Engine Thoughts

[thegambler]

Hello All,

New to the forum, and need some input.

I'm restoring my boat, and part of this is the I/O. She originally had the V/P 5.7L with V/P outdrive (not sure which one). I'm giving serious thought to dropping in a Merc 3.0, but would love the input from the forum on this. I'll preface by saying I am NOT looking for a speed demon, I'll be using her as a general pleasure craft. For a day of light fishing on the lake, and just piddling around. I dont plan on towing skiiers, tubers, etc. I just like to take her out by my lonesome, or maybe with one other person, and just enjoy the sun, do some swimming, cast a line... as my granddad always called it " putting around".

My boat is a 21' CC Scorpion 210 (20' 7" actually) cuddy. She's all glass and weighs in at 3000lbs. I know I'm going to get droves of folks telling me that this isn't near enough engine to shoot across the lake at near orbit speeds so please spare me these types of comments as that isn't my cup of tea ( see above for my needs from the boat). What I'm looking for is input on whether this engine will work for this boat to go out for the day, and maybe cruise at about 18-20mph. Again, I know there are plenty that will say to spend the extra cash, and get the big engine and I will be happier, but lets face it, money is the ruler and I just don't have the type of cash to throw at a new V8 and drive.

Thanks in advance for all of your replies.

 

[steveclv]

Re: Engine Thoughts

Sounds OK to me - what's a 3.0 put out? 135hp or thereabouts.

If you were boating in estuaries and tidal waters then you would need plenty of reserve power - but in a lake, heck, 50hp will do the job for you

 

[ezmobee]

Re: Engine Thoughts

Where are planning to get this 3.0 from?

 

[fat fanny]

Re: Engine Thoughts

Why don't you go with just the V6 and save yourself the re-fab of glass work in the bilge and still have the economy and the reserve power when or if you need it plus you won't be pushin that lil work horse 3.0 to hard to move that 20 footer around

 

[proshadetree]

Re: Engine Thoughts

I think you first need to calculate the amount of money it will cost. For most people a re-power to save fuel will never pay off leaving you with an undesirable boat if you go to resell. If you dont have a good engine or out drive and can find a steal on one then you might come out. I think it would plane out ok. I have seen 3.0 in 18 foot deck boats and will assume they are like pushing a brick through the water.

 

[QC]

Re: Engine Thoughts

I think it would plane out ok. I have seen 3.0 in 18 foot deck boats and will assume they are like pushing a brick through the water.

I am actually worried about planing. With trim tabs, she'd probably be OK, but Deck boats typically have very low deadrise which makes planing easier. I think that Scorpion is near 20 degrees and the 3.0 will work hard to plane her.

Help us with more about existing drive and engine. Both gone? If so, maybe a donor boat with a 3.0 will be easy to find and might be your best option.

 

[getusummm]

Re: Engine Thoughts

I also have a Scorpion 210, although mine is a bowrider. Mine has a 7.4 that has been warmed up a bit. Not sure you will be very happy with the boat with a 3.0 It is a very heavy boat and I think it will tax the 3.0 to no end. You will probably end up with something like a 11 pitch prop to even think about getting it on plane. Good luck though. I think you would be far happier and better off with the 5.7. What type of running gear do you have left in the boat?

 

[6meter]

Re: Engine Thoughts

Putting anything that is different that what was in there will create problems with wiring, outdrive gear ratios, will need new manifolds which will all cost $$$. With the right prop you might get on plane with a 3.0, but you'll be working it hard and fuel milege will awful.

 

[johnrv]

Re: Engine Thoughts

Hi people,I'm new to any forum but I have gotten my boat fix at night with this forum.I am currently repowering a 1983 230 aft cabin that was equipped with a 230 hp 5.0 GM. I bought a NY lake boat with a 190 hp 4.3 with 260 hours and a near perfect Alpha I outdrive.I was looking for a replacement V8 but have opted for the V6 with fuel prices. I guess what I'm saying is you may be able to buy a boat with a good engine and outdrive to use as a donor.I agree with the other guy,the 4.3 should give you the needed torque to get on plane.good luck.

 

[QC]

Re: Engine Thoughts

You guys that are doing stuff like this for fuel reasons need to do more research . . . Maybe a 10% difference, and could even go the other way. Depending on how much fuel you typically use this could be less than $5 a trip, particularly at the same cruise speeds.

The OP's motives may be different, but I haven't seen anything that defines that yet.

 

[thegambler]

Re: Engine Thoughts

"You guys that are doing stuff like this for fuel reasons need to do more research " ... If you read the orginal question, it had nothing to do with fuel economy. Again, I didn't need a bunch of replies preaching fuel economy lossage. I was looking for responces in regards to whether this would work, or if it was simply too small a powerplant. But alas that's what I get for presuming people will read the post in it's entirety. If it's any consolation to those that did read, and post constructive responses ( I thank you) I am going to rebuild the 5.7

 

[QC]

Re: Engine Thoughts

If you read the orginal question, it had nothing to do with fuel economy. Again, I didn't need a bunch of replies preaching fuel economy lossage.

The OP's motives may be different, but I haven't seen anything that defines that yet.

If you read the orginal question, it had nothing to do with fuel economy.

I wasn't referring to you . . . there were a lot of replies regarding fuel economy as should have been anticipated. Frankly, I was supportive, even though I was concerned about enough power to plane her.