28 Speed and HP Ratings
 

Maybe Jo or someone can summarize all the data that is in other threads. What are the speeds of a 28 single, pleasure version with the following Engines/HP ratings:

500HP

600HP

650HP

700HP

750HP

I am tweaking my existing engine to get just over 650HP, but plan to build another for next season.

Thanks,

Kirk

Re: 28 Speed and HP Ratings
 

Hey kirk great thread to start.

I can tell you that my 540ci is approx. 600+ hp and does 72-74ish with1/3 gas and 2 adult passengers and b1- 26 factory prop.

I wonder if I can get Albert to trade with me :D

Re: 28 Speed and HP Ratings
 

LOL, it takes alot of ponies to push the 28, my boat is not to be compared to a pleasure version because it weighs about 1k lbs. less. Jo made this boat very light and at the same time very strong. You need a true 670 hp motor to get you over 80.

Re: 28 Speed and HP Ratings
 

this would be my guess

500- 70 - 72
525- 72 - 74
600- 75 - 77
650- 77 - 79
700- 79 - 84
750- 84 - 88

900- 100 +++++ :eek: kids, do not try this at home ..they are trained proffessionals

Re: 28 Speed and HP Ratings
 

I don't plan on trying that at home but hopefully soon at the lake...

Re: 28 Speed and HP Ratings
 

My single 525EFI with a labbed 26 B1, 2 people and 1/2 tank runs around 69 GPS.

Re: 28 Speed and HP Ratings
 

Im thinkin something is wrong. 500 efi were running faster.
I think You should be running somewhere around 73 mph +-

Re: 28 Speed and HP Ratings
 

Bruce:

I'm wondering if I should try a 26 cut to a 25? My present RPM's are around 5100. Some guys suggest I try a 5-blade. The acceleration with the 25labbed is great and the mid-range is strong. It's at the top end I feel like the boat has more, but I don't get it. Any thoughts?

Ron

Re: 28 Speed and HP Ratings
 

Try a 24 or 25 Hydromotive QIV and possibly a 2 inch shorty lower on your drive. you should be running at 5400 rpms. The guys that ran 500 carb and efi were running 26 B1 with no prob and running 70 - 72

Re: 28 Speed and HP Ratings
 

Thanks Bruce..I'll look into that.


Ron

Re: 28 Speed and HP Ratings
 

What would be the correct X dimension for the 28 without the notch? I know this has been gone over before, Just wondered what has worked the best. I plan on running the 525 this year then a 555 or 598 next year. Thanks, Chris

Re: 28 Speed and HP Ratings
 

My race boat doesnt have a notch and the prop shaft is at 4" below the bottom. I've tried many heights and that seems to be the sweet spot.

Re: 28 Speed and HP Ratings
 

that makes it about 18" ? I would guess that 17 1/4" is probably better for a pleasure version? Or will the extra weight foreward not matter much?

Re: 28 Speed and HP Ratings
 

Don't forget fresh/salt and sea level/elevation influences

Re: 28 Speed and HP Ratings
 

The buoyancy of fresh/salt water has virtually no effect on speed. It’s the elevation factor that will produce different results.

http://www.offshoreonly.com/forums/s...d.php?t=119847

Re: 28 Speed and HP Ratings
 

Interesting viewpoint- what exactly is the difference in buoyancy?? percentage wise or pounds? I mean if it makes the boat "lighter" it has to help, but I imagine it would take 500 lbs or so in that hull to see any gains.

Re: 28 Speed and HP Ratings
 

Actually the general consesus is the buoyancy has a greater effect on speed than the altitude.

Re: 28 Speed and HP Ratings
 

Humidity/barometric pressure/temperature has a huge effect on engine output -Engine hp can vary as much as 50 + hp on a hp500 depending on the conditions . This is why there are correction factors for pressure/humidity, and temp. when dyno runs on engines are made .
I have seen speeds in the same body of water in my old Pantera 28 from 74 to 78 mph . Water conditions also have a huge effect on speed on these hulls .
1-3 foot waves will loosen up the bottom and let them run faster .

