Rebel_Heart

What is the benefit of having scoops in your sundeck? How are you able to tell if your performance will improve? Like most recreational boats, I have padded hatches with minimal intakes on the side of the boat. Just wondering how this might affect having the engine run more efficiently?

stevesxm

hugely. heat is the enemy of performance in all respects. ill bet that you get engine compartment temps well over 100 deg routinely and intake manifold temps much greater then that.

all that hot intake air saps power like crazy... on the dyno it was something on the order of 1 hp per 5 deg of inlet temp over STP. on a carb motor is makes the motor run rich as hell which also hurts power and everything else...

scoops will take care of the inlet air temp issue but getting the air temps down in the engine compartment is a much more important and straight forward exercise...

if you do all this, everything will get better... whether that the work and effort are justified by the increased performance is a matter for you to decide. the boat ISN'T going to go 10 mph faster...

what it WILL do is get better fuel milage, run considerably better all the time and make everything in the engine compartment last a lot longer. on my top gun w/ 502s doubling the air intake area on the sides and doing dedicated air extractors made a world of difference in all respects...

rdoactive

I put them on my cat to have clearance for the superchargers.
They draw in A LOT of cool air. That never hurts an SC motor.
The only problem was that at speeds over 85mph, they would draw in so much air, the hatches would start to lift.
Gary

Croozin2

When Phil was dialing in that 38 TG with 675 Zul's that ran 102mph he determined the boat needed some outside air. The above scenarios are 100% accurate, but another way Phil could tell the motors weren't getting enough air is that all of the PVC sawdust from building the cabin interior was being sucked back into the bilge during WOT runs. If it's pulling air from the bilge all the way up to the front of the cabin, it probably needs a little more fresh air from outside!

stevesxm

well... all that means is your exits aren't big enough... you want flow so you can drive the hot air out as well as feed th supercharger

rdoactive

It was on my Chris Cat. The entire side of the engine compartment had the 4" high vents pointing backwards. And there were 2 3" round bilge blower ports over the transom.
Any more holes, and the boat would look like swiss cheese.
I just added a hatch lock.
Gary

Rebel_Heart

My mill is NA. Does the increased air still make a difference? Do you have to put in a new sun deck hatch? How can they be integrated into my existing set up? Does the height of the scoop make a difference? Appreciate the responses.

DMOORE

Gary, at the rear of my hatch, between my scoops, I have a 12"x12" hinged panel that raises to dump excess air pressure in the engine compartment. Once the boat slows if sets flat again and you can't even tell it's there. It is just hinged, and the air opens and closes it.


Darrell.

rdoactive

Yeah, I started seeing those on race boats.........
Right after I sold the Cat.

Rebel_Heart

DMOORE
Do you have a picture of the hinged panel? That sounds like a great idea.