The German 72bhp OM616 was used in the G Wagen as well as 3xx series truck and Tempo vehicles, it has a different pump and develops max bhp at slightly higher rpm.

__________________
99 Gurkha with OM616 IDI turbo

2015 Gurkha with OM616 DI turbo

2014 Rexton W with OM612 VGT

If you recall Randy's tests for the 617, the vehicle with a rated 123hp was actually delivering 85hp to the rear wheels. I conclude that the 616 is similar and roughly 30% of the rated engine power is lost in the drivetrain. I find this number atrocious and am not fully cognizant of exactly where it disappears, but, I'd venture to guess that the M/B auto transmisions are the primary culprit. Therefore, we also need to distinguish between manual and automatic transmissions.

With the auto trans, the requirement is 65.6 hp. The rated engine power is 62 hp. The reason that the climb is impossible at 65 mph in fourth gear is that the engine is turning 3500 rpm (approx.). This results in an approximate loss of 14% of rated power when compared to the peak power generated at 4000 rpm. This assumes a flat torque curve between the two points. So, the available engine power is estimated to be 53 hp at 3500 rpm and the requirement is 65.6 hp. The engineering shows that the climb speed of 65 mph cannot be maintained.

With the manual trans, I make the assumption that the drivetrain losses are not as severe. It might be possible that the drivetrain loses only 15% of rated engine power. The requirement of 49.2 hp is still necessary at the rear wheels to climb the hill. With 15% drivetrain losses, the requirement at the engine is 58hp. The engine produces 62 hp at 4000 rpm and approximately 50 hp at 3250 rpm (manual engine speed is lower). The engineering shows that the climb speed of 65 mph still cannot be maintained.

You'll note that the manual transmission is within 8 hp of the number required to maintain speed. The recent test by Steve corrolates very well with this calculation. The vehicle slowed from 65 mph to 61 mph at the top of the grade.

Additionally, it's interesting to note that the vehicle could easily climb the grade if it had a 3.07 diff and it utilized third gear. The engine speed would be right at 4000 rpm and the available horsepower would be 62 hp against a 58 hp requirement. But, unfortunately, the 3.69 diff does not allow this.

The only way the stock vehicle climbs the hill in either condition is if our horsepower assumptions are incorrect at the specific rpm's noted or the drivetrain losses are not as severe.

I went back to the hill this morning in the 240 4 spd manual and shot this video

http://s31.photobucket.com/albums/c397/funola/?action=view&current=Video_101607_004.flv

This time, I started from the entrance ramp at a standstill instead of approaching it already going 65 mph. As you can see, I shifted at around 4500 rpm. The hill is a little under a mile long. In 3rd gear I was getting close to 65 mph and if the hill was longer, probably would have made it to 65. If I shifted into 4th, I am sure the car would have decelerated.

Edit: Towards the end of the video, I did shift into 4th but that was at the crest of the hill.

__________________
85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

funola - that's simultaneously amazing/depressing. I have hope for my 240d, yet oh so much work to do

__________________
1981 240d - 135k - Arlene

Call me stupid but isn't it torque, not horse power that defines how fast you can go up a grade? Horse power being the rate of change in that speed?

__________________
http://superturbodiesel.com/images/sig.04.10.jpg
1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

What's so amazing? Amazingly slow? Mine needs a lot of work in body restoration so don't be discouraged.

I was curious how my 83 300D turbo would do on that hill and took this video.

http://s31.photobucket.com/albums/c397/funola/?action=view&current=1192569105.flv

It easily reached 65 in 3rd gear and shifted into 4th and reached 75 before it crested the hill.

__________________
85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

Not to be too big a geek, but it doesn't make sense to talk about torque and power as two separate things. The are interrelated, multiply torque by engine speed (rpm) and you get power (which can be directly converted to horsepower. To answer your question: both.

dont even think about ac while going up a hill...

__________________
Have you ever noticed that anybody driving slower than you is an idiot, and anyone going faster than you is a maniac?

As long as they would add one additional commandment for you to keep thy religion to thyself.
George Carlin (Wonder where he is now..)

1981 240d (engine donor 1983 240d) recently rebuilt engine hurray! - No more.. fought a tree and the tree won.

pearl black 1983 240d 4speed (Converted!@$$%) atleast the tranny was rebuilt.

Excellent job and great video.

Firstly, and confirming my suspicions, the maximum horsepower for the 616 is definitely above 4000 rpm. This vehicle continued to accelerate all the way to 4500 rpm. The speed at 4500 rpm was 63 mph. I'm confident that the 240 could hold 63 mph on the hill at 4500 rpm.

In typical M/B fashion, the rpm for the rated power is noticeably low.

So, with the maximum power at a point that is considerably higher than 4000 rpm, the use of third gear will just about allow the 240D to climb the hill at 65 mph...........if not, it's damn close.

Using fourth gear with an attempt to hold 65 mph would not be successful.

Actually, it's horsepower, which is a combination of rpm and torque. The faster you go, the more horsepower you need to climb.

