We traded in our P5 wagon and are now flogging a Mazdaspeed Proteg in anticipation of some go-fast mods. Mazda USA warned us to keep things sane; perhaps rumors of our 20B three-rotor swap escaped the building. Still, this will be an interesting project, and we'll see how far we can push things without going completely off the chain.
We learned long ago to never bash a factory turbocharged vehicle because the beauty of the turbo is its vast tuneability. At issue here is the Mazdaspeed Proteg's factory-rated 170 hp and 155 lb-ft of torque. Considering the Civic Si makes 160 from 1.6 liters, the Sentra SE-R pumps out 175 and the Celica GT-S and older Integra GS-R both deliver 180, it's easy to be critical of the MSP. All the aforementioned comparison vehicles are naturally aspirated. But there's more to driving performance than peak numbers, and the MSP proves intriguing where it counts most-on the road.
The ball-bearing T25 is quick to spool, allowing the MSP to granulate rubber in first gear and pull admirably to the engine's 6500-rpm redline. Mazda has addressed all the correct ancillary systems to withstand the added boost drive abuse. A Super LSD by Tochi Fuji Sangyo KK puts the twist on upgraded 24mm axles, while a heavy-duty clutch and pressure plate keep the gears banging.
However, the intercooler needed improvement. The stock vertical-mounted air-to-air unit is no bigger than a girl's shoe box. The piping is all plastic, which killed our desire to put temperature probes on both sides of the cooler and chart its performance. The plastic piping needs to be replaced with polished aluminum. The blow-off sounds whimpier than it looks, and there's no factory boost gauge.
Project SE-Rious Sentra was able to pull 220 to 240 whp with a standard T25 turbo, so we should be able to move more air than the MSP system's current 5 to 6 psi. The plan is to max out the stock turbo. First we'll do the typical bolt-ons-exhaust, intake, downpipe. Then we'll add a front-mount intercooler. We expect the engine's stock "special" injectors will be able to fuel a touch more boost, so we'll add a controller and eyeball the air/fuel ratio as the boost is bumped. Stay tuned.
Key Specs
| ENGINE |
| Displacement | 1991cc |
| Compression ratio | 9.1:1 |
| Turbo | Garrett T25 BB |
| Intercooler | vertical-mount air-to-air |
| Stock boost | 6 psi |
| Injector size | 320cc |
Driveline
Bigger axles 24mm vs. 22mm in regular Proteg
Super LSD by Tochi Fuji Sangyo KK
Heavy-duty clutch and pressure plate
Suspension
17x7 Racing Hart wheels
215/45ZR-17 Bridgestone Potenza tires
Euro-spec 10.7-inch front rotor
Euro-spec 11.0-inch rear rotor
Tokico shocks
Racing Beat bars
| OTHER |
| Curb weight | 2,843 lbs. |
| MSRP | $21,000 |
MSP engine: The Mazdaspeed Proteg is motivated by a 2.0-liter, DOHC turbocharged four cylinder that is factory rated at 170 hp and 160 lb-ft of torque.
MSP turbo: Boost is supplied by a Garrett T25 ball-bearing turbo. The T25 spools quickly and provides excellent response. We hope to challenge its top-end flow as Project MSP progresses.
MSP cooler: Intercooling is one part of the equation needing attention. The vertical-mount I/C is supersmall and awkwardly placed. We plan to add a front-mount chiller, which will expand the engine's detonation threshold and allow us to turn up the wick. The plastic piping has to go as well.
MSP wheel: The Mazdaspeed Proteg wears 17-inch Racing Hart wheels and Bridgestone Potenzas from the factory. The driveline has been enhanced for turbo thrust, with bigger axles, a stout LSD and a heavy-duty clutch setup.
MSP seat, shifter: Inside, sporty buckets are joined by a trick shifter, aluminum sill plates and drilled aluminum pedals. The big player is the 450-watt Kenwood based audio system.
Dyno: With 700 miles worth of break-in, it was off to the dyno for some baseline runs. Wheel horsepower checked in at 158.2 and torque clocked 160.9 lbs-ft, which is quite good considering the factory ratings. What caught our attention was the horrible air/fuel ratio. The stock tuning strategy delivers a ratio that is nowhere near the 12.5:1 range where optimal power is made. The ratio starts out lean and drops like a rock to overly rich. We need to take control of the fueling and generate a more efficient ratio. We observed boost pressure rise to 7 psi before settling around 6 psi for the remainder of the run.