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Fresh air in the bilge to make more power.

bigsbetter

bigsbetter

Active member
Has anyone messed around with trying to duct or channel more air into their engine instead of the engine sucking the 150 degree air from the bilge/engine compartment? I sure there's got to be some horsepower gains here. I'm thinking of some kind of duct from my side vents or something, or raising the front of my engine hatch a few inches or raising the rear of the hatch a few inches??? Has anyone tried anything like this? It's got to help. My boat runs 3-4 mph faster during my first WOT run of the day, say maybe 4-5 minutes after I put it in the water (before the engine has gotton the air in there so hot.) The outside temp. is the same 90+. as the rst of the runs of the smae day. I don't want to install a scoop on top. Lets do some expirementing and share with us your results....It's almost free HP!!!!
 
i have heard of this, but don't know the results - my first thought - install a couple of blowers in backwards - having the air flow into the bilge instead of out. shoot the hose right to the flame arrestor. might be worth a shot.
 
Simplest way to check this is crack the hatch a few inches and run the boat. If it helps then yes, it needs more air in the eng compartment. If not, then its something else. My friends cobra jet (Olds powered at the time) gained a couple MPH from installing a velocity stack through the engine cover. 150 degrees in the engine compartment seems kinda high. Is the engine at normal operating temp on your first fast run of the day and the same in later runs?
 
I was just guestemating the 150 degree air in the bilge. But if my engine is 160-180 degrees or better in some areas, I think the temp. inside the compartment would be pretty high. When I make my first run, the engine is at normal operating temp (160) but it has just gotten there. Yes it still shows 160 on the other runs also. It goes to 180 at times when I run it hard and then idle. Next time i'm gonna bring a thermometer to see how hot it is in there, and raise the hatch a li'l and then check the temp. and do some comparisons.
 
Yeap !! sucking that hot ass air kills h/p for sure...why race cars have a scoupe sealed off to the outside air, as i do on my top sportsman camaro, and yes on the on a boat to...I years ago had a sheet metal guy make me a airbox with 2 4" duct connectors on the sides, covered my carb top, tapped into 2 outside louveres and had my old liberator breathing fresh air..2 mph on hot days over the std way.....going to be close with your blower !! time for a scoupe !!!!Rob
 
ROB! What are you do'n inside peck'n on the computer? You're sopposed to be wrench'n on that Checkmate!:banana: Ha Ha!
 
I've really thought long and hard about this as well. This winter i am going to remove the vinyl off the top of my hatch and add a low but wide scoop. The idea here is not so much getting fresh air into the engine compt, but exhausting the hot air out. It's much easier to get the air in with scoops, blowers and lifting the hatch. But getting it out is the problem. You need to vent the compt. to a negative air pressure area. In a car, that area is usually under and behind the engine itself. Cold air enters the front, hot air leaves under the car. In a boat, there has to be something that exits out the back. My ideal project would be to add vents in the transom area above the swim platform. Then, either lift the hatch an inch or so, add a scoop, and/or figure out some entry point under or around the back seat, bigger than what's there now. Then, I'll also switch the starboard side engine vent to exhaust as well. You may have noticed that one side vent is facign forward, one facing back?
Whatever you do, keep in mind water intrusion needs to be limited. Also remember, you don't need to go crazy with it. Creating a simple draft will suffice for stock engines. Now, if you're feeding a big block blown engine, you will need to stick the carb out in the open:bigthumb:
 
Winter, glad you see it as I do. I too have thought about the vents on the sides. Thought about adding more than just the current 1 12" long vent. Maybe have 2 on each side. I thought about the drag it would create by raising the hatch a little, but I remember VinnyP doing a test with a smokebomb and not much air was forced up against his deck. But then again I think he had the smoke bomb at various points in FRONT of his windshield. Anyways, it's enough for me that I need to do some trial runs with the GPS in hand on a hot day. It's sopposed to be 98-100 degrees for the next 5 days straight! Anyone wanna go for an expiermental ride?
 
I think air is good but I would never cut my hatch platform. I am always sitting on it drinking beer. I have been in a boat like a Checkmate before and after a scoop was added. Going down the lake it pushed hot air into the cockpit area and made you sweat your balls off.

I have side scoops on my boat on both sides and also have a scoop at the back of the swim platform. My engine bay also gets air on both sides of the rear seat.

If more air is needed or you want to cool it down why can't you turn the blower on or add a extra blower. The engine compartment does not get half as hot as a car for the reason the exhaust is water cooled.

I don't know how much everybody uses their engine hatch but the engine hatch on my boats gets used alot and the women love laying on it to tan. I think the engine hatch and swim platform are the most used parts on my boat.
 
yeah I gotta have my "sundeck" aka engine hatch.
even if it cost me a couple mph. like red said, the
women tan there and we drink beer there, take that
spot away and it just aint the same.
so.. I gotta have it:cheers
 
Yep Mine has to stay too, It's the dance floor for the girls :drool:and me too sometimes:banana:. That's why I don't want a scoop.
 
I have seen people that have scoops that face rear and are molded to the hatch and covered. They stand about 3 inches and are about 2 ft wide and are mounted the back of the hatch, so it leaves plenty of room for beer drink men and dancing women.
 
I like scoops but I like the sunpad better. I would hate to interfear with ladies crossing over my boat.

:eyecrazy:

 
Now where the h3ll are you finding these chickies to grace your sundeck? :drool: I may decide to keep mine if i could find them to pose on the back, but to me, mph is everything right now. And yes, scoops on the top should face backwards imho. That will help the draft. I may actually try to incorporate that into the sunpad, but we'll see. If my new motor can get me to 70mph with the sunpad, then it stays :D
 
it's your party!

Lol, I was once on that 70 mph quest. But 70 seems so slow
when the Baja or other runs by me running 80 mph. Screw it,
bikini's and beer on my sundeck/engine hatch and 67 mph will
have to do. The couple of mph that the scoop may get me is
just not worth it to me but to each his own. You gotta dance
to the beat of your own drum, not mine, and vice versa!

Party on!:cheers

also, if you aren't getting bikini clad women crossing over your
sundeck, your going to the wrong places to party bro!
 
Well... i don't know about you or others posting on this thread, but i'm happily married with two little kids and want to try to keep it that way ;)

I pushed it the other year when i drove my freshly resto'd 69 Camaro to Hooter to have all the little minkies pose on and around my car :bigthumb: Strange chickies on my checkmate might push wifey over the edge :irked:
 
I'm also extrememly happilly married with 2 kids, but I still get the girls on the swim deck....my wife is the main one who gets it all going in the first place! With 1500 watts and 2 subs and some partying music,and alcohol, you never know whats going to happen!
 
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