Modifying your car is always fun and I haven’t had a car that hasn’t been modified in some way. This TT RS is no exception. On some cars I’ve only had a tune, other cars a suspension and wheels, and a couple of cars fully custom. This has become a car which is being modified to a large extent. In February it was time to change the turbo.
Modifications usually start with simple things, wheels and tires, a tune and other easy mods that don’t require permanent alterations. I did mine in an odd order.
First I started with downpipes and mid pipes to get more sound out of the car. It was way too quiet and I needed to hear that beautiful five cylinder note.
Then it was time for a tune. First it was just a stage 2 tune with 91 octane as fuel then it moved into stage 2 E70 mix by putting a couple gallons of gas in for every tank of E85. That worked for a bit. I soon got tired of mixing fuel so I upgraded my low fuel pressure injectors and put in a low pressure brushless pump from Iroz Motorsports.
Keep in mind that at each stage I thought I was done, I didn’t need anymore power. I was pushing 480 wheel horsepower in a car that weighs roughly 3350 pounds. Why would I need anymore power?
Well when you get used to something you find you could use more. It was time for a turbo upgrade. I’ve met different people through this entire process and one thing has continually led to another. Earlier than I expected, I was finding myself upgrading my turbo.
After a lot of consideration, I decided to go with a hybrid turbo from Pure Turbos in Oceanside, California. I'll explain what a hybrid turbo is in a second. There were several reasons for this decision. Pure Turbos has a fantastic reputation in the BMW community and I wish I had known about them when I had my 135i. I might have gone down a much more powerful option with that car instead of the Dinan stage 2 tune.
Just because Pure Turbos has a great reputation doesn’t mean that they are insanely expensive. They are actually very reasonable in pricing compared to some of the other options available on the market today.
Being local to me was big reason to go with Pure Turbos. I have appreciated all the support they have given me and endless help. My car has been one of the development cars and so we have been ironing out the tuning on the TT RS after the install was done. More on that in a few minutes.
Finally, there are a couple of different routes that one can take when upgrading the turbo on their car. Big turbo setups, which are also called full frame turbos, use a bigger turbo housing and in turn a bigger manifold, turbine wheel and downpipe. Hybrid turbos use the stock existing turbo housing, just a different turbine wheel in the housing to flow more air. Pure Turbos is a hybrid turbo setup.
Let me discuss briefly the differences in more detail. A full frame turbo is capable of making more power when pushed to the max. An easy way to think of it as follows let's use the fire hose versus a garden hose analogy. You can use a garden hose to push 28 pounds per square inch (PSI) of pressure versus using a fire hose to push the same 28 PSI of pressure. It’s the same amount of pressure, however the fire hose is flowing more water. The same principle applies to the airflow from a turbo. A big turbo with larger diameter inlets and turbine wheels will flow more volume at the same amount of boost. There is no getting around the fact that a fire hose or a big turbo will always be capable of more flow and therefore more power.
I went with a hybrid turbo for a couple of reasons. First of all I wasn’t ready to build my engine to withstand all the power that a big turbo can produce. You can tune them to keep them in the safe zone but then I would most likely want more right away.
I went with a hybrid for a second big reason. A big turbo setup requires a different set of downpipes and manifold. That is a lot more money invested to purchase and install them. They look amazing and sound different letting more sound from the amazing five cylinder out.
Above you can see some comparisons. In the first two pictures the stock turbo is on the left and the Pure Turbos on the right. You can see the difference in the turbine wheels even though the housing is the same size. In the third picture is the air inlet to the turbo to be compressed by the turbine wheel. An engine is basically a big air pump getting air in and out and to feed the additional turbo wheel requires more air to feed it. I used an APR inlet and carbon fiber pipe. I’ll discuss that more in the future.
In the pictures below you can see the difference in the install. It looks different even plugged into the stock intake box. These changes allow more flow to the turbo.
Ok going back to the development of the tune for this turbo. This was a completely new experience for me learning how to log for the tuner to see what needed to be changed. Pure Turbos was just finishing up building the first of these and beginning to sell them to the public. There wasn’t a tune available for them at the time of installation. That required working with my current tuner, Custom Code, to tune for this combination.
They developed two tunes at the very beginning to drive it to the dynojet at Pure Turbos. I needed to drive it from HG Performance a few miles away to Pure Turbos to put the car on the dyno. One tune was an extremely safe tune, which is what I loaded on the car first, and one was a more aggressive tune that needed to be tested on the dyno to make sure it wasn't going to create too much torque for the engine to handle. I wanted to keep my rods straight and not bend them under too much stress from the torque created at lower RPM's.
I had HG Performance do the install as I'm not a mechanic by trade and only know enough about mechanical things to be dangerous. I'm learning more day by day but not quite at a level where I felt comfortable doing a full turbo install on my own. HG Performance has done other work for me throughout the past year and a half and I'm always very impressed by the care they take with my car. They provided these pictures for this blog post.
We've gone through a few revisions of the tune but still have a bit more to finish up. I opted to keep the torque levels down since my engine rods and pistons are still stock and not forged. When I build my engine I'll be able to add more torque and power to the mix. So far on the latest revision its made 650 wheel horsepower and 506 wheel torque. My fastest 1/2 mile event I did before the turbo upgrade was 159 miles per hour and with the Pure Turbos hybrid it has increased to 173 miles per hour. You can read about those events in other related posts. I'll do additional updates as soon as I've been able to get a 1/4 mile in. I've also run Big Willow at Willow Springs raceway. I'll need to do more track events soon as well.
Related: Speed is addictive
I've been very happy with my choice of a Pure Turbos hybrid. I know its a great product, I've been extremely impressed with their build quality and with their customer service. They put their customers first and get any problems fixed as soon as they arise.
Thanks for visiting and remember to always "Strive to Arrive"!