grease

ive been reading this form for a bit now but just became a member. i see that all of you are quite knowledgeable and was wondering if you could teach me the way of the force.

i see a lot posted about the merc #6 and the 1000hp rating on it but im think of another set-up.

i want to use a Cummins diesel that is in the 600hp but about 1500fpt. is there any kind of set-up that could both handle the torque and still provide good speed (proper gearing)

mind you i am new to this so plzzz use lame's terms

great thanks to any help or ideas

offshorexcursion

iTrader: (5)

Arneson.

But it sounds like you want to custom build a boat using a modified truck cummins? We all would love that set up! Just does not work that way. Sorry. Correct me if I am wrong and no hard feelings.

grease

yes thats it exactly. plz tell me why something like that wouldnt work? remember im new to this and would love to know the rules of boat building

Philm

There was a ski boat with a Duramax in it. Set up for marine use the guy never saw less than 1600ºF EGTS while on plane and up to 1800-1900ºF while WOT, and it was only at relatively stock power levels. This might be acceptable for 1 second or less, but not for miles and miles on end. It will take a fair bit of work to actually get the EGTs to an acceptable level, especially on a tuned out diesel. You would have to get cut and coated pistons, lower the compression, different (inconel) valves, probable change the cam, and completely rework the cooling system to handle raw water or set up closed cooling.

The closest thing to marine use is hooking your truck up to a 12k lb trailer and towing it up a 6% grade ALL DAY. Oh, and leave it in 4th gear. Their is a constant load that never lets the engine cool off.

It would be great to get it done, but you wont ever see 600hp out of a standard Cummins set up for marine use without SERIOUS money spent. Think twins, meth/water injection, full engine build, water jacketed turbos, complete new exhaust setup (custom of course), ect. It is easy to do in a truck, not so easy to do in a boat and make it live. Hence why drag racers can make 700hp small blocks and we run giant 572-598ci for the same HP, all about making it live on the water.

But to answer your original question, a #6 or an Arneson would be the way to go.

A.O. Razor

Have you looked at this one. There is an OL SV52 running 4 @ 112 mph.
http://www.ivecomotors.com/en-uk/Pro...es/N67560.aspx
If you want to mod a diesel for high hp, at least start with a strong marine diesel with good power from the factory.

And yes, the Arneson's are the drive to get. One of the ASD#8 would be good, or the ASD#10 if you can swing it.

HabanaJoe

grease -

1st -look through all my posts on here and get a feely for who I was and you'll find all the answers you seek including dyno sheets from 1990 of 600hp Cummins B's that can live and those were 2 valve heads.

But to give you the short version of what your looking for here we go:

Don't worry about what drive because you need prop speed, 3,600 rpm's is a good prop speed. Do your homework figure out what kind of transmission are you going to use, how much of an overdrive to go through for your outdrive gearing to get 3,600 of prop speed. Chances are you won't get an outdrive with much taller than 1.32:1 so figure the OD of the trannny you'll need to get 3,600 of prop speed - that is where you start.

A #6 drive is a waste of your money and the boat will be a pig unless you have an OD tranny - look at all the slow diesel boats ever posted on here vs the faster diesel boats, it's not the drive it's the prop speed.

Also 600 hp is 600 hp the torque makes no difference what so ever because by the time you OD it the troque drops - 600 hp of gas and 600 hp diesel at 3,600 rpm of prop speed is exactly the same torque - do the math you'll see I'm right.

As far as a 600 hp Cummins B, did that in boats 21 years ago, no sweat. Diesels have had inconel valves long before gas engine people ever knew what the word meant, don't need any injection or custom rebuilding to do it and make it last. Let's call it what it is, you take a 500hp Merc and run it on a dyno at 500hp and how long will it last - I don't know but not long at all. Even in a race boat it's not making 500hp the whole time it's racing, you throttle it, it breaks loose, you slow to corner, etc, etc not like a dyno where you can break it. But a 600hp Cummins B on the dyno and keep it there, my guess the Cummins will run longer than the Merc will!

Here is the key to diesel performance and it's from the late great Jim Fueling a man who understood engine breathing better than almost anyone. You need more CFM's not more PSI's.

