I was curious what the plastic caps are for that are on the hub?

This is for ventilating the exhaust gases, for those who have thru hub exhaust.

Julie

vandeano,

There are 4 different sized plugs. You can mix and match forever till you get the best combo.

They won't do you much good without through hub exhaust.

I guess those plugs do nothing for me since I have my exhaust going out the transom w/ silent choice.

Thanks for the info

If the boat comes on plane well then leave the plugs in. Opening the holes is typically for high HP, low or moderate torque applications where you need to spin the engine up some rpm's to get it to where there is enough power to get on plane like a turbo motor or an outboard. Most stock motors have enough low end torque that the plugs in yield the best performance. Some custom engines with radical camshafts have the powerband at a much higher rpm will benefit from having the holes open. Even if you have through hulls air can still pass down through the drive and out through the vent holes.

I guess I'll take them out once and just see for the heck of it if it does anything