Ya know a persons mind gets to wandering and engineering and designing from time to time. It has often wondered me as the effects that a supercharger rather than a turbocharger would have on diesel engines. A diesel has plenty of torque down low to drive a supercharger to begin with and I think it would widen and flatten the torque/power band plus there would be no turbo lag.

I dont' know if a supercharger would easily build the 20 psi of pressur that some turbo's do, but initial compression ratio could be adjusted in the engine to create the desired combustion pressure. I could imagine that a whipple type supercharger with a water-cooled intercooler would create a wide and tall torque curve without robbing too much power.

I could envision diesel engines with 500++ foot lb from idle to 3000 RPMs that would be geared to run at highway speeds around 1250 rather than 2000+.
I think there is a airplane diesel being manufactured in Wisconsin that is supercharged. Blackhawk comes to mind, but am not sure that is it.

Anyone know if this idea has been experimented with in trucks or semi's? I know detroit had a industrial supercharged/turbocharged 2 stroke years ago, but that was a 2 stroke.

I know diesel guys are 'in love' with their 'free power' turbo's, but we all know it's not really FREE.

Comments, ideas or boo's accepted.

Tony

 

My dad and I are looking into purchasing a '76 FWD with a supercharged Detroit v-8 diesel in it. I don't know how good they are, but supercharged diesels have been around at least that long.

 

Supercharged diesels have been around almost as long as diesels.

The 6-71 and 8-71 blowers were actually used on 6-71 and 8-71 GMC diesel engines. The first number before the dash is the number of cylinders, and the number after the dash indicates the CID of each cylinder.

A lot of us don't necessarily remember those days, so 6-71 blowers were associated with chevy 350's and 8-71's were associated with big blocks, because we see them on hotrods all the time at shows, thanks to weiland making manifolds for both.

But, both blowers originated from GMC Diesel engines.

So, know if you can fab all the pieces, theres no reason why it won't work.

Superchargers and turbochargers result in the same thing, except they draw their power from different places. Superchargers steal power right off the crank snout, and turbochargers take heat and airflow off the exhaust, increasing back pressure.

 

The aviation motor that I'm thinking of is called the Deltal Hawk. It is currently a v4 watercooled 2 stroke with both a whipple style supercharger and a turbocharger. The turbo feeds an apparently mild supercharger after boost kicks in. They are expecting to get 220-240 HP out of a 202 Cubic in v-4 when they add an intercooler. They are developing a v-8 version also with 404 cubes. But the price of the v-4 is about the price of a F150.

While searching the net, I saw aslo where russian tanks had a supercharged 4-stroke tank engine producing 880 HP. They recently converted to turbocharging and now are producing 1000 hp from the same displacement. There may be other changes though also. The turbocharged version is also more fuel efficient based on HP rating.

Other comments that I found simply say that turbocharging is the cheaper route to go, but I think there is room for development of a supercharged low rpm diesel.

 

The only setback I see with a SC'ed diesel is that the supercharger itself would have to be pulley'd down a ton to make "decent" boost becuase of the lack of RPM's...and then you would definately have major belt slip issues.

 

Blurry has a point. I say twin turbo it before you supercharge it.
Unless someone makes a supercharger with a RPM increase thing that multiplies the revolutions to spin the SC faster than 1000-3500 RPM's of a diesel.

 

As for belt slippage, a toothed belt as is on other supercharger systems would probably take care of that problem.

The Deltahawke engine has a supercharger to give mile constant boost and turbo's feeding the supercharger to give the added kick needed. If the turbo's fail somehow, the supercharger will supposedly supply enough power for a limp home mode.

Putting a twin turbo unit on a truck would be interesting but the turbo's would have to spool up before they would give aide and the idea of the supercharger would be to have boost as down low as possible. One benefit of a super over a turbo would be that boost could be relatively constant over the full RPM range of the engine giving increased torque and power below the RPM's where the turbo's currently kick in. This would enable higher gear (lower numerical) ratios and engine operating RPM's in the 800(or less)-2500 range rather than 1500 to 3300 rpm range.

This would suit the pulling croud ok, but the leadfoots who like to drive a diesel like a gas motor probably wouldn't like it too much.

Whipple makes a supercharger for among other things, the ford v10. They state that the engine has "gob's" of torque basically from idle all through the rpm range and "unbelievable" acceleration. The super is able to feed the air needs of the engine as engine rpm increases maintaining pretty constant and high levels of torque. On a intercooled v10 they were pushing 650 ft lb on the dyno chart at 2800 and it looked like it was still going up as it was going back. http://www.superchargersonline.com/p...ber=WIP-FORD68

Just some thinking outside the box.

Tony

 

You'd be better off sticking with the turbo. A supercharger would be a step backwards.

 

I was watching that show TRUCKS a couple weeks back, "How It Works" segment. They were at Wyotech, IIRC, in a room full of turbo-supercharged diesel truck engines. Can you imagine how much work that would be for a light duty? Once it was done, though.........

brent

 

You will be hard pressed to find a Cog setup for diesel, especially for the crankshaft. It'll probably have to be a custom made piece, and I'm sure it'll be very expensive! Then, the next challenge is finding the correct belt length. Also, when you spin a blower that fast then heat/discharge temps become an issue....at that point an intercooler will be needed.

 

Wouldnt a roots style blower, IE Kenne Bell, Eaton, work best? Or are you wanting boost after you come out of the low RPMs for passing? Not totally sure...and I think that is the important factor. What would you want it to do for you. You wouldnt ever need a centrifagul blower if you were hauling a load.

Garrett

 

Yes, a roots, whipple, Kenny Bell, Eaton style was exactly what I was thinking about. I think you could drop the rear end ratio to 3.09's or maybe even less, if you'd have power to pull at 1000-1200 RPM's and passing power at 2000 rpms. I think this combination could produce high torque at low RPM's and if gearing 3.09's or something similar, would accomplish the same outcome (especially in terms of towing) and be more durable and possibly more economical than the higher revving turbo style engines.

Tony

 

Guys a turbo is going to be more efficient. Blowers take engine power to run, and turbos are free power, and you'll make more of it. There's a reason why every big diesel engine other than the old detroit diesels and EMDs use a turbo, from Cats all the way up to the 100,000 shp monsters that power the biggest ships.

 

Yes, you are probably correct, but it doesn't hurt to wonder and think outside the box. Remember the buffalo stampede who would follow the herd over the cliff....to the buffalo skinners knives. A few must have thought "outside the box" or else they all would be extint. :-)

It is true, a super takes off the crank.. obviously, but turbo is not totally Free power... most likely more free.... but not totally free. Why do drag racers run superchargers rather than turbo's? I know that is a question about a 'other fueled' vehicle with ultra high octane, but it's still a question.

Tony

 

Drag racers use blowers because they spool up instantly. What do they have the 1/4 down to now, 3-4 seconds? It's halfway down the track by the time the turbo spools. So if you are a drag racer you'd probably be happier with a blower. Personally, I get off on the fact that with a turbo I'm getting (almost) free power. As for thinking outside the box, I wholeheartedly endorse that, it's what our country was founded on. It's just that I've had this conversation with numerous diesel engine mechanics and they all say the same thing, so I'm trying to pass that knowledge on to you guys.