Only problem I have is in weedy water. The transom mount plugs up easy and I need to back flush with air to clean it out.

Aside from that, it flows HUGE water ! If my striner isn't tight, it sprays out the top seal when running at top speed.

I have a 600 sci with a merc xr that had the same problems. I plugged all of the vertical holes on the xr except the bottom 3, oversized the nosecone holes by 1/16" each. Routed an external bottom pickup to feed the intercooler only through a separate strainer. Problem was solved. The 600 requires water pressure to be in the 30's at high rpms. One of my problems was that when I trimmed up I was starving the outdrive for water.

I have a 600sci in my Heat, and an IMCO extreme outdrive. I was continually having the problems you describe with water pressure. I was frustrated with this for months!

You are correct in that as you trim up that the nose of the IMCO lower is shadowing the water inlet.

My solution was to drill a 5/16 hole on the top of the nose-cone directly towards the rear of the outdrive. The hole is about 1.25 inches deep before hitting the water inlet channel from below. I determined how close to the nose to go by putting my IMCO hose fitting on the outdrive, and marking it so that the upper inlet would be covered by the blue, hose water inlet, and I could still run the boat on a hose when needed.

I had zero reduction in speed, and the over-trim/water pressure problem is gone. Water pressure stays in the 40 psi range at 81.5 mph on GPS.

My outdrive is at 4.5 inches below the keel.

Hope this helps.

Chris

P.S. Another option is to have Dustin re-program your ECM, but I have not had the coin to do that yet. Supposedly worth an additional 75hp.

I also had Dustin do the reprogram. I like the results! I have alot more torque and the motor pulls much harder. The boat is much faster now. Most of all I like the torque.

Chris,
thanks for the good info. I´m not quite following your description of where the extra intake hole is. Can you give more details.

Whipple`s reflash does sound tempting, although I´ve been pretty convinced of keeping my blue motors bulletproof stock up till now!!!

My boat is at OCM in Oregon for some warantee work, or else I would take a picture.

The stock water inlet on an IMCO lower is a slot at the lower leading edge of the pointed nose cone. When the outdrive is trimmed up , this pointed, front nose-cone, shadows the water inlet, thus reducing water flow. I drilled a 5/16 hole in aproximately the same location as the lower pickup, only on top of the point. This hole is pointed from the front of the outdrive towards the back, and connects with the lower stock water inlet about 1.25 inches into the aluminium. This way, when the outdrive is trimmed up, water is still in direct contact with my new water pickup, which is located on the top of the cone.

I determined where to place my new inlet by placing the stock, IMCO, blue, hose connector, onto the front point of the outdrive, and marking the top front of the point on the outdrive with a permanent marker. I wanted to make sure my new inlet was covered by the blue, hose connector, so that I could still run my boat on a hose if desired. I drilled my 5/16 hole aproximately half way between this mark, and the point on the outdrive.

I hope this helps.
If not, I will be getting my boat back in a couple of weeks, and I will take a picture.

Chris

Now I´m following. It makes sense and sounds like a good solution.
Although my 600 hasn´t complained about trimmed out pressure loss. the readings I see off the Smartcraft (when trimmed out) make me wonder why. I´ll try your mod. Thanks!

This mod also increases water flow to the engine... and that is a good thing. More water flow equals a cooler innercooler which in turn makes more horsepower.

Chris

Chris,

Do you have a pic of the hole you drilled yet? I think I am having a similar problem and would like to duplicate your solution over the winter.

Thanks,

Tom