Tuning : EVO-X Custom Exhaust, Dump Pipe and Dyno Tune

This EVO-X came to us not too long ago in need of some mechanical revisions after the owner wasn’t completely satisfied with the build outcome at another workshop. As most tuners will tell you, a project is never really complete and this was very much the case with the EVO Ten. The engine build itself was A-Ok, although we did make revisions to the fuel system by completely redesigning it to accommodate the owner’s target goal of 400Kw. When the EVO arrived, the engine was being fed by a single fuel pump and being controlled by a factory ECU that had simply been flashed. Just as we have stressed in our past tuning features, it is imperative that the correct amounts of fuel are being delivered to the motor. With a 400kw target goal, a single fuel pump will simply not suffice.

So with that in mind, our first job was to install the 1800hp Holley Dominator fuel pump into the (already existing) under-car surge tank. The Dominator is essentially a twin fuel pump in a single-billet body. We know from previous experience, that it will consistently provide our preferred minimum of 2L per minute of fuel delivery at the desired power level of 400Kw. On top of the fuel system update we have replaced the factory ECU with a MoTeC M800 paired with a C125 Display. A flashed ECU unit does not allow for custom tuning in real time, meaning that Chea cannot simply put the car on the Dyno and tune the parameters as he normally would. More importantly, we cannot stand behind a flashed ECU unit when a person has poured tens of thousands of dollars into their engine build. Not only is it impossible to tune live but we are also unable to add any protection sensors, which could spell disaster on the next spirited drive.

Spec List :
Built 2.3L 4B11T motor with standard block, no sleeves
Standard 5-speed manual, upgraded single-plate clutch
Under-car Surge Tank
Holley Dominator 1800HP fuel pump system
1300cc ID Injectiors
Radium fuel rail
Full Race exhaust manifold
Borg Warner EFR 8374 (internal wastegate)
Powertune Custom 3.5inch dump pipe
Powertune Custom 3.5inch exhaust
Varex Muffler
MoTeC M800 ECU
MoTeC C125 Dash Display
Fuel Flex sensor
Tuned to Flex 98/E85

After we completed the revisions to the fuel system and upgraded to the M800, Chea could finally get the EVO up on the Dyno to see if we could reach the owner’s target of 400Kw. Instantly Chea could physically feel that the Turbo’s flow was being smothered by a very restricted exhaust system. We could only yield around the 370Kw mark. Now this is where we could take one of two paths: One; Keep increasing the boost pressure until we reach the desired 400Kw target. (Needless to say this is NOT the safe or correct way!) Or two; Redesign the exhaust system to allow for greater flow. Together with the owner we decided that option two was the more sensible one (obvious, right? You’d be surprised!).

To increase exhaust flow, we decided to go from a 3 inch exhaust and dump pipe setup, to a more free-flowing 3.5 inch system ending with a single outlet Varex muffler. This essentially makes it a straight-through exhaust when the valve is in the open position. Our technician, Adam, custom designed and fabricated the new exhaust and dump pipe out of 304 grade Stainless Steel. As you can see from the fabrication photos, the EVO-X makes for a very tight work space but with Adam’s attention to detail, the new setup was done in no time.

Now that we had a high flow dump pipe and exhaust system installed, Chea once again got the EVO up on the Dyno. To no one’s surprise and with NO increases being made to the boost pressure, the EVO hit the 400Kw mark. This immediately justified the modifications because we were not having to increase boost pressure to compensate for the restricted flow. In turn, this meant that we were NOT adding excessive stresses to the motor. Instead, it was quite the opposite. We now had unrestricted exhaust flow, which at the same boost pressure actually took a massive amount of  stress off the engine.

In terms of tuning, the MoTeC M800 had completely opened up the tuning capabilities of the EVO’s engine package. Now that we could safely monitor and adjust the parameters, Chea was finally able to start dialing in the settings. Immediately after the Dyno run, Chea noticed that the Air/Fuel ratio was leaner compared to the previous run that had the restrictive exhaust. This was an immediate indication that the wider diameter 3.5 inch exhaust and dump pipe modifications were effective. (In a nutshell, the leaned out Air/Fuel ratio was directly linked to the increased exhaust flow).

Another very important aspect of the MoTeC ECU is that it enables individual cylinder knock control and monitoring. This is a huge benefit in regards to tuning because if there is a problem in one cylinder, we don’t have to adjust the ignition timing across all four. Instead, we can adjust the single problematic cylinder, which in turn will yield more overall power. Essentially, we are tuning four 575cc engines and with the individual knock control, we can maximise the power output for each cylinder. After all was said and done, we reached a final safe output power of 425Kw, superseding the owners target!