Create a smaller engine box?

[CCAnderson]

those nice little vents on the back work great for the blower but when you are running the engine hard all the air flow will be in the vents plus any other opening, through the engine, and out the exhaust.

[JimN]

Originally Posted by DanP

Thanks Frank. Very simple and concise explanation for what could have been a lot of bumbling in the dark. So, does that mean those little vents at the back of the box would be more of an intake vent rather than an outlet? Or would the vent system from the hood be able to easily handle that kind of airflow?

My google-ing tells me that 500cfm is a bit of a tight squeeze through two 3 inch tubes without some sort of pressurized system. Especially since the surface area at the intake in the hood is even smaller than the cross sectional area in the tubes.

Sorry if I have gone way off topic from my original post. Im just curious about the air flow direction and source now.

The air coming in at the front and exiting the rear are there so the bilge is ventilated, with the added benefit of providing air for combustion inside of the engine. If the vents weren't there, the concentration of combustible vapors in the bilge would cause major problems in the event of any kind of spark, assuming the fuel:air ratio reaches the danger zone.

The direction of air flow doesn't really matter but if the enclosure is too close to the engine and there's no vent on the cover, heat won't be allowed to escape through convection. You also don't want to have hot surfaces too close to combustible materials.

[DanP]

Great guys, thanks...

So even though they look like outlets, they could be inlets for combustion air, but are also convection heat release.... interesting.

As for a new compartment size, I was going to take a look at the clearances of the newer models and just duplicate something like that. You're right Jim, no point to pushing the clearances for no reason.