I still don't think it all that cut and dried. The hill he is climbing is of an unkown grade, and it is entirely likely the rated horsepower comes at the prescribed rpm, and that at the higher rpm he shows on the tach (what is the accuracy of that instrument or the speedometer - what size and brand of tires are on the car?) he may very well have the same or lower horsepower, but still enough to accelerate in third gear because the sum of the hp lifting the car up the hill and the air resistance/other losses does not exceed the available hp, at the rear tires.

In all of my assessments I used factory data for the inputs, meaning 83 mph being the top speed, which many of us know is not the real max speed on all these cars and I assumed the engine was at rated hp which is 62 hp. We typically get a few more miles per hour on the flat and near sea level. Any assumptions like 85 mph as a top speed, and running the engine past its peak horsepower at that speed (it will go until the hp equals the load and if the speed vs. power curve droops over 4,000 rpm, it is likely the top speed happens at less than maximum hp ) makes the math in this exercise predict the car can make the 5% grade in 4th while running at 65 mph.

I personally think with an engine in good shape and over 150,000 miles, filled with Delvac-1 oil, and similar, modern lubricants in the transmission and differential with an extra 4-6 psi in the tires may make a few more hp available at the rear wheels. That is the normal condition for my 240D. I very much doubt the losses would be 25% for a manual transmission, and have no personal observations on the performance of a 240D with an automatic in a hill climbing contest, other than to recommend you not buy one.

Basically this is an interesting but essentially academic and speculative argument from all sides. We need to know the relationship between automobile speed and engine rpm in at least one gear in the transmission to calculate the 3rd and 4th gear actual performance. We need a hp vs. rpm curve for a well cared for engine with 200,000 or so miles on it, and some idea of what the transmission losses are for a similarly well used but also well cared for transmission and differential, and the wheel bearing losses to get all your decrements figured out. Without that we are looking at the ability to make calculations without any idea of their accuracy, and using the purely factory data is moot because they don't make new ones for us to buy, and all the anecdotal experience that has been quoted one way or the other is coming from twenty four year old, or older cars.

I am not in this to suggest my 240D is a hill climbing champ - it isn't and neither is any other 240D. My experience is that a well maintained 240D can be slug on the highway climbing hills, but most of the time it is due to driver error. There just are not any cases on the highways I travel frequently, which consist of Rt 9 in CT, I-91 north to I-90 West to I-787 to I-87 to Plattsburg, all of which have some pretty steep, long, hills, where it is a given that I will be in a 3rd gear, ear fatiguing event, all the time, to maintain 65 mph. Sometimes they are, especially if there is traffic that slows me down on the hill. No recovering from going under 60.

I just don't think a couple of horsepower is that compelling in this argument with so many unfounded assumptions that could be changed slightly and significantly alter the outcome of the analysis. Jim

__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)

torque is the amount of work a motor can produce, HP is the amount of work that can be done in a specific time...
and climbing a hill and is work, maintaining a specific speed is a time/work variable.
you have to fight both gravity and wind resistance. gravity wants the car to go downhill, wind and inertia want the car to stand still, or travel at the same speed.

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Agreed. We've got a lot of assumptions and many variables and a small change to any of them can affect the final result.

I do note that you personally needed to use third gear to hold 65 mph on the hills that you traversed. If the vehicle could accomplish the same task in fourth gear, I'd presume that you would have utilized it..........to save the thrashing and the noise of the 616 at 4400 rpm.

I'll additionally note that it's highly unlikely that the peak horsepower is at 4000 rpm and the vehicle has sufficient power all the way to 4400 rpm on the far side of the peak. These diesels typically have a massive falloff of power right after the horsepower peak due to the dramatic fall of torque in this area. They make a ton of noise, but all acceleration ceases at that point. I'm convinced that the peak power is at 4400 rpm.........give or take.

Jim, I have stock tires 175 70R14, tach is as accurate as a tach from a 300D turbo since the circuity and components for the tach in my 240D are basically the same as a 300D turbo. Don't know how accurate the speedo is but I intend to verify it if I get this old GPS I have working. Can't seem to get it to lock onto any satellites.

__________________
85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

Yeah, like I said, driver error and not planning for traffic can get you in a situation where the only option is to run in third gear - like being under 60 when the hill gets steep, or being boxed in because you were being considerate of other traffic instead of butting out into the left lane to maintain speed. I typically won't run in third at WOT for a couple of miles because of the noise - that is more unpleasant than boiling your blood while you curse under your breath about screwing up or being screwed by some bozo who boxed you in, etc, for a few minutes. But my point was, I have made every one of those hills in 4th, and stayed above 65, many times in the last 25 years.

I agree the hp curve drops precipitously after the peak, however, if less than peak is needed you will end up at the intersection of load and available hp on the other side of peak, which may only be a few miles per hour past peak. My point is, you won't stop at the peak hp if less than that is needed. You will accelerate (slowly, I agree) until there is no difference between demand and available hp, and then, if demand goes up, you slow down. Been there.

Jim

__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)