water mist coming up the back of the 300x cowling, see it in the video

[Instigator]

gary, you want to laugh, i have an extra map sensor hooked to the engine that is not being used(but wired), i will data log my next run w/ the boat starting at idle w/ the sensor open to the atmosphere under the cowl to see whats going on

Awesome stuff Charles!
Would expect nothing less from you
Course there's the difference between you Merc guys and us tractor guys. You use computers and science and we use...., welll, duct tape.

[Mr. Demeanor]

gary, you want to laugh, i have an extra map sensor hooked to the engine that is not being used(but wired), i will data log my next run w/ the boat starting at idle w/ the sensor open to the atmosphere under the cowl to see whats going on, i'm actually heading out to the garage now to do some cowl mods w/ the faceplate. incidentally, the 300x has some venting slots on the backside of the cowl

Ill bet you see nothing. We did this sort of thing when racing dragbikes. Tested pressure in a Hyabusa airbox created by the "ram air" system that the bike manufacturers claim added power at high speeds. What we found was that there was no boost in air pressure but with the ram air in place, there was less of a pressure drop when you would crack the throttle open. This was on a very small sealed system compared to a engine cowling (large unsealed box). The big advantage is just airflow direction as opposed to actual pressure. You might try putting the sensor the actual intake on the back of the motor. That might tell you something. Cool test regardless.

[mrcrsr]

i'll let everyone know what i find this weekend. i ended up removing the faceplate, cutting a slot in it that is roughly 1.25" tall by 4.5" long, then i drill ed 2- 2" holes in the cowling just above where i cut the slot in the faceplate, then spaced the faceplate slitely off the cowl, this way if a deviant wave blasts over the boat it won't go directly in the cowling, i have a 260 cowling here that i basically patterned it off of. next thing is to route the water dumps differently in the back as well as the exhaust relief

[mrcrsr]

Ill bet you see nothing. We did this sort of thing when racing dragbikes. Tested pressure in a Hyabusa airbox created by the "ram air" system that the bike manufacturers claim added power at high speeds. What we found was that there was no boost in air pressure but with the ram air in place, there was less of a pressure drop when you would crack the throttle open. This was on a very small sealed system compared to a engine cowling (large unsealed box). The big advantage is just airflow direction as opposed to actual pressure. You might try putting the sensor the actual intake on the back of the motor. That might tell you something. Cool test regardless.

the real thing i'm looking for is to see if there is a vacuum forming in the cowl, if there is a vacuum water will be drawn in, as long as i see neutral pressure to even slitely positive it will not draw water in the cowling, as well as increase performance

[Mr. Demeanor]

i'll let everyone know what i find this weekend. i ended up removing the faceplate, cutting a slot in it that is roughly 1.25" tall by 4.5" long, then i drill ed 2- 2" holes in the cowling just above where i cut the slot in the faceplate, then spaced the faceplate slitely off the cowl, this way if a deviant wave blasts over the boat it won't go directly in the cowling, i have a 260 cowling here that i basically patterned it off of. next thing is to route the water dumps differently in the back as well as the exhaust relief

Did you ever test?

[4fiddyR]

This amazes me. Didn't Merc do any testing prior to offering the motor for sale?

You would think so. They have an "X - site" that they brag on and on, and carry on about like they are so proud of it. Plus, they have a "racing" division that they plaster a logo all over everything.

However, a manufacturer can't just go around admitting they made a mistake because of the fekked up and bullshiv legal system we have.

[berg969]

is it a factory cowl or an aftermarket the factory liner works as a water trap

[Dingie 2]

DBR Dave Bush Racing blocks off the rear opening /opens up the front of the cowl than has a square that bolts over the hole. Looks like a reverse cowl induction.

just saw the first video of my 21 skater running, you can clearly see mist/water climbing up the back of the cowling, i thought i was having an issue w/ plugs/tuning at hi speed(the motor would start to breakup after awhile at hi speed) but after seeing this the motor is getting wet, i'm dumping the tstat housing water and poppet dump behind the engine, so i need to reroute that, any other suggestions? http://www.youtube.com/watch?v=xKHd9Bct6sc

[mrcrsr]

it is a factory cowl, all the mods worked, and i do have slite positive pressure present when up and running above 90