Warlock28SXT

It seems the harder I run the boat the richer it gets. IT seems that when its looking for more air it cant get it. I tried to run the boat (@ slower speeds) with the hatch open. The AFR leaned out to around 12.7 @ 2000 RPM. I am going to install larger vents and thought of installing a bilge blower sucking air into the engine bay. I also need to verify timing. If I'm not mistaken I'm only at 8* base (set it last year and don't remember) If this is the case I have set up my own rev limiter. I will post after I get the run the boat again. I feel I am now making progress with this and a big thanks to all who have posted givin me some direction. It's been a great learning experience.

Griswald

8* base timing should stay. However, your total advance will be dictated by the ECU. It would be interesting to get a scan from the mefi during a run and see what bpw, timing, etc are set at. For $200, you can buy the mefiscan software to tell you these things. Otherwise, my opinion is that you're shooting yourself in the foot.

Smitty

Here is my two cents:


Set up the motor on a dyno.

Put it in the boat and re-check the tune using wideband O2 sensors and go up in 200 rpm increments.

Sounds like your injectors are too small. I have found a set of small bodied injectors that will work in a Merc motor as long as the fuel pump delivers the fuel. They are 65 lb per hour Siemens and have been flowed by Mark at Precision marine. Also a customer of Marks bought these injectors and made an additional 30 plus HP due to the ability to accurately deliver more fuel at a lower PSI.

Turbojack

I was just reading an article where it was stated if the wrong springs were installed they would start to float & limit RPM. After reading this made me think of your problem. Sure you got correct valve springs with this new cam?

DMOORE

Just reading the thread, and seeing that even though you went to a smaller prop, and the the speed decreased, you were still only able to turn 4300 rpm's, this is where I would look. Even though you are rich at wot, you would think the motor would still pull some more rpm's.



Darrell.

Warlock28SXT

I have the Brodix Race Rite BB-R heads, I do not know which valve springs I have. I will give Competition Products a call on Monday to verify which springs. I looked at my paperwork and it does not list. The choices were 140LB or 240lb closed and 400LB or 550LB open.

articfriends

Warlock,lets sum things up
1.-your boat runs 4300 28 or 30 pitch at about 80 mph,loses 5 mph with 28 pitch.
question-does it free rev to rev limiter at 5300?
2. your afr's are as low as 10-1?
Q- At what rpm do you start seeing 10-1?
3. Turbo jack mentions valve springs BUT-you
would have to have some waaay off to only rev 4300 rpm's
4. Your motor is running 150 degrees-
Plenty hot for a procharger,in fact most run 100 to 120 but either require a "signal conditioner" or ecm re-programming to get it out of warm up enrichment.
Your fuel pressure at 60 psi at wot is on the low side compared to most procharged motors but your afr's at 10-1 tell me its too rich. What heat range plug are you running? Being your afr's are rich all the way acrossed the board I would back the boost referencing regulator off and primary reg until you see more like 13-1 light cruising,12-5-1 hard cruising (0vac-o boost) and 11.5-1 under boost. Usually if the programming is right your base timing at 10 degrees with a mefi will give you about 34 at wot but you probably have something in your programming pulling timing back under boost also. To really get this to run correctly your going to have to see how your ecm is programmed and the best way to do it would be on the dyno backed up by some on the water fine tuning,I know this isn't what you want to hear,try lowering the fuel pressure and watch your afr's CAREFULLY,check all your plugs too,maybe you have a couple fouled out,around 10-1 they will start loading up,Smitty

articfriends

Even at 8 degrees base you should still have enough total timing unless your programming is set to pull out too much under boost,I had a ecm once that pulled 1.5 degrees out for every pound of boost (8 base plus 24 =32-6 psi x 1.5=23 total,you will want to verify this isn't what you have going on,its hard to do unless you drive it with a mefi tuning program with a tuner watching the computer,or data logging or on a dyno. You need to make sure your ecm is set up for your map sensor also (ie-2 bar map sensor with 1 bar program or vice versa),Smitty

tunertech

contact Ben at www.mefituning.com he'll pull the program and send you a printout for about $75.00. This will give you a base on the ECU. Quick turn around too!

Turbojack

When you give motor more free air are we still at 4300?

You may have stated the before, but have you replaced coil, dist. cap, and wires? Have you replaced plugs?

Have you run a compression test since rebuilding? I do not think even if you have something bad here your RPMs will be exactly the same with two different pitch props. Just grasping for straws.

If you do not have a degreed ballancer, make some marks on it aprox 10 degrees apart. Then take timing light and run engine up, what is timming doing? This will give you some idea what timing is doing.