My RXP Intake and fan mod and why I like it.

[Water4fire]

As many know people are placing fans in there intakes and
modifying there air intake to work with it. Well this is my intake
mod and why I think it is better.

On most intake's and kits people use the cap to the stock
air intake vent to secure the fan, then use a elbo up to the
fresh air vent. Well I don't like it as when the SCer out pulls
the fan it can still bring in hot engine air from around the stock
cover it attaches to. And it will out pull the FAN!.

Others try moving there intake further up front in the hull.
Thus still using hot engine air.

Well here is a picture of my intake and some thoughts I have
about it. Notice when the SCer out pulls the fan it has so much
space around the fan to still pull in only fresh outside air when
the fan is over come. And it will be. Also I am placing a
pre-filter on the cap.


Please click on my yahoo link and view the detailed
picture's and somewhat my instructions. Click on every
picture to enlarge it and see more of what I say about
that picture. Please give your feedback. I went with just
a switch and no relay as the fan is annoying at idle.

My link.

http://pg.photos.yahoo.com/ph/austin...en%3as,1%3af,0


Here's what I think.

The first 2 picture's show what I didn't want.

The second 2 picture's show what I did. But please click
my link above to view it all and give me feed back. Please.

[Jarrett]

How do you insure water won't be sucked into the intake when riding in rough water?

[Water4fire]

Well there are many ways, but the very best way is that I have
installed a per-filter (outter wear ) on the front of my underseat vent.

Also the stock air box is superior for water resistance.

[Thomas]

I've been hesitant to do this mod for the same reason. I occasionally submarine my RXP (ALL THE WAY UNDER!) and this simply does not provide enough protection for me.

I do plan to use some fans, but it will be to evacuate the hot air out of the rear of the hull (probably use existing rear vent), thus pulling fresh air in the front.

[Water4fire]

With the pre-filter on the front of the seat vent I believe
it is impossible for water to get passed it in any amount
that will get to my intake.

I have also placed the PVC pipe high enough in the vent
that if water did get passed my pre-filter ( Not likely) it
would drain into the hull.

[Thomas]

since we almost posted at the same time, I didn't see your pre-filter statement untill after I already posted. Not a bad idea. Let us know how it works.

[Water4fire]

Will test when I have baby sitter for my youngest.
But I love my boys they come first.

I also installed Denson 27's. Can't wait.

[Thomas]

Damn, I'm getting myself discouraged.

The 3" atwood turbo blower is rated to 145 cfm
The 4" atwood turbo blower is rated to 230 cfm

But those are "open" ratings. meaning with nothing connected.

with 3' of duct, one 90 degree bend, collector box and louvered vent on discharge side of blower:

the 3" atwood turbo blower is rated at 100 cfm
the 4" atwood turbo blower is rated at 125 cfm

So, what does this all mean?

well I'm gonna do this witout figureing in the boost from the supercharger (since I could only guess how to do that)

1 ci (cubic inch) = 16.387064 cc
1 cf (cubic foot) = 1728 ci

Therefore for a 1500cc engine
1500 cc / 16.387064 = 19.535616 ci

1728 ci / 19.535616 = 0.052972 cf

1500 cc = 0.052972 cf

a 1500 cc engine will pump in 0.052972 cf of air per revolution,

at 1800 rpm (idle) the engine requires ~95 cfm
at 2000 rpm the engine requires ~106 cfm
at 3000 rpm the engine requires ~158 cfm
at 4000 rpm the engine requires ~212 cfm
at 5000 rpm the engine requires ~265 cfm
at 6000 rpm the engine requires ~318 cfm
at 7000 rpm the engine requires ~371 cfm
at 8000 rpm the engine requires ~424 cfm
at 8200 rpm the engine requires ~435 cfm

to make sure that the engine received only fresh cool air at all rpm's, I would have to install about five 3" turbo blowers or four 4" turbo blowers in the rear of my ski!!!

Of course these are guestimate calculations because it doesn't account for inefficiencies of the ducting or the engine, and it doesn't account for boost since you would have to know the boost level at each rpm.

[Water4fire]

exactly why I put my fan were the SCer could pull around
it when needed and still recieve outside cool air. Instead
of still pulling in the hot engine air with the stock intake mount.

Also my fan is to keep engine compartment temps down,
but aid in the richness of the low end grunt.

I am glad to see someone thinks that fan can be overcome
by the SCer.

[Thomas]

I am glad to see someone thinks that fan can be overcome
by the SCer.

Yep, right around 2000 rpm.


not that the ppg setup doesn't still help at higher rpms by getting at least SOME cool are in there.

I just hope that in your design that the fan itself doesn't end up being more of a restriction at higher rpm's