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On3 Performance BMW 335i N54 Top Mount Single Turbo System

  • Sale
  • $2,995


Over the past year we have been developing one of our newest turbo system options. It was brought to our attention by a friend that the BMW’s needed a new option. We know turbos well and figured it would be a change to get involved with the N54 platform 335’s. There are not a lot of options and those that are would generally require you to take out a small loan. We have set out to change the market and design an affordable, top mounted, single turbo system. From a design standpoint, this application is a challenge with the tight engine bay and a lot of tubing to fit in a small space.

Our system starts with a completely custom designed manifold that is a 2pc design. We have designed it from an extremely thick schedule 40 tubing and only use 304ss for the construction. By making this unique manifold, it allow for a much easier install. Most of the single top mount kits also require you to modify the factory coolant line as its routed through the same area where the factory turbos are. We took serious attention to detail and built around it so it retains the hard aluminum tubing. This is not a good area to run rubber hose like some systems do. Sure it would be easier but in the long run, we have a better design. Our manifold is designed to use our On 3 Performance 44mm v-banded wastegate to control boost. Out of the box your kit will be setup to make around 14psi on wastegate pressure. Coming out of the wastegate, we have it setup to atmosphere. Let me tell you personally, this car has factory exhaust and sounds pretty much like any other 335 driving around….until it rolls into boost. We build a lot of cars around here and this 335 engine rolling into boost sounds like nothing else we have worked with. The exhaust note is amazing and just right for for this caliber car that has all the comfort and now the power to back it up. The 304ss dump tube routes down from the wastegate and terminates right at the factory exhaust connection.



Turbocharger Details
Our turbo system was designed around 2 of our already popular turbochargers. The first option is going to be the On 3 55mm GT30 turbocharger. If you are looking for the quickest spooling option and sticking to around 450-500hp max range, this will be the option for you. Although spool time will be almost identical(~300rpm slower), the On 3 Performance 61mm GT35 is the top shelf and will yield the highest HP that we can offer. You will be able to select when ordering your system two other options. The standard option included is our journal bearing turbo and dual ceramic ball bearing is offered for a small fee. This turbocharger is one of our newer models and has a very trick feature. We had this exhaust housing cast from stainless steel and best of all it is v-banded inlet and outlet. With any tight engine bay, this is key to allow for endless adjustments. This will not only look great but when the install time comes, it will make life that much easier.

Moving the air out of the turbocharger, we designed a 3″ downpipes from 304ss. This will take the gases back to the factory exhaust location and splits into duals. With each kit we also include the necessary stainless steel v-band clamps to secure the turbo in place, downpipes as well as the needed clamp for the turbo manifold. To make our kit that much easier to install and to keep it a direct bolt on, we also include a set of billet fittings to help with a number of complications. When removing the factory twin turbos, that will leave oil ports for supply, draining as well as water passages used for cooling the stock units wide open. We had custom machined billet fittings made to do the following:

Billet Plugs Factory Water Ports
Billet Plugs For Factory Oil Supply Ports
Billet Plugs For Turbo Water Drain
Billet Plugs For Factory Turbo Oil Drain
Custom Billet Oil Supply Fitting for New On 3 GT Series Turbo
Custom Turbo Oil Restrictor Fitting
Custom Billet Turbo Oil Drain (Into Engine Block)


Cold Side Technical
To address the cold side, coming out of the turbo we designed a short 2.5″ charge pipe out of the turbo to the massive 7″ core On 3 Performance air to air intercooler upgrade. In order to maximize power to redline, the IAT’s with the factory intercooler will become a problem. Airflow surpasses what the factory air to air will handle and start delivering hot air to the engine. As that warms up, the computer starts pulling timing and that will become a power loss. Cool the air with the new 7″ On 3 Intercooler and your not pulling timing, air temps drop and everything is good. Although that is all that is required to get the car running, we didn’t want to stop there. We wanted to improve upon what most see or already on the market. So we also designed a custom throttle body charge pipe to include with each turbo system standard at no additional cost. This is a 3″ polished aluminum charge pipe and also intergraded in our 50mm On 3 Performance blow off valve flange. Each system will come with the 50mm On 3 blow off valve, this will not only sound good but fight compressor surge. Most will look at this feature and like it for the sound but its a very crucial piece to a turbo system to keep the turbo alive. Also hard to see but we do have the map sensor bung welded in so its ready for a plug and play install. Another touch which was not required was the power steering reservoir. We built a custom billet aluminum fabricated reservoir which contains a custom washable filter element. This is simply a nice dress up item to the engine bay, clearly not required but looks sleek and how BMW should of produced the car. They just forgot to call and ask us for our opinion