06-05-2006, 11:00 AM #1
SCIC Air Intake Mod - engine compartment fed enough?
Following SOMEFUN's lead, I shortened my 06 SCIC's air intake to about 20" and expanded it to 3.5" with fat K&Ns and noticed @ 500 rpm / @ 5 mph gain. Two events tell me that the engine compartment doesn't get enough air supplied to keep up with the enhanced demand: 1) I initially rigged the air intake to the pipes feeding in off the boat's side-vents. They were sucked closed/in on themselves (hose too weak) at rpm's over 4500; 2) a "retired" sea-doo mechanic said that side vents didn't provide enough. The engine compartment seal seems pretty good, understanding that engines could still get air thru the hull. Anyone done anything to open up the engine compartment to feed it more air?
06-05-2006, 02:36 PM #2
Wow..thats some big rpm increase The longer the run of hose the more restriction. I'm running 4" kanaflex to my side vent and I just can't see it not providing more then enuff air. I'm just going to make sure my run of hose is as short and direct as possible. When you plumbed it to the side vents, were you still utilizing the stock air box?
06-05-2006, 03:40 PM #3
no exaggeration on the rpm/mph increase - it was that significant! Yes, the first time around when the hoses collapsed, the stock air boxes were plumbed directly to the boat's side air vents. Now, with such greater demand for air, I really question whether the side vents are sufficient. Does the air available thru the boat's hull flow freely enough? Don't know. Air available from nowhere else. I LOVE the nose mod you did for air & need to come up with something like that for this boat.
06-05-2006, 04:06 PM #4
I'd have to see some pics. I'm just headed out to my dealership and will have a quick peek at their SCIC Sportster. I was just trying to determine if your increase in rpm was due to the shorter intake or if it was because you bypassed the stock air box and plumbing. The stock airbox is restrictive and bypassing it altogether is a huge improvement but if you could draw cold outside air it would help even more. I'm not sure if your engine bay flows air well or not but I'll check it out for you.
06-05-2006, 05:27 PM #5
does length matter?
Yuji - thanks for the scouting...look forward to your thoughts. My guess is that the increase is due to both shorter intake as well as less restrictive opening. Not much by way of physics, but practically opining, the girls seem to agree its harder to suck a ball thru a long hose than a short straw. Any practical application there? I'd be curious to know if you notice a difference between running your 4" intake on the "longer" hose, and then trying a piece of "scrap" or shorter hose just to see. My guess is that length and diameter both factor into resistence . . . just don't know how much diameter is needed to overcome how much length.
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