twin242ls

Any new performance data?

Revspan

Not yet. Heading to LC for the weekend, and will have lots of time to report back.

Revspan

After cruising at 4000 rpm for about 20 minutes, under hatch temps.were plus 22 deg from ambient. This seems to be a big improvement. Was super windy with the storms everywhere, so no top speed runs. Having under hatch temps under 100 deg is a success for me though. More to come when it is hotter tomorrow[ATTACH=CONFIG]559000[/ATTACH]w

SB

Not sure if you did this, but make sure temp sensor is right at flame arrestor screen as that is what really matters.

Revspan

SB. Yep, the sensor is strapped to a bracket within a few inches of the arrestor. If anything, it is hotter there add it is closer to the engine.

Revspan

Well, I have another idea in the making. Someone, in another post mentioned that cracking the hatch helps move a lot of air, and this got me thinking.
First, the idea has a few issues, such as the whole hatch being supported by the ram...not the hinge and all other perimeter surfaces. This is also an issue if anyone ever gets on the platform with it up. Quite a pain to have it up, down, a 2x4 holding it up etc. Second, there is quite a bit of engine noise.

So, I got a pen and paper out and came up with a support aystem to hold the deck up with full support and a vent hole design that would have some sound baffling.

Basically , a 2.5" spacer with a series of 2" holes drilled in it, sandwiched together for a wider support base and some space in between to cancel out some noise(a little I know). Then, some wedges to put on the sides to support the side of the deck. I think it will work well, and is totally reversible. In addition, the 2.5 inches will make the sun deck level with the sides of the boat....almost like it was designed to be like this.

I know there will be ventilation directly to the engines, but no one is ever on the boat while it is not in use, and it can also be removed if needed.

Any thoughts...? I will go and do a test fit in a week or so and get some more pictures

[ATTACH=CONFIG]563183[/ATTACH]

Revspan

I got the chance to see how the parts fit, and they are going to work fine. Will need some more fitting to get the bimini top supports back in(already done...just need to install). Then need to push the vent pipe outlets back a little so they are flush, letting the bimini top slide in...again, not much work.
Then, some minor adjustments needed to make the parts easy in and out, and the engine compartment can vent all day long when hot to help prevent heat soak. There will be no reason to have the parts in all the time...just when needed. You will also note the if you look at the side hatch support that the hatch will really be level with the adjacent fiberglass. It will look like it was designed for this from the hatch standpoint...although it will be a litte more angle to it.
[ATTACH=CONFIG]563699[/ATTACH][ATTACH=CONFIG]563700[/ATTACH]

Splitdecision271

REV... love your commitment and dedication to this. Puts a smile on my face. Hopefully it will work out and i'll get to see your progress in person this summer. I'm still interested in making the trek down to Lake Cumberland.

Revspan

Quick update,
Well, this solution seems to really work well. I took the pieces that need to support the hatch on either side, and installed some rivnuts so I could take them on/off, and the spacer that is under the seat is notched so it stays in position with the hatch sitting on it. My original idea was to install these when we were on anchor, but have simply installed them and left them in place at all times. Just easier not to take the parts on/off.

What I have observed is that the opening really helps keep the engine compartment much cooler when running(around 110 deg or less), and the engines will not heat soak when the engines are hot and you stop to relax for a while. It was not uncommon to have the whole compartment at 165 deg last year, and with the venting, I can usually count on the temps to not go past 130...and will drop down quickly depending on how long we are stopped. If you are stopped for a few hours, the temps will drift back to 115 or so.

There is some noise from the engines, but that is not an issue for any of us on the boat, and it is a few more inches to step up to get on the hatch, but this is also no problem for us.

As far as any top speed numbers....I am not going to say that this is worth any speed(may very well be the case though), but is simply directionally correct to get the heat out of the engine compartment. Does it improve hole shot with a hot engine...yes. Do engines like a cooler environment...yes. Can I back this up with unequivocal data other than engine compartment temps.....no, and not really trying to as this boat is simply for family fun and trying to optimize an already great boat.

AmiableDave

Revspan, I quickly read through the 7 pages of info. I have a 2014 292. Mine is hard pressed to hit over 60 mph with full tank of gas, 2 people, dog, etc.

What was the part number of the FA you used and the type of hold down? How did they hold up in use? You did say that you gained MPH right?
Are your 28p props Labbed? Bravo 1's?
Did you buy new props or are yours stock from Formula? I believe they came labbed.