lower unit paint

[kyle9108]

hey guys new to the forum and new to boat racing is there a speed advantage or disadvantage to a bare aluminum lower unit over a factory painted lower unit, thanks for the help you can give.

[zul8tr]

Generally no if both finished the same, paint chips and then a difference if below water. Aluminum can be sanded and polished I prefer that as easy to keep refreshed. Some classes do not allow mods to any part of a stocker even paint.

[kyle9108]

well there isnt anything in the rules that says you cant take the paint off or blueprint the lower unit motor is a stock mercury 40hp 3cyl 2stroke going on an inflatable trying to find a couple more mph out of it.

[zul8tr]

Don't know about the rules related to your inflatable class. What I was refering to was APBA stock outboard racing hydroplanes and runabouts. They are specific as to what you can do to the engines. You will have to research your rules or ask those in the know of the class you are in.

I doubt if paint vs bare aluminum will get you a "couple more mph out of it." Look into props, setup, tuning, etc for those mph increases.

Speed increase requires $$$$, how fast do you want to go?

[kyle9108]

well the class is apba superlight tunnel bandit class, its a stock class ive read the rules and it dont say anything about lower unit staing factory color or bare aluminum, im in the middle of working on the lower unit and have some paint sanded off to fix it just trying to see if leaving it bare with slow it down or speed it up. ive noticed most of the stock runabouts and hydros have bare lower units not painted along with alot of other outboard classes, im am new and trying to learn thanks for your help

[zul8tr]

Well if the rules do not specify you have stay OEM than run no paint. As I first stated there will be zippo difference so what ever pleases you. If they allow shaping the lower unit gear case and/or adding a cone that's is different there will be an advantage but that is not OEM stock. Ask the inspectors at a meet for specifics.

[phillnjack]

if you took the paint off and sanded the gearbox to a mirror finnish it would be a gain for sure.
it might be an almost un-noticable gian but would be a gain due to the box being smaller all round.
Think about how thick the paint and the primer is ?? taking the paint off will decrease the width of the gearbox.
The engines get painted at the factory and they just want good coverage,they dont care about how thick it is or
if it is uneven etc, look at the 1991 60hp merc gearboxes they looked like they were a brushed finnish paint was so thick!!!!
When trying to gain speed every little helps,
if the paint was something very special to help in getting less water adhesion then that would be another matter.
But do check with officials, as they might want to measure the gearbox width in your class, you might get a jobsworth turn up with his micrometer and disqualify you.
most race boats i see on this forum seem to have silver / alloy coloured gearboxes,maybe some are paint and some alloy.

But in answer to your question about a gain, yes it would be again but very minute.



phill