hello; anyone know of how to get some additional performance out of my 1987 300D Turbo? One mechanic turned some screw that provided more fuel (and more black smoke but what the hell) and it gave me quite a bit more power; dealer turned it back when tranny was recently replaced.

It seems that putting a less restrictive exhaust/intake system would do the trick for a diesel; any comments? This thing is seriously plugged up for emissions/sound reaons.

Thanks,

Carl

Turning that screw definitely decreases life of the engine. The only way you get more power out of a diesel is to increase the amount of fuel injected into the cylinders. The only way you can make the engine live for the long term when doing this, is to increase the amount of air inducted into the engine a proportional amount.

Changing intake manifolds and the like by themselves does nothing.

As far as power goes, a diesel without a turbocharger, is only half of an engine.

As the history of MB diesels go, your '87 is one of the better performers.

If you want long term economical driving, a diesel is a good way to go. If you yearn for power, you need a spark ignited engine.

My $0.02,

So what does that "screw" actually do; mechanic told me it was fuel regulation and it simply increased amount of fuel being put into the system. Seems that by doing this and opening up the exhaust I would achieve what I am looking for. Is the engine not strong enough to stand up to another 20 horses or so? My experience is that what I would wind up with is simply a freer breathing engine that makes a bit more noise if my experience with motorcycles many moons ago can be referenced.

Regards,

Carl

ps: after putting a new tranny in the car I really "bought it"; this car is staying until the motor is gone and it has 240k on it now.

Carl
What did you have done to the transmission and why? My tranny is acting up big time. Huge clunks at every shift no matter the driving style, sounds like slack in the rear end. I am trying new fluid tonight, what kind should I use?Mine has 127000K, but the interior is banged up from the california sun and it doesn't like the cold winters here in WA comparatively. Any thoughts?
Elliot Easton

__________________
Elliot Easton
1987 300D Turbo 151K
1996 C220 stock (Mom's car)

There have been quite a few posts claiming the clunk can be caused by a worn rubber flex plate by the rear end. There is another at the front end of the drive shaft, but they say this hardly ever goes bad. The same goes for the center bearing, very reliable, but look at it while you are checking out the flex plate.

If you do this yourself, becareful under the car, here are my standard canned tips:

Use good quality Jack Stands/Ramps on solid level ground
Chock the wheels securely and set parking brake.
Put a big block or tool box under the car in case it falls off the stands (Mike Tangas California Earthquake tip!)
Use safety glasses while under the car
Have a second person around at all times who knows how to use a floor jack
Have a phone handy for 911
Think about what you are doing, don’t put your body parts at risk!

Good luck,

Carl,

I'm sure your motorcycle was not a diesel. Gas engines are completely opposite of diesel engines on many counts.

Indeed, I'm sure that screw increases fuel flow. In a gas engine cylinder cooling is increased by adding fuel. In a diesel engine cylinder cooling is increased by adding air. Increasing the fuel amount in a diesel without adequately increasing airflow will result in an early engine death.

Opening up the exhaust system will only increase air flow enough to add a small amount of fuel without decreasing engine life.

I do not doubt at all that you can add 20HP by turning that screw, but you will have to SIGNIFICANTLY increase air flow to add the needed additional air to prevent andearly engine grave. If you took the entire exhaust system off and threw it away, it would not increase the flow adequately for a 20HP increase to not kill the engine early.

A diesel engine is a completely different animal, proceed with caution.

Best of luck,

Larry, thanks for the information. Last thing I want to do is hurry up the demise of this rather expensive engine. It stays as it is. The car will continue to be used to make 400 mile runs every other week.

I think I'll have to put in an order for a new Audi S6 Avant or RS6 and sell the Porsche as I am clearly not getting any jollies from the diesel. Seriously, I had no illusions when I bought it. I will say that these expensive german toys continue to disappoint me from a design and maintenance perspective. I've owned more than a couple Hondas and Toyotas and I've never had anything fail other than normal wear 'n tear stuff (brakes, wipers, water pumps). I love my 911 but I wound up purchasing my 1991 model after wading through "if you buy the 1971 model you have make sure you have this upgrade and do that and blah blah".

It seems like just about every little frigging electric motor has gone south at one time or another on this car. The sunroof is requiring attention again. I know the car is 14 years old and I have put 240k of Hard Miles on it. But.....Is Toyota reliability too much to ask for? I know, I know; that's just the way it is and we have to live with it. Yep.

Regards,

Carl

Turbo: I replaced the worn out tranny with a rebuilt unit and a new torque converter. If you ever do this make sure you specifically address the question of a torque converter. RAB Motors (mercedes) of San Rafael did NOT install a new converter; about a week later my tranny was not engaging at all...it was destroyed. I took it to another dealer, smothers in santa rosa; it fixed it after putting another tranny AND a torque converter in. Then, the two dealers started arguing about who was to pay for the cost of the ruined tranny. I made it quite clear to the customer service rep who got involved that this is NOT my problem (dealer would not release my car until it was resolved) and that I think that he should contact me attorney immediately. The car was released.

final cost was about 4k; probably higher than an independent but I wanted this one installed by an authorized dealer.....and you can see why!

Carl

I'm gonna respectfully disagree with Larry here.

Adjusting the aneriod compensator changes the injection
pumps response to boost pressure. It may increase the
engines maximum power, but only to a limit. There's
only so much oxygen in the combustion chamber, hence
only so much fuel can be burned. Excess fuel is
essentially inert, since there is no additional oxygen
with which to react. I contend that adjusting the
aneroid *may* increase maximum power, but only to a
point. That point may or may not cause unreasonable
exhaust gas temperatures.

If you want more power, add more air and more fuel. That's
where you can get into real trouble.

I've more experience with the five-cylinder 617 motor
than the six-cylinder 603 motor. On the 617, just about
everybody I know has adjusted the aneriod full rich.
Seat-of-the-pants, this does not increase the maximum
power at all. However, it does completely eliminate
turbo lag, which makes the car much nicer to drive.

On the 617, a common problem on older cars is the
wastegate going out of adjustment and permitting only
about half the specified boost. Needless to say, this
reduces power a bit! Don't know if this problem is
common on the 603, but it is one of the first places
I'd look. Offhand, I don't know the maximum boost on
the 603 engine, but it's probably about 13PSI. Good
place to start looking for more power.

How does one go about checking the wastegate? Car is not smoking (a little after cruising or idling; not muchy)and turbo seems to kick in (but not very much power) about 3k.

Another issue; seems like my tranny (new from dealer in 11-00) does not kick down nearly as easily as it did it the original tranny. I have to mash the pedal down at 45 to get it to kick down; before the new tranny I think it would kick down at over 50 and without having to pound the pedal to the floor.

Regards,

Carl

Checking the wastegate is easy. You need a boost guage.
Just hook it up to the manifold by inserting a tee
fitting into the line which feeds the aneroid. Mount
the gauge in the cabin, and go drive.

Have you had the trap oxidiser removed? From your
description, it almost sounds as if your car still
has the trapox, and it's getting clogged. That's how
mine drove when purchased w/trapox intact. Upon removal,
the boost comes on more quickly and aggressively. My
car accelerates in quite a spirited manner at 2500RPM
with lots of boost.

trap has been removed and something that looks like tin foil replaced it...I got the same power boost after they took it off. I am going to have the turbo system checked out soon.

Thanks,
Carl