Mike Kojima posted on August 21, 2009 03:45
EVO IX Power Tweeks Part 2
When we last left project EVO IX we had just tried out the most basic bolt on mods and ended up being pretty pleased with the results, picking up nearly 30 whp from stock with just a few hours of work including dyno time. Drivability was improved as well making our experience a win win situation.
Of course the power increase left us wanting more as our EVO’s more than capable chassis didn’t flinch with the additional power. Since we were just touching the tip of the proverbial iceburg in our path for more power, we ordered up more parts and got wrenching and testing.
The first thing on our list was to free up the exhaust some more. We were pretty shocked that the exhaust we had installed in our last segment of project EVO did not make as big of a difference as we suspected. This meant that one, the stock EVO exhaust isn’t that bad and two; additional restriction probably existed upstream. We trecked to our favorite shop, Technosquare and installed a WORKS O2 sensor housing, downpipe and resonated race pipe to enlarge our exhaust system to 3” all the way to our Greddy TiC exhaust system.
The WORKS O2 sensor housing replaces the stock cast iron housing with a new cast housing that makes a more gentile bend out of the turbo for less backpressure causing turbulence while keeping a full 3” internal diameter through to the downpipe. All other O2 housings we know about neck down to around 2.5” before merging with the downpipe. The WORKS housing’s cast construction should be trouble free and its OEM like fit allows the stock heat shield to bolt back in place for a stealthy install. With the supplied adaptor ring, the housing works with the WORKS big downpipe, as well as stock and any other aftermarket downpipe. The housing comes coated with a gold ceramic thermo barrier coating to reduce engine compartment heat and resist corrosion.
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WORKS 02 sensor housing features OEM quality cast construction and thermal barrier coating. Mounting ears allow the use of the stock heat shield. A bigger radius and a larger interior volume give superior flow. The WORKS housing is compatible with most aftermarket downpipes and the stock downpipe
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The huge difference in the interior of the stock O2 housing vs the WORKS housing is shown here
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The stock housings exit is much smaller than the WORKS full 3" exit. The WORKS housing has the largest exit of any aftermarket O2 sensor housing
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The WORKS housings less severe exit radius is shown here. This gives better flow from the turbo
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The O2 sensor housing led to WORKS big 76mm downpipe. WORK has taken a lot of care for the big downpipe to fit in the tight confines of the EVO IX under carriage. When the EVO IX was introduced, its ACD torque control system caused fitment issues with many downpipes on the market, an issue which many manufactures addressed by dimpling the pipe or not at all. Not so for the WORKS unit, it fits perfectly with plenty of clearance. It also fits perfectly with our CROX plate underchassis brace. You can see the many subtitle bends in the downpipe for this reason. The downpipe is fabricated from 304 stainless tubing and has a coating of gold color thermo barrier to reduce heat soaking of the drivetrain. While we were under the car, Technosquare’s ace fabricator, Richey Watanabe welded in a Burns Stainless O2 sensor bung for our wide band sensor to make tuning the car easier and enabling us to leave all of the stock O2 sensors in place while we tune.
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The WORKS downpipe is TIG welded from 304 stainless and thermo barrier coated
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The entrance of the WORKS downpipe is a full 3" to complement the 3" exit of the WORKS O2 sensor housing. Most other downpipes neck down to 2.5" here
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Careful bending of the WORKS downpipe allows for clearance to the ACD housing found on the EVO IX. Many downpipes have fitment problems here
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 Ritchie Richey Watanabe of Technosquare TIG welds in a Burns Stainless bung for a wideband O2 sensor into our downpipe. We added an extra bung to make tuning easier
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The bung in place
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The WORKS downpipe clears our WORKS CROXS plate with ease
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At a full 76mm, the WORKS downpipe is as big as the stock downpipe with its heatshields in place!
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