What is the difference between the Volvo D6-330, 370 and 400 ?

[jsc7]

The Volvo D6 engine has 3 versions with different horsepower ratings, 330, 370 and 400, but the engines appear to be identical in size and design. What is the difference between them?

[billknny]

The service category. Engines with lower power ratings can put out power for longer uninterrupted periods.

Many manufacturers have the same block certified for 25/7 service (at low horsepower) up through occasional intermittent service (highest horsepower).

"Recreational marine" service normally gets the highest high horsepower rating by assuming the engine will not be operating at full rated power for days at a time.

[jsc7]

All "three" engines have a shared engine drawing which is just labelled "D6 long block". Therefore, it would appear that all three engines are absolutely identical.

Are they just using different computer settings to differentiate the engines, or is there some actual physical difference between the engines?

The price difference between the engines is $40,000, so if I can turn a 330 into a 400 just by switching out the computer that would be useful information to me.

[Sailmonkey]

It may be as simple as the software limiting max speed and fueling or it may be more complex like turbo pitch and injector nozzles.

As was already mentioned the same block will be sold with different ratings. Such as commercial where full throttle operation is permitted 24/7/365 but the engine is limited to 1800 rpm and 300 hp. Or pleasure where operation is assumed to be 30-50 days per year with speed allowed to range up to 3000 rpm and horsepower of 500.

[mikeod]

I don't know about those models but I have a d2 75 and it's just a d2 55 with a turbo I believe everything else is identical. There may be one between the 55 and 75 also w a smaller turbo. Could be same deal with the bigger engines.

[jimbunyard]

Well for starters, the 330 is turboed only; the 400 is turboed and blown (supercharged). The turbos are also different, there are likely other internal differences as well. I have no experience with these particular engines, but the information is available from Volvo's website

Specifications

and by a comparison search between the different model engines for specific parts at this website

https://www.marinepartseurope.com/en...D6-435D-C.aspx

[Cadence]

Originally Posted by jsc7

The Volvo D6 engine has 3 versions with different horsepower ratings, 330, 370 and 400, but the engines appear to be identical in size and design. What is the difference between them?

Possibly no more than what they are governed at for different duty cycles.

[Midnight Son]

The difference in output used to be by injector size, max rpm and compression ratio (turbo extra, dropping the cylinder comp. ratio). Now you can add to the mix the computer controlled injection rate/timing (common rail fuel injection). So needless to say it's getting complicated. I think if you look you will see some engines with up to 6 power ranges/ratings (M1, M2 etc) all out of the same block, but with different pistons, injection, aspiration (turbo, none, turbo/supered). Just waiting for Volvo to marinize their turbo compound diesel from their trucks.
Cheers all, best of the season.

[DougR]

The base engine is the same for all three models, but there are software and hardware differences between engines. Because you specifically called out the 400 engine I guess you are looking at a sterndrive application.

In this case, the 330 engine is turbocharged only, while the 370 and 400 are turbocharged as well as fitted with a belt driven supercharger.

Also the gear ratio in the stern drive differs depending on the power rating of the engine.

What you need to realize is that all engine companies are in the business of selling horsepower, and to upgrade your engine will entail the cost of the mechanical upgrades necessary as well as the cost of buying the upgraded software package.

In all likelihood you will be better off buying the package that you want from the start and not trying to cobble something together later on.

DougR