Formula 27PC Complete Power plant rebuild

[DRAG27]

I've been following with great interest. Thanks for sharing. There aren't many guys trying to make a lot more power on their cruisers, so I enjoyed the read. Do you know what brand of engine dyno your builder used?

I have a 27PC also and have been debating adding pro chargers or whipple's kit if they would even fit. I have twin 350 mags with bravo 3s. I'm just not sure how much performance could even be had with this hull...even with another few hundred hp, or if the drives could even take it...or if it would even be enjoyable ha ha. I run 47-48 with the boat trimmed anywhere and I can squeeze 50-52 if I work with the tabs a little.

Id be real interested to see how your boat takes off with 1 prop. Thanks again for sharing.

 

[alldodge]

Don't know where he went, he lives in Mt Juliet TN which is east of Nashville. The print out shows Stuska Dyno so figure it is a water load, but just guessing.

Have noticed that the trim can not come up as high as it use to and this could be from all the water that was removed in the boat rebuild. Boat is lighter in the stern but the nose is still just as heavy. I could get some more out of the boat if the anchor chain was shortened back to original. They come with 70 feet (as you probably know), but I have 110 feet.

Once a boat reaches it's max planning speed it takes a lot to get more out of it. Whipple's should help some, but these boats being so heavy need low in torque to get them up. Installing them will help but how much I don't know, would be interested to hear.

 

[alldodge]

Have been continuing with this issue on OSO due to those folks kept asking questions. Anyway, to do a quick catch up for those interested.
Basically it comes down to with 415hp and 3x3 24 pitch prop set I could do 5200 rpm at 46 mph. Now have 530hp with 3x3 26 pitch prop set and still WOT is 46 mph at 5050 rpm. So my prop slip is staying the same and the extra hp is only helpful in taking off.

Called some prop places and was leaning toward the 4x3 Merc XR props, the issue is no one would call me back, or return emails. I then called Hill Marine and they did call me back. Talked to "Dad" which is a retired school teacher and got into making props after Merc wouldn't make props of the type Yanmar wanted. Hill decided to do it, they worked so well he took them to the Miami Boat show in 2007. They were also a hit and since then along with Yanmar contract he is selling 60 sets a month.

So he recommend a 4x4 set at 24 pitch. The icing on the cake is if they need to be tuned more, change to a different pitch set, it will only cost me $60 for shipment round trip. You just cannot ask for better service

Did notice the front props are not as wide as the Merc 3x3




Plan to install them in the morning if the rain holds off.

 

[tpenfield]

It will be interesting to see how they work. I am wondering if you were hitting the limits of what the standard Bravo set could do, so your 120 extra ponies were going nowhere.

Looking forward to the results. I have not checked your OSO thread in a while . . . did the 'power & prop' guys over there have any insights?

 

[alldodge]

It will be interesting to see how they work. I am wondering if you were hitting the limits of what the standard Bravo set could do, so your 120 extra ponies were going nowhere.

Looking forward to the results. I have not checked your OSO thread in a while . . . did the 'power & prop' guys over there have any insights?

A little here and there, but all in all a good discussion. The biggy over there never came in to comment

 

[alldodge]

Will made it out for the test this AM prior to the rain. Boat does come up quicker, still no runabout but I did like that. Cruise went to 3800 rpm at 35 mph, so slip reduced but not much, down to about 19%. WOT rpm back up to 5200 but reached a solid 47 mph, so slip is at 20%.

Put another call into Hill to see if they have any other suggestions, but I'm starting to think the boat is at it's limit without some real drastic change. What that change might be, who knows

 

[Scott Danforth]

you could add this http://www.ebay.com/itm/ROLLS-ROYCE...YOUR-DRAGSTER-BOAT-FUNNY-CAR-or-/191606574307

seriously though, are you getting full power? I know dual prop drives run out of thrust advantage at about 50-55mph,

 

[alldodge]

you could add this http://www.ebay.com/itm/ROLLS-ROYCE...YOUR-DRAGSTER-BOAT-FUNNY-CAR-or-/191606574307

seriously though, are you getting full power? I know dual prop drives run out of thrust advantage at about 50-55mph,

Good one Scott, LOL

Well all the throttle I give it, is not over reving the motor so the prop is taking it. Don't know, as it could be that the hull is at it's limits with current setup. There are some folks on OSO which claim to use the twin B3 up thru 70+ mph. Was a good thread to read, I'm really starting to think the boat is what it is, just no way around it. Look forward to talking to Dad again just to bounce some ideas

 

[Bondo]

so slip is at 20%.
but I'm starting to think the boat is at it's limit without some real drastic change. What that change might be, who knows

Ayuh,..... Have ya crawled under it on the wagon, with a straight-edge to see how flat, 'n true the hull is,..??

 

[alldodge]

Ayuh,..... Have ya crawled under it on the wagon, with a straight-edge to see how flat, 'n true the hull is,..??

Nope, haven't done that with a straight edge. There is a bit of a hook on the outer edges (1 to 2 ft each side), but have spent many hours under, over and around it during the rebuild. Without breaking out the edge I would swear the hull has not changed from factory just looking how it sits on the trailer

What ya thinking?

 

[Bondo]

Ayuh,.... Any wafflin' is less than Ideal,.... just lookin' for a way you can cut yer % of slip,......

 

[alldodge]

What would I be looking for with a straight edge or waffle ?

 

[alldodge]

Just talked to Chad at Hill Marine, he says that since it is a heavy single engine cruiser I'm pretty much the best I can get. While 20% is on the high side, he expects to see 15 to 20 slip on heavy cruisers. Is willing to let me try the 26 pitch but also believes that it will not help, but will hurt hole shot. Do like the quicker plane, that's at least a plus

 

[tpenfield]

It just seems strange that you got a 120 HP increase and do not see anything at the top end . . .

 

[alldodge]

It just seems strange that you got a 120 HP increase and do not see anything at the top end . . .

That's the thing I think about the most, so is the answer it is what it is or maybe I didn't get an additional 120hp like I was told :noidea: and things that make you wonder. Sure wish there was I dyno I could hook up to the drive

 

[Scott Danforth]

http://www.dynomitedynamometer.com/prop-shaft-dyno/marine-dyno.htm

 

[alldodge]

http://www.dynomitedynamometer.com/prop-shaft-dyno/marine-dyno.htm

That does look good wonder if anyone has one around my area and if they can do a B3

Was PM by a quality member indicating I might want to try the prop area, going to give it a try

 

[Tail_Gunner]

Ayuh,..... Have ya crawled under it on the wagon, with a straight-edge to see how flat, 'n true the hull is,..??

I believe Bondo's going to the right area here, while nothing is for sure it seems almost certain your fighting bottom paint or the hook. Is the hook on the outer edges of the hull....that could actually be built in tabs i have them on my wellcraft and do not like them but im not going to flatten them out. Your pushing a lot of hull and a lot of weight yes bottom paint could be holding you up make no mistake. Itr's as simple as a orbital two hundred grit and half a days work doesnt take to much to cut that stuff off.

Where's 45 auto this big boat stuff is right down his wheel house so to speak.

 

[alldodge]

Pulled the boat out today and winterized.
Here you see a strength edge with the transom and it's right where it should be from my point of view


Here is the hook, first I thought it went across the hull but the only hook is just on the outer 12 inches of the hull and just in front of the tabs, did notice a new discoloration, hope its not a crack, but will get into it later

 

[muskyfins]

did you ever test with the 26P prop set?