340 SUNDANCER THREAD

[Mittens]

Was curious and bored so ran the math and Just going off Mercruiser specs, not arguing either way or the other but my personal choice is always buy the biggest motor option and let them not work as hard. mathematically it seams to favor the bigger motor not working. will have to run numbers at slower speed to see if the 6.2s are better at that speed.

6.2 vs 8.1s fuel burn.

Cruise
6.2 at is 14GPH@4000 X 2 === 28GPH = 23-24mph
8.1 at is 15GPH@3500 X 2 === 30GPH = 27-28mph

WOT
6.2 at WOT is 24.5GPH@5200 X 2 === 49GPH = 31mph (using cliffs real word numbers)
8.1 at WOT is 30.5GPH@4800 X 2 === 60.5GPH = 41 mph (using my real world numbers)

For fun say you drive 10 going and 10 coming. 20 miles round trip on a sunny saturday
with 6.2s thats 20miles/24mph = .83... or 49.8 min on plane = 23.24 gallons burned.
with 8.1s thats 20miles/28mph = .71...or 42.6 min on plane = 21.3 gallons burned. Saving 1.9 gallons and 7.2 min (at 3.65 a gallon where I am $6.93)

if for some reason you raced the two set ups at WOT
with 6.2s thats 20miles/31mph = .65... or 39 min on plane = 31.85 gallons burned.
with 8.1s thats 20miles/41mph = .49...or 29.4 min on plane = 29.65 gallons burned. Saving 2.2 gallons and 9.6 min (at 3.65 a gallon where I am $8.03)

I don't know my gps speed at booze cruse speed / cocktail speed but will check this weekend for fun and complete the math, maybe cliff knows his?

For reference later
6.2 burns 1000=2GPH, and 1500=3GPH
8.1 burns 1000=2.3GPH, and 1500=3.5GPH

 

[Strecker25]

Very interesting numbers, thanks for posting that. Since most of you in here already have a 340 and we're so early in the process here's the boat in question:

http://www.bonniecastlemarina.com/Boats-For-Sale_ep_48.html

 

[Mittens]

it looks clean, not sure the hours on it.

if you buy it I will trade you all Gold knobs for the 3 silver ones. on the shiftier and throttles. ha

 

[Zac]

Thanks for the info. I'll have to check what I'm getting this weekend

 

[Stee6043]

Just seeing the distance between the headers leads me to believe 6.2s offer quite an advantage for service. I wonder if you could even change your own spark plugs without employing three small children! What a luxury. I suspect I've got about 6" between the headers on my 7.4's. Those 6.2's look to have double that?

That boat looks clean, very clean. The price may be a bit steep for salt water (assuming) and without major electronics (radar, autohelm, etc) but if it's super clean and surveys well maybe it would be spot on? Camper canvas is definitely nice.

 

[Stee6043]

One more thought - if you're looking to spend the price range listed for that 2002 340 you may want to strongly consider a 1997 400 that's listed here for sale for not much more money. If that boat survey's well it is a steal.

 

[CliffA]

Just seeing the distance between the headers leads me to believe 6.2s offer quite an advantage for service. I wonder if you could even change your own spark plugs without employing three small children! What a luxury. I suspect I've got about 6" between the headers on my 7.4's. Those 6.2's look to have double that?

just like the boat in the ad my 6.2's are raw water cooled so I do not have heat exchangers.....I have room to stand between my engines and I can reach over them for 'reasonable' access to the water pumps for impeller changes.....I can change spark plugs relatively easily also....

as far as running fuel consumption numbers I feel confident that if you are running the boat on plane most of the time the big block and short block engines will probably use around the same amount of fuel....but if you are running the boat at 1800 rpm's at 9 mph (cocktail speed) like we do 95% of the time the small blocks will use less fuel.....

cliff

 

[Mittens]

Cliff I plan to check out my rpms/gps speed today actually. so whats lower rpm points and speeds? statisticly I have 1000, 1500 and 2000 rpms fuel rates for both motors I cant plug in 1800

. I will check my speeds at these RPMS today for fun. and plug in the numbers always nice to know what the sweat spot is. My normal cocktail speed is 1200-1300 but not sure the speed. will have to take notes and test.

