Whats the diff between a #5 and #6
 

What is the power rating that a #5 can handle vs a #6. I have #5s wet sump mounted on a Stellings ext. box with a 1.47 gear and Bam 1440 trans. Is the #6 dry sump that more effecient or will it rob about the same amount of hp. I really like my boat but want to pic up some speed, presently 83 mph, and if can do it through being more effecient with converting to a dry sump #6 or Weisman drive I might go that route, cause I have 2 people interested in the drives from tranny on back. Thanks Jeff

Re: Whats the diff between a #5 and #6
 

Ask about the X Dim

Re: Whats the diff between a #5 and #6
 

There may be a few mph waiting just by changing your set-up. Things you would have to do anyway if you were to change drives.

I would make sure the drives are at the optimum height, props are at the optimum diameter and pitch, weight distribution has been moved around to find the optimum weight distribution and the motors are running at the optimum rpm for speed.

You may be surprised how much more speed there is just from a proper set-up. Not only may you pick up speed but the entire attitude of the boat may change, for the better. If you are not experienced in setting up a boat there are riggers out there who can make the best of what you have. Paying a good rigger for a couple days work dialing in your boat is probably one of the most cost effective things you can do for your boat for speed and handling.

It is not surprising for a properly rigged boat vs an improperly rigged boat to pick up 5-10 mph. Without any engine work!

If you would like any more information don't hesitate to give us a call.

Matt

Re: Whats the diff between a #5 and #6
 

I am uncertain where the x dim is at present. Nortech has never done a #5 boat, and then on top of it with boxes. What I was trying to orig. do was with the boxes put the prop further out into the water to gain more speed and react if anyway possible somewhat closer to a #6. I know dry sump is more effecient to begin with, but I was told the leverage of the boxes is about the same as a 6, and with only 750hp per side it would be over rated for that application. Jeff

Re: Whats the diff between a #5 and #6
 

Jassman may want to do a search on this site. HP ratings and HP losses with wet vs dry sump Speedmaster drives was discussed about a month ago. As I recall, #5 was rated for 750 hp and the #6's for 1000hp. I believe dry sumps picked up at least 35 hp. I'm doing these numbers from memory. Obviously the Speedmasters will tolerate more then they're rated for. I've got #5's with a high 'x' dimension on my Slingshot. Next chance I get, I'll measure where the prop shaft is relative to the bottom of the hull. Throttleup makes good points about proper setup. Everyone focuses on the props, but simple bottom changes, drive height,etc definitely help. Not popular except with the racers is weight in the bow that puts the prop shaft roughly parallel with the bottom of the boat.For what it's worth...Lou

Re: Whats the diff between a #5 and #6
 

I am also a customer of TMP, however you might want to contact Competition Marine Center in MO. They are very knowledgble in set up with SSM drives. It might be worth your time to talk to them. They will want to know your "X", prop info, HP, speed vs RPM, ect.

Re: Whats the diff between a #5 and #6
 

I sent you a pm, thanks Jeff

Re: Whats the diff between a #5 and #6
 

Loe, thanks for the advise, I found the threads you were talking about, 35 hp gains, and 50-80 hp gains from another guy goin with dry sumps. Jeff

F311fr1, which motors from TMP do you have, and what kind of boat. thanks for the help. Jeff

Re: Whats the diff between a #5 and #6
 

Jeff-Put a couple of 900 to 1000 horse motors in a 43 Nortech and I guarantee they'll put a permanent smile on your face. Only downside is the wind resistance from that ear to ear grin may cost you 1-2 mph! Is that Mayfair steering? With my Mayfair steering, the rams attach to the transom next to the mounting plates for the k-planes. Youve got a beautiful boat/boathouse,etc. Life is good in America! Lou :D

Re: Whats the diff between a #5 and #6
 

Everyone I have discussed the V vs the VI switch with has pointed out the loss in speed with the VI due to the increased resistance due to the physical size of the gear case. Secondly, the weight of the VI is greater and it is all located off the transom moving the CG rearward. This may or may not be an issue, depends on the initial CG. However, the VI obviously has some nice advantages :D

Re: Whats the diff between a #5 and #6
 

Don't forget the #5 SSM was Mercruisers answer to the Kiekhaefer #6 before the companies merged.
I believe the #5 gets more power to the prop. Those massive shafts and gears in the #6 are strong, but it takes more power to turn them.
Correct me, but aren't the #5s much less expensive?

