Northstar repower?

[frank246]

Re: Northstar repower?

The log GM 350 weights `bout 650 lbs, the northstar weights ~450 lbs both fully dressed, id say lets try out.

 

[TilliamWe]

Re: Northstar repower?

The log GM 350 weights `bout 650 lbs, the northstar weights ~450 lbs both fully dressed, id say lets try out.

Sure frank, but add a heat exchanger, expansion tank, and anti-freeze to the weight of the caddy, and the weight advantage won't be as great.

And "fully dressed" with what? Since there are no marine exhaust manifolds for the Northstar, are you comparing a Marine dressed 350 to an Automobile dressed 4.6? The exhaust manifolds in a Cadillac weigh a lot less than what will be required in the marine industry. So there's more weight to the 4.6.

 

[jtybt]

Re: Northstar repower?

A merc 5.7 weighs somewhere above 900 lbs.

About 'false' advertising...why do you think they make 9.9 HP outboards.

Oh Yeah, 45...if you know the torque/HP curve was a fake/false graph published by GM, Why did you post it. Just look at the position of the numbers of the curve compared to the graph. Very misleading.

The marine vortec IS a marine specific build whereas the Northstar is not.

 

[Howard Sterndrive]

Re: Northstar repower?

custom stainless marine exhaust for the N* would run $3,000 to $5000 to have made around my area.

 

[45Auto]

Re: Northstar repower?

Oh Yeah, 45...if you know the torque/HP curve was a fake/false graph published by GM, Why did you post it. Just look at the position of the numbers of the curve compared to the graph. Very misleading.

What are you talking about??? Who said the dyno charts were fake (besides you)???

Are you incapable of understanding that the 5.7L graph (from the GM marine division) has torque on the left and HP on the right axis, and the Northstar graph (from the automotive division) is the opposite - HP on the left and torque on the right axis?

Give me about 10 minutes here and I'll put them on the same graph, with the same units, if that's what it takes to make them readable for you.

 

[45Auto]

Re: Northstar repower?

Maybe this will make it easier to understand. I thought the GM charts were pretty clear, obviously I was wrong!

See how the yellow curve (5.7L torque) is above the purple curve (Northstar torque)?

See how the red curve (5.7L HP) is above the pink curve (Northstar HP)?

There is no logical reason to put a Northstar engine in a boat instead of a 5.7L. Only way it makes sense is if you're looking to spend a LOT more money for a slower boat with a different name on the valve covers. Probably why you don't see too many of them out there ......

In addition, the Northstar curves are with the street cams, which have about 128 degrees of LSA (lobe separation angle). With a wet exhaust, marine cams generally stay below 112 degrees LSA to prevent sucking water back into the cylinders (reversion).

 

[TilliamWe]

Re: Northstar repower?

A merc 5.7 weighs somewhere above 900 lbs.

Ummm, that INCLUDES the OUTDRIVE (and the transom assembly) Frank! Again, know your material.

 

[jtybt]

Re: Northstar repower?

Advertised weight for 5.7 seem to be different at different site.

http://www.boattest.com/engines/113/specs.aspx

http://www.rivermarinesupply.com/xc...ureted_Inboard_250HP_Package_w_Alpha_Dri.html

http://www.uship.com/shipment/MERCRUISER-57L--COMPLETE-ENGINE/84611929/


Gee 45, you can't even plot your own numbers. How about match the northstar plot to the graph.

...and again, the northstar isn't a marine build with low end torque in mind.

I'd also like to see where you got the 128* LSA. That seems excessive...but again, you have things bass-ackward. An LSA below 106 would begin to be dangerous for water reversion. The closer the lobes separation, the more overlap.

Maybe you should go back to school...it has been 30 years.

Oops! Looks like I got your colors wrong. Pink looks red and purple looks blue. But like I said, the northstar wasn't built for low end torque

 

[scipper77]

Re: Northstar repower?

Just a thought but....
The northstar HP ratings are for an as installed automotive application SAE certified horsepower. Wouldn't a marine application free up some horsepower due to reduced exhaust back pressure, less accessories (no A/C, smaller alternator), a lack of automotive emmisions and feul economy standards (I/E catalitic converter)?

As I see you guys are pretty punchy on this subject I would like to point out that the above is a question and not a statement. Personal attacks will not be tolerated.

 

[Maclin]

Re: Northstar repower?

No Replacement for Displacement.

That mantra rings true and the new TORQUE graphs from 45auto show it. Even with less restrictive exhaust and new camming it would be hard for any 4.6L engine to make up for that lost 1.1 liter(some 66+ cubes), I'm just sayin'. A smaller displacement engine would need higher compression in all likelihood and require the higher octane fuels. Being able to work at 87 (87 R+M/2, 91 RON) octane in heavy duty applications is a parameter not often looked at but very desirable in my mind.

The 4.6 Caddy "system" is not in any heavy duty trucks either, and the heavy duty applications are somewhat less encumbered by emissions. My opinion is that if it was a good heavy duty candidate GM would have wrapped a truck (not SUV or Wagon) around it by now. And if it was in a heavy duty truck app then a Marine edition would soon follow, again just my opinion.

 

[45Auto]

Re: Northstar repower?

Gee 45, you can't even plot your own numbers. How about match the northstar plot to the graph.

Quit whining. My graph is as close as you're going to get picking numbers off the scales on the original dyno charts. Feel free to post your own if you disagree with it.

Maybe you should go back to school...it has been 30 years.

Maybe so. Always looking to learn new things. Pretty obvious it's not going to be from you, though.

 

[TilliamWe]

Re: Northstar repower?

