2005 Dominator. What Top MPH Should I See?
 

496 HO Mags. everything is stock w/28 pitch props. I am having MPH issues and only see 72. I have only owned the boat for a year. I am in the midst of numerous checks in determining the problem, but what should I be seeing for top MPH? I'm not talking about a day in a year when the stars are lined up correctly, but what I should see on GPS generally when everything is running correctly?

At least high 70s. 72 is a perfect scenario speed for the 6.2s.

I'm curious. I have 23p props on my Dominator with 383s. What about the big block Sunnys makes such a difference messing those much bigger props?

Three words: Torque is King

30p on mine :)

Sure, but that's a little simplistic.

Certainly and I can believe they make great use out of a big prop from down low. But, after you start getting in to the mid-range and high end, I'm making more HP and torque than a 496 Mag or 454. But jumping to a 28 sounds like a huge change despite similar power at fast cruise. I'm curious if the X dimension is different.

Just trying to learn! Prop is definitely my next thing :) Don't mean to hijack the thread.

Love your boat :)

Not simplistic at all, Evan. Torque carries the weight, period. Not quite sure where you're getting the idea that you're making that much more power than an HO. (based on the dyno sheets that Bob posted. maybe I misread but I thought your numbers were on the stand) A 496 will make nearly 100ft lbs more than your small blocks at the prop, not the flywheel. That alone will allow a big block boat to spin a bigger wheel. If your boat were mine, I wouldn't hesitate to bolt a pair of 24p Hydros on it and see what happens. I think you might be pleasantly surprised. If you're making that much torque you may even be able to go bigger. X dimension will play a part but there are numerous other factors involved as well. If you've been able to get slip numbers with your current setup it's very easy to see theoretical improvements with the calculator by changing prop size. I seem to recall you were getting 30% and then -5%? Something doesn't seem right with your input to the calculator. (Not trying to be a dickinsee in any way)


CATF800 - there could be numerous details that are slowing you down. Anything from power loss, bottom hook, knicked blades and/or skegs, down to the way you're running the boat. For instance, Capt Y and I have a mutual acquaintance who has a 32 that had those ****ty stainless skeg guards on his boat and while they look cool to some, they were costing him nearly 4mph. Every little bit helps.

Oya 496 HO kills me for sure, I've driven a Dominator with them. I was referring to a 496 Mag 375 hp. More power across the range with those, but if we're talking WOT top speed my 383s have more torque.

I tried another calculator and got 11% slip if I remember right.

Maybe I'll give those hydro 24s a shot and see how it goes. After my next bonus I'll call BBlades to get a pro perspective and get a couple sets to try.

11% sounds a lot better and likely correct. Not a bad number at all, either.

Brett will set you straight. It's only a couple hundred bucks, if that, for a set to test.

Don't own one but 28s seem kinda small. But like said so many thinks come into play. I put drive showers on my boat and lost 1 1/2 MPH.

First off, im not a Sunny owner, but my buddy has had two. A 28 and a 32. I've spent a lot of hours riding in and wrenching on both thru a lot of variations of both boats with him. But his 2001 Dominator (note - bare bones...no A/C heat, head, fridge or mcloud int.) with bone stock HO's would go 80+ almost everyday and when the moons aligned...82.xx. He also ran 28 bravo's stock. I know of several other HO boats in the same range. Also, I know other 385 boats in the 76+ range. Point is you are certainly missing a few MPH. I cant speculate as to where your loosing it without more info. Are you sure there stock 28 bravo's? What is limiting your top speed, just out of power or rev limiters? Compression check both motors. Is compression even across the board? How you are trimming the boat is certainly is a factor.

I'm looking for what I should be shooting for. I know that my MPH is down and looking at all possibilities in that. The drives are stock with stock 28p props in good condition, and was looking for those that have experience with the boat and set up to provide realistic point of where it should be so I know I'm in the ball park of having it right. I don't know if its ever been right. I have seen 78mph on GPS. Now it is pulling 72 and I'm standing on my head every night in this thing working on items. engines have 375 hr's.

all the what I am doing and what I need to do to regain proper MPH is posted in the do it yourselfer forum. Thanks.....looks like I'm shooting for 80mph which was my understanding, but wanted to hear reality from owners of boats. Of course who wants to post that real top speed is 78mph while its all over the place of the stars being aligned and adding 2 to 3 mph that their boat runs 85? I have compression checked one engine and doing the other one tonight. The starboard is between 162psi and 172 psi in the 8 cylinders.

bottom clean with no knicks? What about the props and skegs? Anything else dragging below the hull? That boat should run 80 all day long.

CATF800, sorry if I was not clean in my first post....yes you should be looking for 79-80 on normal days. I have ran on and with several Bone stock HO boats at those speeds. Those experiences are from participating in the annual Sunsation Rally a couple times (Awesome time BTW!) and recommend it for any Sunny owner!

