cutting holes in outboard cowls!

[Wellsy]

I have a 40hp oil injected 2st Mariner
I am looking at cutting or drilling 1 or more holes
in the front part of my engine cowl. :o
This is to allow cool air inside and hopefully
increase the performance of the engine.
I have seen it once only but the bloke was going the
other way.
I just wanted to know if anyone has done or has
heard of it being done and if it was any good.
A lot of the new Hondas (130/150hp 4st) have vents
in the engine cowls to help with cooling.
Any comments would help.

Cheers, Wellsy.

[coasty]

my suzuki has a big vent at the rear that lets the heat out , i never thought about one to let air in. why not force it in with a bilge fan . that way it would act like a supercharger if it was connected to your air intake.

[Kerry]

....This is to allow cool air inside and hopefully #
increase the performance of the engine....

Are you expecting a bit much ::)

There has only ever been one reason to cut the cowl, and that's to effectively to put snorkels on motors/boats that have a (bad) habit of sucking the ocean dry. In these cases (fairly rare depending on the boat) the normal air intakes are blocked up to reduce moisture intake.

I tend to think your kidding yourself with this extra performance stuff, the worst thing you can do is induce excess moisture.

Cheers, Kerry.

[DAVE_S]

wellsy kerry is right in what he saying had shark cat did this to 90 yammys to leave some water for fish to live stoped the water intake problem and a expensive repair bill made no difference to preformance .

[banshee]

Yep Kerry is right,I'd only be mutilating my cowl if I owned a cat.

[finga64]

Wellsy, have a listen to Kerry.
He gives some really good advice and my first thought with a hole/s in the front of the cowl is what keeps all the water spray out of the air intake??
Sounds like a good way to get a belly full of water to me.

[QldKev]

As the other have said; don’t do it.
#
Remember that with every 10degrees of lower intake charge temp change you are only going to get about 1% more hp. #Now on a 40, that is 0.4hp for every 10degrees. #Add this into the equation the risk of water ingestion into the engine and also covering your electricals, the risk/benefit analysis says no don’t do it. #If it way that easy to safely get extra hp for minimal mods, don’t you think the oem would do it. #

With the Honda’s added vents, I’m not sure but I think it would be more to do with under cowling temps getting to high cause other problems; (vapour locks, problems starting due to an over hot starter, etc) not for the extra 1hp they may find.

[Wellsy]

thanks for all the input guys.
I was in two minds about actually
doing it, and thanks to all the great
feedback, I will be leaving the air saw
alone!

Cheers, Wellsy