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-   -   38 Lightning ram air (https://www.offshoreonly.com/forums/fountain/286850-38-lightning-ram-air.html)

mcprodesign 10-24-2012 10:21 AM

38 Lightning ram air
 
I was wondering if someone could measure the free board on their 38 behind the ram air vents. My free board almost covers up the entire intake area. Just measure the angled board in the back from the bottom to the top I would appreciate if someone could do this thank you

4bus 10-24-2012 12:44 PM

I can mesure for you tomorrow, but not really sure what you are asking?

mcprodesign 10-24-2012 03:09 PM


Originally Posted by 4bus (Post 3801819)
I can mesure for you tomorrow, but not really sure what you are asking?

When looking into your 2 ram air vents on the side.. Look for a black board that slopes up tward the rear . I think it is for containing water so it goes out the drain, and not into the bildge. but don't quote me on that. Anyway Measure how tall the board is top to bottom. Thanks !

mcprodesign 11-27-2012 12:53 PM

Does anyone have access the their Lightning that could measeure this ?

4bus 11-27-2012 02:52 PM


Originally Posted by mcprodesign (Post 3822166)
Does anyone have access the their Lightning that could measeure this ?


Mc, I completely forgot about this. I do have access, and will take measurements by the weekend.

I am just going to measure all sides of the box cause I am still not sure what you are asking for.

Did someone cut the box out on yours?

mcprodesign 11-27-2012 05:03 PM

there is a black board behind the ram air vents on the side. It starts at the bottom bet by the drain hole and goes up towards the back. I am just curious what the newer ones have this far as how long that board is. Or how tall the board is

keegan 11-27-2012 06:53 PM


Originally Posted by mcprodesign (Post 3822321)
there is a black board behind the ram air vents on the side. It starts at the bottom bet by the drain hole and goes up towards the back. I am just curious what the newer ones have this far as how long that board is. Or how tall the board is

Mine has leaf blowers installed there...not sure if that is factory or not?

mcprodesign 11-27-2012 09:50 PM


Originally Posted by keegan (Post 3822386)
Mine has leaf blowers installed there...not sure if that is factory or not?

As long as they pressurize the engine bay . ;)

mcprodesign 11-27-2012 09:55 PM

This board

4bus 11-28-2012 08:21 AM


Originally Posted by mcprodesign (Post 3822541)
This board

Mine does not have a board, it is a "box" with a drain on the bottom and 3 holes on the inside to let air into the bilge area. The holes look to be about 2"

I forgot my phone when checking out the boat, but I could take pictures of the complete box for you.

mcprodesign 11-28-2012 09:38 AM

So, your boat was a 575 boat from the start. I wonder why the air is limited. Only reason I can think of is possibly too much air pressurizes the engine bay and puts fumes into the cabin? Maybe Reggie will let us know. It seems like more air would be better to me. Rob, is yours the same as 4bus?

1 MAIDEN AMERICA 11-28-2012 11:23 AM

Mine's the same, board comes up and sides have large holes. There's plenty of room for air to get into the bilge.
I've thought about putting vents on the back of the boat to relieve air pressure in the bilge and on the rear of the boat. Kinda like Outerlimit flaps. And building ducts to direct the air flow right to the air cleaners. I started making the ducts and handed my molds to someone to finish. He f#$%@& them up so I never continued.
I've also contemplated ducting and adding small fins ahead of the windshield to lower air pressure and direct air flow. I was set up with an air pressure gauge, red yarn, tape, video camera, and an aeronautics engineer to do it once and blew a head gasket. Never tried since.

mcprodesign 11-28-2012 01:12 PM

I think your air duct set up might be good for 100 rpms pr so. Run your boat with the hatches off or open ( you can strap a couple tiedowns accross it to secure it) I picked up 100 rpms w my last boat , something about plenty off fresh clean air. My boxes are probably the old school ex stlye .. when mine was built the ram air tops were new. Pressurizing is great for na motors but probably not so much with the blown motors. I think directing air to the engine intakes might work for more speed.

4bus 11-28-2012 02:12 PM


Originally Posted by mcprodesign (Post 3822790)
So, your boat was a 575 boat from the start. I wonder why the air is limited. Only reason I can think of is possibly too much air pressurizes the engine bay and puts fumes into the cabin? Maybe Reggie will let us know. It seems like more air would be better to me. Rob, is yours the same as 4bus?

Yes, boat is exactly the way it cam from fountain.


I have experimented with running the hatches cracked and it helps, even more so on extremely hot days. The split hatches work great for this :D I get a high pitched whistle from between the hatch cushions when the hatches are closed, which leads me to believe that the holes in the air ducts are not large enough to feed the required cfm to the engines. The whistle goes away with the hatches cracked 1 inch

Wildman_grafix 11-28-2012 02:36 PM

If you want to know how well true ram air can help a NA motor, just take a look at what sport bikes have been doing the last 15 years.

mcprodesign 11-28-2012 03:03 PM


Originally Posted by Wildman_grafix (Post 3822981)
If you want to know how well true ram air can help a NA motor, just take a look at what sport bikes have been doing the last 15 years.

They offer Ram Air. Not a pressuriozed air box. I have run presurized air boxes before on Superbikes I have raced. Not only do they force air, they also force fuel when it is pressurized. That is the effect of the engine compartment having ram air. It is ram air and fuel like a pressurized air box. Or it is more volume. 1 of the 2.


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