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Old    JS (dreamer)      Join Date: Nov 2008       09-19-2011, 3:56 PM Reply   
I have been thinking about what my "must haves" are for a new boat so when I go to the boat show this winter I will know what I am looking for. The one thing I can not decide on is the engine power. The main use of the boat will be wakesurfing with something around 2000#'s of ballast. PCM engine size goes from the 350 to the 364 and Mercruiser from the 350 to the 377.

If the boat has the correct prop for the extra ballast do you need the upsized engine?

The larger engine will have more torque so will the rpm's be lower when surfing and use less fuel then the small engine?

Can you get a prop with less pitch with the larger engine because of the added torque?

Anyway, let me know if you have experienced the two different engines and what you would do.

Thanks in advance.
Old    David Langston (rdlangston13)      Join Date: Feb 2011       09-19-2011, 4:46 PM Reply   
I do not think a larger engine is needed for surfing. You get a standard engine and prop it right and it will work just fine. Also the way I understand it having a lower pitch prop will increase engine rpm but also increase acceleration, like putting lower gears in car. High pitch prop will hurt acceleration but you will turn lower rpms. i have the standard indmar 350 ci 325 hp in my mobius lsv and we surf with 2000 lbs of ballast and have no issues at all. turn about 2500 rpm with a 14.25x14 prop
Old    Art (rallyart)      Join Date: Nov 2006       09-19-2011, 6:31 PM Reply   
I've never seen anyone complain that they had too much power but for surfing the prop will do more than the torque or HP. The more powerful engine will accelerate better an give a slight increase in top speed. There would be no significant advantage to either engine in fuel economy while in use surfing. The more powerful engine will get lower economy when at full throttle but it also gets up on plane faster when just cruising so you spend a little less time at full throttle.
Old    David Langston (rdlangston13)      Join Date: Feb 2011       09-19-2011, 6:50 PM Reply   
who goes to full throttle to get on plane when cruising around??? my 325 indmar doesnt need to go past 1/3 or 1/2 to get up to speed to cruise around
Old     (nitrousbird)      Join Date: Sep 2008       09-20-2011, 8:49 PM Reply   
If you are buying a new boat, why buy one with an outdated engine? More HP will only help you - the LSx based stuff will get better fuel economy, make more power, are easier to work on, and in the end you won't have to make as many sacrifices to do what you need the boat to do.
Old    Scott Schroeder (silvtondvl)      Join Date: Dec 2002       09-22-2011, 8:02 AM Reply   
I have found that it depends more on boat size and ballast than anything else. That is taking into account that the correct prop is on.
A 21 to 22 ft boat does fine with the standard motor.
Larger boats 23 and up could use/ need a larger motor. You get a bigger boat, it requires more ballast. All of this just = weight.
Almost every wake boat has a top speed between 42 and 50 because of the prop.
Wakeplates help you plane faster and help you shape the wake.
Old    Kevin R Baugh (krbaugh)      Join Date: Mar 2002       09-22-2011, 8:25 AM Reply   
I have heard countless times dang i should have gotten the bigger motor
but I have never heard dang my motor is just tooo big
Old    Jeff D (Jeff)      Join Date: May 2010       09-22-2011, 9:22 AM Reply   
If we were talking 310 vs 350 HP I'd say definitely spend the extra to get the bigger engine but 350 HP is pretty good for just about everyone's needs on a 20-23' boat. Certainly 350 is more than sufficient for just surfing with 2,000 extra lbs unless you're getting into 24' boats or some of the really "meaty" 22-23' ones out there. I wakeboard with 2,700 lbs + people in a 23' boat with only 330 HP and the power is more than acceptable. I've done the same with a 310 HP 20' boat and it felt a bit weak and approaching the unacceptable limit.

I'd definitely consider the 364 or 377 HP options but the $/HP ratio would have to be good for me to pull the trigger on it. If you could get the more powerful engine for free due to a dealer's stock on hand or something like that then it's a no brainier. If they want something like $7k for 14 or 27 more HP forget it.
Old    Bruizza (bruizza)      Join Date: May 2009       09-22-2011, 1:45 PM Reply   
This is America! Bigger is always better!!! I would rather have the engine and not need it than need it and not have it.
Old    david pierce (desotodave)      Join Date: Mar 2009       09-22-2011, 2:26 PM Reply   
Dreamer, why nobody has yet asked is where you use the boat. If you are only going ton use it at sea level, then smaller engines are usually very sufficient. Of you are going to be using it at 4000 feet or higher, a larger engine really becomes mandatory.
Old    Tdc_worm C (tdc_worm)      Join Date: Sep 2002       09-22-2011, 2:41 PM Reply   
why are we all suckers for HP numbers? it wasnt too long ago that diesel engines in HD trucks had 250-300 hp while gasoline engines had 300+ hp. it was always a no brainer to go with the diesel engine for towing. even on this forum people are routinely begging for diesel engines. who gives a rats ace about HP ratings when it is all about torque?

