I wonder what drivetrain in a boat will stand up to the torque of an 800hp tuned diesel? I plan on building a 40 Skater cat with diesels but it will be 3 or 4 years before I have $500,000 lying around to have Skater build it.

I'll say this again and again, many think pressure is flow, the more pressure and you inversely affect the flow - basic flow dynamics raise the pressure 1 unit you get 1 unit of flow increase, raise the pressure 2 more units you get 1.5 units of flow and so on and so on until you have diminished returns. the more pressure the more heat, the bigger & heavier the aftercoolers and it goes on forever.

I keep pointing you all to Jim Fueling and his designs if you decrease resisitance to flow, the pressure automatically decreases, which increases flow and lowers temperatures which increases flow further and that cycle continues forever as well but to the better to make RELIABLE & SUSTAINABLE HP.

Multispeed transmissions are your friend, without them it is difficult.

ps steel pistons in Cummins are as old as Cummins itself, this is nothing new and Mahle made hybrid steel/alum for Seatek almost 25 years ago with internal oil passages to cool the dome. Early Komatsu and some today still license of Cummins you can't get away from the "C" word - LOL

oops also forgot on the lower end carillo rods and a balanced komatsu 6d102 crank

Joe,

Them 400hp units you did back in the day was just some turned up M-3s? if so clue me in on the pump mods.

To keep things cool mods.

1. Relocate & bigger raw water pump.
2. Inter cooler & after cooler from 600hp 6CTA
3. Raw water oil cooler
4. Bigger coolant catch tank
5. Komatsu MCR coolant

I suggested compounds not for pressure but to have a very wide efficiency range, which would help with any smoke concerns.The waste gates are to keep the needed exhaust flow with tighter turbine housings, and without extreme back pressure or egts. By doing this you can control the pressure, have great spool, low back pressure, low egt's etc I think it would be a little difficult to get a single to make the same power and behave as well.

I do not recall the CC's, I looked but no notes I could find easily, I'm guessing around 210cc was 400HP?

That was not the only mods, we took pistons out and cut tapered on the lathe starting a .100 or so above the top ring land with a 7 deg taper in. Like I said before the pistons at TDC come above the top of the block and the gaskets are the same size for stock or oversize bores so there was room between the deck, gasket to get flame on the sides on the pistons (was very common in small diesels). The tapered allowed the psiton to expand and not drag on the cylinder walls. Many people who hopped them up thought high EGT's or other things caused the piston scoring but those did not cause it, the top of the piston swelling from fire around the sides from the deck did.

Another mod we did was mild head porting, we mapped the intake ports on a CNC mill so you could duplicate the cutting on each intake valve pocket and not hit water jackets. The main reason was the swirl ramp reduced the volume (CC's) right above the intake valve to a point that cronologically the valve could not be open long enogh to get in enough air to burn well, in a turbo engine you need a reserve capacity of air the ramp took out all the space. The swirl ramp was from the orginal non-turbo B engines, again common in small NA engines to excite the air flow and get it spinning down into the cylinder, the higher the HP you try and get from that head you get to a point of diminished returns which is the case with any positive pressure engine.

Just that with a stock turbo gave 400hp, steady state 380hp for hour after hour on the dyno. Again our dynos were designed to run steady state not this acceleration, peak stuff but run hour after hour. We had the small Superflo 901(?) mounted in the trailer with water pumps to use dockside, a large 8 vane Clayton water brake and the electric brake so we could run endurance testing. Our partnership with a certain Cummins distributor who did all the Coast Gaurd rebuilding for the 1710's & 903's gave us the ability to put engines locally on a stand and run for days on end. It was an adventure that at the time seemed to make sense - looking back, how F'in stupid were we????

You tell me how you are going to fit all that on an engine, plus a heat exchanger (which you have to run or the cylinders will cavitiate in a short time to swiss cheese), a water cooled after cooler, water cooled manifolds, the plumbing to exhaust the waste gates and still keep 2 engines at 30"-32" a part for side by side installation in a V hull?

I say this because they are longer than a big block, the trans say multispeeds are longer than just plugging in to a bravo, XR or anytype of drive like that adding more over all length. The engines get sooo long you can hardly stagger them without rebuilding the entire cockpit in a already staggered boat.

Just saying, there is more than meets the eye to being able to do something like you suggest and have it workable.

JD you know why I asked that right? Any race tranny will have a higher than stock stall speed, even stock it's like 800-900 rpms and it takes a little more for full lock-up, right?

The boat is always 100% locked-up there is no stall so you have a propeller with 4 blades that is designed to only have part of one blade in the water at a time, now fully submerged with no way to throw water off the front side of it, it's 4 times the drag plus the water on the front - this is tough on the engine with full lock-up on the trans.

Well I see the rest if us should just let you answer all the questions and not try and think of new ways or ideas good luck.