I only hit 4k when I have to pass someone... usual territory is 3500 when taking off.. and I still get 25 mpg

Mine probably hits it at least twice a day

__________________
1985 CA 300D Turbo , 213K mi

I agree at redline components are being stressed, but conversely, I also believe that the low RPM while starting the car cold stresses components too.

Anything manmade has a finite life, BUT there are many contributing factors in defining that life, i.e. not changing oil regularly, running out of oil, overheating, to name a few.

4400 RPM is really not that high, in fact it is a few 100-1000's RPM less then where most gas engines red line, so accessories, bearings etc shouldn't be an issue. I think that maybe the redline on this fine diesel engine is low because of the amount of time it takes for the piston to travel up and down, not other components such as bearings and accessories.

Now I don't hit redline everytime I accelerate, usually 4000 RPM is the shift point (after warmed up of course), but none-the-less I guess I'm performing a daily endurance test on my engine.

"Drive it like you stole it." has been mentioned soooo many times here in this forum that it really can't be THAT bad for the engine. I dunno, maybe time and RPM's will tell.

Fortunately I don't use alot of oil (leak) on this car, others I've owned would spray oil all over the engine compartment if the RPM exceeded 3500.

So I guess I'll have fun in this car until I have to call the wrecker, or it gets too cold to burn 100% WVO.

__________________
Closing the store
Benzbonz.biz on your smart phone or tablet.

if you are revving high make sure you are on synthetic. I hit 4k daily but try not to go over it.

__________________
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

Mine hits at least 4K every time I merge onto GA 400 or I-285.



Kind of hard to avoid spinning it up like that.

gas engines have much different cam timing, and much lower compression ratio, so they are stressing the crank etc, MUCH less at 7K than a diesel does at 3K, so be gentile with your old diesel, else you may be walking one day...

__________________
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!

Bah humbug. When I was following all you guys advice to do " an Italian TuneUp", I was finding redline ( 5500 ) frequently on that 606.

The Italian tuneups did NOTHIng btw, except stress the tranny and bottom end!

I normally keep things under 4000 rpm. I do get it over 4500 rpm briefly when I'm cleaning out the oxidation cat but the engine is not under load when I do. I don't think that 4400 rpm is a problem mechanically with these engines provided that your cooling and oil system are in good working order. Brandon had his tan engine up to 5750 rpm. The last I heard he had it all apart and everything is still tight. I don't know about a mercedes gasser, but there is no red line on the tach of my car.


However, at higher rpms your power and torque drops off due to a drop in volumetric efficiency and prechamber design not to mention the governor cutting back on fuel. The OM617 just wasn't designed to generate optimal power at these rpms because it didn't need to. You might be able to improve on volumetric efficiency with a custom cam and porting the heads. You can also adjust the governor to get more fuel at higher rpms, but redesigning the prechamber is going to be a lot of trial and error.

__________________
green 85 300SD 200K miles "Das Schlepper Frog" With a OM603 TBO360 turbo ( To be intercooled someday )( Kalifornistani emissons )
white 79 300SD 200K'ish miles "Farfegnugen" (RIP - cracked crank)
desert storm primer 63 T-bird "The Undead" (long term hibernation)

http://ecomodder.com/forum/fe-graphs/sig692a.png

I think you can redesign forever but cannot overcome the limitations of the burn rate for diesel fuel. It takes a certain amount of time for the flame to propagate and once you get over 3800 rpm or so............torque starts falling off in a big hurry.

the governor red line on the 617 is 5400.. our friend Brandon would see 5500 in his last 617 before it was wrecked..

Starting the engine cold stresses nothing. It's a contributor to wear, not stress.

4400 rpm is very high for an unbalanced 5 cylinder engine. The internal forces are huge at this speed. The reason for the lower redline has more to do with the burn rate of diesel fuel. Torque begins falling precipitously above 3800 rpm and, therefore, the horsepower peak follows soon thereafter.

You are.........and it's not accomplishing much.

Ever hear of an "urban legend"? Running the engine at redline does it no benefit. Running it at maximum power at rpm's that are approx. 75% of redline is actually what you need.

It's your vehicle.........do what makes you happy. Just don't confuse your preferences with the preferences of the engine.

I don't now why people want to rev diesels so high. Every 617 I have driven stops making power above 4k, all you get is more noise. Even the 603 starts to feel flat after 4,500. These are just not high RPM engines. If you want to rev buy a BMW and you can rev that I6 to 8k rpm every day.

Diesels in boats typically run at 80% of max RPM. So whats max rpm for a 617? About 4,500? If it were in a boat then I would run it at about 3,600, for thousands of hours.

__________________
1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

The 606 sees 5000 rpm maybe once a week, but there is no point besides the racecar-like sound (seriously!) and black smoke.

The most powerful acceleration comes between 2500 and 4000 rpm, so there's no reason to wind the engine up to redline. The same is true on the TDI--power drops off after about 4000 rpm.

__________________
99 E300 TD -- sold
01 540i 6 spd

You'll find the same behavior on every diesel. None of them are good for torque above 3800 rpm. Not enough time to burn the fuel.

Never. But then again with natural aspiration the urge never really strikes.

__________________

1980 300TD-China Blue/Blue MBTex-2nd Owner, 107K (Alt Blau) OBK #15
'06 Chevy Tahoe Z71 (for the wife & 4 kids, current mule) '03 Honda Odyssey (son #1's ride, reluctantly) '99 GMC Suburban (255K+ miles, semi-retired mule) 21' SeaRay Seville (summer escape pod)