Northstar repower?

[justchange]

Re: Northstar repower?

Of course, I could put the 3406 Cat from the truck in my current boat and see if it still floats.

 

[45Auto]

Re: Northstar repower?

How do you explain the offshore boats relilability then.

Maybe you're just on the wrong forums. Try OSO (Off Shore Only).

You'll find that very few offshore boats run "stock" Mercruiser (Alpha or Bravo) or Volvo outdrives. If you're talking about going to an Imco or SSM or something similar, more power to you. Of course, they start at about $11,000. Anybody running at that level isn't screwing around with the dinky motors (less than 500 HP) typically discussed here. The caddy stuff would be great for getting a good laugh out of them though ......

After all. Where would we be if someone hadn't tried anything different? Rowboats and birchbark canoes?

What makes you think you're trying anything different??? The performance of a boat has nothing to do with the name on the valve covers. Replacing a Chevy with a Ford with a Dodge with a Toyota with a Cadillac etc etc isn't exactly an earth-shaking new concept. A caddy engine with less power than a 5.7L is going to perform worse whether you like it or not. If you aren't capable of understanding what makes a boat work then you'll just have to build your caddy special and learn the hard way. People have been putting every kind of engine imaginable (car, airplane, helicopter, etc) in boats for about 100 years now. The mathematics that make it work are pretty well understood. Have you ever heard of Gar Wood?

If you're interested in turbines, you can buy a boat with twin 1850 HP turbines out of the showroom today. All it takes is money.

What you're proposing with the caddy engine is the equivalent of replacing the birch bark canoe with an oak bark canoe. Your oak bark will be heavier and slower, and maybe then you'll realize why they use birch bark. If you aren't capable of learning from the experience of others, you'll just have to discover everything the hard way.

If you want to do it just to have something different, why don't you just do it then post pics and tell us about it? You don't have to try to justify it to anyone on this board ......

 

[Howard Sterndrive]

Re: Northstar repower?

I had a N*powered 2001 Deville and used to often wonder why the 4.6 caddy motor had never been marinized.

-Amazing low end torque
-Wide power band
-Light weight
-heavy duty bottom end
-Starter motor up high, out of the bilge!!

All that said, for anyone to try and take one out of a caddy and try to drive a boat with it would be wasting a lot of time and money.

 

[scipper77]

Re: Northstar repower?

It seems to me that mercruiser likes to use the same "staple" motors for the last 20 years. GM is the same. How long has GM used a variant of the 3800 in there cars? How long has mercruiser been using the 3.o, 4.3, 5.0, 5.7. If you ask me sticking your neck out to try to marinize and produce a new block is never going to happen until someone else starts making a better I/O than mercruiser does.

 

[joncrisler]

Re: Northstar repower?

I dunno. I proposed this as a hypothetical and seems it got out of control. [imagine that]-----lol

I'd think that it'd be something unique. Since I tend towards things that are not the average. [I've seen one boat online powered by a helicopter engine with a jet outdrive]

After all. Where would we be if someone hadn't tried anything different? Rowboats and birchbark canoes?





"At 5000 RPM (considered the upper end of reliability for a stock outdrive) either one of the Northstars is only making about 20 HP LESS than the "lead sled."

How do you explain the offshore boats relilability then.


I know, my mind works a bit slow at times.-----

The offshore boats typically run Speedmasters, #6's, Arneson surface piercing drives etc. At the low end they might use something like a Bravo XR if they are pushing more than 400 hp or 500 ft/lb torque. They also get overhauled frequently. The turbine powered boats are sweet- generally they will use a rebuilt helicopter engine that has amassed too many hours to go airborne- but each of those engines costs north of $100k. A turbine powered boat like a Skater is generally a $500k+ project which is why you just dont see many of them. I have been up and down the Chesapeake for the last 20 years: I only recall hearing about 2 or 3 turbine boats in that entire time.

Look on Youtube for Miss Gieco for some nice video on a turbine boat.

 

[jtybt]

Re: Northstar repower?

