 70. thanks for any input.

No.Spend your money elsewhere. Counter rotation helps with steering torque and drivability,not speed.

Magic, will the counter rotation lift the stern and allow bigger props?

Theorically,yeah,but reality,doubt there will be any difference.

just use triple widgets magic alphas and hang on!!!!!

Try a 23 Mirage 3 blade on that once and if you gain any speed

your talking about a 24% increase in speed. you not going to do that with props and c/r, you could gain a little if you did it and really played with props, but if your lifting the back end with the props thats going to put a lot more strain on the alpha's. is that flat-flat water?? that would be the most drag, how easily are you pulling 5 grand?

It was real flat water. No chop. It pulls 5000 pretty easily and was trimmed out , but no tab. The props had a couple of dings (I boat in the Great South Bay,which is pretty shallow), and I had them redone, but didn't get to re-test before winterizing.

sounds ike you need more prop to begin with, so you prolly should figure out where you are, so you can figure out where your going.

Get one counter rotation and a set of 23 3 blades from michigan props ( BALISTIC ) and you will see your # !!!