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motor advice

stclairriverblaster said:
so can someone explain to me why a slightly tighter bore machining process and closed loop cooling is a bad idea? i really dont see any downside to it.. all these high hp cars i see built are built with tighter than marine tolerances and they last quite awhile..
the only reasoning i see for the looser bore tolerances is because of the variances you can have in water/block temp.
the max rpm i plan on running is 5800-6000 i mean obviously until lately boats have been way behind in technology compared to cars.
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Chuck,
Car technology and marine technology is two different technologies, your comparing apples to oranges.

You can do it how ever you like but your ideas are against the grain of practical marine practice. There are big companies that have big money, engineers and R&D time. From stock boats to all out offshore racing. It's best to learn and follow what works set down by the these companies that know. Than waste your time ,money and short live boating time do to trial and error.
If you think you have thought of something better they did not think of. your wrong.
 
The more power you make and the higher the rpm's, the more heat you create. Pistons swell when they get hot. Build it to tight and it will get tighter on it's own. I mean LOCK UP! boatman
 
you know thats why im on here.. to learn.. im sorry for thinking outside the box for a change..

care to explain how it runs hotter in a boat ?
i know fuel docks dont sell it..
my whole tighter theory is based on what i seen when i pulled my boat motor apart.. i could literally see the piston rings and rock the pistons back and forth in the bore decently well which seems stupid to me.. when i pulled hte pistons there was major scuffing on both the piston and walls and you can see where the piston would start to chatter in the cylinder walls.
 
Quit pissing around and do this!!
Here is what the GM engineers were thinking when they built the ZZ572/720R: Think Space Shuttle power and grizzly bear ferocity. Hence the 720 horsepower and 685 lb.-ft. of torque—Chevy crate engine 572/720, the most powerful big-block Chevy crate engine ever offered by GM Performance Parts.
The 572/720 is built on the solid ZZ572/620 pump gas street engine platform with some major mods: They added 12:1 compression pistons, hotter camshaft, and their rectangular-port aluminum Bowtie heads with stiffer valve springs to work with the new camshaft. The solid roller camshaft is a .714" lift monster that feeds the air/fuel mixture into the stroker big-block.
The ZZ572/720R is rated at 720 horsepower at 6250 rpm and 685 lb.-ft. of bear like torque at 4500 rpm. The short block is built with a 4340 forged steel crankshaft, shot-peened forged steel rods, forged aluminum pistons with full-floating wrist pins, stiff dual valve springs, and a louvered oiling windage tray. The Deluxe ZZ572/720R ships with a 1090-cfm Demon four-barrel carburetor, tall-deck single-plane intake manifold, HEI distributor, aluminum short-style water pump and 8 mm spark plug wires. Special 572 cast aluminum valve covers complete the Chevy crate engine package. All you need is a starter to fire it up!
 
stclairriverblaster said:
you know thats why im on here.. to learn.. im sorry for thinking outside the box for a change..

care to explain how it runs hotter in a boat ?
i know fuel docks dont sell it..
my whole tighter theory is based on what i seen when i pulled my boat motor apart.. i could literally see the piston rings and rock the pistons back and forth in the bore decently well which seems stupid to me.. when i pulled hte pistons there was major scuffing on both the piston and walls and you can see where the piston would start to chatter in the cylinder walls.
Click to expand...


The new Flex fuel automobiles designed to run ethanol fuels have the fuel management system that is designed for it's use. The cars have a computer controlled management ECM that will richen the fuel delivery on demand and they drop a couple cylinders at freeway speed. They also have valves and cylinder heads to handle it, all the way to Indy cars that run one race and go through the engine. I doubt you can afford to put that technology in your boat. I wouldn't even know where to start. Also cars have gears, driving a boat at full throttle is like driving a car a 5500 rpm in first gear try that for ten miles. This fuel has already been tested for marine use and true it has high octane values there are to many problems associated with using it in a marine application. One thing was running to hot and burning valves because the fuel mixture needs a wide adjustment span to run correct at low end to substained top RPM.
Ethanol fuel that may get in your bilge without your knowledge, It will melt your fiberglass.
One day a manufacturer of marine engines such as Mercury may develop an ethanol fuel engine if they see it as beneficial and can over come the problems using it.
.

I don't mind the conversation but there is something about old school in boating with even the latest technology that works and I like it.
 
Happy,
We have nothing better to do in the winter than start some pissing matches.
Point well said. Put the bucks up and buy or build a real engine if you want to be bad.
 