 

[CliffA]

Cliff I plan to check out my rpms/gps speed today actually. so whats lower rpm points and speeds? statisticly I have 1000, 1500 and 2000 rpms fuel rates for both motors I cant plug in 1800

. I will check my speeds at these RPMS today for fun. and plug in the numbers always nice to know what the sweat spot is. My normal cocktail speed is 1200-1300 but not sure the speed. will have to take notes and test.

sometimes we go slower at around 1,600 rpms which gives a speed around 7.5 - 8 mph......so you could probably use 1,500 rpm's with a speed of 7.5 mph....

cliff

 

[CliffA]

(deleted)

 

[Strecker25]

One more thought - if you're looking to spend the price range listed for that 2002 340 you may want to strongly consider a 1997 400 that's listed here for sale for not much more money. If that boat survey's well it is a steal.

That boat looks clean, very clean. The price may be a bit steep for salt water (assuming) and without major electronics (radar, autohelm, etc) but if it's super clean and surveys well maybe it would be spot on? Camper canvas is definitely nice.

I absolutely love that 400 and at that price it's a steal. A 340 is the biggest boat we can put in our current slip, and we really like where we are so I'm not sure I want to move past it yet. I have a note into the broker to find out hours and other details, based on where it's slipped currently it's a fresh water boat but that's not saying its been that way forever so I want to find out more.

There's also a beautiful 380 nearby for 85k but again bigger than what our slip can hold so we'd have to make a decision there. We're all over the map as far as models go so what we really need to do is go step foot on some boats and let the wife get a feel for the different options.

 

[CliffA]

Very interesting numbers, thanks for posting that. Since most of you in here already have a 340 and we're so early in the process here's the boat in question:

http://www.bonniecastlemarina.com/Boats-For-Sale_ep_48.html

one thing I will mention is I noticed this boat is under a covered slip.....this could be a significant advantage if it has been under cover for most or all of its life while not used.....it is common knowledge that this era 340's had problems with soft decks due to water rotting the core around the windlass, windshield, hatches, and other deck hardware.....if the boat has been under cover this should not be a concern.....also by being under cover the condition of the gelcoat, cockpit vinyl and carpet, and canvas should be very good.....

just something to consider as these can be expensive items to repair or replace after the sale.......

cliff

 

[Stee6043]

There's also a beautiful 380 nearby for 85k but again bigger than what our slip can hold so we'd have to make a decision there. We're all over the map as far as models go so what we really need to do is go step foot on some boats and let the wife get a feel for the different options.

For what it's worth the 380 (hopefully I don't get strafed here) is more of a stretched 340/350/370 than it is a fundamentally different boat. Once you get into the 400 you've got doors on both state rooms, two heads and some other "big boat" features. For quite some time I thought the 380 might be my next boat but it's just not "different" enough from the 340, in my opinion. Of course I'd love to have the extra beam and room in the ER but overall, from an upgrade perspective, I'd really like to see the doors and separate crappers (and diesels!) on my next rig.

My two cents only...

 

[Stee6043]

For what it's worth the 380 (hopefully I don't get strafed here) is more of a stretched 340/350/370 than it is a fundamentally different boat. Once you get into the 400 you've got doors on both state rooms, two heads and some other "big boat" features. For quite some time I thought the 380 might be my next boat but it's just not "different" enough from the 340, in my opinion. Of course I'd love to have the extra beam and room in the ER but overall, from an upgrade perspective, I'd really like to see the doors and separate crappers (and diesels!) on my next rig.

My two cents only...

I should add - all of the above being said I would absolutely have picked a larger boat than my 340 for my first, given the option at the time of initial purchase! The 380 is still a bigger boat than a 340, definitely. My opinion above is more in reference to upgrading from a 340 to the "next boat". Not trying to bash the 380...

 

[Underwater254]

Help!! Looking at a 2001 340 with 8.1s 180hrs. Boat has been under shrink for 2 years. Haven't seen In person yet. Salt water and supposably not closed cooling. What should I look for motor and drive ??? Thanks

 

[rcknecht]

Help!! Looking at a 2001 340 with 8.1s 180hrs. Boat has been under shrink for 2 years. Haven't seen In person yet. Salt water and supposably not closed cooling. What should I look for motor and drive ??? Thanks

I don't believe the 2001 340 came with 8.1s as an option.... I would get the maintenance records to see when the engines were replaced... Make sure the aluminum exhaust were replaces...Also, the cool fuel system on the 8.1s have had problems... I should be partially closed loop... only the 6.2 were RW cooled...

