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davesboat

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"I currently have a 20 year ol

"I currently have a 20 year old VP aq211a running a 290 duo prop,pushing a 21 foot boat weighing 1.95 tons, planing hull, top speed around 30 knots, comfortable speed of 20 knots.
I am thinking about changing the engine to a new VP 4.3GL and a sx single prop drive.
Would I save much gas? or even burn more running the 4.3 at around 20 knots?
I have searched and searched for this answer.
does anybody have any idea of the fuel consumption for both engines?"
 
"My question seems to be the w

"My question seems to be the worlds biggest secret, I can not get an answer from anybody including volvo penta !!!!!"
 
"You got that right, Dave!!!

"You got that right, Dave!!!

You could try to obtain both engines' specific fuel consumption (grams/kW/hr) curve, just to compare their fuel efficiencies. But even if you got that information, the torque curve may be different for both engines and you may not get the best performance at the RPM/speed range you want. And then, a DP should give you a better performance than a single prop.

I trust you realize you have too many variables in the equation for anyone to give you an accurate answer. But my guess is that any higher fuel efficiency you may get from the carburated 4.3 GL (Vortec) versus the AQ211 will be eaten away by the single prop arrangement."
 
"Further "Els" post...

"Further "Els" post...
Why change out the drive? Series 200s if maintained and kept away from high speed meetings with hard objects last a loooong time!

My choice would be to go with a new fuelinjected 5.0. This would make installation labor lower.
The new Volvo 5.0s would give you a nice HP bump and an RPM bump. However, I'd just keep to the comfortable speed for you boat and real the benefits of improved fuel efficiency of the new FI engines. I's also seriously consider a "closed cooling" system, often misnomered as "freshwater". These can be safely run at higher temps than raw water cooled engines for better engine life and fuel consumption.

IF your existing DP290 is sound there is no economic or performance benefit (worth the cost) of going to ANY other drive. As far as life is concerned. 40 years of operation from a 200 series drive is not unusual. Keep the seals in good order, change lube, keep zincs fresh and avoid hitting anything! There are still some 100 series drives running around out there, and these date from the very early 60s."
 
"Thanks for the replies I did

"Thanks for the replies I did consider just an engine but I also found that there seems to be a lack of info on what engine will match up to my drive, I have seen the term "bobtail" is that what I need?
Yes my drive is in good condition, I am working on the theory that my 20 year old engine is a bit worn and not giving me the performance it should.
I would surely like to swop just the engine, but i'm not sure what I am searching for. I would like to mate up a 4.3 to my drive but I dont think its possible.
dave"
 
"RE: 4.3 to your drive..It sho

"RE: 4.3 to your drive..It should be, however I believe that the engine mounts will hit the stringers in a different place, and that will have to be delt with.

Re: Bobtail... no.. A "bobtail" is an engine whose "interface" to the drive system is intended to connect to an inboard style transmission."
 
"The stringers should not be a

"The stringers should not be a problem, as long as the v6 engine fits my leg.Do you know where I can find out for sure if a v6 will bolt up to my leg?"
 
So if i bought a vortex 4.3 or

So if i bought a vortex 4.3 or similar I just take off the bell housing from my aq211 bolt it on the new engine and I am in business.
please say YES
Thanks
dave
 
"Dave, I have not done it myse

"Dave, I have not done it myself, but I cannot foresee any reason why not. I know, however, of some problems you might encounter. The older 4.3 had a flywheel that measured 12.5" (or 12.75") diameter and the new ones apparently come with a 14", which means the starter is different. To make a new 4.3 fit on an older drive, you either needed a 12.5" flywheel and a smaller starter (like the one you have now), or a larger bellhousing, as the 14" flywheel and starter would interfere with the old style bellhousing. You may want to check this link and consider giving those guys a call, they may be able to give you more precise info.

http://www.ebasicpower.com/engines/base/262.htm

PR. Your current flywheel will probably not fit the new style crankshaft bolt pattern, just in case you were thinking of swapping it.

Perhaps Ricardo or Robert may have something to add to this....
happy.gif
"
 
"I don't understand why yo

"I don't understand why you want to go to a 4.3 and not stay with a 5.0. The price difference is minimal. My experience is that for any given boat a larger engine that is not working as hard will give better fuel consumption than a smaller one that is working hard. It is not a given that going to a 4.3 will improve your fuel consumption. Boats aren't like cars. The same rules do not apply. I re-engined a 23 ft boat once that had a 283 CID 185 HP engine with an 318CID 225 HP engine and the fuel consumption improved! And no, the old engine was running fine. It's fuel consumption was even slightly better that the published curve for the engine."
 
"Thanks for all your help, I w

"Thanks for all your help, I was going down the road of a v6, working on the theory that I can get one that pumps out 225 hp while my aq is giving "210 hp". My other reason behind going for a v6 is that its a little smaller,so therefore easier to get at and service. My engine bay is a pain in the butt to get into. I am going to carry on looking into it for a while.
I will let you know how I get on with it.
I am very grateful to you 2 guys for taking the time to help and advise me
dave"
 
"Just an update on my old post

"Just an update on my old posts above.
I have indeed changed the engine in my boat, to a VP 4.3 gl (was running a VP aq211a)
from the aq211 I was getting around 1 mile to the gallon at a mix of speeds.
From the new 4.3gl I am now getting close to 3 miles to the gallon, granted at running in speeds, even so I can still rev to 3/4 throttle for short periods.
The only difference I can see going from the DP to the SX single prop is the shape of the wake and slightly more revs to bring her up on the plane.
All in all I am well pleased with my decision to repower.
dave"
 
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