Baja Outlaw 23 top speed
 

I picked up a new to me 2005 Outlaw 23 SST and have had it out a few times this year. I’m curious to what others are seeing for top speeds and rpm’s at WOT. My boat has the 6.2l with a 23p mirage prop. I’m getting 48mph at 4550 rpm (throttle all the way ahead) with full tank of fuel, my wife and I, and in light chop. I have played with the trim and tabs and was able to dial it in and to get the results listed above. The engine has had a new distributer cap, plugs, wires, and fuel tank check valve installed prior to this boating season. The engine runs great (no bog, missing, or backfiring). Is this setup about right or am I low on rpm’s and speed?

Something is WAY off...that calculates out to 27% prop slip...two to three times what you SHOULD have. Are you getting it trimmed up/out well?
https://cimg1.ibsrv.net/gimg/www.off...689325a983.jpg

Sorry, it’s a 21p not a 23p. I just went and double checked. Yes, I’ve tried many different trim settings and that’s the best I can do. Thanks for your thoughts.

That is still 20.4 slip ratio...way too high still.
What outdrive, and what ratio on the outdrive?

The older 23' - 24' Outlaws, which I am more familiar with having had friends with them, have a 24 degree deadrise and are about a 4,000 pound hull...24' long with 96" beam. My 252 Islander is 25'6" long, 100" beam, and 4400 pounds dry by comparison. I run a 4 blade Revolution 4 prop, 21" pitch, can spin it to 4500 - 4600, and hit 53 - 54 mph.

The 6.2 comes in 300 hp and 350 hp versions...which is yours? Both are rated to spin 5400 rpm...it's a pretty cool engine! You may simply be over-propped. IF you can spin a 19" @ 5400, you'll be tickling 60 mph.

I'd check everything including a spun prop hub.

The engine I have is a 320hp 6.2l with a 1.5 drive ratio. I just confirmed this with Mercury. WOT setting is 4800-5200 rpm. Do you guys suggest I try a different prop before I dive deeper into engine performance specs such as compression testing and fuel pressure?

Ah, okay...one of the older 6.2 versions, cool. Well, there are a host of things you can check to see if the engine is making proper power, compression amongst those. Have you had the ECU scanned to see if there are any does of any sort? A scan will reveal MANY things like injector duty cycle, timing, temps...all good to know. But if you are making full power then yeah...something is still off. You SHOULD be able to spin a 21" Mirage close to or at the recommended WOT rpms. Your boat should be faster than mine, put it that way.

Have you checked if the throttle plate is actually at wide open when the throttle lever is?

I would think it would run in the 50’s

I haven’t had the ecu scanned yet. It’s odd that it runs so smoothly thru out the power band. I will check the throttle plate/linkage tomorrow. Would very small dings or curls in the cup of the prop cause this much lack in speed or rpm? The previous owner must have hit something. Thanks for all the ideas.

No...small dings and dents really don't affect things that much...remember it is the 'front' of the prop (facing the boat) that does the work. Big dents in the edges of the blades or chunks missing can cause problems, but not like you might think.
I would see what a scan might reveal on the health of the engine, check the throttle plate as suggested, etc. You have all the classic signs of being over-propped, you really need to be able to pull the manufacturer's rated WOT rpm.

I have a call into the local marine repair shop to get the scanner hooked up. I’m also going to order a 19p to try (I need a spare prop anyway). Thanks for the help. I’ll post again when I try the 19 or get the engine scanned.

So an update from this weekend:
I installed a brand new stock finish Mirage 19p prop. In slight chop I was able to hit 51mph at 4600 rpm’s. I was also able to cruise at 32 mph at 3000 rpm. This was all with full fuel and 2 people. I ensured that the throttle plate was visually opening all the way. I don't have the capability to scan anything to see if the TPS was showing WOT. Any more thoughts on my low WOT?

Just to circle back a minute...are you going by the speedometer or by a GPS or radar reading?

51 @4600 is around 8% slip, which is much better. Actually very good.

I’m running a Livorsi GPS Speedo in place of the old pitot style. Why would running a 21p cause such high slip numbers?

I wonder if it is possible you have a spun hub on the 21" prop?
You may just be running out of ponies, frankly. Small-block torque is not the same as big block. Still...it just really seems to me that your engine is getting held back, I know some folk with that (albeit later version) engine and it screams in those applications.
One of the problems is you have no idea what the boat ran like before you bought it...and it would be a crap-shoot if the previous owner would tell you the truth. Something definitely seems amiss. A sub-50 mph Outlaw is just unheard of, frankly. How 'wet' are you running? Do you have or can you get pictures of the boat running at full speed? Even at around 50 mph you shouldn't have more than 6' - 8' of the hull in the water. Make sure your tabs are fully retracted. Keep playing with that trim until you blow the prop out, then tuck back in slightly.
Beg, borrow, or steal a scan tool or bite the bullet and have a COMPETENT and qualified Mercruiser tech hook you up or ideally take a ride. I'd be curious about fuel flow, injector duty, etc. Is your fuel tank vent open and working well?
You really do need to determine that your mill is putting out full power. If it is, then you can start looking at things like the X-dimension on the outdrive, or if the hull has any deformities in it. If it isn't making full power, you need to understand why. Or you can just go enjoy the boat for the rest of the season, don't go challenging anyone, lol...and fool with the thing in the off season.

Here’s the latest on my low WOT saga. I purchased Diacom for my laptop and rigged up a fuel pressure gauge. First off, the engine has 370hrs with many of them under 3500 rpm’s. There were some non active codes stored in the history from about 10-15 hours ago (this was prior to me owning the boat). The codes were for an over speed and a couple sensors.

When I ran the boat on the trailer with muffs, I was getting 33-34 psi of fuel pressure (taken from the rail where the schraeder valve is, near the flame arrestor). The spec for this model of 6.2l is 38-43 psi. Any thoughts on this?

Today I brought the laptop out with us and had the wife drive so I could monitor things with Diacom. At WOT the TPS was only measuring 93%. Is this enough, or does the TPS need to be adjusted? Also the tach is off by about 100 rpm at WOT, so it was actually only reving 4450-4500. The spark advance at WOT was 25 degrees.

25° at WOT is pretty low. Even good chambers that burn quick want about 29/30°.

You're heating up your exh valve and engine a bit, while losing power.

Does your TPS give you a voltage as well? What does it read when it's closed.