Originally Posted by Tinkerer (Post 4463538)

Laugh all you want but I actually built a hood around the flame arrestor on one of my boats and ran a 4 inch rigid hose to it and ran it to open air at the side of the rear bench seat. Worked great untill it sucked up a pop can. I then installed two 4 inch pipes to it and ran well with 100% outside air without being preheated. I work with a lot more than ductwork.. Did I log into Yellowbullit?

Originally Posted by SB (Post 4463549)

http://www.ramairbox.com/product.html
http://www.ramairbox.com/images/proinstl1.jpg

Originally Posted by tomcat (Post 4463446)

The amount of air flow you need to remove heat given off by the engine is much higher than the amount of air needed for combustion. You can get a feel for this by looking at performance data from marine engine builders like Cummins.


In this case the answer is 2493 CFM. Add the 1140 CFM you need for combustion air and you are at 3633 CFM per engine. Getting over 7,000 CFM into and out of an engine compartment isn't easy, which is why you can see air temps under the hatch much higher than 120F.

I agree with the posters above advising air temp measurements in the engine compartment. When you can keep the temp rise at a max of 30F you are doing well.

Originally Posted by endeavour32 (Post 4463566)

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?

Originally Posted by SB (Post 4463549)

http://www.ramairbox.com/product.html
http://www.ramairbox.com/images/proinstl1.jpg

Originally Posted by endeavour32 (Post 4463445)

I will be documenting what I do and what the results are, including air temp at the air cleaner. However I think it's way more than a temp issue. It would take a little time to have a temp issue cause a problem, but when the hatch would bounce open and closed the engine would instantly react to the change. It was change you would really feel, and at WOT you need a lot of power to feel any difference. I certainly wasn't creating a 15 hp difference.

Originally Posted by SB (Post 4463505)

Many V boats with a windshield I've been in, the air moves backwards (towards the frt) at the rear seat/ hatch.

The shorter peoples hair blows towards the windshield, the taller people may have their hair go towards the rear.

If you sit on the very corners of the rear seat and stick your head out, your hair will go backwards.

And Yeh, I got geaky enough once on a certain boat (and a few cowl hooded cars) to use those air flow direction ribbons .