On 3 Performance BMW 335i N54 Top Mount Single Turbo System – T4 Manfold Upgrade

(1 customer review)

$4,250.00 $2,699.00

No deletes from the kits, do not email or call about this!!


***5-11-16:  We have this kit stocked and ready to ship.  The amounts are limited at this point but we are current with orders placed and we have several systems on the shelf right now ready to ship out.  If you are interested in a kit, please let us know.  The wait was long, development takes a lot of testing to ensure we put together a proven system that does what we advertise it to do.  For those that have been following our design and build stage, the time is here and we are ready to fulfill the orders!


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.  This is our newest option that we have developed for this platform and its currently in stock.  Our stage 2 T4 kit will now support our larger 60mm and 67mm ceramic ball bearing turbo line.  This kit will be more focused on the customer wanting to support 550 – 800 crank HP.

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 our already popular turbocharger line that have powered other cars into the 8’s in the quarter mile.  The first option is going to be the On 3 60mm T4 series turbocharger.  If you are looking for the quickest spooling option and sticking to around 500-650hp range, this will be the option for you.  Although spool time will be almost identical(~300rpm slower), the On 3 Performance 67mm 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.  We had this exhaust housing designed and cast specifically for our line of turbochargers 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

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There is only so much reading one will do before losing attention, here is a few video clips from us strapping the car down and testing throughly testing this turbo system.  The video doesn’t do the car justice and it sounds amazing.  We are still testing with downpipe back factory exhaust.  Clearly we are leaving power on the table without upgrading that yet and still making the numbers.  Being that there is not any control currently for our tuning to adjust timing, we have so much more potential in the future with this car.  Keep in mind we are on an entirely FACTORY fuel system, 93oct fuel, no meth and all boost:

Here is a quick clip of the car doing a 40 roll on around 19psi, sounds AMAZING!


Back to the details…

Dyno / Boost Details

All customers looking are clearly going to be focus on power potential clearly with this turbo system upgrade.  Right now if you have a factory stock 335, you can compare our numbers simply to what you would/can make without other supporting fuel, trans, etc mods.  We are sitting at just shy of 17psi right now with the car and its starting to lean out so the factory low pressure pump is only going to support roughly 480rwhp.  We had to bow out at this point although we are more than pleased with the power and the level of boost currently running.  We hope to work with a new tuning software company, upgrade the fueling and go back for more testing.  Our target for this car is going to be around 525-550 wheel as thats going to bring us to the limit of the factory transmission(automatic).  This is also an important point as we would be making slightly more power with a manual transmission car so we are eating up a little power for those strictly interested in power numbers.


Intercooler Technical DATA:

We initially base lined our test car with the factory intercooler at ~17psi of boost.  Since then, we upgraded the car to our new 7″ Core 335i Intercooler and went back to the dyno for a few more pulls.  Not surprised, the IAT’s were down and from the start of the pull till the end, we are only getting about a 10 degree rise.  The pull was starting at ~100 degrees F and ends right at 110 degrees F.  This is a HUGE gain and by simply keeping the temps cool going into the engine.   We were down 1psi at 16# of boost and making 40 MORE HP to the tires at 6100rpm.  So if you are pushing the stock turbos or on an upgraded turbo setup, this is a must have.  We do sell the intercooler upgrade by itself so check out the BMW section for that specific upgrade if you are interested.  Serious power potential and keeps the IAT’s in check.  This is included with your turbo system purchase so your going to have the most efficient setup and coolest air charge temps possible  


Keep in mind with this car, its a completely stock 335i we started with, there is zero upgrades and it is an AUTOMATIC transmission so our numbers will be a little lower than a manual car(still making killer power).  We are running out of fuel so the stock low pressure pump needs upgraded if making anymore power than this.  We are more than satisfied with the system and easily going to crack 500rwhp after the pump upgrade.  That is the only thing holding us back right now and this is on pump 93 oct fuel, 7 degrees total timing!








Included With Each System:

  • On 3 Performance 2pc SCH 10 304 Stainless Steel Turbo Manifold – T4 600+HP Option
  • On 3 Performance Massive 7″ Core Air To Air Intercooler
  • 3″ 304ss 16 gauge Tig Welded Downpipe
  • On 3 Performance 6466 Billet Wheel Journal Bearing V-band Turbocharger  *Other Upgrades Available
  • On 3 Performance Cast Turbo Exhaust Housing
  • On 3 Performance Oil Feed System
  • On 3 Performance Oil Drain System
  • Billet Machined Custom Turbo Fittings
  • On 3 6061 Aluminum 2.5″ Charge Pipe
  • On 3 6061 Aluminum 3.0″ Throttle Body Charge Pipe
  • 5 ply Silicone Coupler Kit
  • Stainless Steel T-Bolt Clamp Kit
  • On 3 50mm Blow Off Valve Kit
  • On 3 44mm Wastegate Kit
  • Custom Billet Aluminum Power Steering Overflow Tank
  • Instructions and Support From The On 3 Performance Staff


Coolant Overflow Tank Relocation Info:  We get calls on the coolant tank and what needs to be done very often.  It cannot stay in the factory location as it interferes with the tubing and the way we have it routed.  It simply is relocated to the firewall, if you need photos, please let us know and we can send you exactly how we have ours mounted.  It doesn’t require any brackets or anything special, you can simply drill a few holes and bolt it right to the firewall on the Driver side.  We then run a new coolant hose to make the connection for the extended area and your good to go!


Want to see the prototype car run, photos, and anything new?  Follow us on instagram, On3Performance is our user account, that is where all the sneak peaks happen.  We already have some other photos and video currently posted

1 review for On 3 Performance BMW 335i N54 Top Mount Single Turbo System – T4 Manfold Upgrade

  1. Joshua

    Do you guys have these in stock?

    • admin


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