Kirk,

Seeing some of the other problems you have posted (boat listing to one side etc) I think your problem is in the setup and not necessarily the engine even though it is rich.

To me is sounds like you need to re-tune the engine, optomize drive height and reverse the rotation of your prop (new drive).

Just an educated guess based on what you've posted in the past.

PS, I have the same speed issue with my boat but I don't have the time or feel like spending the money to get the optimum setup...but I know what can be improved upon. Little here, little there....ya know.. ;)

I don't know if this is relevant, but if I run an outboard on a dyno (stuska), and then try and run the same fuel map on the lake, I have a pig fat motor. At least in my case, I can never get the motor to load like the water brake.... not even close. I have to takeout 5%ish.

Depending on the exhaust used on the dyno the engine is ususally a little fatter in the boat, at least from what I've seen...

in our case, we run it on a midsection so it is like it is on the boat.

My plan this summer. Pull the extension box off, remove one water pick ups and longer tabs.

I will set the X dimension where it was before with the bravo drive. Removing the intercooler pick up will help with wate flow to the prop and the longer tabs will stop the port tab from sticking into the water like a spike. I HOPE!!

At least these are inexpensive ways to change the set up for the better. I'll then run an O2 meter and fine tune the engine.

Then it will be new hull time.

I appreciate the input guys.

Hi Kirk,

As requested, I posted my emals to you on the forum.. (I added some more stuff, hope it helps)

Are you using an intercooler for that Quad Rotor, or are you using fuel to cool the charge instead? Was the VE indicated for the motor in the dyno run? Was the AFR on the very rich side? Was the reading on the dyno taken with 1 wideband, or 2 widebands? (Hopefully NOT a narrow band, as it will not give a correct reading at WOT. You must use a wideband, and better yet, 2 widebands, one in each header collector) Were EGT’s used on the dyno? (This would be the best, as you could correlate directly to cylinder to cylinder)

Reason I ask, is that I think the motor is not as efficient as it can be. However, it also depends on the design of the engine. If you are not using a big cooler, and run a bunch of heat through the motor, some people use the fuel to help cool the charge, which will affect the BSFC, the AFR, and the fuel comsumption.

If you are running a big cooler that is awic, then you also have to consider the size of the tank and the amount of flow of the pump, and the ability of the heat exchanger for the after cooler to reject heat into the raw water stream. Water has a speific thermal capacity, and can only take so much heat. The abiltiy of the second heat exchanger will play a part in the efficiency of the specific system based on coolant storage volume, heat input, coolant flow, intercooler efficiency, and secondary heat exchanger efficiency.

I have done extensive research on the intercoolers and efficiency, and the best I can find to date for AWIC is Laminova... (www.laminova.com)
Do you know the rated heat exchanger's efficiency that you are using? If so, at what airflow rate, and at what coolant flow rate is this efficiency level? Are you exceeding that level?

On another note, how fast are you spinning the compressors? (Are they Whipples? DO you have a compressor map that tells you the heat gain, pressure ratio, and airflow rate? ) What is the pressure drop across the core of the IC?

All these things add up to inefficiencies in the system...

If you are running efi, the computer could be trying to compensate for detonation by richening the mixture. If carb, then it may be jetted rich etc. The thermal capacity of the water in the tank could be exceeded if the tank is too small, and the cooler will not be as efficient. You can calculate all this out if you have the info.

In general, though, I believe your engine is using more fuel than it should to produce the stated power. Question is, why? I would examine sensors, and design of the motor for the given power output. There is something in the calculation that will not jive when compared to the Dyno readings.

Hope that helps with your diagnosis..

Richard

Quad Rotor Whipples, large intercooler.

Kirk,
Meet you at oshkosh poker run. We had a 27 daytona with a Pfaff 1000 in it. Let me say one thing tuning is not easy in a boat with EFI. We have had every expert brought in. I believe we can all say Pfaff is a recognized engine builder. You can ask any good marine builder after tuning on a dyno for a base line you must retune in a boat. They all build cookie cutter motors but every hull,gear ratio, prop size and every altitude puts different loads on motors. Put it this way G.M. puts 10,000 hrs of tuning to try all posibilities in each of there motors so they can recognize the changes needed. I believe you are on the right track by running the boat with an o2 sensor and see where you are. We gained an honest 12mph by tuning in the boat. Bottom was very lean and top was so fat it was washing the cylinders. Also remember every prop change or gear ratio effect the load times the computer reads. Just curious what system your using.

Hi Kirk,

Just browsed some of the posts again, and as you have EFI, I agree with BBoater. You must tune the EFI in the boat. The lake/river/sea is a perfect dyno, the prop functions as a water brake. You will need a good baseline, and then can play with the fuel and ignition maps as a function of load at various rpm points. Not sure which EFI you are running, but ideally, you would want to do some datalogging, and then evaluate on the laptop in the boat, then retune for optimum, then make some more passes, and tune some more until you have comfort that the system is operating as desired.

The land calibration dyno tune will need to be readjusted for your application, hull, prop, driving habits etc..

Hope that helps,

Richard

Its an Autronic and it appears much simpler than the Merc MEFI software I learned on. We actually have an Autronic tuner/distirbutor abut 4 miles from my boat and he said he would assist.

Maybe all of this together will help my cause.

Bboater - It was great meeting you, werent you guys talking about drive issues? How did you work that out? I cant believe you picked up 12 MPH with the tuning!! Honestly?