N55 F30 Top Mount Turbo Kit Development

Hi guys, I thought I would share some news on what we've been working on at the shop. We have ourselves a new player in the N55 upgraded turbo game. With such great results with the N54 turbo kits I figure why change things.  We will use all the same great parts (Precision, Tial, Vibrant) even the same size exhaust tubing, hell we are even using the same head flange.  There have been some tweaks but the new kit is practically the N54 kit. We just had to make some small adjustments to accommodate the new chassis.  So we know the kit is easily capable of 700+ hp. But we also know the N54 motor is known to hold much more power than the N55. We have decided to use a smaller 6062 Gen2 turbo for now until we throw a built motor in it which will max out at 650whp and will produce a very factory like spool.  The one thing we made sure to focus on was to keep drivability.  It's one thing to make 600hp, but its another to have that type of power and having the car start up and feel like it is completly stock. 

So far I have only put a few miles on the setup. I am running only off the wastegates right now which is set at 10psi. Terry has sent the single turbo firmware for JB4 so hopefully I will have time to load that up this weekend and start to control boost.

I am also working with Precision Raceworks with their fuel components to get some good fuel in before we hit the dyno.

More info to come but for now I will leave you guys with some pictures. I will have some videos soon also to show how the exhaust sounds with a tubular manifold and open wastegates. 



It's a tight fit but it's in there. This time around we had our own shorty air filter to use versus the turbo screen we used on the N54. The engine cover has to be trimmed but as you can see it can look very factory if done right.

Twin Tial MVS wastegates are being used as they have been proven to control boost very well.  They are mounted down low away from all the heat.  This will make it easy to change out springs if needed.  You will not have to take off other turbo kits components in order to service the kits.  On the development car we have chosen to go open atmosphere dump, we want to hear when it hits full boost.  There will be an option to go recirc when we start to manufacture the kits for guys that don't care for that. 

Here is a rare shot of the manifold.  Notice it has a v-band connection going up to the turbo.  This makes installing the kit that much easier by just tightening one nut for a full connection.  This was something that we wanted to do on the N54 but because of how the O2 sensors were setup with the twin turbos it required us to do twin scroll.  We have free range on the N55 because they came factory with a single turbo.  Some might be thinking we're going to lose some spool by going away from twin scroll but lets hold off on speculation until there are some results.   We can always go back to twin scroll if needed. 


One last thing I want to show is this custom billet machined coolant neck.  The factory piece could have been left in place but if you have ever held one in your hand you will notice there are some kinks in it that may cause overheating issues down the road.  The kink in the factory pipe is there to get around the factory turbo which we have tosed.  I figured while we are here and about to double the factory horsepower rating we may as well help the cooling system as much as we can. 

Written by John Pham — March 16, 2017

DOC Race 335i 135i N54 Single Turbo Kit Videos

With many of our turbo kits now installed and on the streets we are finally able to capture some of them in action.  The first video shows the shop car which made 750hp@30psi tuned by AD Engineering.   



This video shows our newest AWD kit which is now available making 534awhp@18psi with a PTE 6266 turbo.

And then we have a little bit of street action going. 

We hope to have more videos coming in as more of them will be installed in the upcoming months.  


Written by John Pham — May 19, 2016

BMW 335i single turbo kit is now available!

Our test car was bought completely stock with the thought in mind of 335i owners looking to make more power from their N54 engines with an otherwise stock car.  The very first mod that was done on the car was the turbo kit.  Originally a bottom mount kit was designed using a Garrett 67mm GTX4088R turbo.  We were not very happy with the design of the log manifold and how laggy the car felt we were back to the drawing board to see how we can get some torque back into the engine without choking it up on top.  The only way we know to do this is to design a longer runner manifold much like we did with the S54 engine which has been proven to make great numbers and take a beating on very competitive race cars.  But making a part like the S54 top mount race only manifold fit into a street trim 335i is a task on its own.  After we pulled the car in and started tearing into build again we came up with a design very similar to S54 without having to delete or relocate any major components.  We were excited to see this manifold in action on an N54 motor and this time with a much smaller 64mm turbo. 

