Cayman 4.0 Turbo

Cayman 4.0 Turbo 1
Cayman 4.0 Turbo 2
Cayman 4.0 Turbo 3
Cayman 4.0 Turbo 4
Cayman 4.0 Turbo 5
Cayman 4.0 Turbo 6
Cayman 4.0 Turbo 7
Cayman 4.0 Turbo 8

With another rebuild or swap in front of him, he wanted to find a shop nearer his new home in Las Vegas to perform the work. A few of his friends from the track and the forums suggested he call Vision Motorsports of Laguna Hills, California. Owner Dwain Dement has been working with Porsches since he was 15 years old, and as a former shop manager for Andial he’s overseen the builds of the some of the most dominant engines in racing history. After a long conversation with Dwain to discuss the kind of engine he wanted built, Blockus said he chose Vision because Dwain had all the right answers.

The project’s original plan was to take the 3.4 up to 3.6 liters using bigger pistons. And then Dement mentioned he had a spare 3.8-liter Carrera S engine that had been bored out to 4.0 liters. Blockus was, not surprisingly, all for it.

The engine uses 101mm forged JE pistons, which are lighter than a stock 3.4’s 96mm pistons. The crank was cross-drilled, grooved and knife-edged, and mated to forged Carrillo rods. Regarding the bearings, Vision left nothing to chance and used components from a Porsche Cup engine. To keep the oil flowing properly under heavy lateral g-loads, Vision added baffled oil sump extensions, 997 swirl pots, and a factory Porsche Motorsports air-oil separator. An oil cooler from a Cup car is a further guard against damaging temperatures.

Dement opined that the rod bearing failures could be attributed to some of the newer oils that have had the zinc taken out of them. Bearings, said Dement, need the zinc for lubrication. To offset that problem, the engine in Blockus’ Cayman runs on Redline Racing synthetic, which he buys by the drum.

After the engine was tightened up, Vision installed the TPC turbo system to see how it would run. Unfortunately, the TPC turbo is a proprietary design, and Vision could not attain the flow charts they’d need to dial in the 4.0. It was then that Vision decided to change the turbo and use different ECU programming.

Dement said he took a look at the flow charts of several turbos and found that Garrett’s GT4094R offered what he was looking for. In order to address one of Blockus’ main concerns—a lack of speed out of the corners—he wanted to make sure turbo lag was kept at a minimum. The Garrett GT4094R bolted onto the TPC exhaust manifold, and though Vision retained TPC’s liquid-to-air intercooler, fuel injectors and exhaust system, they decided to fabricate a higher flowing, 4.0-in. intake to attach to the 4.0’s mass airflow sensor.

The new turbo required new ECU programming, so Dement contacted old friend Todd Zuccone of Evolution Motorsports to help sort out the coding. The car was shipped to Zuccone’s shop in Tempe, Arizona, for the first phase of programming and then fine-tuned at Vision’s shop. The engine now cranks out 662 hp and 613 lb-ft of torque at a relatively relaxed 0.8 bar (11.6 psi) of boost. More power was easily available, but Dement, who has built many Boxsters and Caymans for the track, said that additional grunt would be too much for the drivetrain.

Also from Issue 215

  • David Donohue track tests the Turbo
  • A missing link in the 911's life story
  • Who should get credit for the design?
  • 987/997 ignition events and your warranty
  • Porsches and guitars--a great mix
  • Restoration as a labor of love
  • 1975 Carrera finds a new venue
  • A historian's look at the 356's birth
  • RS enthusiasts gather at Rheims
  • Could this car be worth $500,000?
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