Re: Whats the diff between a #5 and #6
 

The dry#6 put's more power to the water than the #5, but the other arguments "may" be true depending on the application. If you put standoff boxes on the 5's and external steering, the weights are not really that far apart. If you can run a high x dimension, the drag issues are not far apart either. Also add in the cost of the standoff boxes and steering cylinders when considering overall cost. It's still probably less costly to put on 5's, just pointing out the other things to consider.

Re: Whats the diff between a #5 and #6
 

I've have an old (1984) 38 Cigarette flat deck with a kevlar hull. The boat came orig. with a pair of 540 Hawks and #3 SSM drives. I now have a pr. of 572 PSI supercharged motors using #5 drives and Stellings box's. It now runs 104-105.
I thought about using #6's, before I bought the #5's, and went with the 5's for the cost and I was also told that the boat would be slower with #6's. I'm not sorry that I used the 5's as I have not had any trouble with running 1100hp. motors through them with a 1.48 ratio and 17.5x31 4 bbl. props. With no spacers in the drives, the prop shaft is 1/2" above the bottom of the boat.
I've tried spacers from 1",2" and 3" and they don't seem to make any difference other than it is a lot easier to get on plane with the 3" installed.
I noticed that you were running 5 bbl. props. Have you tried others? Have you tried spacers?
Keep in mind that if you switch to #6s and don't run driveline transmissions, the tailstocks for a plug-in #6 are approx. $2500 ea. and that does not include the transmission. Factor that into your decision.
If I can be of any assistance, I would be happy to.

Re: Whats the diff between a #5 and #6
 

It sounds like alot of trial and error. I to am running either a 1.47 or 1.48 ratio. The spacers if they didnt hinder performance on top end but helped getting on plane might be the anwser. Just wondering if boxes help or hurt. Nortech did a beautiful job prefabing a few pieces to make everything work for what I gave them. Looks like Im going to have a little paint work once I pull them off. Jeff

Question: is it better to pull boxes off first or just try spacers, thanks Jeff

Re: Whats the diff between a #5 and #6
 

If you decide to try spacers, you will need the stud kit for the thickness of spacer that you choose. You can use a 1" or a 2" or you can combine them both to make a 3". I've never seen anything thicker used, as I think you run out of internal splines at that point.
I have a set of 1" spacers, that I had machined from alum., that I added a 9" "tail" to act as a cavitation plate, that helped in getting the boat on plane. If you are interested I would sell them for $500.
Gary @ 763-473-8963 eves/weekends

Re: Whats the diff between a #5 and #6
 

Do you by chance have a picture of what you are talking about, thanks Jeff

Re: Whats the diff between a #5 and #6
 

Jassman..... Before you do anything, check the height of the prop shaft in relation to the bottom of the boat. What I mean is, with the prop shafts perfectly parralell with the bottom of the boat, run a straight edge down the bottom in line with the drive.
Generally speaking, with boxes, and this will differ from boat to boat, your prop shafts should be somewhere within 1" of the bottom. The deeper you go, as with the spacers, usually the more drag you will have therefor slowing you down a bit.
On the other hand, the higher you go will make it harder to get on plane, but let you run faster on the top.
You need to find the "happy medium" then prop it accordingly.

Re: Whats the diff between a #5 and #6
 

Call me and lets talk.
Gary @ 763-473-8963

Re: Whats the diff between a #5 and #6
 

wet sixes eat a few more horses on the way to the prop (than a 5)
dry sixes eat a few less horses on the way to the prop (than a 5)

six gearcase has atouch more drag than a 5 gearcase.

high x dims negate that difference (when running w/centerline above bottom of hull)

My guess is that if you already have fives installed, that there would be questionable benefit in swapping to dry sixes for the cost and hassle involved. There would be no benefit in swapping to wet sixes.

