What Does A Cowling Do?

[Budman13]

Does a cowling serve any purpose? I was thinking of replacing the stock flame arrestor with a slightly larger one that is a little nicer looking. Although to do this I would have to lose the cowling. The stock arrestor is about 2" high and about 8" across. Would replacing this with a slightly larger one help at all. The motor is a 502 chevy with 502 hp with a single carb. and covered engine.

[Duane HTP]

It should help some on that many cubic inches. It will also help to get it out from under the cowling and give it some fresh cool air.

[SmokinLowriderSS]

I've heard the engine cover is good for costing ya about 50 RPM, and it is true on my Taylor. 1st run of the day she runs that much harder, and looses those RPM the next time she's fired up, till the next day, and it's not morning coolness either, does it midday, till she's been driven a bit to heat it up under the hood. I'm not giving up the engine cover tho for those 12HP.

[kp216]

Removing my engine cover and putting the K&N on will give me 150 rpm.
Cover on = 4200 at best until motor gets good and warm, then it's about 4150.
Cover off/K&N on = 4350 all day.
I won't run without the cover when the kids are in the boat though. That's why I'm going to a scoop.

[jbone]

http://www.***boat.com/image_center/data/500/3295engine1.jpg
This is the marine K&N flame arrestor I went with. I get 5200 rpm on my 502.
I have never heard that a hatch restricts rpm. Why is that??
If it is air flow, is there anything to help, besides a scoop?
J

[kp216]

Not sure about others, but my cover has no venting. It's a solid "doghouse". The only air my engine gets with the cover on is what little flows past the sides of the rear jump seats. In addition, I have a very small exhaust leak that is putting hot dirty air into the engine area.
I don't really want to cut up my original engine cover, so I'm probably going to make a new one. And I've been holding off on that until a Blue Oval takes the place of the small block Olds.

[Duane HTP]

I have never heard that a hatch restricts rpm. Why is that??
Because the carb is only gettiing HOT air from around the engine, not fresh air. it is thinner, less dense air at a higher temperature. That's why the first run of the day is always faster with more rpm. The engine is not hot enough to heat the the air yet.
I've made several air duct systems that help a lot. Wish I had a picture. I'll try to explain without. The last one I made was by taking the plastic back off of a thunderbird bucket seat. We mounted it between the carb and manifold, (as a gasket), and installed it with the four outer sides turned up, ( kind of like a box with no top), to where they went against the bottom of the engine cover. Then we made air ducts on both sides of it that went to two cowl vents on the side of the boat. When the cover was shut, the only air that could get to the carb was fresh air that came through the insulated ducts from the outside. On that particular boat it was good for 45 rpm every time.

[Budman13]

When I say Ihave a cowling i'm talking about a large piece of plastic that sits over the flame arrestor. I'm not talking about the motor cover. Does this plastic piece do anything or is it just for looks.

[Duane HTP]

Sorry, I misunderstood. Probably looks only.

[kp216]

Can you post a picture of what this thing is/looks like?

[Budman13]

Yes, I will try to post a picture of it within the next day or two thanks.

[Budman13]

Sorry I can't post picture, I forgot my boat is boat is at the shop. But, I hope can explain it better. If you look at the picture above of the other persons motor where his flame arrestor is put a piece of plastic over the top of the flame aresstor 20" long by 15" wide. I see these cowlings on EFI motors but not on carbs. Do these things serve a purpose on motors or are they for looks. Thanks again for any info.

[squirt'nmyload]

something like this???
http://i90.photobucket.com/albums/k265/squirtnmyload/MC_350_Mag_MPI_Ski_.jpg

[Budman13]

Yes, that is the piece I'm talking about. Does it serve any purpose, or can I get rid of it.