Why no supercharged diesels
 

Why is it that diesels all seem to be turbo charged? It would seem that a supercharger would work well. With the new quite and clean fuel efficient diesels from GM and Ford, do they have a future in performance boating?

The "roots" style superchargers originated (I believe) on 2 stroke diesel engines on the exhaust side. Turbochargers are lower in cost, lighter in weight and don't rob a lot of power.

Most of the early 2 stroke Detroit Diesels were supercharged, I believe. Some even supercharged and turbocharged.
Gary

I always figured it was because turbo chargers use the exhaust gas to produce the boost so you dont have to use any power initially to turn a pulley. I think it is more efficiant for a diesel. My.02 cents

Check out this site. www.marinediesel.nu They sell diesels with screwtype compressors ( branded whipplechargers in the US.)

Roots blowers were used on the intake and exhaust of GMC/Detroit (I have no experience with the others) diesels. The size of ther blower was indicative of how long the rotor blades were and from what I can tell denoted whether the supercharger fit 4, 6, 8, etc. cylinder varieties.

Most V8 gasoline retrofits used either a 6-71 or 8-71 type supercharger. Nitromethane guzzling fuelers used 14-71 superchargers (until the hi-helix rotor roots-type superchargers appeared). We make roughly 55psi of boost with our hi-helix setup on our FM/A Olds (big Chevy) dragster. :D

More Detroit Diesel info...

The models numbers refer to:
Number of cylinders and cubic inches per cylinder or 6-71=426Cu in.

Models were and some still are:
3-53, 4-53, V6-53 & V8-53
2-71, 3-71, 4-71, 6-71, 6V-71, 8V-71 & 12V-71 s)
6V-92, 8V-92, 12V-92 & 16V-92
8V-149, *12V-149, *16V-149, *20V-149
Note* a 20V is one V8 and two V6's bolted together and so on.
Many models share common (4 exhaust valve only) heads as there are CW
and CCW rotation drive models that are mirrored. The big 149's have a
single head assembly for each cylinder.

Many have N, T, TA, and DDEC added. N=normal aspiration but still have
over pressure with the scavenging blowers. T=turbo,
TA=turbo+inter+aftercooling, DDEC= Detroit Diesel Electronic
Controlled. All have roots blowers but turbo's use both and do a
functional bypass on the blower, when on turbo boost.


GMC 6-71's and 8V-71's were the most common. These were and still are
used in 'then' general motors GMC two cycle diesel engines, developed
in the late 30's and for the most part still in production, albeit in
smaller numbers and very specific applications, where their
compactness and high output per liter are required. I believe
Hildebrand (sorry spelling) is now building their own Hot Rod roots
blowers based on the Jimmy design. The drive ratios and other stuff
had to be modified for high RPM automotive engines.

Penske bought Detroit Diesel in the 80's, bailed them out and made
them profitable again, after that GOD Awful sorry ASS American icon,
General Motors, ran them into the ground, like so many other once
profitable industrial divisions.

I remember installing a V-16 diesel generator. That engine had dual everything. Dual oh cams, 4 valves per cylinder, dual superchargers AND dual turbo chargers.

Now having my own diesel with a turbo, I become a believer that the turbo and the diesel are a perfect match.

The new high horspower diesels seem like they would be great for performance boating. Is it just that people dont like the sound and smell, because that has changed. I would love to have 450hp and 700ft pounds of torque in my boat and get triple the fuel consumption and four times the longevity.

My dad taught diesel mechanics in the Navy, after he retired, he taught for Cummins for a few years. I once asked him about Cummins engines and his reply was "They ain't no Detroit Diesel".