increase air flow into engine compartment

[ynot]

hello there
any one tried to increase air flow in the engine room for better engine performance ?
i have a 400 sea ray sedan bridge i feel my engines perform better when my hatch is open
any advice is welcomed

 

[dtfeld]

Have you checked the pressure differential? You can buy a Manometer for about $40 to measure differential pressure and make a better assessment. I've seen others complain about lack of air flow, but whether or not it affects performance...

I'd measure it and see what the specification is.

 

[bobeast]

I doubt it's starving for air. More likely any perceived performance gain is coming from lower temperature. To that end, running the bilge blowers can help remove some of the hot air.

Bringing in outside air is an old hot-rodders trick on cars which is usually good for maybe 5 HP. This is because cooler air is denser. On a boat, you'd have to run a bunch of ductwork from your spark arresters to the outside to achieve the same effect.

 

[dtfeld]

Here are the specs from Mercruiser. There's more to it, but basic requirements.

Per Engine

Engine Air Requirement @ WOT - 657 Cu Ft/min
Minimum Combustion Air Vent (area/engine) - 66 Sq In
Max pressure Differential @ WOT - 2" H2O (measured with a manometer)

The hard part is figuring out the area of the Sea ray inlets...they are oddly shaped in most cases. The easiest way to tell is to tell is with a manometer. That would be with both engines @ WOT and blowers going.

https://www.perfprotech.com/blog/articles/mercruiser-combustion-air-requirements

 

[ynot]

Here are the specs from Mercruiser. There's more to it, but basic requirements.

Per Engine

Engine Air Requirement @ WOT - 657 Cu Ft/min
Minimum Combustion Air Vent (area/engine) - 66 Sq In
Max pressure Differential @ WOT - 2" H2O (measured with a manometer)

The hard part is figuring out the area of the Sea ray inlets...they are oddly shaped in most cases. The easiest way to tell is to tell is with a manometer. That would be with both engines @ WOT and blowers going.

https://www.perfprotech.com/blog/articles/mercruiser-combustion-air-requirements

Thank you guys I ll do that this weekend with sea trial check rpm and performance with hatch closed and with it open
Snd see the difference

 

[my3sons]

Interested in hearing what you discover. Diesels consume much more air than gas and I’ve never had a problem.

 

[dtfeld]

Thank you guys I ll do that this weekend with sea trial check rpm and performance with hatch closed and with it open
Snd see the difference

i doubt you’ll notice much difference , but good luck getting the hatch open with them WOT running might be tough!

 

[sbw1]

Wondering what practical significancef this will amount to? Spend $40 get some numbers. Burn some fuel. Look at some numbers. Then what to do next?

 

[CaptRonn]

View attachment 100577
Wondering what practical significancef this will amount to? Spend $40 get some numbers. Burn some fuel. Look at some numbers. Then what to do next?

 

[dtfeld]

At least you could make it look good...

I'd consider doing this top side.