Rebuilt both engines in 1988 cigarette bullet.the dyno put the engines at 550 hp at 555 torq at 5200 RPM. what size prop should i be using and what top speed should i expect to run.the outdrives are bravo ones with 1.50 gears.Would they be three or four blade props

With a 1988 boat you may be able to run 4B props successfully. The 3B propeller may produce the greatest top end but the 4B props may produce better handling and performance. Have you tested any propellers on the boat to date? If you have post the data so we can take a look at it. Additionally if you could give me the "wet" weight of the boat I will look at some theoreticals for you.

Julie

Motors not back in the boat yet . weight is about 9,200 wet.I was running 23 quicksilvers three blade with the old motors 502 CI 390 HP .boat ran 67mph at 5,200 rpm.Thanks for the help

What is important if your goal is top end is to make sure that you run your boat at WOT at the RPM at which the peak HP is produced. The stock 502 is at about 5000 RPM. But you have added alot of HP are you sure about the 5200 RPM for the peak HP RPM?

Julie

Julie made several pulls on the dyno and the best numbers came in at 5,200 RPM. At 5,500 RPM the numbers dropped to 526.0 TORQ and 540.7 HP.

With a 320 hp gain and the desire to run at the same rpm, you will be looking at 26 pitch Mirages (there are none). The 27's may give you good top end numbers after they are Labbed and when you run light in the correct water conditions.

I would test with some 26 Bravo 1's and get a base line. Then I would Lab them with the correct recipe to get the most out of them. You may not see the speed you could get with 27 Mirages in the perfect situation but the over all boating experience will be better and we can get some really good numbers on your hull with these propellers.

Most importantly, get some numbers to start with once the engines are back in. Call if you need test props.

Brett thank for the input . Should have the project done by june i will let you know how it turns out