ever notice how the engine makers are quick to post desktop dyno HP numbers but will never get anywhere near touching the torque curves? why would that be? maybe, just maybe, the torque curves between a 350ci engine and a 364ci engine arent that great....dont take my word for it, look at the specs as these engines come from GM. the 6.0 peaks at 4k rpm but is about equal to the 5.7 from 2k up...where we use our engines...

http://www.gmpowertrain.com/MarineEn...Portfolio.aspx

also, do you think a boat builder would outfit their rigs w/ and under performing engine and put their reputations at stake?

the bigger fancier engines may have VVT which can help flatten the torque curve a bit, but the HP numbers are useless, especially because those numbers register near the max useable rpm anyways....
Old    JS (dreamer)      Join Date: Nov 2008       09-22-2011, 3:23 PM Reply   
Tdc_worm, thanks for that link. That is exactly what I am looking for. It is a 23' wakesurf boat that we are after and if we prop the boat correctly we run around 3000-3400 rpm for surfing. The difference between the 5.7L and 6.0L torque curve is pretty small at 3000 rpm so it would definetly not be worth paying more $$$. The 6.2L's numbers were higher at that rpm range, I wonder if that engine would run more efficiently (use less fuel). Sounds like I only need the 5.7L with the OJ 5 blade prop.

We are at sea level as well so we will get maximum power from the engine.
Old     (TheSqueakyWheel)      Join Date: Oct 2010       09-22-2011, 3:24 PM Reply   
Quote:
Originally Posted by desotodave View Post
Dreamer, why nobody has yet asked is where you use the boat. If you are only going ton use it at sea level, then smaller engines are usually very sufficient. Of you are going to be using it at 4000 feet or higher, a larger engine really becomes mandatory.
I don't necessarily agree.
I'm at 5000'. On a 21 MB we run 900-1800 lbs of stock ballast, an additional 1500 lbs of bag ballast + people routinely with the 340 hp engine and a low pitched prop without any problems.
Old     (nitrousbird)      Join Date: Sep 2008       09-22-2011, 5:25 PM Reply   
I can't believe people think it is okay to have a 60k+ boat while sporting a GEN-I SBC, that's hasn't been offered in a vehicle since 2004 (and that was a van), and not really used in a truck since the late 90's. If I was a boat manufacturer I'd be embarassed to even have that as an offering in a new boat.
Old    Tdc_worm C (tdc_worm)      Join Date: Sep 2002       09-22-2011, 6:01 PM Reply   
Quote:
Originally Posted by nitrousbird View Post
I can't believe people think it is okay to have a 60k+ boat while sporting a GEN-I SBC, that's hasn't been offered in a vehicle since 2004 (and that was a van), and not really used in a truck since the late 90's. If I was a boat manufacturer I'd be embarassed to even have that as an offering in a new boat.
detail the major changes in the architecture of the otto cycle engine that occurred between the Gen I gm engines and the current engines that make them superior when it comes to moving vehicles inefficient vehicles under load. HD GMs use the duramax and the 6.0L. the push towards the 4.8L and 5.3L are based off of lighter vehicles and spinning smaller, more efficient engines at higher RPMs to move them. hardly applicably in water plows.

i would argue that the best light duty engine that GM uses is the 6.0L. to the best of my knowledge, the 6.0 is a stroked 5.7L, while the 6.2L (used in Denalis and Escalades) is a bored and stroked 5.7L...both gen 1 babies....
Old    Jeff D (Jeff)      Join Date: May 2010       09-22-2011, 6:42 PM Reply   
IMHO 10 year old engine technology is not that old especially when you factor in that most advances in the last decade for truck motors have been in the name of emissions. The funny thing is that my 5.7l Indmar LTR from 2000 is in some ways more advanced than the more current MCX. I have distributorless ignition but the MCX doesn't. The MCX does put out 20 more hp though.
Old    Cory D (cadunkle)      Join Date: Jul 2009       09-22-2011, 7:00 PM Reply   
Quote:
Originally Posted by tdc_worm View Post
ever notice how the engine makers are quick to post desktop dyno HP numbers but will never get anywhere near touching the torque curves? why would that be? maybe, just maybe, the torque curves between a 350ci engine and a 364ci engine arent that great....dont take my word for it, look at the specs as these engines come from GM. the 6.0 peaks at 4k rpm but is about equal to the 5.7 from 2k up...where we use our engines...
...
the bigger fancier engines may have VVT which can help flatten the torque curve a bit, but the HP numbers are useless, especially because those numbers register near the max useable rpm anyways....
Someone who gets it! It's about torque. VVT is unnecessary complexity in a wake boat though. You don't need high RPM horsepower so why bother with the VVT for more duration at higher RPM since with the steep strut angle and hull design you're not running high speed anyhow? Do any of us really need out boats to do 50+ MPH? Mine will do 50 (in a 23' hull no less) but it's rare that I open it up like that, even cruising around I'm usually at 21-25 MPH.

