Top speed on a Launch 20

[Pdowling1]

Anybody have a Launch 20 & can report their actual top speed & RPM? I recently bought a new 2006 with the 325 Assault engine & stock 3 blade 13X11.5 CNC OJ prop. It maxes out at about 39 MPH on GPS at 4400 RPM. Seems pathetic to me after my '95 TS6m w/GT40. It could rip the arms off a skier, ran about 51MPH at 5500 RPM. This boat needs full power to get a slalom skier up. Forget barefooting! We couldn't get to 36 MPH with a footer on the boom. I realize the boat is heavier, but it also claims more power. All these numbers are with empty tanks & Wake Plate down; Driver, skier & spotter, no extra weight. (Ski configuration)
I went from a "Wet Corvette" to a "Lumbering Lincoln"!

[DKJBama92Mariah]

Something's not right. I'd take it back to the dealer and make them go for a ride.

[Diggs]

what are you going off of to determine your speed? the only thing you can really trust is a hand held GPS until you have your speedo and your perfect pass calibrated. my guess is you are going closer to 45, but if you are correct you should check your prop, adjust your wakeplate, and or check with your dealer.

[IndyMatt]

Yeah, I agree sounds like a problem somewhere. With the same motor in my 04 Sunsport (bigger, heavier boat) I will get 48 mph at 4800rpm. Thats with 4 blade 13"x13". I wouldnt try pushing for 55ooRpm; I think thats a little close to redline, but you should be able to do better.

[Dinoz]

IndyMatt,

I'm having the same problem with my '89 Comp. with a 4 blad acme, 13x12.5 I'm hitting 37mph, at 3600 RPM. Even with the 4 blade, I should be getting around the 40mph mark. Do you think that a hesitation issue would be related to the top end issue??

Thanks,

DZ.

[IndyMatt]

Hey Dinoz,

I think you kind of asked about a possible carb issue in one of the other posts. from what I know abour carbs... they are very tempermental espically around humid conditions. The need for service seems to be frequent. Typically during rebuilds you get new gaskets, new or clean jets (where the fuel squirts out) having the fuel delivery and the appropriate compression in the carb are what apply the correct amount of fuel into the cylinders for combustion. If that isnt correct... you could be getting hesitation... that certainly would affect both hole shot and top end. You obviously are not getting the top end RPM you should be.

[H2Oman]

Pdowling1 I would agree, something isn't set up right. I have had two Supras, a DD with a 330mpi and now a 06GG with the 340. Both boats pull hard even with weigh in them. The DD toped out at 42 GPS, the GG tops out just over 47 GPS (empty on both). While I didn't buy either boat for top speed, I did buy them so they could pull like a train and turn like a sports car. The concern you have with pulling up a skier is a bigger issue in my mind. Engine power, prop, throttle control, electronics... the dealer is your best bet.

One additional thought - in my dd if I hit the throttle it would rip the rope handle out of hands, so I had to gradually accelerate. In my GG I hit the throttle 20% and then increase from there to the speed I want or until PP engages. They both accelerate differently.

[Pdowling1]

Diggs, I said in my post I was using GPS. Dealer says maybe a dirty fuel filter. We'll see.

[Diggs]

sorry man.... didn't catch it. let us know what you find out..

[lowdrag]

Could be a lot of things. Fuel filter sounds like the easiest most common sense place to start. You should definitely be pulling more rpm at WOT that's for sure. Other things that come to mind off the top of my head would be something messed up in the throttle cable or linkages, something wrong with the throttle by wire sensor or system, or a tired or weak fuel pump. I suppose bad fuel could be a culprit as well. These engines have knock sensors in them. I guess if there was detonation the computer could be pulling timing out of the motor resulting in a loss of power. Good luck, let us know what you find out.

[Pdowling1]

It was the prop. My dealer loaned me an old OJ 13X13, same as my old TS6m had, what a difference! Now I get 30 MPH at 3000 RPM, and top out at 4650 RPM/43.5 MPH. Down side is, it is a used / reworked prop & has a noticable vibration. He has ordered a new ACME prop to try. I'll report the results.
What doesn't make sense to me is that the CNC prop gave me higher RPM at 30 MPH, but lower RPM at WOT.