Advertised weight for 5.7 seem to be different at different site.

http://www.boattest.com/engines/113/specs.aspx

http://www.rivermarinesupply.com/xc...ureted_Inboard_250HP_Package_w_Alpha_Dri.html

http://www.uship.com/shipment/MERCRUISER-57L--COMPLETE-ENGINE/84611929/

Well, just get a Trailer Boats Magazine annual Marine Power addition, and you'll see the accurate weights that they get right from Mercruiser (And Volvo and the outboard manufacturers)
Plain and simple a 4.6 Northstar, properly marinized will not weigh very much less than a 5.7 SBC. Sorry.

 

[HT32BSX115]

Re: Northstar repower?

Has anyone done or concidered using a Caddilac Northstar for a powerplant?

GAWD!...... you guys make an easy thing really hard!!!

Doesn't anyone know about Google? It works MUCH better than asking questions on a boating opinion board.......

Here's a boat with a Northstar engine in it..... Mastercraft has been doing it for at least a few years..... maybe they're doing it with the current "Northstar" too but I'll bet it wouldn't make 350HP like the one below....... For those of you that think there's no manifolds available (or camshafts).....note the MARINE MANIFOLDS bolted to the 32 valve V-8...... in the following picture..... It's a 99 Mastercraft.


You can buy a new Mastercraft with a VVT engine but it won't be the teenie little Northstar 4.6L engine. It'll be a 5.7 or 6.0L engine...

 

[45Auto]

Re: Northstar repower?

LMAO!!!

Good job HT32BSX115!

I bet it's cheap too!

 

[QC]

Re: Northstar repower?

Gawd . . . what a flippin' train wreck. Knock off the stupid this and dumb that stuff . . .

What I will say is that published OEM performance charts that meet SAE standards are the ONLY thing I trust. EVER, and even though I should probably go back to school too, I am reasonably confident that my 32 years in the engine business may qualify me for making the following statement: Intersecting torque and hp numbers mean nothing, zippo nada. It may look cool, but as far as evaluating anything it means nothing . . .

Also, with no resale value, poorer baseline performance and the need for custom tuning to meet unintended application requirements, I can see absolutely no reason to do this. Unless I am incapable of reading English, I think that was the OP's original question, but he appears to not like the answers as so many don't . . . This is a frank group, with experience matching the question. My guess is that's why the question was asked here

Trust me, if Don takes another look at this it is heading for Stupid Human Tricks . . .

Edit: posted while Rick was posting the Maristar, at least that's relevant . . .

 

[HT32BSX115]

Re: Northstar repower?

LMAO!!!

Good job HT32BSX115!

I bet it's cheap too!

Oh yeah.....everything from Mastercraft is "Dirt" cheep!!



(btw I took Statics and Dynamics 30 years ago too.....thermodydamics & dumbell Aero too....just enough for an EE!!)

 

[QC]

Re: Northstar repower?

You can buy a new Mastercraft with a VVT engine but it won't be the teenie little Northstar 4.6L engine. It'll be a 5.7 or 6.0L engine...

Or you can get a factory GM 530 bhp 6.2, but you'd have to trust the OEM rating charts and who'd be foolish enough to do that?

 

[justchange]

Re: Northstar repower?

GAWD!...... you guys make an easy thing really hard!!!

Doesn't anyone know about Google? It works MUCH better than asking questions on a boating opinion board.......

Here's a boat with a Northstar engine in it..... Mastercraft has been doing it for at least a few years..... maybe they're doing it with the current "Northstar" too but I'll bet it wouldn't make 350HP like the one below....... For those of you that think there's no manifolds available (or camshafts).....note the MARINE MANIFOLDS bolted to the 32 valve V-8...... in the following picture..... It's a 99 Mastercraft.




You can buy a new Mastercraft with a VVT engine but it won't be the teenie little Northstar 4.6L engine. It'll be a 5.7 or 6.0L engine...

WOW!!!! Thaks for that!!! I searched "northstar powered boats" and got nothing. I'll look into that more.


Well, I checked and Mastercraft either never did or doesn't currently offer a northstar engine. Also, if that's a Northstar engine where are the plug wires in the rocker covers? Why is there an oil fill plug in them instead?--------Just askin.

 

[justchange]

Re: Northstar repower?

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

Not personally. I have a friend that use to race those, the side oilers too. Every one thru rods.

 

[justchange]

Re: Northstar repower?

I agree, there's no need for name calling-----------


As I've previously stated. This was a hypothetical question as I've never seen a Northstar engine in a boat. Perhaps you're correct about the performance in a boat. I'll eventually find out.

This project would be no different than putting a Northstar engine in a car that it wasn't designed for. [basically] As I also stated, who cares about resale value? I'm not doing this for marketing, just for me. If this works as I plan [and it will] I'll have perhaps the most dependable engine in a marine application. Remember, it has "limp home mode".

It's not that I don't like your opinions. The data doesn't necessarily translate into real world performance or lack there of. Gearing plays an ever increasing role in any engine application. I've experienced one of these engines in a '94 ETC and the performance was way beyond the rated 300 hp. Engine stats are nice but what really counts is how it feels and works on the road or in the water. Correct?


The one thing I find amusing is how so many are concerned about how my time and money are spent. I'll be 100 percent debt free in another 6 months. My income is such that I want to do a project that apparently no one else has done. So, I'm going to.


Here's the dyno chart from GMPP showing a completely different chart than yours. http://www.gmperformanceparts.com/E...gine=4.6 Northstar V8&sku=12499468&engCat=rpo





The one you posted is correct for that engine as far as I can tell. There's two Northstar dynos on that on that site. They're for the new 4.4 liter. You should look up the specs on the supercharged Northstar. [really big grin]