http://www.ramairbox.com/product.html
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now we're talking, that's some real muscle car engineering right there! Who needs high beams when you have ram air!

Nice 70, who needs cowl induction!

I think they stole that from the 67? Ford 427 falcon. If my memory is right.

So why not use a blow through carb hat and run duct work to my cowl vents? What are the opinions of that? Worth a try or stupid idea?

I'd look at it a bit differently, as that 1140cfm of air the engine is bringing in is also removing some engine heat. Either way, to keep temperatures down would take a lot of air. !!

1 x 3" or 4" would be too restrictive.

Now that's what I'm talking about. Damm straight.

http://www.ramairbox.com/index.html

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Rereading this I see what your saying, no way that hatch bouncing open would change heat that fast so I do agree you must have a supply restriction. Again, a vacuum gauge/map/kpa gauge on manifold should show this in back to back testing.

so placement of vents and the direction the vent flows is another key factor. (pointed front back or sideways)
a sleeve of dixie cups in the cockpit and the go pro pointed as to record what they do might aid in placement and direction

I am very interested about your findings when you start taking temps. I have single planes and tall arrestors that are very close to the underside of the hatch. I would imagine it gets very warm under there

Tyler-
I have the very same set up as you. Dart single planes, with tall flame arrestors.

That is better than closer to your engine.

Feel the intake plenum after a hard run. It will be cool. Win result of carburetors ! (vs MPI)

Mine might be a tad higher with the TRS, seems like the engines sit abnormally high in the engine compartment. I'm sure whatever works for you will work for me as well.

I'm also ruining a 1 1/2" Wilson carb spacers. I'm close to the limit of how high you can be in our boats. What size are your engines and how many RPMs are you turning?

Mine are 454's .. spinning them 5200 now, would like to turn them a few hundred rpm higher.

I never noticed this problem with 454's. I spun mine to 5200 RPMs. I also think the 311 has an additional set of side vents compared to the 292.

True that. Bring in 3633 CFM and the intake air temp will be ~ 110F in that example. Cold air intakes make sense and are common on supercat lites where the big 12" air duct entering the engine compartment is pointed right at the front mounted throttle body on the 525. I don't know why we don't see more of this on performance boats, except for the challenge of keeping water out of the duct.

I did not say it was a fix all, just one way to get some cool air into the engine room, every little bit helps..

My point is that at WOT and probably anything above and including cruise those fans are nothing but an obstruction to air flow. They are actually in the way of the airflow the engines are trying to suck in. Those fans work only at idle and low speed. IF the boat ( just about every stock boat out there doesn't have anywhere near enough) had enough air ducting then the fans wouldn't be an issue.

how do you figure that, air merly blowing by the side of the boat, with a 4" hose connection, vs the blowing helping draw that outside air in ? not talking about being hooked to engine, just bringing outside air in

The point is that when the engine is running it is causing a high negative pressure inside the engine compartment at speeds above cruise. The exhaust fan is trying to push air out and by doing this causes a slight negative pressure inside the engine compartment thus drawing air in ANY opening. The problem is that the engine creates a much higher negative pressure than the fan can. SO - ANY opening including the one the fan is trying to push air out of are now flowing air inward not out. The fan is restricting that air from coming in. IF you have enough opening in the engine compartment this doesen't happen.

To put it another way - If you had a twin engine Cat with 1000 HP per side that was capable of 150 MPH and you mounted a 50 HP outboard engine between the drives do you think the boat would go faster or slower?



The outboard engine would create far more drag than it could possible overcome with 50 HP of thrust.

Just throw that heavy azz engine hatch in the lake and go grab a screen door at the hardware store and be done with it. Lol

That would be too easy, and I like a challenge. I'm going to get the boat to run well with it on and have it be 100% functional.

I remember back in the Speedwake days, we had gone thru this with a ton of people, and many where able to raise their hatches (all different boats) up an inch or so and problem solved.

I just don't understand how the manufactures didn't solve this issue out of the gate. Oh well, I'm about to head down to the boat, put on the new props, and inspect what I need to do to get the issue resolved. I'll report back later in the day. The best speed I've had so far was 80 mph with the hatch off and labbed Bravo 30p castings @ 4800. New props are BBlades Bravo 26p castings, I'd like to get these engines in the 55-5600 RPM range today.

NVH. Seal them better and less noise. + to some designers and customers, less venting looks better, fits better, etc,etc

+ Water intrusion (typical boater doesn't cover their boats like what we do and etc,etc.

+,not too many builders are Reggie Fountain's that are willing to make a boat faster at all costs (shorter than advertised boat, lighter lay ups, less sealant ((doh !)), and etc, etc.

People give too much credit to all OEM's - cars (especially), boats, and etc, etc. for believing they know more than 100% what they are doing. This is not always true !

I have heard this allmy life on cars/trucks and semi recently snowmobiles - why would the car manufacturer choke the air intake so much ? Reason, they have to , by law, as they have intake air noise regulations too ! Yup - believe it !

They have gotten extremely good, however, in the past decade with quiet intakes and exhaust that still make good power. In fact, with snowmobiles, the louder aftermarket systems make less power than the extremely quiet OE exhausts. Exhaust extremely critical on 2 strokes !

Starting from 18yrs old, I worked for, and helped with, a respected performance and circle track guy. Everytime my little brain came up with a way to make more performance, the glasses would get raised, the eye's would dilate, and I'd get the "If your idea/design is so much better, someone else would have invented it already."

After, believe it or not, 4-6 (maybe more?) things I designed and went to try on a car or circle track car, and got that unwise wisdom, 1-2yrs or more later I'd be thumbing thru NationalDragster or Circle Track mag or Stock Car Racing or even Hot Rod or Car Craft and bang ! There was the item and there it was being tested. No, no one copied my things, it was just evolution and someone else stumbled up on it.

My wise mentor, was not wise in this regard. I had to stop listening. Which I did, and didn't look back.

Well I blew my port drive guys. So I am down. I need to try and find a new set of gears today, and hopefully I can have the boat back on the water next weekend. It never ends does it!

I will say this. The only real venting are the two vents that are right behind the windshield. The other vents for the blowers are a joke. Each only have 2 3" holes in them and the starboard side has blowers hooked to them so that size is really choked down. While the other vents are large and completely open on the back side, there is no way they are large enough.

Sawzall :party-smiley-048:

Hole saw- easier to get in the little area I have to work with. However I need to build a new upper ASAP

any updates?

Indeed-

Both upper drives were converted to XR Drives. I then ran the boat with the hatch cracked 3"- 72 MPH. I was like what the he!!, I'm going even slower. So I then pulled the flame arrestors and back to 79 mph +/-. So with the arrestor on, hatch closed 72 mph. So I don't think it was a lack of air issue, but a dirty flame arrestor issue. Even thought they look clean, they were not. I'm going to clean them and see how the boat runs this weekend, and I have a set of Gafrig 10'x5" air cleaners on order. So far now, those are the results.

did you try hatch closed arrestors off ?

dumb question right ?

Ha- not dumb at all. No, I didn't try with the arrestors off. I filled the boat up with gas, and running wide open drains the tank pretty fast. I need the tank full for this weekend, so my wide open runs were limited to 3 because I didn't feel like pulling the boat to fill it again.

You can cut a few layers of screen out of your stock ones. I only run 1 layer

I already sold the stock one's. Pulling them this weekend.

IF those were the ones that came with the engines they were already missing a few layers.

No- I put them on my old engines. I had HP 500 flame arrestors on it. Either way I'll be 100% fine with 10"x5" flame arrestors that are on their way.

I gutted mine and now just have 2 layers... playing with airflow things myself..