Anyone ever seen a GM (Atlas) inline six in marine use?

[Bubba1235]

Have a strange request from a customer. He has a totaled GMC truck with the Atlas in line 6 cyl. (290+ HP 230ft-lb Torgue) He would like to replace the tired 250 in line six in his boat with the new engine.

Eyeballing things (engine has to be cut from the wrecked truck yet) it looks like it should fit without major headaches. May have to move one of the engine mounts but not certain. (passenger side) From what I have been able to read up on the bolt pattern the bellhousing should not be an issue but if it is there are adapter plates.

Anyone ever seen it done?

 

[proshadetree]

Re: Anyone ever seen a GM (Atlas) inline six in marine use?

Never seen it done. I just question how you will get away from all the automotive fuel injection in such an installation.

 

[zbnutcase]

Re: Anyone ever seen a GM (Atlas) inline six in marine use?

Nope. And no need to reinvent the wheel, either....

 

[proshadetree]

Re: Anyone ever seen a GM (Atlas) inline six in marine use?

Sure it is. Smoother lighter and less rolling resistance. If it feasible I hope you post a thread.

 

[Howard Sterndrive]

Re: Anyone ever seen a GM (Atlas) inline six in marine use?

I don't beleive the fuel injection any different than those used on other marine engines.

believe it

that engine's ECM will be looking for an oxygen sensor... and O2 sensors don't work well in water

 

[HT32BSX115]

Re: Anyone ever seen a GM (Atlas) inline six in marine use?

Huh? I hardly call upgrading to a more fuel efficent engine thats 150 lbs lighter and has 100+ more ponies reinventing the wheel.

It would probably work if you could find a jacketed exhaust manifold. The EFI would probably have to be either modified to work without using an oxygen sensor or you would need to fab a manifold that would not allow water contact (reversion) with the sensor (otherwise it would DIE quickly!)

I would call it re-inventing the wheel if you have build a "one-off" exhaust manifold since one may not exist.... You might also have to re-invent the flywheel-coupler connection since the current crop of couplers may not bolt to the flywheel.

Then add a sealed marine type starter (or modify the current one), a marine alternator (probably the easiest thing to find)

And seal up the EFI to make it "marine compliant".


It's really a "gray-area" when you as, a NON-commercial end-user modify an automotive engine or component to use in a marine application.

If you read the USCG regs carefully, they seem to indicate that the requirements are for MANUFACTURERS. If the end-user modifies automotive parts and uses them in a marine application, (although maybe not too smart) It doesn't appear to be prohibited.

The problems don't start until it blows up and somebody (like the neighbor kid your kid invited to go boating) dies in the fire....... and the blood-sucking lawyer convinces the jury that the owner (or the installer) IS the "manufacturer"......................

If you as marine repair business owner are thinking installing a non-marine engine etc, you might want to check with your insurance company to see if they would cover you in an extreme liability situation.......(like the above)


Regards,




Rick

 

[HT32BSX115]

Re: Anyone ever seen a GM (Atlas) inline six in marine use?

Yeah, I figured an exhaust manifold would have to be made but I don't see that as a huge issue. Drilling a few holes in the coupler should take a half hour if needed. Starters, alternators, etc. are pretty much off the shelf but if need be the local rebuild shop can take care of it.

I agree, there may be some pieces parts to fab but I don't see them as that big an issue. As to the O2 sensor, isn't needed and easily taken out of the loop with a bit of code.

However, I say all this without having the engine out where I can really look it over and take measurements. I was sort of hoping someone else may have done it and could tell me if they ran into huge issues. Personally, if it were my boat I would not do it, easier to sell what he has and buy another boat but the guy is deeply attached to it. (Given to him by his father who is no longer living.) The boat itself is in amazing shape with an all new interior and has been washed and wax religiously.

I hear you!

I had one of those boats (Dads Boat) that I VERY reluctantly sold in 2006 when I got the Lib from my brother!

I got a call last month from a FED out at Ft Lewis, WA who said not only they didn't re-register the boat, but they allowed it to sink in American Lake in Tacoma WA!! And they wanted me to PAY the recovery/clean-up costs to the tune of $3000+!!!

Luckily for me I reported the sale (and then they actually found the "perp"!!)

Oh well.....



I would suggest that the guy just sell the truck engine and put a plain-vanilla 250 cu-in 6 in it or fix what's there.....

 

[Silvertip]

Re: Anyone ever seen a GM (Atlas) inline six in marine use?

Those engines were aluminum from top to bottom so fresh water wouldn't be an issue but salt water sure would unless the boat had a closed cooling system. HP and torque were "peaky" in the RPM range so I question whether they would make a good boat engine. Finding exhaust system parts would also be an issue - but you know that. Sell that engine, find a 292 truck engine that was a variant of the iron 194, 230, 250 series of inline sixes. Or better yet from an economic standpoint, replace/rebuild the 250 or drop in a 4.3 V6 which actually has less HP but more torque than the inline six and marine parts are actually abundantly available for it. That said, anything is possible (generally) and all it takes is "cubic-money".

Note in the info below that the 291 HP engine (@6000 rpm) had torque bumped up to 277 lb/ft but at a real lofty 4800 RPM as is HP. I just feel this is not an engine that would make a good marine engine in that form. Different cams to get some low end grunt would likely make it much better.

