OM606 exhaust headers / VNT turbo upgrade?
 

Has anyone upgraded the exhaust or turbo on their OM606 turbo?

I'd like more power. I know I can simply chip the ECU. More importantly though, I'd like better exhaust flow at high power. The application here is a G300DT, which is a g-wagen with the OM606.964 engine (from the factory). There are two problems with the factory setup.

1) At high altitude (8K+) the torque converter hooks up before the turbo produces any usable boost. The result is several seconds of turbo lag before any real acceleration happens. Low altitude performance is fine. A VNT turbo could make a huge difference in this behavior.

2) When loaded up for exploring the G tips the scales at over 7000lbs. I climb lots of long steep hills with all that weight. The "postal truck" aerodynamics also add to the drag. In the end, the engine is often driven flat out for 15-30 minutes at a time. Realistically, the exhaust system (stolen straight off the E300) was not designed for this kind of use. An equal length header tuned for ~2600RPM should flow much better than the convoluted log-style exhaust. A VNT turbo would also flow better at high loads than the KKK with it's tiny turbine wheel housing.

Well, that was long winded. Anyway if anyone has any suggestions, I'd appreciate hearing about them.

BTW: the OM606 puts up with this abuse very well. I did have to put a new head gasket into it at 170K miles, but that was largely due to a botched repair job performed much earlier in the vehicles life. Some idiot reused the stretch headbolts. Even so that job lasted 100K miles of abuse. About the only recurring issue is the crummy o-ring based fuel system.

A GT2359V from an E320CDI or GT2559V from a BMW would be very good options.

Seeing as you've got a Diesel G, I'll bet you're not in the USA. Look to Finland, they have done some very amazing things with the 606.

I am in the US. There are a few legal G300DT's over here. The Finns have done great things, but they tend towards mechanically controlled engines. I'm happy working on the electronic versions. My preference would be a VNT turbo with electronically controlled vane angle. I can build interfaces between the ECU and the VNT if needed.

Where would I find specs (flange sizes, etc) for these turbos? I don't have any leads on a better exhaust manifold. I might be willing to live with a better turbo and some other improvements. The EGR is not functional and I'll likely remove the EGR intake manifold obstruction next.

ed: perhaps you meant GT2559V?

Hi,

I'd start with a free flow exhaust, easiest mod and you will need it anyway for future mods.
Next huge step: VTG, but the vane control is not an easy job (at least for my buddy who fights almost 3 weeks, but with some progress). Just take what is available and suitable in seize. Don't care about the flange. Then laser cut a flange and weld it to the turbo. I did it 2 times it works.
Building a header is way more complicated and expensive. I'd bet the gain isn't worth the effort. Rather go for an intercooler as additional upgrade.
This is my experience but with OM617a and 603a.

Tom

Thanks for your suggestions.

Past the turbo the exhaust is not very restrictive. It is the manifold that is tight. Vane control should be easy as the ECU is already putting out a variable signal for how much more boost it wants. I do want to increase the size of the intercooler but there aren't too many places to put it. The factory intercooler is housed in the hollow of the bumper.

Adding an air-water intercooler to either end might be an alternative worth looking into.

Something like this light fit on either side of the engine (turbo outlet or intake inlet).
http://www.siliconeintakes.com/image...13_picture.jpg

Turbo control
 

I spent some time and instrumented the boost control signal on my OM606 G. This is a 10V PWM signal produced by the ECU. It controls a vacuum modulator that then pulls the wastegate closed. The results are interesting. The ECU is constantly playing with the wastegate.

• Acceleration: the wastegate is held closed until the max boost is reached
• Pedal lift: immediately opens wastegate
• Idle: back on full boost (not that any boost will be produced)
• Steady & flat @45mph: wastegate partially applied
• Steady & flat @65mph: wastegate partially applied
• Shift points under hard acceleration: wastegate momentarily opened between shifts

Driving on rolling hills moves the wastegate back and forth constantly.
It appears that the ECU firmware was designed to do far more than simply protect from overboost/overspeed. This bodes well for using the ECU to directly control a VNT turbo.

Some of the wastegate movement may be designed to develop backpressure to enhance EGR flow.

Be sure that the EGR is not enabling while you are under acceleration, as that will rob a significant amount of power.

Many people feel that the EGR is useless on a diesel, as the EGR simply restricts combustion, often harming efficiency and power. In a gasoline engine the EGR essentially simulates a smaller displacement, increasing efficiency.

How "free flowing" is your exhaust? Others have noted a significant gains changing from a stock exhaust to a 3" straight-through exhaust.

How bad is the exhaust manifold? Is it at all similar to the 617's?

Besides custom exhaust shops, a motorcycle shop is a good place to get small pipes bent into crazy configurations.

The EGR system failed and was removed. I designed a nifty circuit that tells the engine computer that the EGR is working just fine. This is a bit easier to do on the S & G Class version of the OM606 turbo. Someone has designed a similar mod for the E-class version.

Aside from crudding up the intake, there is another reason for removing the EGR on the OM606 turbo. It turns out that the recirculated gasses are not evenly distributed in the manifold. The overwhelmingly sent to cylinders 5 & 6. As a result The #6 intake valves are subject to valve recession.

The motorcycle shop idea is pretty good, thanks!

Turbo flanges
 

I had flanges fitting to the exhaust laser cut and welded them to the turbo (after cutting away the original turbo flange).
You need Ni (welding sticks?) to avoid cracks.

Have you ever tried to operate a vacuum actuator? If yes the biggest step for a VTG is done. My buddy still works on an independent VTG control.

A final upgrade could be larger elements. We are right now figuring out the swap and adjustment for the 606 IP with e-governor.

Tom

The OM606 already has the vacuum control system built in. This is both good and bad.
Good: because I think it will correctly and automatically operate the variable vanes.
Bad: because using vacuum to position a wastgate doesn't work properly at high altitude.

Background: To pull the wastegate fully closed, the ECU directs full vacuum to the vacuum cylinder. At sea level the vacuum cylinder has about 15 PSI across it. This successfully pulls the wastegate closed. At 10K feet there is only 10 PSI across the vacuum cylinder and the wastegate isn't pulled all the way closed. This is quite simply a design goof, they must not have designed for nor tested at altitude.

That is why I'd rather go for the electronically controlled VNT. I can easily convert the ECU signal into what the turbo wants. Even better I can make my own rules for VNT behavior. Getting information on fitment seems a lot harder.

Header
 

I have a friend cutting the flange for me I will me making a nice size log manifold like the ones made by banks for cummings engines. I to want to use a vnt on my 95 e300d I have. I will be using the vcv valve and the vacum signal for the flapper valves. I would like to use a electronic controller instead.:rolleyes:

I had a stainless steel header made for my 606 turbo project adding a Garrett T3/T4. The guy did a fabulous job. The place is called Woolford Bros. in Glen Burnie Md. 410.424.1957. Just tell him Mario with the 99 Mercedes turbo sent you.

Also I am using a pressure wastegate and the computer knows no difference. I have the wastegate solenoid plugged in but just sitting there with no vacuum attached.

You sound like a great guy to talk to about computer management. What is the best way to max the full load on our injection pumps at full throttle?

I have a chip which is suppose to have done it (and it has created some amazing gains) but I am not sure if it has maxed it out or not. It is a square wave signal and the maximum travel of the rack solenoid is 19.5mm.

Also the throttle position sensor is showing 4.4 volts at full throttle. If I can get that to 5 volts it should make a difference but it hits a mechanical stop on the sensor.

Would you be so kind as to let us know how much that cost?

It was $1500.