Has anyone seen or read or know of LT4 crate motor experience? Seriously tempted for an install in a nice jet boat I have - since I am a Z owner figured I should look into this.

I have read the manual that comes with the crate motor and seems fairly plug and play, but have a few questions for someone who has actually put one in anything besides a Z06. thanks in advance for info / links

 

Other than the , "Not intended for marine applications" in the specifications, it ought to work just fine...I mean anything can be retrofitted...you may just loose the warranty if you put it in a boat...

 

saw that too - not sure what exactly wouldnt be intended for marine aside from maybe cam selection or what not I cant figure. warranty not a big concern for me, more interested in the rigging side of things. Like if I choose dry sump vs wet was there any big deal with it or does basic dry sump plumbing work fine? Does the flywheel have any balancing issues that need to be considered, etc....

thanks!

 

A member on the Camaro6 board replaced the LT1 in his SS with a crate LT4. He created a thread on the replacement.

http://www.camaro6.com/forums/showthread.php?t=469102

I'm sure he can answer any questions you may have.

 

The biggest challenge I see is working out the cooling for the engine and intercooler. For the engine, you'd want high circulation speed to prevent hot spots, but also a thermostat setup with recirculation of some of the heated water to reach a high enough operating temperature for longevity, and so the ECM won't think there's something wrong.
If you use lake water for cooling, you'd need excellent filtration so that weeds, debris etc won't clog up the intercooler bricks, and some of the small passages in the engine. I don't know to what extent corrosion might be a problem in the intercooler without the anti-corrosion properties of anti-freeze. Most marine intercoolers using lake water are made from an alloy like brass that is highly resistant to corrosion.

Another option might be to use liquid-to-liquid marine heat exchangers.

Other challenges might be fabricating engine mounts, finding marine headers or exhaust manifolds, and finding a jet-boat type bell housing to fit the LT4.

Most of us just go with a Big Block, since we don't need the compact package of the LT4, marine conversion parts are easy to find for a Big Block, and one can make more power for a lot less money. Heck, I know where you can buy a complete turn-key 120 mph boat for about the same price as the LT4.

Whatever engine you use, the typical low-end cooling arrangement which pushes water through slowly is far from satisfactory, and the more power you make, the less satisfactory it becomes. Even with the low temperature of lake or sea water, the water velocity through the block is slow enough that the water has time to flash to steam around hot spots like the exhaust ports, and then these areas overheat from having lost direct metal-to-water contact. This doesn't give any warning... the engine temperature gauge won't show it... engines just fail for "mysterious" reasons.

You can look at the cooling systems on some of the Mercury Marine V-8 engines, and see how much trouble they've gone to to sort out some of the various issues to achieve reasonable engine life and reliability.

 

marine application is much more severe duty even more so then a track car. Marine motors are built to a much higher standard.

http://marineenginedigest.com/specialreports/marinevauto.htm

 

A jet boat drive (or any boat drive for that matter) will load the engine 50% or more just driving down the lake. Water is thicker than air.....boats don't go fast if they are in the water. The engine will wear out much faster than in a car. It would be alright for a drag boat application but don't expect it to live like a normal "marine" engine would.

 

Here is the link to GM's powertrain marine partner websites and they provide a good example of the marine industry offerings AND what is necessary for an engine to live in this service:

http://www.gmpowertrain.com/marine.html

 

Yes, exactly. Marine applications, successful ones, have much stronger lower ends to withstand the stress of having to provide big torque at all times. Marine engines basically never coast, they are under "load conditions" at all times.

 

Jet boat depend on torque, pure and simple, lots of it. Mostly blown big blocks can provide that. Would not even think about a small block for that application. Might work for a while under mild usage. Got a 632 BBC with a 1271 roots, yet had to suppliment it with 200 shot. Think a small block will stand up to that? Good luck.

 

I would do a LSA all day over the LT4

 

Thanks for all the info and input. The reason for this thought was just the novelty. The boat is already powered fine with a blown/bbc - I was thinking would be a fun project. Will continue my research and again, appreciate all the info. Attached a few pics of how she sits currently....

 

I don't know, I've seen a ton of big block Chevrolet marine motors cross the dyno, and while most are competition boats, some are pleasure craft as well, and I didn't see anything special about them except good parts, which the LT4 by and large has.

My own boat has a Mercruiser 300hp V8 that I'm pretty sure is just a Vortec chevy motor.

A marine motor runs hard, but so do motorhome and bus motors.

What makes an automotive engine special when an automotive engine is properly prepared for the marine environment?

 

Motive power is still defined by horsepower, not torque. And a jet boat depends on torque a lot less than other types of boat propulsion, since the pump basically acts like a 5500 rpm stall converter.

On a prop boat, you might need low-end torque (which is better defined as a high-horsepower level at low rpms) just to get the boat up on plane, if the prop hooks well enough that the engine can't rev very high at low speeds.

 

Beautiful craft!

 

thanks

 

Understood, and I can relate to that. I still think the biggest challenge might be the cooling for both the engine and the supercharger coolers.

A couple of photos of my current boat, a V-drive: (Yeah, I've owned jets, and I run mufflers, because we get harassed for noise around here from time to time)

 

Gorgeous. And understood with cooling. I already have a sea strainer system in my float so that being in place gets the clean water - but if I would have to go to a closed cooling system that would kill it for me. Too much of a fun sucker at that point. But, in the minds eye, am not convinced that would be necessary yet..... still learning though...

Now if I could just find a hidden hitch for a C7 Z Vert....... lol

 

Just so ya know, that engine in a properly set up V-drive yields about 120 mph, versus about 80 in a V-bottom jet boat.

I realize that your's is a is an air-entrapment tunnel hull, but things get sketchy when producing lift at high speeds on a jet, like the water intake not remaining fully submerged.

I've pulled that boat with a C3, a C5 Corvette (both custom fabricated trailer hitches), but haven't considered it yet with my C7, since I have a Jeep Commander with a class 3 trailer hitch sitting in my driveway.

 

Anxious to start seeing towing options when someone figures it out on a C7 properly and cleanly.

The setup in the boat now runs mid 90's on a AA impeller at 6300 rpm - plenty quick enough for me