The car was driven daily for a few months to work out any kinks before hitting the dyno and the only issue we had was a small oil leak that was caused by a loose fitting.  Other than that the car ran flawlessly.  In order to make the type of power this setup is capable of we contacted AD-Engineering who agreed to help tune the car.  A new list of AD-Engineering parts were now being installed which includes their Port Injection kit, dual core 1000hp intercooler, and the oil catch can.  We also ordered a Motiv twin disc clutch to hold the power. 


The end result tuned on C16 by AD-Engineering is 749.8whp@30psi.  At 20psi it puts out 565whp and that’s where it’s ran on pump gas plus meth.


Currently the kit is on the site and can be found here 335i Turbo Kit.  


Written by John Pham — February 23, 2016

V-Band fittings available!

We here at D.O.C. Race are always bringing you the best products we possibly can. We are also leading the way with industry changes and standards. With that being said, we now offer V-band flanges for all of our manifolds. We have actually been offering these for a while now but wanted to make sure the news got out to everyone!

Why use V-band connections? V-band clamps are the preferred connection for many turbo housings and most any flanged joint. They have been used for years and have proven themselves in racing applications from the Indianapolis 500 to Bonneville land speed cars. They are easy and quick to remove and can be done so many times while still offering a leakproof seal without using pesky gaskets. Unlike bolted flanges, V-band clamps apply equal clamping force around the entire circumference of the flange. They really offer the best connection you can get. The biggest advantage to v-bands is the flexibility they offer. Most turbo manufacturers offer V-band flanges today so this makes it easy to pick and choose your exact set-up! Basically any turbo on any manifold!

Make your install painless, clean and, up to date! When placing your order look for the v-band option in the inlet flange drop box!

Turbo and wastegate mounted with V-band clamps on our E46 M3 Topmount Twinscroll manifold


2JZ Manifold with V-band flanges


V-band flanged turbochargers

Written by Robert Hardin — March 18, 2015

335i Twinscroll Turbokit

After developing the first turbo manifold design for the Horsepower Freaks 335i single turbo-kit, some changes were necessary to attain proper tuning feedback for their ECU parameters. While making these changes, we promoted a twinscroll version for the next design giving benefits across the board; including the tuning portion being addressed.


A pair of open atmosphere dumptubes were aligned to the Tial MVS wastegates alongside of the 3″ turbo-back exhaust..


There really isn’t much room around the exhaust bank of the N54 engine, so this manifold design has completely changed from the original test-piece to implement the divided turbine housing and now Dual Tial wastegates. The new design allows direct control of the front and rear engine “banks” (cylinders 1-3 and cylinders 4-6) for the wastegate/boost controller and equalizes exhaust flow with equal-length runners feeding into the turbocharger.



The car is now back together for continued development on the computer system for the single turbokit. Visit Horsepower Freaks for your 335i upgrades!


Written by John Pham — February 18, 2015

SR20DET O2 Housing

New products for 2014 at DOC Race.  With so many request for new products we felt the need to help the market with our new SR20 O2 housings.  Currently the only worthy company producing these are on national back order.  We are in the designing process and will release these to the market some time in the next couple months.  Check back as we will be updating as we move along.


This shows the significant difference in overall size of our housings versus the factory.  Our housings are made of 3" OD tubing.  Factory housings neck down to 2.25".


Written by John Pham — January 27, 2014

S13 Street

Quite the production and process of building this damn car, so many design plans and counting. Getting it road worthy became a reality just a week ago so here we go…


We have came a long ways and are in the “final” stages of the build process. The vehicle is under it’s own power with a conservative wastegate spring/pump gas tune to get it on the streets sitting at 450whp.