Not sure where 45 auto got those HP/torque curves. Sure ain't from any dyno.

I'm not exactly sure how the variable valve timing works but if it works like I think it should with 4 small valves and only one intake and one exhaust working until higher RPM's, it's the perfect way to build low end torque. Seems to me it would have an extremely flat torque curve which is what you want in a marine engine.

The biggest drawback I see is the cost. I can make all the other component mounbtables including exhaust system.

 

[justchange]

Re: Northstar repower?

The offshore boats typically run Speedmasters, #6's, Arneson surface piercing drives etc. At the low end they might use something like a Bravo XR if they are pushing more than 400 hp or 500 ft/lb torque. They also get overhauled frequently. The turbine powered boats are sweet- generally they will use a rebuilt helicopter engine that has amassed too many hours to go airborne- but each of those engines costs north of $100k. A turbine powered boat like a Skater is generally a $500k+ project which is why you just dont see many of them. I have been up and down the Chesapeake for the last 20 years: I only recall hearing about 2 or 3 turbine boats in that entire time.

Look on Youtube for Miss Gieco for some nice video on a turbine boat.

I watched the one with Miss Geicos 210 mph run. I was impressed with how flat the boat stayed the entire time. Not to mention the sound. It also made me to make sure I don't drive one that fast.

 

[justchange]

Re: Northstar repower?

Not sure where 45 auto got those HP/torque curves. Sure ain't from any dyno.

I'm not exactly sure how the variable valve timing works but if it works like I think it should with 4 small valves and only one intake and one exhaust working until higher RPM's, it's the perfect way to build low end torque. Seems to me it would have an extremely flat torque curve which is what you want in a marine engine.

The biggest drawback I see is the cost. I can make all the other component mounbtables including exhaust system.

I don't feel the cost would be that large. A used ETC isn't that much. The first thing is to figure engine mounts and hooking it to an outdrive. Then, after I'm so very dissappointed in it's performance, I can update it.

 

[mkast]

Re: Northstar repower?

I think Jay Leno's shop is called the "More Money Than Brains Garage".
I'm going out on a limb, but I'm guessing you're not in he's league.
In the imaginary world, you get the Northstar in a hull, running.
So what? You have a unit that's not marketable.
If you're going to dream, build an aluminum SOHC 427.
In this discussion, money is not a perimeter.

 

[TilliamWe]

Re: Northstar repower?

I don't feel the cost would be that large. A used ETC isn't that much. The first thing is to figure engine mounts and hooking it to an outdrive. Then, after I'm so very dissappointed in it's performance, I can update it.

Please, please, please do. We'd love to see photos and video. Perhaps a step by step series of all the mods you make to the boat and engine? Who knows, if you detail it enough, you might come up with a marketable product? That would be worth the effort. Good luck.
(In the meantime, I'll buy a 17' bowrider with a 3.0 and go boating right past you in your garage! )

 

[justchange]

Re: Northstar repower?

Please, please, please do. We'd love to see photos and video. Perhaps a step by step series of all the mods you make to the boat and engine? Who knows, if you detail it enough, you might come up with a marketable product? That would be worth the effort. Good luck.
(In the meantime, I'll buy a 17' bowrider with a 3.0 and go boating right past you in your garage! )

Oh, I have another boat. The one in this discussion would be for entertainment and who cares if it's marketable? Most people that build high performance cars make them to thier liking. Not to maket what they do.

A 427 SOHC? At least Northstars don'thave the constant problem of throughing rods thru the block.

 

[45Auto]

Re: Northstar repower?

Not sure where 45 auto got those HP/torque curves. Sure ain't from any dyno.

Both those charts came from the GM Powertrains website:

http://www.gm.com/experience/technology/gmpowertrain/

How do you imagine General Motors gets their HP/torque curves if not from a dyno??? They claim that the tests are certified to SAE J2723 standards through 3rd party witness testing. Sorry if they didn't meet your misconceptions, I have no control over that.