Wake boats have similar power requirements as tow rigs. You're moving a lot of weight with a large wetted area (drag). It's all about torque. Sure you can get torque from a small block through multiplication, by running a gear reduction trans and a low pitch prop makes it a screamer which is not great for engine wear and you sacrifice fuel efficiency and top speed.

When shopping for my boat most of what I was looking at had 351w Ford motors. Now I'm a Ford man and I bleed blue. I'm sure I would have been happy with a SBF Supra, MC 205, or Sport Nautique, as those were the boats I was looking at. The thing is, you can't get big torque numbers from small displacement no matter what you do. You can spin it to the moon and make plenty of horsepower, but that's not ideal for a 3k-4k lbs boat that may have another 1k-3k lbs of ballast and only need to run low twenties for speed. A SBF is only good to 500-600 HP before you split the block in half down the lifter valley and through the mains, and well before that point you'd need a dry exhaust and it wouldn't be any good around the docks, not to mention fuel economy would be terrible. I can't imagine a SBC would do any better as the design is so similar to the SBF.

One of the things that sold me my boat was that it had a 454. I hate Chevy motors and the BBC is way inferior to the BBF, but at these lower power levels and RPM it's irrelevant and the torque makes a big difference. Big displacement engines make loads of torque from low RPM, especially in marine applications where they are cammed very mild.

For our application it's all about torque, and to get that you need either a diesel or a lot of displacement in a gas motor. A diesel could be better, turning a bigger prop at a lower RPM with an even flatter torque curve.

So to the OP... Look at the torque curve of the engines. If the "bigger" engine makes a fair amount more torque at the same RPM you'll appreciate it. If it's just more higher RPM HP you probably won't notice a huge difference unless you plan on propping pretty low to reach those higher RPM at riding speed.
Old     (nitrousbird)      Join Date: Sep 2008       09-23-2011, 3:51 AM Reply   
Quote:
Originally Posted by tdc_worm View Post
detail the major changes in the architecture of the otto cycle engine that occurred between the Gen I gm engines and the current engines that make them superior when it comes to moving vehicles inefficient vehicles under load. HD GMs use the duramax and the 6.0L. the push towards the 4.8L and 5.3L are based off of lighter vehicles and spinning smaller, more efficient engines at higher RPMs to move them. hardly applicably in water plows.

i would argue that the best light duty engine that GM uses is the 6.0L. to the best of my knowledge, the 6.0 is a stroked 5.7L, while the 6.2L (used in Denalis and Escalades) is a bored and stroked 5.7L...both gen 1 babies....
LOL...not a single engine you listed is a GEN-I.

6.0L is a GEN-III or GEN-IV motor depending on the year (would be the all aluminum GEN-IV LS2 in the car version). The first of the 6.0L (LQ4/LQ9) is based off the 5.7L motor...the 5.7L, 346ci LS1...the first of the GEN-III motors that started off in the 1997 C5 Vette.

6.2L is a GEN-IV motor.

Where the GEN-II (LT1/LT4) shares some parts with the GEN-I SBC, GEN-III and IV share nothing with the GEN-I. which originated back in the 50's. GM started putting the GEN-III motors in trucks in 1999, and the last of the GEN-I SBC's were put in vans and that ended in 2002.
Old     (nitrousbird)      Join Date: Sep 2008       09-23-2011, 4:09 AM Reply   
Quote:
Originally Posted by Jeff View Post
IMHO 10 year old engine technology is not that old especially when you factor in that most advances in the last decade for truck motors have been in the name of emissions. The funny thing is that my 5.7l Indmar LTR from 2000 is in some ways more advanced than the more current MCX. I have distributorless ignition but the MCX doesn't. The MCX does put out 20 more hp though.
Again, know what motor you are talking about. The LTR gets grouped in the LT1 (which uses the Optispark front-mount distributor), but looking at the motor, it is just a GEN-I SBC Indmar did a coil-on-plug conversion. They are both directly based on motors designed in the 1950's. The LAST update done (which is what all modern GEN-I boat SBC's are based on) was in 1996, where they gave the motors cylinder head design similar to the GEN-II (LT1/LT4) motors. So at best, you are talking about 15 year old engine technology, but really they took 20 year old heads and took the reverse cooiling away to make them work the the GEN-I.

