cowl/motor cover extra ventilation

[johndezman]

i've seen add on louvre plates that add / ease air flow "under the cover". anyone have info on benefits in terms of added rpm? also anyone test with and without the airbox?

[vector mike]

I would think that just louvers added with no other changes is useless. Usually they are added to help get in the air after the stock air box has been removed and/or velocity stacks have been added.

[johndezman]

mercury/mariner and suzuki all had models with vents at the forward edge of the side of the cowl from the factory. presumably there was a functional purpose. i could see a benefit just from the cooler air (since the vent/louvre was adjacent the air box openings) and not breathing warmed air that has passed over and around the rest of the powerhead.

guess what i'm really asking is there any proof of any significant negative pressure within the cowl, indicating that the air openings in the cowl are restrictive.

in the automotive world, K&N and others are raking in a fortune replacing factory air inlet stream components, i can see some of the same compromises/improvements being made in the marine world

[Raceman]

I agree with Vector Mike. The louvers in themselves won't make any difference. They will let in rain water, increase the noise, and allow critters in too if they're not screened on the inside.

[Raceman]

Incidentally, I'm completely unfamiliar with Sazooks, but to the best of my memory all the Merc/Mariner stuff with louvers was high perf stuff and even these have since been replaced with strategically located holes. The original Merc race cowls from the 70's were the first of their V6 cowls with louvers and they were moved around over the years to solve problems they created. In the beginning the cowls had louvers on top which allowed rain to run directly in the starter motor. The louvers on the rear also caused water to be vacuumed into the rear of the cowl at high speeds.

[pyro]

On my 200, the intake vents are near the top of the cowl on either side toward the rear. Behind the vents, I can see an intake tube that points up into the area behind the vents. Seems like it should move air good without allowing water to splash in. But I always wonder how it would run if I made some plastic "scoops" to force more air into them...
Anyone ever try that with a '89-'92+ bucket cowl?

[Raceman]

If you want to tell for sure if extra ventilation helps, just take the cowl, or in the case of clamshell type, the front faceplate off, and run it down the lake.

[ROLF]

In search of more speed,installed L&S jack plate $900.00,no increase,switched from bow tank to stern,$500.00,no increase.Left hood and face plate off for a test run 1.5 mph gain,cost nothing! Had my body shop form a polished stainless vent plate on the front of cowl,with air box installed,no increase in speed ,just noise and a cool lookin hood.
Rolf