90-23' Gulfstream Repower IO Volvo Penta DP

AndrewN

New Member
Joined
Feb 6, 2008
Messages
1
Reaction score
0
Points
0
Location
Long Island, NY
Looking to repower original 1990 Volvo DP 5.7 270 hp engine & drive in 1990 23' Gulfstream. Currently sluggish and inefficient cruise 18-20nts at 15gph. Any suggestions or $$$? Preference bet Volvo or Merc? New Power size 300 or 320 hp? Expectations for new fuel and speed? Closed coolant / Neutra Salt System?

I recv'd quotes for new Volvo DP 5.7 300hp installed for ~22k.

:?
 

JeffN

Well-Known Member
Joined
Jan 16, 2007
Messages
582
Reaction score
7
Points
18
Location
Nantucket, Ma.
Don't know how you will do with answers here the group seems to be outboard guys. I repowered my 25' Kingfish last winter. Went with the Merc. 496 - 375 HP very happy with the result. Don't know if that would fit in your 23' or the weight of your boat. Don't Volvo and Merc. use the same GM motors if so I would just go with best local dealer. Mine is a closed system. Good luck
 

jehines3

Well-Known Member
Joined
Jul 13, 2007
Messages
433
Reaction score
0
Points
0
Location
Maryland, USA
The biggest problem you will have is that the outdrive is no longer in production. I liked my VP SX drive, it was great and people say the DP is even better (except for limited prop choices). If it were me, I'd go for the VP hands down. I would keep the 350 base and going to a Multi Port Fuel injection which is rated about 320 HP.

Here's how I'd do it.
http://www.dougrussell.com/Products/ind ... 6&Brand=47

I've done engine swaps before and it is not hard. Changing the transom assembly is a whole different thing that I've never even considered. Good luck. jh
 

JeffN

Well-Known Member
Joined
Jan 16, 2007
Messages
582
Reaction score
7
Points
18
Location
Nantucket, Ma.
jehines3 said:
The biggest problem you will have is that the outdrive is no longer in production. I liked my VP SX drive, it was great and people say the DP is even better (except for limited prop choices). If it were me, I'd go for the VP hands down. I would keep the 350 base and going to a Multi Port Fuel injection which is rated about 320 HP.
jh

Looking at a seventeen year old unit would you not want to repower the whole thing front to back?
 

Amigo

Well-Known Member
Joined
Nov 12, 2005
Messages
183
Reaction score
0
Points
0
Location
Saint Joseph MI
You don't say that you have had any diagnostics done on your ccurrent engine. I would at least get a compression check and if that checks out OK then maybe a tune up and carb clean. Then test again. The good thing that can come from a bad compression test is that you have something to show the wife justifying a repower.

Here are some numbers from a 1988 25' Sailfish with a 7.4 liter 330HP eingine. I cruise at 21 to 23 MPH based on GPS readings at 3200 RPM. On a good day, based on FloScan readings I'm getting 1.9 to 2.0 miles per gallon. On a sloppy day it may be 1.6 to 1.8 MPG.

The engine is a strong engine with a clean carb and recent tune up - plugs, etc.

Your 15 gallons per hour is puzzleing when I'm doing 11 to 12 GPH especially with your lower speed. The 25 ft. Sailfish with I/O is at least a 6,000 lbs. boat. If your set on a repower - yes I would go for more HP. Today's engines pack more HP per CI. But on the other hand more CI equals more low end torque which gets you on plane faster.
 

JeffN

Well-Known Member
Joined
Jan 16, 2007
Messages
582
Reaction score
7
Points
18
Location
Nantucket, Ma.
Amigo - Thats interesting I'm guessing that your 454 is the original engine? I went from twin 470s to the single 496. I only got my boat back at the end of the summer so I don't have lots of specific mileage data yet but from like 20 knots to 32 knots my miles per gallon vary from just under 2 at 20 knots to 2.25 at 32 knots. The boat with only 25 hours on it tops out at 44 mph.
 

Amigo

Well-Known Member
Joined
Nov 12, 2005
Messages
183
Reaction score
0
Points
0
Location
Saint Joseph MI
The new fuel injected engines are much more fuel efficient that the older carburetor engines. I'm hearing like an easy 20% for the same HP.

Looking down the throat of my carb is like looking at a big hole in the bottom of the boat. At 3,500 RPM it really starts sucking the gas.
 

nauditq

Active Member
Joined
May 5, 2005
Messages
40
Reaction score
0
Points
0
Location
Chesapeake Beach
Have the same set-up in a 25ft. kingfish. Did you have the motor and drive checked out? If I had to repower complete, I would stay with VP.
Only for the VP DP system, even tho it cost three grand more for complete system. 22k is alot of bucks, but I guess you know more about what you have need. I remember Jimmy talking of the Merc MPI package, saying he liked it. It is less costly, but I am not sure about the drives.
Do a search here for it'
I have also read the small block higher hp motors have less torque, and the power is in the upper rpm range, so not sure what that would do in the gulfstream.
I have looked at my options for when the time comes to repower and will just drop another engine in. The 290dp will last a long time if maintained.
Glad to see some Grady I/O guys around.
I always head over to the Albermarle site when I have a engine, drive question on my Grady. Check it out, wealth of info for the VP repowers.