Dallas, If you are interested in a Mirage 21 (non +) I have one in very nice condition, solid hub that I would sell for $150 (plus shipping from Houston).

Hmm.. What to Y'all think of this deal? Not the cost or anything.. but the Mirage 21 would have less cupping so it would spin a little higher RPM.. Would it be too much rpm?

I would lean more to Mirage +, they worked out best on past boats for us. 272 Baja and 223 Powerquest, both had same hp as your boat.

Ok, this is a SINGLE 310 hp 454? At 20 inches pitch, 2 inches is 10% diff. You are hitting 3900. 21 (Lil less than 10% change from 23) will get you to 4250 or so. A 20 bravo would get you more around 4500. A 19 closer to 4700.


​​​​



​​

Tried a 4 blade Bravo on my 272. It hated it. Not enough bow lift

Tune a M/P to your needs with a good prop shop. It was the best I found for mine back in the day.

Also, if you can't hit 4k at WOT, don't try. Engine is overloaded and could pop a head gasket. It is a performance boat hull. So you expect fast. But it has a sea ray sundancer engine in it. Cam-intake-exhausts should get 400 out of it fairly easy...in the mean time, there are 19 and 21 props all over ebay under 100 bucks. Alum, but...

Had a 252 islander with a 7.4mpi gen 6 , it had one of those mirage 23 on it also. Had to bury the throttle to get on plane with a good load of people and gas ,but it would eventually pull 44-4600 rpm , my 272 with a 502 mag pulls the 23+ to 5100 rpm , slight chop light load ect ect,
You might have a missing cyl or some low fuel pressure , or your tach just reads low

It gets on plane pretty easy and sounds healthy. I feel like if it was missing a cylinder or something along the lines of that I wouldnt hit the MPH im hitting. I would also think I would be able to tell if a cylinder was missing while running.. Maybe the RPM gauge is just off like others have said... Is the only way to tell what the RPM is to hook up a scan tool?

You can purchase cheap inductive tachs to compare your tach against.
Also, we can supply you with M+21's to test with through our test program if you desire.

Brett

You are trying to troubleshoot too hard. You have too much prop right now. Switch to a 21" Mirage Plus and THEN see what happens. This is the easiest and quickest step. Make sure you are using a good GPS source for your steady state speed measurements.