I have a 1988 242 SS Bravo 1 bottom painted, 502 aprox 500 HP with a brvo1 24 pich prop

I spin out 4950 rpm which is aprox 500 - 600 less then it should, from what I have been told.

Speed 58 mph

I was sure that the bravo 1 24 pich prop should have been a good choice and I expected minimum 64 - 65 mph

What is wrong ?? Obvious the prop, yes but I find it strange that 500 hp not is capable to spin 5500 rpm
With my set up ?

What will be the perfect choice ? I hope to see as mentioned 64 - 65 mph top speed. Nice acelration and good performance

Today the I have 3100 rpm 35 mph 4100 rpm 46 mph

BR
Rune

It would be best to check out the rated RPM spec's for the 502. 5500 RPM sounds a bit high for a big block, but maybe. Spec's are around 5000 RPM for the 502's. My 1991 242SS with 7.4l (454) 330 HP and 21P Mirage would do about 48-50 mph (4400 RPM).

The 'standard' prop is the Mirage 21P . . . the 454 Mags (365 HP) could spin a 23P . . . So, I would think that you are OK with a 24P, and should not have to go any lower. Do you have exact spec's for the engine?

58 mph is pretty good for the 242SS . . .

23 mirage or mirage plus. Should be mid 60s with 500 horse, 70 if it was an ls

Stock 502 is 415 hp, not 500. 4950 is about right for the rpm for a stock 502 also, so if your engine is stock you are propped correctly.

Thank you for the replays :-)

This is not a stock 502, it is a racing version suppose to be 540 hp told by the guy who sold it to me.
It was one of a pair 500 hp engine coming out of a Nor Tech 36 super cat, which needed more power.
It was rebuild, with some more goodies, and has now less then 40 hours use, since that
I think that is more in the 500 hp range.... I have not done any Dyno test.
Attached see picture of the engine and the new Hardin Marine headers with tall pipes

I had a stock 454 330 hp mirage plus 21', best I ever saw was 50 mph

I hoped that + 200 hp should give the boat a speed of aprox 65 mph ? I still hope to get there, with the correct prop ;-)

Summer greetings from Oslo, Norway

FOUND THIS ON DALLAS, TX CRAIGSLIST THIS AM HE DISCUSSES SPEEDS.

Very clean 1988 Formula 242 SS in great shape. Only a little over 100 hours on a 502cid Dyno'd at 550 HP. The entire boat only has a little over 400 hours. Comes with 2 stainless props. Will run 65mph with the 21 pitch prop and 70+ mph on the 23 pitch prop but I normally cruise around 25-45 mph. Silent Thunder Exhaust. Cuddy Cabin w/bed, 2 seats, sink, cabinets and porta pot. Comes with custom trailer with brand new tires put on last year. 99 Gallon fuel tank, 5 gallon fresh water tank. 2 brand new batteries this year. 3 different type of covers; cockpit only, custom full boat cover and 2 biminis with full glass with 6.5'+ clearance from windshield to stern. I am the 3rd owner. Boat is kept in very clean climate controlled storage. Boat is 4200 lbs dry, trailer is 1500 lbs. •do NOT contact me with unsolicited services or offers


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posted: 8 days ago

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A friend has a 242 ss, 500 hp (dyno'd) 468, afr heads, victor intake. Runs well past 65. Didn't check the gps but wouldn't surprise me if it runs 70-72.

Thanks for great info guys :-)

From what I have experience and based on what I have found out so far, it could be that a Mirage 23 plus
or Bravo 1 22'

Attached I screen shot of the present situation according to a prop slip calculator as you can see I have a very high pop slip.

What is normal/acceptable slip on. 242 ?

Why the additional speed with the LS? My LS runs mid 60's with a 450ish hp 502 and a 23p mirage+

I believe that the LS has better balance/weight distribution versus the SS. . . mostly due to the longer cockpit of the SS.