Re: 28 Speed and HP Ratings
 

Hey Jmemoli,
How were you seeing such high speeds with an hp 500. Were there engine modifications or a hull that was lighter than most. I didn't think that those speeds were typical or obtainable with that motor set up unless the motor wasn't stock.

Re: 28 Speed and HP Ratings
 

mikeformula,
The pantera now has a 540ci. I think that was what he was refering to in reguards to speed varations

The hp on the dyno was a 500

Re: 28 Speed and HP Ratings
 

Sorry for the confusion Mike ,
The speeds were with a 540 600+ hp.

Re: 28 Speed and HP Ratings
 

OK thanks for clearing that up. I was starting to get excited about the speeds I might see in mine with a 525. I know the 525's are supposed to dyno around 540 to 560 something like that, and I thought if you were getting that good of top end with a hp500 that I would expect about the same if not a little more. I know that Ron Lombard(has a 525) on this site is only seeing around 70 or so with some fuel and couple of people. I think he even had his prop labbed to get him there. I know that these boats aren't the fastest, but I guess you sacrifice some top end for the great rough water ride. I hope they come out with a procharger for the 525 one day. That would be a power maker for sure.
Mike

Re: 28 Speed and HP Ratings
 

Mike:

I'm going to try what Bruce stated...get a QIV Hydromotive 25p. I think the 26 labbed is great, however, JO always thought that the 525 should run best with the 25p. I have a 24 which originally I saw speeds of 71.4 gps but I hit the rev limiter a few times. JO had my drive set higher when I hit that speed. Now the drive is a bit lower, and the hole shot is great, but the top end is down. All in all a few extra out of it would be great, but I'll take the safety of the ride any day.

If Mercury Racing ever made a 600 EFI internal cooled engine, that is the way I would go. I don't have the ability to constantly flush the system.

Re: 28 Speed and HP Ratings
 

Hi Ronnie,

The trim pin was inverted on the drive so it would tuck in further down which would get you up on plane faster, and handle better in rough water.You just need to trim the drive out at WOT a little further now.The drive height is the same as it was before.

A Bravo 1 25 pitch ( which you need to cut back from a 26 pitch ) will work fine on your boat.You want to turn 5250-5350 RPM consistent depending on fuel and passenger load with the 525 EFI Mercruiser package. A stock 24' Bravo 1 does hit the limiter quite easily with 71-72 MPH performance on GPS. The limiter kicks in at approximately 5400 RPM.The 26' Bravo 1 labbed you have now should get you 5300 - 5350 RPM light on fuel and result in 73-74 MPH top speed trimmed out perfect in a light chop.Remember your 28' has a 140 gallon gas tank so an extra 80-100 gallons in the tank can make a huge difference on your RPM and top speed.

The "full pleasure" version is quite a bit different than Bruce's 28' race due to the cabin weight and sitting further forward in the boat.

Bruce is right : The Carrabbas 28' powered by a single Mercruiser 500 EFI will turn a labbed Bravo 1 26' at 72-73 MPH at 5300 RPM on GPS with a full pleasure configuartion like yours.

Hey Fever Mike good to hear from you !!!

Regards,

Jo - Pantera Boats

Re: 28 Speed and HP Ratings
 

fullthrottle, i heard there was not much more speed to be had with the merc 600 over the 525 package. anyone know what the real speed difference is i heard 2 -3mph?

Re: 28 Speed and HP Ratings
 

Most of the 525EFI's dyno closer to 540hp and the 600SCI is computer controlled to produce 600hp all the time. A 60 hp difference would net about 3mph.

Re: 28 Speed and HP Ratings
 

Hi JO..

Happy New Year to all in Miami.

Thanks for the info. I think I'm always running with too much fuel. I'm going to try the 25P soon and will post the results. I should be back in Naples by March. Should have the prop by then.

Best to all,

Ron

Re: 28 Speed and HP Ratings
 

FYI, I see up to a 5mph difference in speeds when running near full on fuel and with 4 people compared to just me and a 1/4 tank or less. I vary between 63 and 68 with about 550hp. It also depends on the chop. A 1-2' will add a couple mph also.

Re: 28 Speed and HP Ratings
 

:eek:


:D