External Pickup's on a twin engine cat

[DonG]

Hello All-

Has anyone ran external water pickups on a twin engine cat? Did you see any gains by doing this? Is it better to install them directly in front of the lower units or away from them? Is the water pressure more consistent using external pickups?

Thanks!
Don

[DonG]

Here is the issue I am seeing. My boat runs fastest (107 mph @ 6000 rpm) with slightly negative trim. This negative trim reduces the water pressure and I have to lower the engines to be able to gain back the water pressure but then I loose top speed. I have already installed the water ramps in the bottom of the boat but it only helps a little. I was thinking that if I installed external pickups I could eliminate the water pressure issues. Thoughts???

[DonG]

Here is what I am thinking for the external pickups.....

[Go Time]

I think that you will need to plumb the water from the pickups back to the inlet of the water pump on the engine to provide cooling with the engine at idle and to prevent overpressurizing the engine cooling system at WOT. Arranging a hose from the pickup to the Lower unit that will handle the pressure and not cause problems thru the motor trim travel may be challenging.

[Mr. Demeanor]

Have you seen my setup? Read to the end for the final setup. Works awesome. I have 25 psi at anything over idle all the way to 95mph. Plumbed to the water pump with a strainer in the engine well. Impeller acts as a pressure regulator at high speeds and I never go over 25 psi.

http://www.screamandfly.com/showthre...t-water-pickup

[racerx]

What gearcases you using?

[DonG]

What gearcases you using?

Sportmaster lowers

[racerx]

The good ones the ramps in my skater pumped xtra preasure real good ask Eli on hear he had the other pick ups

[eli]

had thru hull pickups to sea strainers to lowers right below water pumps worked great ,reason for the sea strainers is you get some gunk in them tubes will plug things up real fast
where the sea strainers chop stuff up so small it goes right thru never had to clean them

[mlb75]

They will definitely work, a friend had a 32 skater with trips and through hulls, the pickups were actually plumbed to a tank and then the three motors each had a port off that tank. I'll try and see if I can find pictures of his setup.

[Go Time]

So you found S&F did you Mike...welcome!
Oh, this is Mark

[DonG]

From the research I have done I see some people mount the external pick ups (twin engine application) in front of the lower unit and other mount them on the lowest part of the tunnel. Anyone here have any experience with this?

[rude tim]

You should never put anything in front of the prop that can disturb the water going to the prop.

[Mr. Demeanor]

You should never put anything in front of the prop that can disturb the water going to the prop.

If you do it right, its not disturbing the water in front of the prop. These dont stick down into the water at all. You also have a gearcase and skeg in front of your prop. Mount them directly inline with the gearcases or on the port side of the gearcases so if there is any disturbance to the prop, on the side where the prop is exiting the water, not entering it.

[tux974]

On my 28 Skater Peter installed them in the sponson approx 6" forward of the transom and tear dropped flush, worked great!
He also plumb them together and with a Y to also fill the ballast tank.