340 DA 6.2s vs 8.1s

B

btyman11

Member
Mar 23, 2014
94
Long Island,NY
Boat Info
340 Sundancer 2002
Engines
Twin Mercruiser 8.1S Horizon
Hey guys. I am currently in the market for a 340 DA 2000-2003 (maybe an 04). Doing alot of research I see that base power in alot of these boats were 6.2s and the upgrades were the 8.1s. Can anybody give me some insight on the 6.2s and where they cruise at in this boat? Always thought it might be underpowered a bit with the 6.2s but my surveyor suggested it is not. I would love to get some good info from you guys on both power packages.
 
Several folks here have 340's of that vintage with 8.1's and 6.2's. I think it depends on how you plan to use the boat, the 8.1's definitely have a high top end. CliffA has a 340 with 6.2's and he is very happy with the performance, I have also spent time on his boat - I am starting to look at the same boat and I would prefer the 6.2 over the 8.1's. I think some main differences that might affect your decision:

1. The 8.1's create a very tight engine room, so consider this if you do your own maintenance. The 6.2 is not great, but the 8.1 stuffed in there is almost crazy.
2. 6.2's do not come with closed cooling, the 8.1 does - for people like me and Cliff on freshwater lakes it's not an issue, but salt water would be different.
3. If top end and higher cruise speeds are your thing, the 8.1 might have an advantage.

Hopefully people that actually have the boat will comment - I just have some insight because I am an interested in the same vintage 340 and have spent a bit of time on friends 340's. One last comment, I think this vintage 340 is one of the best boats SeaRay has made and is definitely a good value at this point.
 
I do all my own maintenance and im 6'3 so I may have a problem with the 8.1s lol. I also boat in salt. I do like the speed of my current 280 with twin 4.3s as I usually run around 28-29 mph. I would think with the 6.2s Id be running low to mids 20s.
 
I think you will find the majority of the boats in this era were either 6.2s or 454's..... a few latter models may have the 8.1's but I think the late 2003.5 model change had these engines exclusively because it is a bigger and heavier boat.....

here is a thread I started when I was trying to decide which engine was best for my situation....

http://clubsearay.com/showthread.php/70013-2001-340-Sundancer-purchase-decision

Bill is correct in that I am very satisfied with the performance of the 6.2's for the way I use the boat......on an inland freshwater lake we do not have the need for long runs on plane....the vast majority of the time we are cruising at 'cocktail speed' which is usually around 9 - 10 mph at around 1800 rpm.....about the only time I take the boat on plane is to clean the algae from the bottom or to outrun a storm.....

I can cruise on plane around 25 mph at 3600 rpms.....top seed is around 30 - 32 mph at 5200 rpms....

the small block 6.2's were developed to be a replacement for the big block 454's.....the 6.2's will make comparable power but they will be turning higher rpm's....I believe the WOT rpm's for the 454 is around 4600 and the WOT for the 6.2 is 5200.....

the big block 454's or 8.1's with closed cooling certainly do tighten up the 'space' in the engine room.....I am 6' 1" and 210 lbs and also do all my own maintenance and can move 'reasonably' well in my ER to get to the engines and genny....I have looked at similar boats with 454's / 8.1's and just shake my head wondering how anyone could work in such a small space.....

if I were to use the 340 on the ocean I may opt to get the big block engine....not because the 6.2's don't have enough power but primarily because the 454's have the closed cooling system.....but you can add closed cooling to 6.2's......

which ever you choose if the boat has V drives be sure the exhaust has been converted to the 'water lift muffler' design and there are no soft spots on the deck from water intrusion....both well known issues for this era boat......

cliff
 
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Thanks for the info guys. As a boat in salt I would probably go with the 8.1s as they are FWC. I would consider the 6.2s if they were FWC. I dont think I would add them to an older boat as scaling could be an issue in the block especially if coming from salt. All great info. Thanks again.
-Dave
 
I noticed When I cruise at 25mph or below the bow is pretty high. Bring it up to 28-30 range and it flattens right out. I'm cruising at 27mph at 3500 and am trying to get past the 28mph range, It just feels so much smoother. I don't know much about the performance with the 6.2, but 3600 at 25mph would be too slow for me.
 
