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Common om617 Upgrades

The om617 has been used by enthusiasts for off-road swaps for some time now. Swappers have come to learn about upgrades available and how to tap into the potential of the engine. Recently I have had a number of classic Mercedes owners come forward, looking for more power with minimal modification to their classic investment.

The recommended starting point is to make sure you have a healthy and tuned engine at the get-go. Once it’s dialed in, the upgrades can begin. Please keep in mind that the information does not take your local, state or country’s environmental regulations into consideration so please do your own due diligence before pursuing an upgrade. 

  • Fuel. Having more fuel to burn is essential for power. There are two types of injection pumps available for the om617: M and MW pumps. Currently, we can upgrade either pump type by outfitting your pump with Dieselmeken’s 7.5mm elements. Pumps are cleaned, tore down enough to perform the upgrade, resealed, and bench calibrated.
    • M Pumps. The M pump is primarily a European pump. It has the potential to be calibrated for more fuel and will get Dieselmeken’s outside ALDA kit. This kit will allow for more adjustability. The pump is difficult to find in the USA market
    • MW Pumps . The majority of domestic (USA) customers will opt to have their MW pumps upgraded. These get calibrated to 90cc. Some of the backyard hacks that have been promoted by some are to remove the ALDA and rack limiter but with the increased element size, these need to be present to avoid over-fueling.
    • Lift Pump . The lift pump is the “fuel” pump located on the side of the injection pump. While having the upgrade performed on the injection pump, it is recommended that you rebuild the lift pump. It is a very easy task and a search on eBay for “Bosch 2447010004” or “Bosch DGK301” should yield a rebuild kit in the neighborhood of $11. These kits often accommodate several different models of pumps so expect leftover parts at the end.
    • ALDA Hose . On the back of the intake manifold, there is a banjo fitting that needs to be connected to the pump’s ALDA fitting. The pump needs to “see” the boost for proper operation. Some of the older cars have a valve on the firewall that the boost line connects to. We recommend that this be bypassed and the pressure line runs directly to the pump.
  • Turbo. With more fuel in the engine, you will realize more power but you will probably also see a lot of black smoke. To capitalize on that extra fuel, more air needs to be combined to allow it to burn. This comes in the way of a turbo upgrade. The Holset HX30 has been the turbo of choice on the om617 for quite some time. It has a T3 turbo flange and can bolt directly on the exhaust manifold. There are some considerations:
    • Fitment. Just because the turbo bolts up, it does not mean that it is a complete, drop-in solution. The compressor housing on the turbo needs to be “clocked” so that the oil feed and drain are as close to vertical as possible and the compressor housing points in the direction that it needs to go. Chances are you will need to replace the studs on the exhaust manifold and introduce a spacer to allow sufficient room to orient the turbo correctly.
    • Oil lines. Any hydraulic shop can crimp a nice braided line to meet your requirements. For the drain, eBay may prove to be an affordable source.
    • Exhaust outlet. The Holset models we sell have a 79mm diameter v-band flange. This is an odd size and we have seen people cut the flange off of their new turbos and weld a new flange on or buy an aftermarket backing plate. I could not stand either of these options so I had 79mm v-band to 3” exhaust adapters made. I cannot get behind bastardizing a new turbo for the sake of an exhaust connection.
    • Compressor outlet. Like the exhaust, the compressor housing also has a non-standard size. To connect the compressor side, we have both Cummins 90 degree elbows as well as our own HX30 compressor adapters. Both terminate in a 2.5” coupler size for standard intake tubing.
  • Intake. The most common style of intake manifolds are:
    • Turbo manifold. When first bolting the HX30 up to the exhaust manifold, it looks like it will point directly into the intake but it is a little off. The angle of the compressor housing is not a straight shot. Many people will use a 90-degree elbow, cutting it at the appropriate location in the bend, and weld it to the turbo intake. Be sure to see “cooling” below if you are going to take this route.
    • Om617 NA manifold. Using a naturally aspirated (non-turbo) manifold is a bolt-on solution, eliminating the need for welding. Since the inlet on the manifold is pointing straight up it provides a convenient way to add an intercooler.
  • Cooling. Compressed air from a turbocharger is hot, very hot. This decreases air density in the intake system and increases exhaust gas temperatures (EGT). EGTs that get too hot can lead to catastrophic failure; cooling is important. Cooling that compressed air will increase air density, allowing for more oxygen to be present by volume, and lower EGTs. Driving style will have a lot to do with your needs. Here are a couple of options.
    • Intercooling. This is the recommended solution. There are “air to air” and “water to air” intercoolers. Intercoolers almost always come down to space availability and budget. Air to air is the most cost-effective and easiest to install. If you are upgrading a 4x4 and aren’t afraid to take your ride off the pavement a top mount intercooler should be considered so it doesn’t get damaged. For most of us pavement bruisers, a front mount is the ticket. The quality of the intercooler is important to avoid pressure drop. Also make sure it is rated for the boost you will put through it.
    • Water/Methanol. There are many benefits to meth injection. A properly sized system can greatly reduce EGTs, increase power, and are seemingly easy to install. The drawbacks are the reservoir size needed for the mixture and the need to monitor the fluid level. Some options exist to dial in the meth system based on meth fluid level, boost, throttle position, EGTs or combinations of those inputs. If you are running your turbo directly into your intake and driving the car like you stole it, you are asking for trouble. This may be a good option for you – you will need to do something.
  • Misc. Modifications.
    • EGR Delete. I would consider an EGR delete kit to keep the intake manifold clean and keep the air as cool as possible.
    • Filter Housing & Fittings . The fuel filter housing can be a point of restriction. In comparison to the tube diameter from the tank, the fitting on the hose coming out of the lift pump, the holes inside the filter housing, and the fuel filter banjo bolt can all be increased if necessary. For most, this won’t be necessary but for the few that want every extra bit of performance, this is something you can try.
    • Tank Screen . Old Mercedes have screens in the fuel tank. If you ever suspect low flow, you can remove the screen (threaded fitting) from the bottom of the tank and check. It isn’t a fun tank as you will need to catch all the remaining fuel in the system but it can hinder fuel flow if its full of debris.
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