I don't care if it's for a boat or a farm tractor, if you make more horse power, and use it, you are going to make more heat. Do the words " build a bigger fire" mean anything. A boat ( with out closed cooling) is getting constant cool water fed to the fire(engine) so the temp is not changed by warmer air or a stopped up radiator. I may be wrong, but I would think it would run cooler with a constant supply of fresh cool water than it would with recirculated coolant. Go ahead, build a 600hp 13to1 motor with.002 clearence and be sure to post the results(with pic's) after you tear it back down! boatman
 
i think you misunderstood my reasoning for closed cooling..

i was told that a marine engine block never fully expands due to the constant cold water thats coming in.. thats the only reason why the bores are machined looser.. and when they are machined looser that only allows for so much wear before teardown is needed..

my whole reasoning for closed loop is to provide a much more stable expansion enviroment for the block and pistons. but i guess thats just ass backwards.

and red i so wanna do the 4 banger just to spite everone..hp is hp. and torque is torque.. turbos spool faster when you have more load on them.. so if i made a 4 cylinder with 650 hp and 500 ft lbs of torque whats the difference between that and a 454? rpm range of useable power? well its called make up for it in prop.. instead of limiting at 5800 with a big block i could run the 4 cylinder up to 8k without sweating it.. and it will start to build boost and power around 3k. then its game over after that.. hp is now just hp.. and its 1/3 the weight...
 
stclairriverblaster said:
i think you misunderstood my reasoning for closed cooling..

i was told that a marine engine block never fully expands due to the constant cold water thats coming in.. thats the only reason why the bores are machined looser.. and when they are machined looser that only allows for so much wear before teardown is needed..
Click to expand...
this is backwards if it never fully expands you can machine tighter rather than looser
 
not true.. the pistons and block are supposed to expand together.. not one or the other otherwise you run into trouble..

the reasoning behind machining looser for forged pistons is because aluminum expands faster than cast iron. its for inital starts and warming up process.. but a marine machining emphasises on this even more.. because the only thing that fully expands are the pistons.. .. follow?
 
Dude, Aluminum and cast iron, or steel do not expand at the same rate! And you are RIGHT! Horsepower is horsepower and torque is torque. And you little 4cyl may make alot of horsepower at a very high rpm, IT WILL NOT HAVE ANY TORQUE! Why do you think promod drag cars are running 800 to 900 cu.in? They need TORQUE to launch the car and get the rpm's high enough to make HORSEPOWER so they can start banging gears and get the reast of the way down the track! Think about it a bit. boatman
 
actually, one of the basic reasons for the "loose" ness is because of the additional heat created by the load factor. I know of no marine engine manufacture who doesn't use a thermostat to control the temperature of the block assembly. While the heat range differers, the thermostat is there to provide one of the "constant" factors. I am aware that some people remove the thermostats to run a cooler engine. This has been proven only to read cooler temperatures at the temperature sending unit, acutal temperatures vary througout the engine (higher in some spots, cooler in others). I reccomend running a thermostat, in a carburated big block in the range of 140 -180 depending on your set up. 160 degrees is common. By running a certain temperature range you can calculate how much the block will expand at a given temperature, add in a percentage for failures (overheating) and you should come up with an idea of block/piston clearance. Industry standard has always been 6 - 8 thou and has proven to be both forgiving and reliable. How do you calculate your clearance?
 
boatman4021 said:
Dude, Aluminum and cast iron, or steel do not expand at the same rate! And you are RIGHT! Horsepower is horsepower and torque is torque. And you little 4cyl may make alot of horsepower at a very high rpm, IT WILL NOT HAVE ANY TORQUE! Why do you think promod drag cars are running 800 to 900 cu.in? They need TORQUE to launch the car and get the rpm's high enough to make HORSEPOWER so they can start banging gears and get the reast of the way down the track! Think about it a bit. boatman
Click to expand...


yeah i know aluminum and cast iron does not expand at the same rate..

they want torque to get the car moving as quickly as possible because they only have 1/4 mile to work with.. so the more torque the better..

im done talking about the 4 cylinder subject.. maybe one day i will have more money and will make it happen.. but yeah. 500 hp and 460 ftlb of torque at 3200 rpm is very high rpm. :eyecrazy::brickwall::brickwall::brickwall::brickwall:
 
happy said:
actually, one of the basic reasons for the "loose" ness is because of the additional heat created by the load factor. I know of no marine engine manufacture who doesn't use a thermostat to control the temperature of the block assembly. While the heat range differers, the thermostat is there to provide one of the "constant" factors. I am aware that some people remove the thermostats to run a cooler engine. This has been proven only to read cooler temperatures at the temperature sending unit, acutal temperatures vary througout the engine (higher in some spots, cooler in others). I reccomend running a thermostat, in a carburated big block in the range of 140 -180 depending on your set up. 160 degrees is common. By running a certain temperature range you can calculate how much the block will expand at a given temperature, add in a percentage for failures (overheating) and you should come up with an idea of block/piston clearance. Industry standard has always been 6 - 8 thou and has proven to be both forgiving and reliable. How do you calculate your clearance?
Click to expand...

thank you for the informative post.
 
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