 

[Mittens]

6.2 vs 8.1s fuel burn.

Cocktail speed/BoozeCruise
6.2 is at 3GPH@1500 X 2 === 6GPH = 7.5mph (using cliffs real word numbers)
8.1 is at 3.5GPH@1500 X 2 === 7GPH = 9.4 mph (using my real world numbers)
Cruise
6.2 at is 14GPH@4000 X 2 === 28GPH = 23-24mph (using cliffs real word numbers)
8.1 at is 15GPH@3500 X 2 === 30GPH = 27-28mph (using my real world numbers)
WOT
6.2 at WOT is 24.5GPH@5200 X 2 === 49GPH = 31mph (using cliffs real word numbers)
8.1 at WOT is 30.5GPH@4800 X 2 === 60.5GPH = 41 mph (using my real world numbers)

For fun say you drive 10 going and 10 coming. 20 miles round trip on a sunny Saturday

Cocktail speeds
6.2s thats 20miles/7.5mph = 2.67... or 2 hours and 40 min run time = 16.02 gallons burned.
8.1s thats 20miles/9.4mph = 2.13...or 2 hours and 8 min run time = 14.91 gallons burned.

Saving you 1.11 gallons and 32 min of time (at 3.65 a gallon where I am $4.05)

Cruise
6.2s thats 20miles/24mph = .83... or 49.8 min on plane = 23.24 gallons burned.
8.1s thats 20miles/28mph = .71...or 42.6 min on plane = 21.3 gallons burned.

Saving 1.9 gallons and 7.2 min (at 3.65 a gallon where I am $6.93)

If for some reason you raced the two set ups at WOT the whole way
6.2s thats 20miles/31mph = .65... or 39 min on plane = 31.85 gallons burned.
8.1s thats 20miles/41mph = .49...or 29.4 min on plane = 29.65 gallons burned.

Saving 2.2 gallons and 9.6 min (at 3.65 a gallon where I am $8.03)

So math says cocktail speed, Cruise speed, and WOT the 8.1s are burning less fuel in the 340.



Edit for referce I tested mine at 1000 as well.
8.1 at 1000= 2.3GPH X 2 === 4.6GPH = 6.8 mph (using my real world numbers)
8.1s thats 20miles/6.8mph = 2.94...or 2 hours and 56 min run time = 13.52 gallons burned.

 

[CliffA]

6.2 vs 8.1s fuel burn.

Cocktail speed/BoozeCruise
6.2 is at 3GPH@1500 X 2 === 6GPH = 7.5mph (using cliffs real word numbers)
8.1 is at 3.5GPH@1500 X 2 === 7GPH = 9.4 mph (using my real world numbers)
Cruise
6.2 at is 14GPH@4000 X 2 === 28GPH = 23-24mph (using cliffs real word numbers)
8.1 at is 15GPH@3500 X 2 === 30GPH = 27-28mph (using my real world numbers)
WOT
6.2 at WOT is 24.5GPH@5200 X 2 === 49GPH = 31mph (using cliffs real word numbers)
8.1 at WOT is 30.5GPH@4800 X 2 === 60.5GPH = 41 mph (using my real world numbers)

For fun say you drive 10 going and 10 coming. 20 miles round trip on a sunny Saturday

Cocktail speeds
6.2s thats 20miles/7.5mph = 2.67... or 2 hours and 40 min run time = 16.02 gallons burned.
8.1s thats 20miles/9.4mph = 2.13...or 2 hours and 8 min run time = 14.91 gallons burned.

Saving you 1.11 gallons and 32 min of time (at 3.65 a gallon where I am $4.05)

Cruise
6.2s thats 20miles/24mph = .83... or 49.8 min on plane = 23.24 gallons burned.
8.1s thats 20miles/28mph = .71...or 42.6 min on plane = 21.3 gallons burned.

Saving 1.9 gallons and 7.2 min (at 3.65 a gallon where I am $6.93)

If for some reason you raced the two set ups at WOT the whole way
6.2s thats 20miles/31mph = .65... or 39 min on plane = 31.85 gallons burned.
8.1s thats 20miles/41mph = .49...or 29.4 min on plane = 29.65 gallons burned.

Saving 2.2 gallons and 9.6 min (at 3.65 a gallon where I am $8.03)

So math says cocktail speed, Cruise speed, and WOT the 8.1s are burning less fuel in the 340.



