B5boating

I have a 1989 Stingray SVC 235 with a 454 that I just bought a month ago. The guy I bought it from said that I may want to run a different prop since the engine was built up 2 years ago. Stock this boat came with 330hp but the seller said that it is right around 600hp now..(no dyno sheet to prove that). I did take it out on the lake and I was running at about 72 mph at 6k rpms. The prop i have on it now is a Michigan wheel apollo XHS 4 blade 14 1/8th x 20. The boat did come with a quicksilver 23p 3 blade which he did say was a little faster but not as stable. It does seem like this engine has a lot of power so I would like to know what a good prop to use for speed would be.

Red_Hill

600 is a a ton of HP out of a N/A 454. Not sure what you are looking for for speed, but I dont know I'd want to do better than 72 in that boat.

SkiDoc

Stay with the prop design that has the best handling characteristics. Seems in your case at this point it is the 4 blade. 6000 is more RPM than I would like to run most all BBC's. You need to find out what is the recommended top rpm for the build and prop not to exceed that. I would try a 22p and it may be that a 24 is needed. You are going to have to try different props to get real world results. You are going to run across more Mercury Bravo 4 blades. They are a great design. At your speed in a boat like that you need to upgrade to hydraulic steering and trim tabs if you do not have them.

B5boating

I have been talking with cp performance and they have suggested going with a Mayfair add on hydraulic dual ram steering. I would like to be at 75 with less rpms. I think I read somewhere that this boat stock would run 70mph, so I hope 75mph with less engine speed is possible.

Thanks for the input guys!

Speedracer29

Welcome to OSO and congrats on the new boat. You might also want to check out mystingray.com and set up an account using your hull number, lots of brand-specific info over there.

Also, get us the p/n off the Quicksilver (48-xxxxx). I had a 230SX, there was a HUGE difference between the 23p Mirage Plus (good holeshot, fast, stable), and the 23p Laser (less holeshot, less stability).

For your notes:
Listed dry weight for 235SVC with SBC/Alpha is 3200lbs, add about 175lbs for BBC/Bravo.
A stock 375hp BB/Bravo in the 230SX (z-plane) turning a 23p Mirage+ will run 67mph on GPS at 4800rpm.
A 23p Laser on same boat was 63-64 at the rev limiter, didn't like trim, and was squirrelly.
The 415hp 502 Mag turning a 27p Mirage will run 71.8mph on GPS at 4800rpm.


First 2 set of numbers provided from my personal experience.
Third set of numbers provided courtesy of Stingray article linked here:
http://www.stingrayboats.com/product...ws/pb1-96.html
Your hull is similar, but was before the z-plane era.

My speculation from these numbers is- your motor is probably closer to the 450hp mark at 4800-5000rpm if you pulled it today and put it on a dyno. Did the previous owner give a parts list or build sheet for the motor? Going above 5000rpm with a mild rebuild and vintage Bravo is looking for trouble.
Use that 20p for tubing and skiing, start looking for a 25 Mirage Plus or 27 Mirage and get those rpms down. And get a drive shower if there isn't one already.

Also note: I never ran a 4 blade because I wanted to go Ricky Bobby fast, not tow brats or cruise comfortably while talking to the mother-in-law. YMMV

B5boating

Thank you Speedracer

The part number on the quick silver prop is 48-13704-23.

The specs i have on the engine are:
454 .30over
steel crank
forged TRW pistons
dimple rods
squar port heads 2.25 1.88
Manley sever duty valves
bronze guides
Herbert roller cam & lifters
hardened pushrods
motion springs
crane gold roller rockers
Herbert stud gerdle
Edelbrock torque intake
Holley 850 Dp
Lightning headers..

it is the fastest boat i have been in so far and it gets to 70mph in a hurry.. Let me know what you guys think

Speedracer29

That's a Mirage (pressed in hub). It's a great prop on that hull, but if you're running it above 5000rpm, you need more pitch.

What speed and RPM are you seeing with that particular prop?
I'm assuming that Bravo is a 1.5, but I guess it could be a 1.36 ratio, you'll need to look on the drive. (Decal on left side of drive, or alternative is the u-joint yoke.)
Prop slip calculator from a site sponsor's page:

http://bblades.com/propeller-slip-calculator/

Any info on crank mfg. or cam specs?
I'm wondering if the 600hp claim wasn't a little enthusiastic on the seller's behalf.

B5boating

I'm sure the seller stretched the truth on the hp. The seller said he is looking for the cam card but he did say it was the "biggest" cam that was recommend for his build application. I never ran the 3 blade just the 4 blade.. And let me tell you.. It would push you in the seat pretty hard. I want to see a little more speed out of it since I really don't need that much acceleration.

How do I tell what ratio drive I have?

Speedracer29

If the decals are still on the drive, look carefully for small print on the left side of the decal. Should say 1.5R (or 1.35/1.65). If you know it's original to the boat, the transom ring will have a serial number on it, you can input that into various parts websites. If all the decals are gone, wait until you pull the drive to check alignment/service and look at the splined yoke.
You gotta run that 23p yourself to get a baseline speed and rpm if you're looking for top end. 4 blades are better handling, but scrub top speed in many instances. Don't count on a 3 blade pulling out of the hole like the 4 blade either. Also, I'd spend $30-40 for one both those digital tach/hour meter combos. Especially if you're dealing with an original tach that's a quarter century old.

B5boating

All the stickers are gone off the drive.. The drive been recently serviced.. Every thing looks brand new. The gauges are brand new, they are Gaffrig II. Thet guy basically redone everything 2 years ago. I just got a text back from him and he said he still hasn't found the cam card yet but he did say something about the engine being 10.2:1 compression.

I just winterized the boat last weekend so I will need to wait till next year to find out about that 23 pitch prop