wantech

Would like to know about how many RPM when a 90' 6 cycl 300se cruising at 60 mph, just want to know if my transmission is shifting correctly.
thanks

Paco

1st gear:
Speed = 1/2 * (RPM/100)

2nd & 3rd gear:
No Simple Conversion.

4th gear:
Speed = 2 * (RPM/100)

So crusing at 60mph would have you reving to ~3000rpm

MB AMG

3000RPM!? Do all the M103 engines have a 7000RPM redline?

Paco

its around ~6250rpm

top speed is ~120mph

DslBnz

And it will go that all day long, everyday, for the rest of it's 500K mile life.

Mercedes old M103 M104 motors were all hard workers. The bulk of their torque came from 4K + rpms.

MB AMG

How come my friends old 1986 300E had a 7000RPM redline? I never wanted to rev it past 5000RPM though.

DslBnz

Maybe he swiped a tachometer from an early M104?


That's just the M103 with a different head, really.

MB AMG

Pardon me Dslbnz?

His car is completly stock. It was an 1986 so i'm sure it used an M103 of course. So is the redline really at 7000RPM?

DslBnz

No, redline should be at 6200 rpms. You can even look in the owner's manual for this. 6200 rpms is where the electronic limiter will interfere. You cannot overrev the car unless he accidentally uses the gear selector to bump down 2 gears at 110 mph.

6200 rpms is the maximum safe engine speed for the M103. In other words, unlike domestic cars, the 6200 rpm redline can be held all day in 4th without any damage to the engine. It was designed for the autobahn.

MB AMG

Wow! I now know for sure that all MB engines are tough. I got scared when I revved an M119 past the 6000RPM limit to 6400RPM before it shifted! And that was less than 1 second. So you can rev the M103 to 7000RPM but you can't leave it there in 2-3-4 gear? Or like a domestic engine, you can rev it there but can't hold it there? Why does the tach say 7000RPM!?

Nektopoli

Yeah remember there were a bunch of I-6 from MB

3.0L 12V motor with 188HP
2.6L 12V motor with 166HP

3.2L 24V motor with 217 to 228HP
2.8L 24V motor with 192HP +/-

the 4 valve per cyl engine(24V) are the ones with the higher red lines.

NP

PS I was able to get my M111 (2.3L K) up to 131MPH before the the limiter kick'ed in and it was turing about 5,100 to 5,200 RPM.

DslBnz

Actually, forgive me if I was not clear, the electronic limiter should cut the air supply back from the engine and the car "jolts" back if you bump the limiter(not a very comfortable feeling). His ECU limiter might not be working.

6400 rpms one time occasion in the M119? I doubt you even made the engine fuss.

I've had my 300SDL up to a "super high engine speed" of 5450 rpms on video(held my foot there for 5 minutes). Laugh if you want, but I want you to consider it is just a diesel. max engine speed is supposed to be 5200 rpms. Most diesels have redlines around 3 - 4K rpms.

Oh btw, my M103 revs to 6500 rpms in second gear(about 60 mph). Since I don't floor it very often, I don't worry about it.

MB AMG

LOL. You sure are hard on your engines! Can you send me the video please?

So Mercedes made a mistake marking their tach in the 300E?

DslBnz

Yeah, the redlines are a bit conservative compared to domestic cars. Mercedes are built tough. They are built to last.

Here is the video

Surprise; there is no redline marking on the tachometer for diesel models. Might make the video less enjoyable unless you know MB diesels(most diesels this age can barely rev past 4600 rpms).

MB AMG

Wow! 5450RPM's! You were just keeping the engine there and sighed. LOL. Now I need to try that on an M120. I don't know why but since it's a V12, I backed off at 6050RPM since it didn't shift. Were you sitting on the rev limiter because I though the RPM's would fluctuate? And your like 10MPH past the 2nd gear maximum on the speedo!

Adobe

My US version '91 300E is rated at 137 MPH, has a redline of 6,250 RPM and produces 177 HP. I recently had it up to 110 and it was still pulling strong when I backed off (I have new V-Rated Pirelli P-6000 summer tires on it).

Germany is the only country in the world that produces cars that can safely and reliability travel at triple digit speeds all day long with no problems. Sure Italy makes some but not like Germany.

BTW, 6,000 RPM on an M103 is nothing. It could safely rev to 7K w/o much trouble.

Now American cars are a different story. The big, old Ford V8 used to have an oil pump that was good for 3,000 RPM. The big block Chevy had an air cleaner that limited RPM to about 3,700. Ford pretty much limits max speed on the Explorer by putting crappy tires on it and telling owners to under inflate them by 9 lbs. A little heat, a little load and you blow a tire.

MB AMG

Good old german engines.
Now what do you think for japanese enignes?

Adobe

Well, the last I knew it was an ex-Honda engineer who turned the Ferrari F1 engine program around. On the other hand, there isn't much out of Japan that the Germans (or English and French F1 engine builders) haven't shown them how to do.

DslBnz

That's the kicker.

Because its a diesel, there is a fuel stop on the injector pump. What happens is something called an ALDA cuts out the fuel and boost supply when redline is reached killing any further revving of the engine. Since there is not enough fuel to be compressed and ignited, the power is limited to that 5450 rpms. No bouncing off limiters, you just hold your foot WOT in second gear(with the defroster on, lol). If you have a boost gauge, you notice boost drops from a solid 14 PSI to a measly 8 - 10.

Many refer to this process as, "The Italian Tuneup". Do it once a month is what I do. Uphill for the best result(it cleans up the intake manifold). I only do this on a diesel. A gas engine is usually much cleaner. But sometimes a gas engine needs to be driven hard, too.

Marc5000

I drive a 1990 560 SEL... It's got 238HP and 287 Torque with a 6000RPM Redline.. hah.. I've pushed that car to the limits so hard... I actually shift up using the lower gears.. if you run the quarter mile on drive.... you will run 15.9's with a good launch.. which is sorta laggy.. but if you start in 1st gear and shift up.. you might hit 15.1's... last time I was at the track i ran 15.234 @ 91.35MPH with an alright launch.. after heating up the tires.. VERY generously ;-)... but then again.. my tires are almost bald.. so i can't hold the brakes and gas too much to get an effective launch because i will start up that brake stand once again on the line.. anyways.. i smoked the Mazda 6 that i was racing... for those that are curious.. the speeds for each gear redline at...

1st - 40MPH

2nd - 80MPH

3rd - 120MPH

4th - 160MPH

The fastest i have gone yet where i had a chance to... was 145MPH @ 4500RPM out of 6000RPM... and it was still goin stronggg.. doesn't take that long to get up there either... there just had to be a turn coming up on the highway.. dammit..

egxpimp

what about the m117 engine? any good things about it ? iv pushed it to 160 before....i think i drive it a bit tooo hard tho, btw is shifting with gears bad for the tranny with an automatic tranny.
Enrique Gutierrez