Edit for referce I tested mine at 1000 as well.
8.1 at 1000= 2.3GPH X 2 === 4.6GPH = 6.8 mph (using my real world numbers)
8.1s thats 20miles/6.8mph = 2.94...or 2 hours and 56 min run time = 13.52 gallons burned.

WOW, you spent a lot of time on this......but let's look at the numbers in an 'apples to apples' comparison between the 6.2 and 8.1 engines....

first off both boats have advantages and disadvantages and I am sure we agree both boats are great in their own way....

I don't think there is any way to interpret the numbers except like this.....
1. run boat boats at WOT and the 8.1's will use more fuel
2. run both boats at a comfortable cruise speed and the 8.1's will use more fuel
3. run both boats at a slow cocktail speed of 1,000 rpm's and the 8.1's will use more fuel

the 8.1's will move the boat faster at WOT but pay the price in fuel consumption.....the 8.1's cruise at a faster speed but use more fuel as a result....the 8.1's actually are slightly slower than the 6.2's at 1,000 rpm's and they also use more fuel.....

EDIT: I think you changed a couple numbers after I replied dealing or maybe just rearranged them?....

cliff

 

[Mittens]

WOW, you spent a lot of time on this......but let's look at the numbers in an 'apples to apples' comparison between the 6.2 and 8.1 engines....

first off both boats have advantages and disadvantages and I am sure we agree both boats are great in their own way....

I don't think there is any way to interpret the numbers except like this.....
1. run boat boats at WOT and the 8.1's will use more fuel
2. run both boats at a comfortable cruise speed and the 8.1's will use more fuel
3. run both boats at a slow cocktail speed of 1,000 rpm's and the 8.1's will use more fuel

the 8.1's will move the boat faster at WOT but pay the price in fuel consumption.....the 8.1's cruise at a faster speed but use more fuel as a result....the 8.1's actually are slightly slower than the 6.2's at 1,000 rpm's and they also use more fuel.....

cliff

I like math, and was bored so always fun to play with numbers.

and Yes I agree both boats are great boats, its the same boat. and none of this was to disrespect your boat/6.2s. But your statement is incorrect.

“1. run boat boats at WOT and the 8.1's will use more fuel
2. run both boats at a comfortable cruise speed and the 8.1's will use more fuel
3. run both boats at a slow cocktail speed of 1,000 rpm's and the 8.1's will use more fuel”

Well yes if you ran them both for the same time….. BUT that’s not how you calculate MPGs or fuel consumtion, when using a car, or boat, or plane, or any vehicle for that matter, there is a starting point and a ending point in the calculation and thus run time counts in the fuel consumption, and the 8.1s given the same distance traveled uses less fuel.. does it in less time as well.

Now if you boated in circles, for strictly a set period of time, then I guess you can say the 6.2 is gets slightly better, but that’s ONLY in the case of “I have no end point or destination, I just want to drive my boat for 2 hours exactly”

If your are going point A to point B, the bigger motors use less fuel, and get you there faster.

 

[Strecker25]

WOW, you spent a lot of time on this......but let's look at the numbers in an 'apples to apples' comparison between the 6.2 and 8.1 engines....

first off both boats have advantages and disadvantages and I am sure we agree both boats are great in their own way....

I don't think there is any way to interpret the numbers except like this.....
1. run boat boats at WOT and the 8.1's will use more fuel
2. run both boats at a comfortable cruise speed and the 8.1's will use more fuel
3. run both boats at a slow cocktail speed of 1,000 rpm's and the 8.1's will use more fuel

the 8.1's will move the boat faster at WOT but pay the price in fuel consumption.....the 8.1's cruise at a faster speed but use more fuel as a result....the 8.1's actually are slightly slower than the 6.2's at 1,000 rpm's and they also use more fuel.....

EDIT: I think you changed a couple numbers after I replied dealing or maybe just rearranged them?....

cliff

Interesting stuff. The cocktail cruise comparison is probably the one most open to interpretation. Cocktail cruises for us are literally rides to nowhere (around the bay/lake with no destination except get home) so, speed is irrelevant, and the 6.2 would be slightly more efficient. That being said, these numbers are so close it's almost a wash. The appeal of the big blocks for me is being able to run them at lower RPM and theoretically less wear but who knows if that's even true.

What's hull speed in a 340? I'm guessing the waterline length is like 30' so about 7.5 mph?