The LL8 (or Vortec 4200), is a straight-6 truck engine. The straight-6 or inline-6 engine (often abbreviated I6 or L6) is a six cylinder Internal combustion engine with all six cylinders This article is about the semi-truck For the North American use of the word see Pickup truck. It was the first Atlas engine, and was designed for GM's new SUV line. It displaces 4. 2 L (4195 cc), with a 93 mm (3. 7 in) bore and 102 mm (4 in) stroke. When introduced, this engine's power was 270 hp (205 kW) @ 6000 rpm and torque was 275 ft?lbf (373 N?m) @ 3600 RPM. 2003 saw a slight bump in power to 275 hp (205 kW), while torque was unchanged. For 2006, power was increased to 291 hp (217 kW) @ 6000 rpm and torque to 277 ft?lbf (376 N?m) @ 4800 rpm with the addition of a MAF and a complete internal redesign of the engine. A mass flow sensor (MAF responds to the amount of a fluid (usually a Gas) flowing through a chamber containing the Sensor. The Atlas LL8 was on the Ward's 10 Best Engines list for 2002 through 2005. Ward's 10 Best Engines is an annual list of the ten "best" automobile engines available in the U Engine redline is 6300 rpm.

 

[oops!]

Re: Anyone ever seen a GM (Atlas) inline six in marine use?

bubba........

by the time you finish screwing around with making this ....rebuilding that.....you could just get a rebuilt 4.3 with all the trimings for cheaper
the brackets are all different and expencive.....as well......the cooling system will need to be re worked....that means hours of standing in the auto parts store tring to find the right moulded hosing.....

 

[Howard Sterndrive]

Re: Anyone ever seen a GM (Atlas) inline six in marine use?

Anyone ever seen it done?

no, but we have all seen the 3800 Buick V6 install that one iboats member converted.
Impressive. But for the hundreds of man-hours of work, and thousands upon thousands of dollars worth of creations, no better performance than a 4.3. A pile of unique parts and a boat you could only ever sell for part-out value.

Fun to say "I can do it" in January.

Anything can be done. You'll be making an exhaust manifold worth $4000 or so at a fab shop. If you are good with stainless fabricating and have all the equipment, go for it. The materials could probably be had for a few hundred. I love to ogle the creations of talented fabricators.

 

[kilowatts]

Re: Anyone ever seen a GM (Atlas) inline six in marine use?

Hi Guys:

It seems to me that if you've already told the owner about all of the pitfalls and costs associated with marinizing the Altas, and he still says "Go ahead", then it's his dime and it makes for a great project. If you do it it would sure be interesting to see a thread with pics.
I love inline six motors so good luck.

kilowatts

 

[proshadetree]

Re: Anyone ever seen a GM (Atlas) inline six in marine use?

I think it would be a cool project. Unless you are going to eat some of the labor shop rates will kill him. Has he asked for a quote? I built some odd ball cars that a customer could never afford. Cadillac powered 77 Monte Carlo with air cruise and a 4 speed. Customer most likely would have never paid what I had in time. That engine however looks to have greater potential than any 250 I have seen.

 

[Don S]

Re: Anyone ever seen a GM (Atlas) inline six in marine use?

I built some odd ball cars that a customer could never afford.

This is the biggest problem with auto mechanics and marine mechanics. They are different, just most automotive mechanics don't realize it.

That engine however looks to have greater potential than any 250 I have seen.

Potential is only the beginning, paying to get it marine rated and for sale as a viable marine option, which includes the testing to see if it is a potential engine and will actually survive in a boat takes big bucks.

 

[TilliamWe]

Re: Anyone ever seen a GM (Atlas) inline six in marine use?

...That engine however looks to have greater potential than any 250 I have seen.

Potential that it never reached, as GM quit using it, less than 10 years after developing it. (Sure they use the 4 and 5 cyl variants in the Colorado still, but that's cause they don't want to change to anything else.) As soon as they could, they started putting the 5.3 V8 in those TrailBlazers and Envoys, and it only got 1 less mpg. The lack of low rpm torque alone would make the 4.2 a bad choice for a marine engine. (BTW, the torque I always saw it credited with was 275ft-lb, not 230. Its hp was also 275, not 290+) It was also a GAS HOG and would be even worse in a high load marine environment.
Plain and simple, this is a BAD idea. But if you've got more money than brains, go for it. Enjoy the challenge and the (disappointing) results.

 

[HT32BSX115]

Re: Anyone ever seen a GM (Atlas) inline six in marine use?

It was also a GAS HOG and would be even worse in a high load marine environment.

I drove one of those little Trailblazers with this engine in it. It ran well but when I heard that people were getting poor mileage I changed my mind. People were reporting worse mileage than I still get with my 94 (190,000mi) 3/4T 4x4 Suburban!

 

[Silvertip]

Re: Anyone ever seen a GM (Atlas) inline six in marine use?

I don't know about the six cylinder versions but the five cylinder engines seemed to have a problem with valve seats coming undone. Hate to see the results of that at 4800 RPM.

 

[proshadetree]

Re: Anyone ever seen a GM (Atlas) inline six in marine use?

This is the biggest problem with auto mechanics and marine mechanics. They are different, just most automotive mechanics don't realize it. Well, anyone who states a 5.0 merc engine is completely different from its automotive cousin is insane. Cam yes, heads no valves no, rods no, crank no, block no, and pistons no. There are different variants of everything including automotive based engines. Simple fact marine manufacturers use existing technology to save butt loads of money rather than develop their own. Now don't feel lonely equipment manufacturers have been using automotive based engines for years. The parts manual states do not use automotive parts like on timing belts when the gates numbers are the exact same. Automotive heads will not work on that Mitsubishi powered generator. Man I wish some one told me that five years ago before I put that D50 dodge head on that. I will now have to go back to the customer and tell him to shut it down so he can give 3 times as much for the equipment version. I like oddball stuff. If Johnny customer wants it and Bubba has the insurance and the stones go for it. Marine starters are marine converted auto starters. Carburetors same thing. Distributors are curved for marine use. Stay with marine made parts here. Would I do this swap? Heck yes if I had a spare boat play money and time. Would I do it for a customer? No way.