Alright guys. I got the boat out yesterday mind you I changed the plugs, airfilter was clean, checked the super charger, seafoam, and put fresh gas in. Best I did was 34 mph and top rpm of 6800.
Load: 5 small kids (combined 150 pounds), wife is 90 pounds, I'm 150 so really that is light on people. Granted I had a full tank but still.
I ordered an intercooler and ribbon delete piece. Im going to consider a ECU flash but still, if it still doesn't get over 40mph I think I'm going to sell it. Just disappointed..
My buddy has a 27ft bayliner with 200hp outboard and it smokes me with all kinds of load on it. Grrrrr...
While I do not know these engines packages all that well.. IMHO you have some sort of issue going on that is keeping your engine from attaining rated rpm. It should get closer to the rated rpm in stock trim.
In my experience running at high altitude, I needed a lower pitched impeller which allowed me to get up to rated rpm, which increased my top end speed by roughly 8mph.
Having said that some thing is wrong that your motor is not revving closer to rated rpm, and it should be much higher at your altitude of 500’ msl. With a jet, once you get going the engine and pump should be revving to rated rpm in stock trim, which would be its maximum thrust. So, your engine / pump is producing X amount of thrust, which would push the boat to say 40mph, as you add weight to the boat the required thrust to go say 40mph is increased so the maximum thrust is not capable of pushing the boat that fast since you added more drag.
Fun fact: Jet pumps require exponentially more power to go from say 6000 rpm to 7000 rpm, infact the power requirement to do so is probably somewhere near double the power. The only data I’ve seen on this was for a Berkley Jet, to turn that pump at 5000 rpm takes 350 hp, to raise that to 6000 rpm it takes 700 hp.
I think you need to make sure that all of the stock systems on your 9 year old boat are working properly before you start throwing money / parts at it. You will be royally pissed off if you do that and nothing changes. Then the new owner you sell it to may find something simple and solve those issues with all the zoot aftermarket products you put on it and have a little hot rod.
-You mentioned low hours in your previous post… how many hours is “low hours”?
-Does the boat start easily from cold and hot?
-How is the water flow through out of the water outlet for the intercooler?
-Did you check the cable actuated throttle to make sure that at full throttle it is to the stops?
-Do you have a really good stream of water from all of the pilot water outlets?
-Are the intercooler water lines pinched or otherwise constricted?
-Is the intercooler full of crap? Maybe it needs to be flushed out?
-Have you checked the main water intake screen located on the jet pump? This could inhibit total cooling water flow to the engine if the screen is blocked or the cavity it its full of crap.
-Not sure on your year model boat, but you need to verify that the electronically controlled throttle valve is opening all the way.
Start with the simplest things you can do. I’ve learned the hard way over the years that this is the way to do.
The boat is a 13’ so there could be some other issues at play here, first one I can think of is low fuel pressure and or a clogged fuel filter and or clogged / dirty fuel injectors thus limiting the total fuel delivered and loss of top end power. On my boat there are little screens on the inlets of the fuel injectors, I think, that can be cleaned. The cheapest and easiest thing to do would be to run a quality cleaner through the fuel system by adding it and burning a tank of fuel, like Techron. I’m not a fan of seafoam and I think its cleaning attributes are dubious at best, while I know from experience that Techron works, and works well for gummed up fuel systems. Get a bottle of Techron fuel injector cleaner / fuel system cleaner and run a double dose through a full tank of gas and see if that nets you any increase in rpm’s. Don’t leave the double dose in there for an extended period of time, run the tank then refill and run the engine some more to get that high concentration out of the fuel system. You don’t have to run WOT while you are doing it.. take your beautiful wife and kids and just go for a pleasant cruise, stop and have lunch, fish for a bit, let the kiddos swim around, I’m betting your wife and kids don’t care about how fast your buddy with the bayliner can go, you have a swim deck and a very bitchen boat! Enjoy your boat.
Next would be check the fuel filter, then check the fuel injectors, after that check the fuel pressure.
Hope that helps.