Re: Whats the diff between a #5 and #6
 

I had my wife give me a hand, to get it as accurate as possible. I have a notch in my transom so at that measurement the props are approx 6 1/2"-7" above the bottom of the notch. (very bottom of boat)

At the other bottom of the boat, above the notch it is almost dead nuts, about a 1/2" -1"above . Any more help is apprieciated. Jeff

Re: Whats the diff between a #5 and #6
 

Jeff... You take the measurements from the very bottom of the boat, (the V). If your shafts are within an inch above the bottom V in line with the shaft, then I'd have to say that that's just about where you need to be.
Whoever set up that boat for the 1st time using the SSM#5's with the boxes, I'd say did a pretty good job.

If you add any spacers now, and put the props in deeper, I'd have to bet that you'll see a loss in speed.

Now you need to start trying some different props.
What are the drive ratio's? Don't remember if you said earlier, sorry, 1.48's ( we usually round that # to just 1.5's for easy speakin)
What's your prop diameter? I see you're running 5 blades.
What's the pitch?
What rpm are you turning at WOT? and what speed?
Did you dyno the engines? What hp @ what rpm, and what torque at what rpm?
These are ALL factors that you need to consider when selecting your props
Also, is there ANY kind of a hook in the bottom of the hull? I would think that the hull has been blueprinted at the factory before it left. If not, that's another area that you may want to look into.

Bottom line here: I don't think that for the cost of switching over to a dry #6 that you will see a noticable difference. Atleast not for what it's gonna cost you. But, if $$$$$ not a problem here then go for it, I'm sure you will pick up a few mph, done properly.

Re: Whats the diff between a #5 and #6
 

At the very bottom of the v makes the center of the prop appr. 6-7" high, and 1" or 2" will help getting on plane and possibly wont decrease speed. What Im trying to also improve is where the water is in relationship to the hull when trimmed up, its right around the drivers seat, the water needs to be more towards the transom, I think that also is affecting top end. Correct if Im wrong, by putting a spacer in that lowers the props, helps plane up, but also cause of the boxes, places the props further out so when trimmed up I will get more leverage which will increase top end. Thanks Again Jeff

Re: Whats the diff between a #5 and #6
 

Jeff, I think I understand what you mean. But, remember, if the props go too deep, then you will start lifting the stern and the boat will start bow steering.
I really think you might want to look at the bottom of the boat. From what you're saying, it sounds like the drives are pretty close to being in the right place. But if the boat is breaking water at the driver's seat when you're trimmed out, then that's saying that the drives are too deep already cause you're starting to lift the stern, OR, there might be somewhat of a slight hook in the bottom of the hull and that's what's keeping the nose from lifting.

Don't know what kind of HP you're running, or the weight of your hull, but it takes alot of HP to "carry" the nose of a heavy boat, up in the air.

This gets way too complicated to type, if you'd like to give me a call I'd be more than happy to tell you some of the similiar problems we've had with customers boats that had similiar problems as yours.
Frank.....708-579-5434

Re: Whats the diff between a #5 and #6
 

Thanks for the help Frank, apprieciate it.

Gary thanks for your help as well, I will be needing more than 1" spacer, probably 2-3", Ill let you know once Im at Nortech, and find out what they have, maybe they will have a 2" and combine it with yours, thanks Jeff

Re: Whats the diff between a #5 and #6
 

Hey Jeff:

I'll trade you my # 6's for your # 5's. Then, if needed, get my # 6's modified to dry sump units. I even have different spacers to go with them. You pay for the labor......:D :D

Sounds like your COG is too far forward with that fancy cabin and mine is possibly too far to the rear. :drink:

Re: Whats the diff between a #5 and #6
 

If you're looking for more bow lift, how much bow lift could be gained by changing to some props with more rake?

Just trying to learn.

Re: Whats the diff between a #5 and #6
 

Might be a possibility, and the beauty is we are only miles apart. When I get back from Nortech I will let you know, Thanks Jeff