Up-rating power output on turbo diesels

[Carioca]

I have managed a successful "DIY marinisation" on a pair of truck 4- cylinder, 4,2 litre after-cooled turbo-diesels, each rated at 145 HP/2600 rpm.

The fuel-injection shop also increased fuel-flow on the injection pumps by some 20 % for more top-end power, to avail of more efficient water-to-air after-cooling. No black smoke has been observed at WOT.

The 6-cylinder truck version of this engine is rated at 220 hp/2600 rpm, some 50 % higher than the 4-cylinder version, which sounds resonable given that both engines share a great deal of components and have identical design, differing only in the number of cylinders.

However the professionally-marinised version of the 6-cylinder engine is rated at 370 HP/2800 rpm.

I have ascertained that the cylinder-liner/piston combo, cylinder head and cam of the 370 HP/2800 rpm marine version are IDENTICAL to the 220 HP/2600 RPM truck version, but injectors, turbo and fuel-injection pump differ.

Furthermore, I should be able to gain access to reliable data on the specifications of these crucial components as they relate to the 370 HP/2800 RPM 6-cylinder turbo-diesel.

Question: Would it be permissible to "scale down " the latter specs and thereby arrive at a close approximation to the injectors, injection pump and turbo requirements of a 250 HP/2800 RPM 4-cylinder, after-cooled turbo-diesel ?

[stonebreaker]

I'm not into racing diesels, but watching a big 7000 pound 4wd truck running down the quarter mile in 12 seconds is absolutely amazing. I would suggest you find a couple of turbo diesel truck racing forums to get a handle on the mods necessary to achieve your goal. Those guys would really be able to help you with things like turbo and fuel injector sizing, as well as be able to give you a pretty good idea of what your costs will be.

Even if you can't find info on your particular engines, the truck forums will still be able to give you some good basic pointers on what to do and what to watch out for.

[Carioca]

In the vein of your post, TST Products out in the Midwest perform wonders with the Cummins 6BTA series of engines, as well as with other Cummins series and brands of engines.

And they make it pefectly clear as to what can be done and what cannot, unless you wish to wreck the rest of the power train

[Jolly Roger]

Increasing the power output you will need a new turbo (say, to choose an adequate turbo size) and at least a new lub oil heat exchange. Also check your sea water pump, seawater heat exchange, air intakes, gearbox, shaft, etc.
I marinized a Mercedes Benz 6cyl, turbo and aftercooled, some time ago (DIY). Call me offline and I will provide you some additional information about parts available here.

[Frosty]

What engines are they?

[Carioca]

Thank you Jolly Roger. More power output implies greater cooling system capacity, but usually does not entail a gear-box / prop shaft substitution.

The prop, yes, would need to be changed to match the new power vs rpm engine carachteristic.

The engines in question are MWM - Motoren-Werke Mannheim - one of the oldest diesel engine manufacturers. Currently, manufacturing plants are based in Brazil and Spain. The Brazilian plant has been acquired very recently by International Engines of the US.

[fasteddy]

How is the turbocharger boost level controlled? Waste gate tapped to boost pressure? If so, I'd go with an adjustable pressure/vac relief valve in the boost to waste gate line, and set the relief value at your desired boost level. I'd also use egt gauge for tuning the valve. You may need to step up in turbo size, too, to get enough cfm delivery.

[seo]

Typically a dump-truck diesel will be able to inject a lot of fuel and run at high boost for a short time. Good for climbing hills, pulling out of holes, etc.
These parts can be put into a boat, but it's possible that you'll have a lot of problems with burnt exhaust valves, overheated turbo, etc. If you run at very high boost pressures for long, not just a minute or two while pulling up a hill, you have to deal with a lot of extra heat. Stellite-faced, sodium filled valves help, as does a water-cooled turbo. You might find that there are special pistons available that include an oil sprayer that takes the lube oil coming up the con. rods and sprays it out onto the underside of the piston, which cools it. Which means you need a bigger oil cooler.