1988 242 ls?
 

Just looking for some input. I recently bought an '88 242ls. Repowered with a Merc 502hp mag mpi. Still has the bravo one on it. What kind of performance should i be getting out of this boat? What kind of prop should i be running? (Currently has Mirage+ on it) Is there anythingin particular i should watch for on this specific boat?I've owned many smaller boats (mostly outboard). So this is all kind of new to me. Any info/ input is helpful.

i think with the 502 you should be around 58-60, they are nice boats just get some seat time and play with the boat, getting the right trim, play with the tabs. We also need to see a pic!!

It won't let me post a picture until i have 10 posts on the forum lol

Where are you located?
Welcome to the 242 Formula family.

Northwest Ohio

Well currently the water looks like **** to due to a toxic algae bloom so the scenery isn't that great. I can help out with the other part of that once i figure out why my bilge is full of oil and get the boat back in the water

Port Huron, Mi

Gotcha

I love the boat so far even though it's given me quite a few issues. Once i get them worked out i should be good for a while. Motor is rebuilt and cammed with less than 300 hrs on it and now the whole outdrive is rebuilt.

I guess the biggest question about this is which engine is it? The hp500efi or a 502mpi? There is some difference there. Either way I'd say it should be low 60s wirh a 23 mirage plus even if it's the 435hp black 502.

It's the blue 502mpi

If it's a 500 hp engine I would think closer to 70. What size prop? I was getting 64 out of a 425hp 454 with a 23 mirage plus turning it 5400rpm. Seems to be par for the course amongst others.

23p Mirage+. Specs on the motor say max rpm is 4800 though? And that's what it turns trimmed up. I can only get 55 mph on the boat

The stock 330 with 23 mirage plus was 54 mph. Maybe you have a black motor someone painted blue when they overhauled it?

check power steering hoses for oil leakage.

Alright thanks

Yeah i don't get it. Can't break 55 with just me in it and a 1/4 tank of fuel

How do i go about contacting him?

https://cimg8.ibsrv.net/gimg/www.off...46c5531d48.png

Here's a picture of the boat. Still need to get better ones yet

Oh gotcha. Thanks

Im sure you guys remember a while back when user zackevans6.7 was looking at this boat.
https://www.facebook.com/marketplace/item/618002172053281/

Look at the block and verify that is has 8.2 on it. It isnt impossible that someone put the mag mpi intake on the 330hp 454. We have seen stranger things happen. Your speed is dead on what a 330hp engine pushes these boats with a 23 mirage plus at 4800rpm. That works out to a 21% slip which isnt too bad.
I dont want to seem like an ass, but I dont want you to be mislead either. The 502 mag mpi was a 435hp 8.2(502 ci) engine. That power would easily push you into the low to mid 60s with a full tank and a few friends on board.

I saw that boat for sale on FB. Looks like a Gen VI 415-horse 502 Mag MPI. Formula says the 390-horse 502 Mag (carbureted) should run 61-62 with a 23P Mirage... the 415 should be right there.

It would be helpful to know some specs on any of the changes made during the rebuild. It is also very difficult to troubleshoot without a Rinda Techmate scan tool. If you plan to keep the injection set-up, I wholeheartedly recommend buying one. You'll be lost without it.

Search for Rinda TechMate Pro

Sent you a PM Vsyx.

-Tom

TomZ i sent ya a message

Alright I'll look into that thanks

21 % slip wow. The photo on facebook looks like a blue efi on a black motor...?
try hitting the tilt button a few taps when at full trim. You could have the trim limit set too low. That may get you a few more mph 🤔

Ok so what is the difference between a blue and a black motor? And can you explain what 'slip' is? Because I'm not exactly sure lol

Blue vs black= an original blue hp500 was a 500hp 502: black could be pretty much anything really. Blue was the high performance where black was the normal engines.

Slip is the percentage of "slip" the prop has. In a perfect world with 0% slip a 21 pitch prop would travel 21" in one complete revolution. Slip is the actuality that it does not. Slip is good and bad read more in this link.

https://teaguecustommarine.com/teagueblog/how-to-correctly-determine-propeller-slip/

The black engines are GM industrial engines that have been marinized by Mercruiser (as well as other OEMs). They use production line parts that are pretty much interchangeable with their automotive/light truck cousins. The "Magnum" engines are the higher-performing offerings before getting into the "blue" engines.

The "blue" engines are custom-built by Mercruiser's performance line, Mercury Racing. They are blueprinted and hand-built using aftermarket performance parts.

The engine in the boat is the standard Mercruiser "black" set up that someone painted with Mercury Racing's blue paint (or a color close to it anyway).

TZ

21% slip isn't awful, but it isn't all that great either.

A number of things can contribute to slip: prop condition, drive condition, boat bottom, drive trim, water conditions.

My 242 ran 50-54 with a 23 Mirage Plus and a 454 Mag in flat-calm water. But she ran 57-58 in a good chop. What I'm getting at is that these boats need choppy water in order to reduce the wetted surface in order to get speed. I suspect that water conditions are a part of your issues.