Very proud to say that we’ve achieved some great results with this car using VersaTuner and the local fuel. It is running a GTX3071 turbo on the stock motor, stock clutch, and pump gas. The car has all the intake and exhaust supporting modifications. Victor has been a pleasure to work with and has provided the final dyno numbers!
Victor’s MPS made 350whp with a broad torque curve with boost peaking at 25psi. This is about the power limit of pump gas (knock limited) on the DISI motor.
One of our customers, Corin, just participated in a dyno day and sent back his sheet and a photo. This is a 2008 MS3 on 93 octane with the following mods:
jbr 3.5″ intake
gs 3 port ebcs (2 port mode)
cobb xle bpv
tb coolant bypass and tig
cp-e catted dp
STRATIFIED tune
Very consistent numbers at 295whp and 350ft lbs of torque! Looking forward to the E85 tune that should put this car well above 300whp. Awesome car Corin!
MS3 aftermarket catless downpipe versus the stock downpipe. Credit: ATP turbo
A downpipe on any turbocharged engine, if well designed, can have a positive effect on performance. If it is a better flowing unit (less restrictive) than what it replaces it will increase the pressure differential across the turbine and reduce the pumping losses of the motor. This means that the turbo will spool faster, possibly hold more boost, and the motor should also move more air per stroke. In theory this sound great but numbers are even better.
We’ve had a customer who is very consistent with his logging meaning the data logs are taken at similar ambient temperatures and the same altitude. He was able to provide several back to back logs showing the difference between a stock downpipe and a stock downpipe with a gutted catalytic converter.
As a general rule of thumb, a catalytic converter should always be used (a high flow one is fine) but this comparison shows the ballpark difference we can expect from adding a downpipe (or gutting the stock one) on a stock turbo (k04) vehicle.
The results are below. In a nutshell, the turbo will spool faster but more importantly the engine flowed on average 5 g/s more mass air past 5500 RPM. This is worth about 5-7 horsepower at the wheels all else being equal and the gains are coming from a reduction in pumping losses alone – not an increase in boost.
Is this worth it for you?? Well that depends on your perspective. On the same vehicle, the air filter can be worth about the same in terms of power, and a 3″ intake to the turbo is worth TWICE this. That being said, the improved spool and throttle response (as well as sound) from installing a downpipe are much harder to measure and these can make for a more pleasant driving experience.
Happy Tuning!
To facilitate one-stop shopping and offer a discount for the “tuning essentials” for the MazdaSpeed platform we are now offering COBB AccessPort and Stratified Custom Tune bundles. You can further customize your order with Autotech HPFP (fuel pump) internals if you need these as well. The HPFP internals are needed for maximizing the power potential even on the stock turbocharger!
Happy Tuning!
Many modern gasoline engines utilize direct injection technology (GDI) versus port injection (MPI). This technology is actually not something that was invented in the last couple of years although it has been commercialized recently (Mazda DISI, Ford Ecoboost, etc.) Direct injection has been experimented with since the 1990s. Mitsubishi was one of the first companies to work with this technology and it has been written about academically throughout the last couple of decades. Below is an easy to read paper on the topic. It is on the technical side but offers good insight into direction injection and its advantages.
