The GT30 and GT35 turbos offered in this kit all use a ported shroud compressor housing. C
Even with all the mentions of future ECU tuning plans in our previous installments, we still received a flood of complaints about Project Evo VIII MR and why we chose to save costs and use a temporary piggy-back fuel computer when the suspension cost almost $5000.
Thus far, our Evo has been through some mild power tuning and significant chassis work, all done at Road Race Engineering and Road Race Chassis in Santa Fe Springs, California. There's a reason why it seems like an RRE exclusive car: RRE has a complete tuning program and is familiar with what works and what doesn't with the hardware that's already on. So guess who we took it back to for its final big power installation. Why shouldn't we? No one would take their car to one body shop for body work and then to another for paint.
Now here's the disclaimer: we liked the Evo the way it was (aside from temporary AFC tuning) and knew what we were getting into when we asked for big power involving a Garrett GT3076R turbo, Cosworth CNC head and lumpy cams. This is purely an experiment on how much useable and reliable power the stock bottom end would put up with on 91-octane pump gas. Take the term 'useable' with a grain of salt.
RRE's GT turbo kit comes available with four different turbos: a ball bearing 50 trim, GT
RRE Evo VIII GT turbo kit
We start with the heart of the newfound power: RRE's functional but no frills GT turbo kit. RRE assumes you already have all the basic bolt-on plumbing for intake and exhaust, so only includes the turbo hardware itself, hence the term `turbo kit'. Along with a selection of four different types of turbos, our kit comes with a cast, smooth bending T3 turbo manifold, all the plumbing, TiAl 44mm wastegate, trick turbine outlet housing and wastegate plumbing. More impressive is all the thoroughly thought-out additional hardware, including manifold studs, gaskets, proper nuts and washers, V-band clamps for the wastegate, coolant lines, flexible hard oil return pipe, and even an in-line oil filter for the turbo.
To complete the kit, you can pick from an E-Pinions Fashion ball bearing 50-trim turbo, Street Power/Track Whore ball bearing GT3076R, Track Whore Deluxe custom ball bearing GT35R or Drag Queen/Race Gas Slut ball bearing full GT35R. The intercooler and intake plumbing might have to be modified, depending on the turbo. We went with the GT3076 Street Power/Track Whore turbo, which, in theory, can flow up to 525 wheel-hp. How much horsepower can be squeezed out is limited by the clutch, bottom end and how much fuel we can keep pouring into the cylinders.
Since the car had to go back to Mitsubishi, the original plan was to cut some corners and just strap on the turbo kit, temporarily tune the AFC and throw the car on the dyno before adding the Cosworth CNC head and doing a final tuned ECU reflash. Don't ask how we know, but this is a pointless exercise with the stock intercooler. Like the intake and exhaust, everything the air has to flow past to get to the intake valve and beyond the exhaust valve is a flow restriction. Each restriction is a little gate and acts as a limiting factor, some more, some less. Obviously the easiest, and sometimes most significant restrictions to get rid of are the intake and exhaust. Some people will also change the cat and the downpipe, which essentially opens up the exhaust side. But all these parts are at the ends of the engine breathing apparatus. The intake charge still needs to go through a turbo, intercooler and all its plumbing, the throttle body, intake manifold and then into the head, all of which still play a part in pinching off air going into the cylinder. In this case, the biggest restrictions are the turbo, head and intercooler, all of which we will deal with.
Regardless of how big a turbo we strap on, it still has to blow through the stock intercooler, which could only cope with 360 wheel-hp worth of air--according to the tests we're denying we ran at Injen's all-wheel-drive Dynojet. So it was off to RRE to get Injen's 23 3/4 x 11 3/4 x 3 3/8-inch FMIC and intercooler pipe kit installed. In order to clear the hardware, we also had to change the AEM intake out for an Injen polished cast aluminum short ram intake system, which also comes with a mandrel bent upper intercooler pipe. Although smaller in appearance, Injen rates its intercooler for up to 700hp. The added flow and cooling ability comes from a much thicker core and larger core passages. The Injen intake was modified with a 2.5- to four-inch silicon hose expansion to fit over the larger compressor inlet on the new turbo.
The monstrous Garrett GT3076R we decided to use comes with a 56-trim compressor wheel and 0.60 A/R. The turbine side uses a 60mm 84-trim wheel that we chose to mate with a 0.63 A/R turbine housing. In addition to the usual ball bearing, watercooled bells and whistles, the large compressor housing also includes a ported shroud that effectively pushes the surge limits of the turbo to lower flow rates, preventing premature turbo damage.
Even though smaller in appearance than the stock intercooler, the Injen unit can deal wit
To better reflect the output most tuners should see with this kit on a non-MIVEC Evo, we had RRE temporarily install a set of aggressive HKS 272 duration intake and exhaust cams, retarded two degrees on the intake and exhaust side via adjustable AEM cam gears. The retarded cam timing will push the power curve further up in the rev range and allow the high-lift, longer-duration HKS cams to take advantage of the added volumetric efficiency of higher rpm, since a pump gas dyno whore was what we were after. Theoretically, this further delays the turbo's spool-up response in exchange for top-end peak power.
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