In english, you need to open up the heads, the size of intake passages, increase the size of the turbo charger discharge piping make everything larger & smoother so the boost pressure drops by itself. The higher the boost pressure the hotter the air, correct? Lower pressure - cooler air, lower pressure means more CFM's and more oxygen to the engine.

Aftercoolers, the problems with standard aftercoolers and most aftermarket is they flow water through a core 1 time and they increase surface area but decrease thickness of the core for less resistance. The core needs to be very thick and made with multi passes of fresh cool water ex: take a standard core 2" inches thick and stack 3 of them together each with it's own water supply not a back and forth loop. You'll drop the temp about 50% more than the one core would have and cooler air will drop the boost pressure that much more, all about lowering boost pressure through flow and temperature control.

Higher boost needs stronger and stronger valve springs to stop flutter, the stronger the spring the quicker the valve wears, doesn't matter what it is made of.

If you have very high exhaust temperature in a modded diesel then whoever built doesn't know their azz from a hole in the ground. That tells me the exhaust backpressure is to high, usally the compressor is trying to make so much boost pressure that it's approaching a stall and the exhaust just can't escape - could be other things but not because you're making sooo much power. The balance is wrong - if you check the exhaust pressure in the manifold, before the turbocharger you'll find it is equal to or slightly higher than the intake pressure, when that happens the engine stopps making power, goes flat and exhaust temps skyrocket. Not many people check that or look for that. Jim Fueling was big on that and his engines made Hp at way higher rpm's than similar engines by some of the best builders of Indy & F1 engines back in the day.

You achieve that and making the Hp you want is no trouble and making it live (relative to a gas engine) is no real problem.

PS the easiest drive to get proper prop speed with is the areneson, it has nothing to do with how much power it can take over another it's just the ability to play with direct and OD ratios without a OD tranny where as regular outdrives need their OD in a tranny because the drive can't do it.

If you want to call me my cell is 732-718-2711 all I ask is you call during normal hours, I have 3 kids and they wear me out!

grease

thank you all HabanaJoe i understand the part about the running both motor on a dyno untill they die very well. thats what got my hole project rapped around the diesel. i work for a farmer seasonal work, and we rap out the diesels on the combines like hell those things run 3,100 rpm's 15-16 hours a day in 100+ deg. . i've pull those motor apart after 1,000-1,500 hours on them and they look like they just got put together, no wear, and its not like they don't have a load. i run them so hard iv stalled the 12 liter motors.

then the EGT's i understand the heat, was going to custom fab water jacketed exhaust manifold and the same for pipe after turbo, the only thing is i was just going to go with something like Kevlar insulator on the turbo. (any suggestions?)

and last i do a lot in the automotive but first time in the marine, could you throw me some numbers in what you see a project like this costing. i mean just on the marine side like the areneson or gear boxes, props. cuse i looked around but the prices jump so much its hard to even get a ballpark figure.

and thank you again for all the help.

HabanaJoe

reach out to RIK here on the site he is Arenson and can give you all the prices you need.

You are better off to start with a used marine Cummins B because you need the manifolds, engine mounts, SAE#3 bell housing, raw water pump, heat exchanger, etc. The internals are all the same as far as crank, rods, heads, different pistons for some different Hp applications but otherwise the same.

You know you can not run seawater through the engine, the cavitation around the cylinders will eat through in no time with seawater. You can and it is adviseable to relocate the oil cooler from the block to a remote unit that uses seawater rather than jacket water and just block that area off so water flows around cylinder 1 easier.

I didn't explained it well enough but the EGT needs to be lower on it's own not because of water jacketed manifolds, when the engine runs correctly the EGT will lower, when it's running very rich, like I explained where boost and exhaust manifold pressure equalize then all you are doing is pushing unburned fuel right past the exhaust valves and buring it in the exhaust manifold on both sides of the turbo charger, that is why their is a flame coming out the turbo when you push it hard. A good running engine won't have too much flame, a rich engine has a flame 5'-8' past the turbo.

grease

hay Habana Joe, thanks a lot for the help this gets me pointed in the right direction. and yes i was going to use a closed loop cooling system