Auto engine marinization

What a good idea. Ive kept fish and chips warm by placing them under the engine compartment of a car ,--but this could make serious self regulated oven.

Perfect for more delicate cooking like fish or warming pies. For a single hander this is a must. Imagine tying up knowing that your chicken and roast potatos was ready.

Err not sure if it would do roast potatos.

 

Straight up Resolve

O.K., I have read almost all 15 pages of this thread, lots of differnt opinions.

I recently bought a boat,1988, 19' open bow, family ski/ fish. The bearings SPUN on the second time out.
It has a "Mercruiser" 350 Magnum (Chevy) I have a friend that works at a GM dealer in the parts department, the block casting number is correct for the year and matches a standard 350 that may or may not have a four bolt main. He can get me a NEW long block, 290 HP 4 Bolt, Stainless head gaskets, brass freeze plugs (all standard), for $1900.
Is there a reason this wont work? Is the cam gonna be a problem? Should I change it? I will not operate this at WOT for long periods as my wife doesn't like goin over 30 mph and it did 50 at 4800 rpm before it blew.

 

He should be able to match the cam. The oil pump should be a low pressure high volume type. The reason for the pump is that the engine will run at higher RPM than a car's for extended periods.

 

Only $1900, that's a bargain. The engine will make less than 3000 rpm for 30 mph so it will feel quite happy in your boat. But I've never heard of stainless steel valves. Valves must absorb lots of heat and transfer that to the seats when they are closed, something ss cannot do. But maybe it is just a misunderstanding: the valves may be tungsten or titanium coated.

 

Hey everybody, just read this whole thread, wow! I'm currently building a 33' deep v runabout boat, and I am planning on running two Nissan VH45DE engines (they come in Infiniti Q45's, a 4.5L V8). I want to run a closed cooling system with a heat exchanger, and this is where my questions start. Does anyone have some link or more info on construcing my own heat exchanger for the cooling system? The other question I have is how do I go about sourcing some sort of transmissions to use with these motors? I would like to usestern drives. I have realtime tuning software and was planning on running the existing individual coilpacks in each cylinder (no distributor). I they should see about 400hp (not shaft hp, more around 300 shaft hp), but they can be run all the way up to about 1000hp each (again not 1000 shaft hp) with twin turbos. Would I need to get anything else besides a marine alternator and starter of some sort? Any finally, I am new to the marine thing, I have 2 nissan race cars, and I am very familiar with all aspects of building and tuning the nissan engines which is why i plan on running them. My last question is this: both engines rotate the same way. On a marine dual installation one prop needs to have counter rotation, right? If so, how would I go about making the scond prop rotate the opposite direction? Is there another type transmission that would reverse the prop rotation? Sorry for the long post and if my questions are silly. Thanks in advance for any help!

 

Let's do the easy question first. To have one prop counter rotating you'll need one sterndrive that does that. Or if you will use Merc. Bravo 3's, you can simply put one in reverse all the time (the gear ratio must be identical in both directions).
Engine cooling is a different matter. Can you get water jacketed exhaust manifolds for the Nissans? If you can, but they have no integrated heat exchangers, you can buy std types from Mesamarine. Making them yourself is not impossible but you need some custom made rubber parts that isolate the raw water tubes from the casing and allow expansion. Such parts are available at replacement items for commercially available heat exchangers from Bowman.

 

I have not seen any exhaust manifolds that are water jacketed as of yet. Would it suffice to extensively wrap the exhaust manifolds with exhaust wrap, as I do on my race car, or will that not be enough? If not, I can probably fabricate some water jacketed exh mani's for the engine if I see what others look like. What about on the Bravo 2 drives? I just need to make sure that one of the drives is counter rotation? I have found a used set of the Bravo 2's that I'm considering thats why I ask. Thanks for the help!

 

Justin,
In a sterndrive setup, all shift and gear reduction functions are generally housed within the sterndrive unit. In rare cases a 2-speed transmission is placed between engine and drive to improve time-to-plane, but the usual setup is a direct connection from engine to sterndrive. In the case of the counter-rotating drive, this too is included in the drive unit (it is often accomplished by replacing the standard lower unit gearset and dog/cone clutch with one that moves in the opposite direction to normal). To check, just try to turn the shaft a quarter-turn with the gearset in forward (note that the drive is removed from the engine at this point!) and watch what happens.
The Bravo 2 is almost always used in counter-rotating pairs, they are designed for heavy cruisers with large-diameter props, and would have a strong tendency for asymmetrical, torquey steering if used as a single installation. If you're thinking of a fast boat that isn't wide fat and heavy, a pair of Bravo 1's would be the most common choice.

