James wrote:
> "Matt Colie" <m2colie.DeleteThis@provide.nospam.net> wrote in message
> news:407D3DD5.7030901@provide.nospam.net...
>
>>O
),
>>
>>Of course you can, BUT:
>>
>>1. If it is run at its sutomotive rating it will probably fry. Passcar
>>automotive ratings are most often peak ratings that do not reflect the
>>long term capability due to internal heat buildup.
>>
>>2. Without air flow around the engine lots of stuff can get cooked -
>>ignition wires, valve gear cover gaskets and other things that I don't
>>remember right off.
>>
>>3. Like with the above, the oil will not be cooled by the dwell time in
>>the oil sump, so an oil cooler will probably be required even with
>>derating to marine output.
>>
>>4. If you try to run it with raw water cooling, the passcar headgaskets
>>will probably last about a week because they corrode and the coolant
>>flow pattern will change. This is unit specific and you will have to do
>>your own research.
>>
>>This does not include changes required to meet USCG regulations.
>>
>>Matt Colie
>>Lifelong Waterman, Licensed Mariner, Marine Engineer and Naval Architect
>>
>
> And the gearbox has all the wrong ratios... But more important, The auto box
> is designed to only TURN the propshaft.
> Forward thrust of the car is transmitted via the Wheel/axle to the chassis.
> In a boat....Forwad thust is transmitted dirctly along the prop shaft to the
> back of the gearbox... A propellor PUSHES the entire engine along. Which
> is bolted to the boat... An Auto gearbox cannot withstand this thrust for
> more than a few hours at most! (many would fail in minutes)
>
>
Exactamundo!
You will need some kind of thrust bearing to take the thrust from
the propellor, as neither the automotive gearbox nor the engine
crank bearings can withstand the end pressure thrust required in
boat installations, unless, of course you are building a side
wheeler, as I have seen done. That installation was an old fishing
scow with an automotive rear end and differential brake pedals to
aid in steering. The old guy was some proud of it, too! Built it up
into a houseboat with a radiator vented and baffled to provide heat.
He used two transmissions in series to get the reduction required
For 'normal' marine use, a thrust bearing could be cobbled together
from conical roller bearings like on an automotive wheel bearing at
the end of a rear wheel drive differential and installed in the prop
shaft line with some arrangement to keep it lubed. Don't doubt it,
you will need something like that, or the engine / gearbox will not
last long. Don't forget, you will want to absorb reverse thrust, too.
You might wish you had a marine cam and heavy duty cooling, marine
gaskets, spark wires, etc. Salt will get into the engine wiring if
you go in salt water, and that will cause corrosion, rotted wires,
open circuits, and electrical shorts.
You will also want a carburettor that cannot spill gas into the
bilge, and spark proof starter and alternator.
A properly sloped wet exhaust system will also be desirable, if not
a neccessity, else you will have to live with a bunch of hot pipes
and loud noises. Many boats use flexible pipe bellows to isolate
engine vibration from the fixed axhaust pipes and water injection to
cool the exhaust gasses, and a water cooled rubber muffler to quiet
the racket. Direct cooling water from the hot block is often
expelled through the exhaust for this reason, but some boaters
prefer to use two water pumps, one to circulate cooling water
through external pipes underwater to avoid salt water rotting the
block, and the second one to pump water for the exhaust. You do not
want exhaust cooling water getting back into the exhaust valves.
It ain't real easy, or everyone would do it, eh?
Good luck, let us know if you survive. It ain't impossible.
Terry K<!-- ~MESSAGE_AFTER~ -->
>> Stay informed about: Marine engine question 
FAQ
Search
Profile
Private Messages
Log in/Register/Password