From

http://media.gm.com/us/powertrain/en/product_services/2010/gmna/10car_us.htm

Horsepower and Torque SAE Certified Power = A new voluntary power and torque certification procedure developed by the SAE Engine Test Code committee was approved March 31, 2005. This procedure(J2723) ensures fair, accurate ratings for horsepower and torque by allowing manufacturers to certify their engines through third-party witness testing. GM leads the industry in applying the new voluntary SAE Certification process, and will certify horsepower and torque for all new engines under independent review. For the 2007 model year, GM certified an additional 24 engines, totaling 102 applications.

I'm not exactly sure how the variable valve timing works but if it works like I think it should with 4 small valves and only one intake and one exhaust working until higher RPM's, it's the perfect way to build low end torque. Seems to me it would have an extremely flat torque curve which is what you want in a marine engine.

I know exactly how the variable valve timing works. Obviously it does not work the way you "think" it should, and it "seems" that the torque curve isn't what you "think" either.

No need to make uninformed guesses at performance when all the data is out there. Your choice whether you want to believe it or not.

 

[mkast]

Re: Northstar repower?

A 427 SOHC? At least Northstars don'thave the constant problem of throughing rods thru the block.

Apparently you don't have much time with a 427.

 

[guyaverage]

Re: Northstar repower?

Both those charts came from the GM Powertrains website:

http://www.gm.com/experience/technology/gmpowertrain/

How do you imagine General Motors gets their HP/torque curves if not from a dyno???

I'm dont want to speak for him, but he may be questioning why the torque/horsepower curves dont intersect at 5252 like every other dyno chart. I know I am.

 

[Maclin]

Re: Northstar repower?

The scales are not the same on the torque (let) column and the HP (right ) column. I think they would intersect if both parameters had the same vertical scaling.

 

[jtybt]

Re: Northstar repower?

45auto,
As Maclin says, those HP/Torque curves abstractly superimposed on a random graph which may or may not even represent either actual curve.

If you believe everything any manufacturer of any product claims, you are the perfect consumer.

IF those are advertisements by GM, they are directed to uninformed consumers.

Instead of trying to explain how HP and Torque are connected, I'll let you read about it.


http://www.howstuffworks.com/question622.htm

 

[45Auto]

Re: Northstar repower?

Thanks for the link to the Hp/torque basics, but I had all that stuff in statics and dynamics 30 years ago and none of it's changed.

Maclin is correct about the graphs. The only thing that controls the intersection point is the scales of the independent Hp and torque axes. If both axes have the same scale, they will intersect at 5252. If the scales are not the same, they won't.

If you're really interested in what makes your boat work, you may want to check out this old thread:

http://forums.iboats.com/showthread.php?t=225803&highlight=secrets

 

[45Auto]

Re: Northstar repower?

If you believe everything any manufacturer of any product claims, you are the perfect consumer.

IF those are advertisements by GM, they are directed to uninformed consumers.

Ok, I have to ask:

While you've got your tinfoil hat on, can you explain WHY General Motors, the Society of American Engineers (SAE), and the independent third party witnesses would want to lie about the caddy power output????

 

[mkast]

Re: Northstar repower?

Ok, I have to ask:

While you've got your tinfoil hat on, can you explain WHY General Motors, the Society of American Engineers (SAE), and the independent third party witnesses would want to lie about the caddy power output????

Back in the sixty's and seventy's it was to shut the insurance companies up.

 

[45Auto]

Re: Northstar repower?

Back in the sixty's and seventy's it was to shut the insurance companies up.

It was that, and also to get favorable Hp/weight (favorable meaning you got put into a slower class) class breaks in different racing organizations.

i can see why GM would do it, but not the SAE. I wouldn't be surprised if that's what started the whole SAE certified process and independent witness testing.

Dyno's weren't too common back then (big bucks, no real electronics to speak of), so it was harder to verify. But now with computers and controllers as cheap as they are, every little mom and pop speed shop has one. All the dyno tests I've seen of stock motors in the last 15 - 20 years agree very closely with the manufacturer's figures.