 

Thanks for the reply! So would the Bravo 1 be a better choice for me then? Like I said before, the boat I am building is 33' with an 8' beam. I would like it to go pretty fast, I am shooting between 50-75mph under ideal conditions. This may require that I make more than the 400 hp out of each engine, in which case I can modify them, but my concern is will the sterndrive be able to handle a power increase over the 400hp (300 shaft hp)? I should elaborate on how I intend to use the boat. I will primarily be just taking it out on the weekends for pleasure...just crusing the beaches, coastline, the st. lucie river here, etc, moderate use. I would eventually like to make the trip down the coast from here (Vero beach) to about west palm beach (actually a little further south), which is approx 50 miles south and then heading over to the bahamas, which is about another 60 miles or so. Which stern drive unit would be the best option for what I would like to do? Bravo 1? maybe the bravo 2? I just want to be able to upgrade my power if needed without worry of damaging the stern drive. I assume that the sterndrive will connect to the flywheel in some manner? I also am curious as to what gear ratio stern drives to use, along with props, but I assume I need my engine data to know what rpm I want to cruise at, right? Thanks for all the help, and sorry for all the newbie questions!

 

I should also note that I am not planning on running 50-75mph all the way over to the bahamas. I would like to cruise around 30-50mph

 

If you're interested in Merc drives, they publish most of their specs at
http://northamerica.mercurymarine.com/engines/inboards/sterndrives/
Alpha is for smaller boats, less than 300 hp.
B1 is the all-rounder for fast boats, they warranty some of the new ones to 600 hp now.
B2 is a specialized drive for heavy, twin-engine cruisers that need large-diameter props, max 450 hp.
B3 is the American answer to Volvo Penta's Duoprop, counter-rotating props and up to 525 hp.
Compare to the VP range at http://www.volvo.com/volvopenta/global/en-gb/marineengines/drives/
Important note with all sterndrives- note that no matter what brand/model you choose, the driveshaft couplings and bearings will be quickly destroyed if you run the engine while the drive is tilted up in trailering position. You can only run the engine while the drive is within its normal running-trim and shallow-water-trim angles.

 

Thanks again. I actually have no preference in which drive I use, just want the one thats the best all-around and dependable, which seems it may be a merc bravo1

 

A quick survey on the Internet shows no sign of water cooled Nissan exhausts, so most probably you are about to enter uncharted territory. That challenges some people and scares the hell out of others.
As you mentioned lots of horses (= lots of heat) from compact engines, water cooled manifolds are the only solution. I once read the diary of a guy who was determined to build his own submarine with a rowboat's budget. He tried to sand cast some parts, but the last I saw was the unfinished hull sitting in his garden as entertainment for his children. Casting the manifolds would be an option, but certainly not a do-it-yourself project.
An alternative would be to compare what is on the market with what you need. If there is a model from Glenwood or Bowman that comes close, you could make adapter tubes with flanges from mild steel.

Another item that will not be available of the shelve is a bell housing that fits the Merc sterndrive.If the Nissans have a flat flange with the flywheel recessed, you can make an adapter plate, otherwise you'll have to construct a complete bell housing with two lugs to match the holes in the transom housing engine support. An engine coupler, available from Mercruiser or Sierra Marine, must be machined to match your flywheel, but that is quite simple compared to the manifolds and bell housings.

I just finished converting 2 VW turbo diesels. There were water cooled exhausts available, albeit for a smaller engine without turbo charger, so I had to make dozens of parts myself, both mechanical and plumbing. I hope to start them for the first time at the end of this week when the last electrical parts arrive. It kept me busy every day for about 12 weeks now.....

 

I have seen the same engine I intend to use in an open-air ski/drag boat in New Zealand. If I make some sort of fresh air circuation system for the engine compartment and wrap the exhausts well, wonder if that would be enough? Here is a link to a video of the boat on youtube. I believe in that small boat he goes around 120mph, with a twin turbo, 1,000 hp engine.

http://youtube.com/watch?v=9nsVNpkk_D8

 

"The mechanic said it could be a variety of things and omc is **** and he wouldnt recommend fixing it....."

He's right, although I wouldn't put it so crudely. The 4-in line is a GM product, designed before 1950, with very little success in passenger cars. Its main applications are AC generators, compressors and small stern drives. OMC's contribution is only a paint job.

To transplant the Nissan you need to do the following jobs:

-Fit the OMC bell housing to the Nissan or make a new one with the proper geometry (shaft height, distance etc).
-Attach the OMC engine coupler to the Nissan flywheel.
-Find a water cooled exhaust manifold that fits the Nissan or make an adapter to use the existing manifold if that is in good shape.
-Construct an engine support for the front of the engine in the same style as on the OMC, or two separate supports if the Searay's bottom offers that choice.
-Make a linkage arrangement for the gear shift cables on top of the valve cover, with a microswitch that shortens the ignition during gear shift.

First concentrate on the exhaust issue. If you can solve that, the rest is easy.