The advances in current truck motors has been packaging, power, emissions, totally different block/bore/stroke/ignition system/very different head and intake design/valvetrain design...pretty much everything you can think of.

More significant changes in GM truck motors has happened in the last 12 years than in the previous 40 years before that.
Old    Tdc_worm C (tdc_worm)      Join Date: Sep 2002       09-23-2011, 8:06 AM Reply   
I guess I wasnt clear enough w my point, hahaha, and i dont profess to be an expert on GM engines which i have clearly exposed above hahaha.

i was reducing an otto cycle engine to its most basic parts, the architecture of block and the rotating assembly. many of the advancements you refer to are in an effort to make the engines more efficient and more environmentally friendly.

one thing i suspect is that packaging of Gen-Whatever is issue due to OH valvetrains and tons of emissions doo dads making the engine being package larger. Correct me if I am wrong, but wasnt the first C5 vette a pushrod engine due to the hood line not being conducive to OH cams?

i suspect GM is the one to blame for the Gen-I powerplants being implemented. They are the ones that supply the Gen I engines to Indmar, PCM, Mercruiser, Volvo-Penta and Ilmoor before they make it our boats.

Last edited by tdc_worm; 09-23-2011 at 8:09 AM.
Old    David Langston (rdlangston13)      Join Date: Feb 2011       09-23-2011, 9:54 AM Reply   
I am pretty sure all vettes are pushrod engines. Even the LS7
Old    Scott Schroeder (silvtondvl)      Join Date: Dec 2002       09-23-2011, 10:23 AM Reply   
JS - to answer your question
There is NO substitue for cubic inches if you require it.
Changing from the small block engine to a big block in a new boat will cost you 8 to 11 grand depending on manufacture. If thats in your budget - go for it.

Moving up in hp with the small blocks usually will get you direct fuel injection vs a throttle body type. Direct is better! - cost is 1500 to 3500 depending on manuf.

Have you decided on a boat/manufacture yet?
Old    JS (dreamer)      Join Date: Nov 2008       09-23-2011, 2:50 PM Reply   
Looks like all of the torque numbers are pretty much the same in the 2500-3000 rpm range so I do not see any reason to spend extra money on a larger engine. I would have expected more low range torque on the larger engine.

I have an Enzo but like the looks and ballast system of the MB B52V 23' widebody. I'm just not sure it's wake will match the power of the wakesurf wave with similar amounts of ballast as my current boat. I also really like how quiet the Malibu LSV 23 is inside the boat while underway, but the port side surf wave has nothing on my boat.

No local dealers around to try but I will hit a boat show this winter for sure!
Old     (nitrousbird)      Join Date: Sep 2008       09-23-2011, 3:28 PM Reply   
Quote:
Originally Posted by tdc_worm View Post
I guess I wasnt clear enough w my point, hahaha, and i dont profess to be an expert on GM engines which i have clearly exposed above hahaha.

i was reducing an otto cycle engine to its most basic parts, the architecture of block and the rotating assembly. many of the advancements you refer to are in an effort to make the engines more efficient and more environmentally friendly.

one thing i suspect is that packaging of Gen-Whatever is issue due to OH valvetrains and tons of emissions doo dads making the engine being package larger. Correct me if I am wrong, but wasnt the first C5 vette a pushrod engine due to the hood line not being conducive to OH cams?

i suspect GM is the one to blame for the Gen-I powerplants being implemented. They are the ones that supply the Gen I engines to Indmar, PCM, Mercruiser, Volvo-Penta and Ilmoor before they make it our boats.
All Vettes are pushrod motors, excluding the 91-96 ZR1 which was a DOHC motor, and excluding prototype stuff of course. The only thing in common the GEN-III and IV SBC's have with the GEN-I is being OHV and the same number of cylinders.

As for blaming GM - they haven't put a GEN-I in a vehicle in about a decade (and that was leftovers put in vans). They still sell them in crate form and sell them to various companies who convert them to Marine use...can't blame GM for selling what someone is willing to buy. But they sell a large variety of other motors that could (and should) be purchased instead. I get putting a cheap motor is some basic V8 I/O. These wakeboats are big, big dollars - the powertrain should match accordingly.

Last edited by nitrousbird; 09-23-2011 at 3:31 PM.

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