A lot of adjustments are being made, suspension is far from setup to get the car trackable. No better way to work the bugs out then daily drive a car and put it through normal wear and tear. Surprisingly with all of the modifications and part replacements this car has been mechanically sound. I suppose it should be fine since everything is new but that is just me preparing for the worse. The amount of tools i’ve carried in this car since driving it would put some workshops to shame…


Initially getting the car onto the road the brakes were dragging…The braking system on this car is a Brembo Gran Turismo setup that has been custom coated to the D.O.C flourescent green scheme. To support the larger caliper duty, a brand new 300zx master/booster combo was added coming with a larger diameter master cylinder piston. That ended up being the issue, a small pedal adjustment was made and the brakes are beyond golden. This car stops like nothing I have every experienced in my life…


The cooling system is a very unique design with quite a few different goals in-mind. One of them being since this car is daily driven, temperature needs to stay reasonable for traffic and complete grid-lock. We have a motto at DOC Race, if your stopped stuck in traffic what the fuck are you driving for anyways?! You should be moving atleast 30mph of air and that has been more then enough to keep the DOC Supra cooled even in 90 degree weather. I would be speaking of absolutely NO cooling fans in this system (which sounds crazy to some), by taking the Supra to PARC (Pat’s acres) we had some temperature issue’s due to the short track/low airflow conditions. The S13 has a custom Dual-pass Ron Davis radiator which was specifically designed for this vehicle, giving it the best radiator ability within a mechanical water pump system.


The V-mount design also alleviates airflow being blocked by the intercooler, decreasing the cooling ability of your radiator. Front-mounts are so 1992, can’t forget about your cooling system!


Another key to this v-mount system is the airflow escaping through the hood vent drawing thru the intercooler. This specific hood has a large cowel drawing engine bay heat from the rear of the bay and out of the windsheild/firewall cavity as-well..


We don’t have a ton of HOT weather in the Pacific Northwest, recently we have been pushing around 90 degrees but tend to have higher humidity then the dry heat climates such as California or Arizona. This has been a great test on cooling abilities and I had an un-expected test last week sitting in 95 degree weather on the highway, full grid-lock with no cooling fans or anywhere to go. Car did fine through 35min of this traffic, no airflow or speed to help cool temps. Going into downtown Portland limping around the one-way streets in more traffic, we were stopping for lunch and as we pulled up to park I noticed the temperature just coming above the desired running temp. Not too bad if you ask me! Again, if your sitting around in traffic this probably isn’t the most entertaining time to be “enjoying” a drive so I don’t focus on rush hour times to drive anyways; it has done well though and I have been putting it through the paces to find any type of limit/issues with things.


Still have tons of plans and parts going on the car so as the bugs get worked out we will knock down the lists of improvements and upgrades. In the end, getting this car on track will be a large focus while still being more then streetable driving it to-and-from the track for whatever event is on the menu. It’s thoroughly enjoyable to drive even with 4″ oval side exit exhaust, Magnafuel Gear-drive external pump, Cusco 2-way differential and a plethora of other “inconveniences” to enjoy driving a vehicle on a day to day basis. About the most comfortable i’ve been cruising to work everyday in a lot of years.


I’ll have updates periodically as there’s lots of things in the works to continue reaching this projects goals. Baby steps I tell ya, baby steps….




Written by John Pham — November 25, 2013

S54 Twinscroll Topmount

I’m just going to place some of our production process pics for our S54 twinscroll topmount right here.


In this case, we are building a slightly different variation of “up-pipe” from our standard divided T4 design and fabricating it to accept the stainless steel twinscroll v-band merge from Garrett Turbo.



With the up-pipe in place, everything was disassembled and the tubes were welded in sections for a re-fit.


Up-pipe sections welded up, a re-fit was done and the v-bands were welded up. Sequencing to the merge collector from Garrett and the up-pipe is complete. With this setup (Platteforme A.G. time attack manifold) we are running a single 44mm outlet merge for the wastegate.


We fit the setup onto the S54 engine and built the dual merge outlet. With a direct path of flow to expend an ample amount of gasses into the outlet, for optimal boost control from the single gate.


Global Time Attack will be one to watch with Platteforme coming for blood!


Written by John Pham — October 24, 2013