I am actually surprised we have not had someone from the Sunsation factory chime in already with more info and help for you. If you havnt done so already you might want to post this question on the Sunsation websites forum.

Lastly, another thing you might want to check drive alignment. As in Toe in and Toe out which is set via your Tie bar. I believe its recommended to set them with a very very slight toe out but don't quote me.

CATF800

My Dominator is an 05 with 496's not the HO's with labbed props seeing 78 with a really light load of fuel and 75 everyday. My buddy has had two different Dominators the first was an 03 with HO's about 80 everyday of the week and his most recent an 01 with 500 EFI's 88. Are you using the speedo or a GPS?

I had the outdrives removed this winter, gone through, engines aligned with outdrives, steering aligned, props checked, gimbals replaced, etc......

GPS speedo. one of the engines is not running up to snuff and having a hard time figuring this thing out.

CatF800 I believe we met the other day at the marina. I know you have the scanner for the engines so which engine is not running correctly? If you want to go for a ride together I might be able to help you out. Just let me know. I am going to try and go out tomorrow so maybe we can meet up then and go for a spin. You can PM me and we can chat more!!

Starboard engine runs 4600 rpm top speed and port runs 4900 rpm. all compression seems good between 155 to 172 in all 16 cylinders. Everything is clean on the bottom with props looking good and outdrives stock and cleaned. 32 wanted we can go for a ride this spring and check it out. i will be going through a lot of things this spring as well.

Did you give the thing a tune-up yet. Plugs, wires, cap , fuel filter and so on. What did it run before you had the drives off the boat ?. I would also check to see if the motor mount has not backed off and let the motor drop a little and put everything in a bind.

Those motors should turn 5150rpms, if I remember correctly. Seems you're quite a bit off on RPM's. However, I do not believe a straight hull will run 80. The newer SS, twin steps, with HO's are usually around an 82mph boat, so you may be asking alot out of a straight hull to hit 80 with the same power.

Dragonheart new had HO's and ran 80 MPH GPS with 4 guys at the rally back in the day. 5150 is the rev limiter. Merc's RPM range is 4,600 - 5,000 RPM. Motors make peak HP just shy of 5K RPM (per Bob Lloyd's dyno testing).

Teague tested a 454 mag (385 HP) boat, I think in 1999, that ran 80.5. But take into consideration that was a brand new boat, almost no load at sea level. Still remember that boat with red stripes fading to a black checker flag pattern at the back of the boat, and an american flag painted on the nose. Great paint job for that boat, made it look 35 feet long sitting in the water. Then again, I always liked the old dominators lines sitting in the water better than the new ones.

I have 2001 Dominator with 385 454 Mags. I see 75-76 on most days and I have labbed 28's I also think I am missing a few MPH but I think you have something limiting your RPM's if you are only seeing 4600 and 4900 on your engines. It might be the props themselves? I think we should put my props on your boat and see if we can get the rpm. Thank goodness spring is right around the corner.

I think I would be looking to try a different set of props also if I was the OP. Even if the props on the boat look perfect to the naked eye the actual pitch could be way off. The fact that he has several hundred RPM's difference from one side to the other makes me wonder if the lower rpm motor has a prop that might have a tweaked blade or something.

Trying 32wanted's props is a decent idea. You could also try swapping props from one side to the other. You would have to operate the shifters in reverse but if the RPM difference migrates to the opposite motor with the prop you can be pretty certain its the prop.

Also, personnel opinion and experiences with props. A "labbed" prop is a mysterious thing and can behave differently from one boat the next. Also not all "lab" jobs are created equal. There are so many things that can be done to a prop. I have seen a "labbed" prop that was said to be "X" but it never worked like one thought "X" would. So the prop was sent to a prop shop for measurement. The shop didnt do anything to the prop except literally measure each blades pitch and provide a print out. None of the blades were within 1/2 inch of each other...there was literally 2 inches of pitch variation between the blades of said "labbed" prop. Also another experience is I have actually seen a brand new prop get measured and have blade pitch variations of a 1/2 inch. Point is, in my experience having props measured by a reputable prop shop and seeing the print out of your personnel props is very good knowledge to have. Especially if you plan to try and tweak every last bit out of a prop. If you talk to any racer(I have experience with SVL). You can try 8 props and have them all "labbed" the same. But one of them will be "the one" that just works like none of the others and if or when something happens to that prop its a real catastrophic! Ok im kinda off topic now....sorry.

Interested in hearing the outcome.

No cap. plugs and filters have been replaced. I will be replacing wires this spring. Engines have been realigned just recently along with drives so everything there should be good. Drives removed serviced and gimbals replaced.

I believe we have boated before on St Claire. Mine is the green/blue on white 2005. Has single step.

Sounds good. i am sending props in this spring to have them checked. I am also servicing the injectors and will be checking fuel pressure at WOT. We will get together.

good info and i will be sending them into (?), my boat mechanic certain somebody that is the only person that he will use. I'm quite certain that i will have the straight up on the props soon.