Rev the crap out of it? - PeachParts Mercedes-Benz Forum

richard u · #1 03-24-2007, 06:06 PM

Does it REALLY do any good to to accelerate madly from time to time with a 300TD?

84300DT · #2 03-24-2007, 06:10 PM

sure .. it heats everything up nicely ..

do a search on 'italian tuneup'

#3 03-24-2007, 06:25 PM

Short bursts won't do much. It needs to be for a long, hard run.

dannym · #4 03-24-2007, 07:33 PM

Quote:

Originally Posted by ForcedInduction

Short bursts won't do much. It needs to be for a long, hard run.

Under load. Don't rev it in park or going downhill.

#5 03-24-2007, 07:40 PM

Quote:

Originally Posted by dannym

Under load. Don't rev it in park or going downhill.

Yes, I should have pointed that out.

Angel · #6 03-24-2007, 08:44 PM

The short explaination (since I'm sure its been mentioned many times. but none easy to find) Is that when you floor it under load for a long time (up a long hill on an interstate/those same speeds) the cylinder head heats up more than just beating around (thats why you need the sustained load.). When the cylinder head/engine heats up, so do the prechambers (little chamber where fuel is injected into right before it 'detonates' and starts making power. The prechamber has holes through which the burning fuel passes when it is compressed to the point of ignition.
The idea is that when running cold/cool/not-really-hot the fuel doesnt all burn and carbons up the holes in the prechamber, which consumes/slows down the flame front/power from each combustion event - Heating up the cyl head every so often burns these deposits off and opens up the holes in the prechamber - some people claim that they can see a small cloud of black smoke from the exhaust when they do this (or when the engine has been idling for a long time then they floor it...) I've never seen a black cloud, but I have a 240D, so I'm always flooring it =)

a Prechamber is what makes these engines "Indirect injection" or IDI, big truck engines have no prechamber (and a much smaller rev range) and are "DI" or direct injection motors. IDI It was a good idea if you wanted to 'passenger-car-ize' a diesel motor back in the 60's/70's/80's, but has been surpassed by the electronic direct injection motors (VW's TDI and MB's CDI/Bluetec).

The forum can correct me here, but I think this is the gist of it.

-John

connerm · #7 03-24-2007, 09:16 PM

Fact: Engines have a finite number of revolutions built into them. Use them as fast as you want. Me? I don't want to get there any faster than necessary.

Wiping tear from my eye thinking about my long dead 1970 Barracuda HT.

#8 03-24-2007, 09:29 PM

Quote:

Originally Posted by connerm

Fact: Engines have a finite number of revolutions built into them.

Then an Italian tuneup won't make any difference.

Once you are in 4th gear, you will be turning the same number of revolutions over a given distance no matter if you are going 50mph or 100mph.

mespe · #9 03-24-2007, 10:06 PM

Quote:

Originally Posted by connerm

Fact: Engines have a finite number of revolutions built into them. Use them as fast as you want. Me? I don't want to get there any faster than necessary.

I don't really agree with this statement, too many variables. unless that finite numbers fluctuates with italian tuneups.

300SD81 · #10 03-24-2007, 10:09 PM

Quote:

Originally Posted by ForcedInduction

Then an Italian tuneup won't make any difference.

Once you are in 4th gear, you will be turning the same number of revolutions over a given distance no matter if you are going 50mph or 100mph.

Unless you shift into neutral

but then you eat up the transmission

DslBnz · #11 03-24-2007, 10:27 PM

I never hesitate to do so in any of my cars.

The only problem is if I'm too aggressive on a gasser like on the 560SL, you could almost see the gas gauge slowly dip over to the left. Of course the car nearly spins its rear wheels in 2nd gear, so how could anyone complain?

These diesels seem to get the similar mileage WOT everywhere you go versus conservative driving efforts.

Its an effort to restrain myself from doing a 90 degree burnout every time I have to make a turn. Just a small amount of pedal (about 1/2) can cause such a disturbance in my ole' SDL.

But it is fun to hear the inside tire CHUUUURRRRRRP, as it struggles for traction and then constantly CHIR-CHIR-CHIR on the straight until it hits 2nd gear CHUUUUURRRRP.

t walgamuth · #12 03-24-2007, 10:33 PM

personally, i think all this talk about italian tuneups in a diesel is silly.

just get them out on the highway for a good long drive from time to time and you will never have any carbon buildup.

italian tuneups were for cars with carburators.

running wide open to dislodge debris in the carburator float valve was the reason for them.

cars with injection don't count.

just get them out and drive them on the highway and forget about it.

my $.02.

tom w

rudolfgreen · #13 03-25-2007, 05:20 AM

Quote:

Originally Posted by Angel

The short explaination (since I'm sure its been mentioned many times. but none easy to find) Is that when you floor it under load for a long time (up a long hill on an interstate/those same speeds) the cylinder head heats up more than just beating around (thats why you need the sustained load.). When the cylinder head/engine heats up, so do the prechambers (little chamber where fuel is injected into right before it 'detonates' and starts making power. The prechamber has holes through which the burning fuel passes when it is compressed to the point of ignition.
The idea is that when running cold/cool/not-really-hot the fuel doesnt all burn and carbons up the holes in the prechamber, which consumes/slows down the flame front/power from each combustion event - Heating up the cyl head every so often burns these deposits off and opens up the holes in the prechamber - some people claim that they can see a small cloud of black smoke from the exhaust when they do this (or when the engine has been idling for a long time then they floor it...) I've never seen a black cloud, but I have a 240D, so I'm always flooring it =)

a Prechamber is what makes these engines "Indirect injection" or IDI, big truck engines have no prechamber (and a much smaller rev range) and are "DI" or direct injection motors.

-John

agreed.. after travelling around town, getting onto the interstate running open from 2nd, to 3rd, to 4th..
a few miles down the road you will notice black cloud 'puffs' while under steady 'throttle'..(even though diesels dont have a throttle)

it may have come from carbs, but the italian tuneup stands solid in my book. (with my repects to tom

)
it may take a bit longer in the turbo slushbox, but dont we all agree that these engines sound best opened up anyways?

84300DT · #14 03-25-2007, 05:37 AM

Quote:

Originally Posted by t walgamuth

personally, i think all this talk about italian tuneups in a diesel is silly.

just get them out on the highway for a good long drive from time to time and you will never have any carbon buildup.

italian tuneups were for cars with carburators.

running wide open to dislodge debris in the carburator float valve was the reason for them.

cars with injection don't count.

just get them out and drive them on the highway and forget about it.

my $.02.

tom w

well i have to agree and disagree with that... the long highway drive is very good (for a lot of reasons) but a proper italian tuneup for an engine mostly used around town at low rpms is also good.

signalredcoupe · #15 03-25-2007, 02:06 PM

I agree with Tom. I've ran mostly on Interstate 75 to & from Tampa & when I tore my engine apart I found no carbon deposits anywhere at almost 300,000 miles. Paul.