OM606 NA-T Guide

The om606 platform has gained much popularity over the last decade with the advent of easy to access parts and growing knowledge of the platform. However, the subject of using the N\A version of the engine in a performance application is still a bit taboo and for good reason it has finite limits that simply don’t coincide with most people’s power goals. Let’s just get it out of the way you physically cannot make 400+ hp with an unopened N\A engine and every single digit past 300HP will just be getting you closer and closer to a nice window in your block. Realistically 300HP is the limit and if that’s too little for your application then you must break open your pocketbook and either get a .961/962 (OEM turbo engine) or purchase some rods that fit the 26mm wrist pin.

If you choose to use the N\A piston in your build, be aware that it does not have a full skirt like the turbo version and in general is a weaker piston. Mercedes never intended these motors to see large amounts of fuel and manifold pressure so it makes sense that the components chosen were extremely light and therefore weaker.

You will need a turbo manifold there are several options available you can use the OEM turbo manifold or if you have some fabrication skills the OEM N\A manifolds can be used as twin scroll collectors. There are several aftermarket turbo manifolds that all work great, the best solution that we know of however is the Kangaroos Team they offer just about every version of an OM606 manifold you could want and their casting quality is great for the price, I must add in here Benzforce just dropped their own cast manifold and while we don’t have r&d on it yet it does look very nice. Also it must be noted there is 0 difference in port spacing / shape between N\A and turbo engines. If you are a good fabricator then just make your own manifold there are a few head flanges on the market and nothing beats a v-banded turbo manifold om606/605 for sound. Wastegate sizing/location when it comes to keeping your na from bending a rod is important. All of the aftermarket manifolds have previsions for a single 40/44/50 and all of those options work great in the past we have put a 44mm gate directly on the turbine housing and have had great results it also is super easy to access that way. Whichever route you chose just make sure your boost pressure is regulated according to the size of the turbo you chose to run.

On the intake side you have a plethora of available options all of which when talking about an unopened na engine will work and there really isn’t any advantage or disadvantage to either. The stock na intake has very long runners and therefore a bunch of volume don’t forget that diesel power has no throttle blade so the runner length really doesn’t matter like it does on a gas powered setup. What we have done in the past was to take the stock crossover pipe and modify it to fit a single 2.5 intercooler pipe it then connects to the oem intake manifold with the stock single m6 fastener. If you decide to go this route you must I repeat MUST weld up the oem pcv ports on the topside of the intake right near the cylinder head. The entire stock pcv system on the intake must be eliminated if you don’t do this youll send boost into the crankcase and you’ll be wondering why the engine keeps shutting off when you floor it. K2 designs offers a plenum solution that looks very slick and if you’re a tig welder this type of design is easily copied. If you don’t have a tig welder or know someone that does don’t fret there are many other options, kangaroos team and dpuk, both offer plenums that are extremely short and minimize plenum volume tominimize spool time. Whichever option you chose will work and as stated previously on a lower horsepower setup it really doesn’t matter.

Now this is the important stuff, while your na om606 might be able to spool a gt37 no problem, can it actually use it? If your engine is stock the answer is no, the stock rods will exit the building the second you make real power. That being said having driven both small and big turbo unopened na om606’s the big turbo just feels better its way more of a rush when the boost comes in and with a bigger turbo in our experience it tends to get less hot when driving on the freeway, around town not so much. What we’re trying to express here is that you can use everything from a stock om606 turbo all the way up to turbos with a 82-84mm exducer on the impeller. The sweet spot is the medium sized options like the borg s200 holset he30 and the gt3071, its all about limiting that top end though because the bigger the turbina is the more of a ticking timebomb it is. Realistically an unopened na engine will survive 1 bar from any turbo but getting up to 1.4-1.7 is just asking for it no matter what turbo you use.

Think of the injection pump as your fuel pump ecu and wiring harness all wrapped up in one and you can start to appreciate what a masterpiece the Bosch R series pump is. As with everything there’s a lot of options whether you build a rs156/203 or an edc pump you can’t go wrong so long as the pump builder you use is an experienced builder who knows your exact goals. Dieselmekken is the original and still the go to name in the om606 world and for good reason that being said we have found success using dpuk, anchev and wicked injection pumps. You can build it yourself and save some serious money but be prepared to learn along the way and that’s really what you’re paying for with choosing one of the aforementioned builders. Element sizing is important here and to be honest you can get away with a 6mm element sizing for a na-t, however we have used 7.7 and 7.5mm elements and to be honest the 7.5 really is the sweet spot in our opinion, but that’s the best part this is merely an opinion if you ask 10 om606 builders what they’d do for na-t you’ll get 10 unique answers because there really is no bad way to get it done. Whether you opt for a stock edc turbo pump or get a mekken 7.5 mechanical you cant go wrong. Edc pumps are very cool and offer tunability with the oem ecu, sean tracy is the go to for om606 tuning and has been for the past decade. While edc is cool it kind of misses the main advantage we love about the platform the option to have an engine that runs 100% mechanically with 0 wiring except for glow plugs and a starter wire. The oem lift pump will flow enough fuel to window the block on a na-t so there really isn’t a need to upgrade the lift pump unless you have a built motor. The mechanical pumps use a vacuum shutoff so you will either need a vacuum solenoid ran from the vacuum pump or a ball valve if you’re cheap.

Later model na om606’s came equipped with the same vacuum pump from factory that the turbo engines came with and to be honest this pump is a big upgrade, the early model 95-97 engines have a wheel that rides on a cammed path that is part of the injection pump sprocket. The later model uses akeyway on the sprocket that fits into the pump and is a far better system. If you can get the later model na for this reason alone. Turbo feed / drain The easiest way to handle the feed is to take the m14 x 1.5 plug out of the filter housing and run it over to the turbo feed. There are remote filter options available that have a npt port as well if the oem filter housing doesn’t fit in your application E30/36/46 guys I’m talking to you. For the drain the best way to do it is to take the pan off and weld a -10 bumg onto it. That being said most modern car enthusiasts are a tad lazy, you can route it through the oem dipstick and it will handle the job I wouldn’t recommend this route but it must be stated that it will work.

Unfortunately these years of na om606 that has a couple of issues that need addressing if you want to maximize your time ripping and minimize failures. For starters the harmonic balancer is a 2 piece design on these that’s carried over from the om603. Simply put its heavy and failure prone, not to worry though the 96 and on motors came with a single piece design that’s far lighter. These also have an oil warmer/cooler that’s integrated into the oil pan, the o-ring on the pan is prone to leak and the location is annoying to say the least. If you wany to remedy this issue you will not only need a later model pan but also the later model oil pump that doesn’t have the warmer priority system.