Our hand-fabricated TIG-welded...
Our hand-fabricated TIG-welded ARC radiator is a visual work of art that will help keep our engine cool on track days.
On the dyno it was hard to determine the effect of the airbox. Although the wideband indicated that our air/fuel ratios were nearly unchanged, the airbox allowed the turbo to spool sooner and increased airflow. The flow increases and subsequent increases in cylinder pressure caused the engine to sport a knock count of over nine, and the ECU was pulling enough timing for the power readings to be awash. The ECU's timing curve would need a retune at this point if we were to see a gain from the airbox. The airbox simply worked too well for the tune at the moment. Another plus, we noticed a reduction of intake air temperature of 12 degrees. We couldn't readily explain this, but many people have observed how the ARC box partially sucks underhood air.
The ARC cooling system pressure...
The ARC cooling system pressure regulator ups our pressure from 1.1 to 2 bar to reduce localized boiling and improve cooling within the engine.
Since we had a relatively high knock count we decided to install XS Engineering's front-mount intercooler before retuning. The XS intercooler has a large tube and fin heat exchanger that's wider and thicker than the stock front mount. The tube and fin core also has a lower fin density than stock. While it would seem like this is a bad thing, the lower density actually allows the cooling air to penetrate more easily into the thicker core, improving efficiency. It also allows more cooling air to pass through the intercooler to reach the engine's radiator, helping to improve overall cooling.
The XS intercooler was a direct bolt-on and only took about a half hour to install while the car was strapped to the dyno. We once again did some pulls and found that the intercooler eliminated knock count across the map and gave us around 8 whp. From this starting point XS Engineering's ace tuner Koji Arai went to work. Koji was able to add quite a bit more timing to our ignition map without increasing knock count and, with a combination of adding more timing and more cam advance to our Mivec system, he was able to extract 9 more hp, leaving us with an impressive 321 whp-a whopping gain of 17 whp just from the intercooler. The power gains were huge and across the board.
We installed the regulator...
We installed the regulator by the coolant overflow bottle.
We considered adding more timing and fuel or possibly tweaking the boost but when reviewing our data logs, we realized that we were completely out of injectors as we were at 100 percent duty cycle in the last two load columns of our fuel map. Although some tuners in other states have extracted more power with equivalent mods, we feel that our 321 whp is pretty impressive for our exceedingly crappy 91-octane pee water fuel.
Stay tuned; we have some big RC Engineering injectors and more parts waiting in the wings. We intend to see how far the stock turbo and bolt-ons can be taken with California's weaksauce pump gas. Once we max that out, we intend to test a bolt-on turbo upgrade and eventually even bigger and better things!
 The Titanium ARC air guide...  The Titanium ARC air guide helps make sure that most of the air going through the grille opening is forced through the radiator. The use of titanium for this part is pure bling-bling is cool if it's functional. |  Nukabe's silicone radiator...  Nukabe's silicone radiator hoses are much tougher and last longer than the stock parts, which is important since we boosted our cooling system pressure. |  The ARC airbox is perhaps...  The ARC airbox is perhaps the most beautiful Evo air intake system on the market. The best thing about it is that it had minimal effects on the sensitive Karman MAF-unlike your typical cone filter that often requires a retune for this reason. |
 The WORKS exhaust components...  The WORKS exhaust components gave us a pretty respectable 15whp boost. |  The big XS intercooler dwarfs...  The big XS intercooler dwarfs the stock unit. |  The XS intercoolers more open...  The XS intercoolers more open tube and fin construction allows for more flow, increasing the amount of air for the radiator. |
 The intercooler and the more...  The intercooler and the more aggressive tuning it allowed gave us 17 more whp. Believe it or not, this is the biggest gain of any single component installed to date. If you count the intercooler and the hard pipes installed in our last segment together, the total gain is an amazing 24 hp. This pushes the XS intercooler kit to the top of the mod pile by a large margin. |  To date we have gained 61...  To date we have gained 61 whp with just these basic bolt-ons. The gains are big, fat, and across the board. | |