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We stuck with the Kelford 272 cams that we’ve always run, but unfortunately, Manley didn’t produce a valve spring with the proper amount of seat pressure for said cams that fits in the Evo’s head. Long-time sponsor and friend of the team, MA Performance does though and came through in a big way! We ended up with a set of their Ultimate Duty valve springs and titanium retainers to keep the Manley +1mm valves in check and valve float at bay. This was especially important considering we would be increasing the rev limit.
Here are the Manley +1 valves in the otherwise stock combustion chamber. Manley's 4G63 valves are stainless steel from their race series and after seeing the damaged valves hold up to such extreme deformation, we are impressed with their strength and ability to handle abuse. The intake valves also look amazing even after 3 seasons of use.No major work was done to the cylinder head other than installing new exhaust valves to replace the damaged ones. This particular head has been around the block a few times and has been decked more often than Chris Brown’s love interests, but still serves us well. No porting, just the usual new seals and valve lapping to ensure everything was in working order. One day it sure would be nice to replace this head with an Evo IX Mivec unit, if only… (foreshadowing perhaps?!)
With the engine refreshed and geared more towards higher RPM output, we also saw fit to switch turbos to match. On the previous build we had been using MA Performance’s stock frame EF4 series turbo. This turbo worked well for us, but being a stock frame based turbo, had it’s positives and negatives. The positives were extreme ease in installation and service. Having a built in wastegate and the ability to use all the stock cooling and oil lines came in very handy. The negatives revolve around the turbine and compressor housings not being as optimized for the size wheels used as they could be, due to the limitations of working with the stock exhaust system and stock mounting location. These actually turn out to be positives on the street, as the turbo is a torque monster at low RPM, but as our engine spends most of its life north of 5000 RPM, it wasn’t optimal for our needs. While not a major negative, this particular MAP turbo still had standard OEM journal bearings. While reliable for us, these require more oiling and have more friction than ball bearing turbos.
With a new engine and a goal of increased higher RPM power comes a new Garrett GTX3582R turbo! The previous fastest Limited AWD car at Buttonwillow Raceway, JC Meynet's Subaru STI, also utilizes this turbo. They say imitation is the sincerest form of flattery.We switched to a Garrett GTX3582R, which is similar in overall flow, but more efficient at higher RPM, exactly what we needed. The GTX series turbo has a newly designed billet wheel and continues to use the dual ball bearing center section of the previous GT series turbo. Mike Kojima did a great job writing about the new GTX’s, so I’ll let you read about them here. We ended up going with a twin scroll turbine housing with a 1.01 A/R. The idea was the balance both high RPM flow by going with a larger housing along with response from the twin scroll design.
MA Performance custom made the exhaust manifold for our Garrett turbo. Top notch fabrication is apparent throughout the build with careful attention paid to turbo mounting location, ensuring the primaries are equal length, wastegate placement, weld quality and more! Not seen is the addition of a brace connecting the manifold to the block to ensure the weight of the turbo and associated components don't crack the manifold.
All finished and ready to be shipped to us! Notice the bellows utilized to compensate for expansion and contraction during heat cycles. We were also very impressed with how well the wastegates integrate into the exhaust flow to ensure peak performance. The guys at MAP also made the downpipe with plenty of room for their dry sump system. Sadly we don't have one on the car yet, but who knows what the future holds!MA Performance continued to help us with this new application by designing and building a gorgeous equal length manifold and downpipe. MAP utilizes CNC machined 3D flanges and schedule 10 304 stainless steel tubing for reliability and performance. These also incorporated twin Turbosmart Comp-Gate 40 wastegates to keep boost levels in check. Everything was well thought out for our application and MAP utilized bellows to account for heat expansion and flex couplers to account for vibrations in order to keep cracks at bay.