I believe that a 340 of that era has 11.5 beam. Same as my 320. I can't imagine how you can stuff big blocks in there and expect to be able to work on them. My 320 has 6.2 closed cooling and is not under powered at all. I have had full fuel, full water and 8 people on board and the boat jumps onto plane. Working in the bilge, however is terrible.
BilgeYoga_zpsbscqpkzc.jpg
 
Vince_nj1 said:
I believe that a 340 of that era has 11.5 beam. Same as my 320. I can't imagine how you can stuff big blocks in there and expect to be able to work on them. My 320 has 6.2 closed cooling and is not under powered at all. I have had full fuel, full water and 8 people on board and the boat jumps onto plane. Working in the bilge, however is terrible.
BilgeYoga_zpsbscqpkzc.jpg
Click to expand...

that is correct...the beam is 11.5' and dry weight without genny is 13,000 lbs......I believe this is about the same as your newer 320.....

I have a dock friend that has a 2008 330 with 8.1's and closed cooling and V drives and genny.....not sure what the beam is but i believe it is smaller than my 340.......you can barely even see the floor of the ER when he raises the engine room hatch......

cliff
 
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I recently purchased a 2001 340 with 6.2's and I don't think it is underpowered. At 3400 RPM's I can cruise at 19-20MPH. WOT the boat gets to 30 MPH. For a number reasons, I never go that fast though.

Yo will be fine with 6.2's
 
Part of my thinking also is the 6.2s being RWC have to have the exhaust done every 5 years in salt. The 8.1s FWC manifolds go longer and the Risers/elbows are stainless. Correct me if im wrong but wouldnt the 8.1s be less expensive to maintain in the long run?
 
The 2008 330 has an 11.5 beam. Same as my 320 and your 340. I saw a picture of engine room on a 08 330 with 8.1s V drives stuffed in there. I really don't know how you can work it. The exhaust manifolds almost touched. My only reason for posting was to suggest that 6.2's are fine in that boat and while the 8.1's may provide more hp and top speed, you will likely be cursing them when you attempt to change an impeller. A better setup, would be a 2004 or newer 340 which has a 12ft beam.
 
I have 6.2's in my 330. I'm more than satisfied with the performance. I'll admit that I was not at all satisfied with them out of the box. I had to get the props tuned and enlarge the tabs to bring the fuel consumption down and the nose over. Nose high seems to be a SR shortcoming on this boat as opposed to an engine shortcoming.
 
Cliff,

You should send that pix to SR corporate and tell them the design team should consider the maintenance aspect of boat ownership in the design phase. You can start it: Dear Arseholes:

They aren't going to listen so you should at least have some fun with it!!!!!
 
Vince_nj1 said:
I believe that a 340 of that era has 11.5 beam. Same as my 320. I can't imagine how you can stuff big blocks in there and expect to be able to work on them. My 320 has 6.2 closed cooling and is not under powered at all. I have had full fuel, full water and 8 people on board and the boat jumps onto plane. Working in the bilge, however is terrible.
BilgeYoga_zpsbscqpkzc.jpg
Click to expand...

Lol! You should post detailed instructions on how you got yourself there!! Btw; I can't do that on my 320; I'd be laying on my genny!



Sent from my iPhone using Tapatalk
 
I call it Bilge Yoga :grin: except I usually emerge bleeding and swearing that I should have bought a bigger boat! :smt021 I was reattaching the lower hose on the water pump after changing the impeller. That was the "easy engine" :smt013
 
btyman11 said:
Part of my thinking also is the 6.2s being RWC have to have the exhaust done every 5 years in salt. The 8.1s FWC manifolds go longer and the Risers/elbows are stainless. Correct me if im wrong but wouldnt the 8.1s be less expensive to maintain in the long run?
Click to expand...

No. Plugs still have to be changed. "Stuff" not engine related has real estate low in the bilge between the engines. It's not just the engines themselves, it's everything else in the bilge you cannot get to in addition to the crappy design that will make it a PITA regardless of engine....... Just more of a PITA with big blocks.
 
Everyone says stern drives are the worst and cost more to maintain but I can do an impeller change on an engine in 30min and can change out a set of manifolds in 1.5hrs.


 
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