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Turbos For The Street

Want to Make 1,000 HP? Add a Pair of Turbos

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Home Builders
Weekend warriors need not be intimidated by turbocharging. Here are a few regular guys who've built effective combinations at home.

Joshua Minder
1972 Plymouth Duster
We think all our readers can appreciate Josh Minder's '72 Plymouth Duster with a homebuilt, turbocharged 225 CID Slant Six. Josh bought this car from his next-door neighbor when he was 17, and in just four years, he's transformed it into this cool sleeper you see here. He didn't have much money to spend, so a V8 swap never really entered his mind, but when a friend gave Josh a used Toyota Supra turbocharger, Josh and his father, David, got to work scrounging junkyards and online parts listings. In addition to crafting the turbo system, David and Josh also straightened and painted the car themselves, and Josh tells us he had the car finished just 30 minutes before he had to leave for his senior prom. On the road, he surprises lots of unsuspecting sports cars, routinely walking away from the swarms of Porsches and Mercedes that litter the roads and freeways of Southern California. Imagine how those Europhiles must feel, getting spanked by a throw-away car that sounds like a UPS truck.

Randy Seward
1991 Ford Mustang

Watching Randy Seward's Mustang click off 8-second passes at Bradenton Motorsports Park during the NMRA Spring Break Shootout, we wondered if it was time for an eye exam. How could this plane-jane Notchback be so fast? Aside from the Garrett stickers on the sides, there is no indication that this is anything other than the secretary's car Ford intended the non-GT Mustangs to be. Randy was the overall winner in True Street that weekend, and this was not the first time that's happened. In all, he's taken home four King of the Street trophies, with more likely to come.

Randy is an engineer, so it wasn't a surprise to learn he designed the turbo system in his Mustang. He said the turbocharger-sizing guide on Garrett's website is very good, because it walks you through how to calculate the volume of air your engine needs to move to make the amount of horsepower you desire. Determining those parameters will narrow the choice of turbochargers to a relatively easy choice.

Based on his personal experience, Randy tells us turbochargers don't like backpressure in the system after the turbine, so he designed his system such that the exhaust gas enters the turbine housing from above, then exits the turbocharger straight back toward the firewall. Randy purposely kept the tubes leading away from the turbochargers as straight as possible before dropping down under the car into a 3-inch Flowmaster exhaust system.

His combination consists of a Dart block, forged internals, and Trick Flow cylinder heads. He stressed the importance of quality cylinder heads with a good sealing surface. That, combined with quality head gaskets, keep combustion pressure contained within the cylinders where it's supposed to be. He likes a 9.0:1 compression ratio, claiming it provides a good compromise of off-boost power for street driving without being too much at the track. Judging by the fact that Randy's car is making somewhere in the neighborhood of 1,100–1,400 hp and has run a best time of 8.45 at 164 mph, we think he's on to something. Need more convincing? Randy drives his car about 5,000 miles per year to and from the events he competes in.

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