Wild Card 09

Your description of the throttle response at top end is exactly my experience, too! I came from a 525EFi, and was used to arelatively linear increase in power and speed in relation to throttle position and rpm. The 600 doesnīt like to run at high rpms, or the system ist cutting the power at top end. Iīve tried many different props and still feel that something is holding back.
The water pressure on my settup is low, but will get into the low 30īs if I donīt trim my Imco lower up too high. I have only had one Guardian mode in 50 hours (accelerating, as the prop cavitated the boat speed was low, the water pressure was the error code).
Iīm starting to think that the ECU could be cutting power at top end, causing the last third of the throttle movement to have little or no effect.

Wild Card 09

Thanks Dustin.
No power reduction without a buzzer, then?

Whipple Charged

Some early 600sci's could reduce power due to high IAT2 temps but it still cut the rev limiter, but would not throw code. They control power by the boost bypass, but not during fail safe modes, thats always done with engine misfiring/

CB-BLR

Wild Card,

I feel you man.....

I think that Mercury is bypassing the boost at top end to only make 600hp. I believe that they are doing this so that they are not competing with the 700sci, which they charge a lot more money for. I am hoping that Dustin's ECM upgrade is the answer.

Chris

Wild Card 09

Thatīs exactly what it feels like!
After running a 496HO, the 525 was a revelation! Big power increase, and the motor made it very clear if it liked the prop it was pushing. The 600 is more like the 496, as far as not really wanting to use itīs rev range until you prop down that the speed is out of reach. longer props draw more torque out of the motoras the blower lights up, but the power tails off at 5100. Mid range pull is sharp, and the boat doesnīt mind being loaded up with a few extra passengers and full tank, but the liveliness of 525 isnīt there.
Keep me posted on the ECM upgrade!

CB-BLR

Wild Card,

I agree.... 5100 is where my poops out also. Even with a variety of props. The speed seems to be always about the same on the top end. When I propped it to spin about 5350, with a Hydromotive 27 pitch P5x, the snappiness of the midrange is awsome, at the expense of a couple of mph on top.

I will let you know about the ECM.

Chris

relaxalot

Hello all,

I hope my problems with the 600 sci are finally over. Based on my talking to many 600 owners all with the same problem of the boats cutting out over 4600 rpm's. Mercury is aware of these problems but they ignore them hoping they will go away. I spent my whole summer and alot of money chasing these problems. Mercury's stock setup with the water feeding the motor and intercooler from the outdrive only is less than adequate. I think the problem was solved by feeding the intercooler with a separate bottom pickup and isolating the outdrive to feed the motor only. I plugged the top vertical holes in the outdrive leaving only the three bottom ones open. I slightly drilled out the nosecone holes. The result is the end to the constant beeping, engine cutting out and Mercury problems that they can't fix. The motor is finally running well.

I will be testing this weekend and posting results. If you have problems with your 600 let's talk.

CB-BLR

My guess is that both Wild's and my outdrive lowers are IMCO's, which are notorious for producing lots of water pressure and volume. my only gripes with the 600 are its lack of power on the top end because of Mercury's bypassing of the boost in order to sell 700's, and the low water pressure issue if I over-trim the outdrive much past the horizontal plane of the keel of the boat. If I trim up too much, the nose of the IMCO shadow's the water inlet causing pressure to drop and the motor goes into Guardian mode. This always seems to happen at about 5100 rpm when I am trimming up to get those last couple of mph on my boat. I have found some relief in Hydromotives P5x prop which gives me a lot of bow lift and reduced slip. Because of this, I don't have to trim up as much to see max speed, and the water pressure issue is mostly resolved.

Chris

Whipple Charged

Chris,

I had another customer that had a similar issue with the imco. One thing that helped was opening the hole towards the top of the current one, since the hole is going away when you trim the outdrive. This will really help in the high trim application.

Thanks

Whipple Charged

This is certainly the best case scenario. There is simply not enough water supply for the engine and intercooler through the outdrive on most applications. If your going 120+mph, no problem, but 600 and 700 can't typically get you there. Other than idle water flow, the seperate pickup creates far more flow. Were also coming out with some IC upgrades that have to do with the water flow, and this will also improve performance. A good strainer is needed to keep it very reliable. CP makes a nice IC strainer.

Let me know how testing goes!