Twin Turbo 400ci Small-Block Chevy - Horse Power!

Twin Turbo 400ci Small-Block Chevy
Kenny Duttweiler, Saticoy, CA
Turbochargers are the new buzzword if you want to talk big-time horsepower. Combine a hair dryer with EFI and you have a killer street package, which is exactly what Kenny Duttweiler built for a mystery car owner from South Central Los Angeles. Duttweiler built this monster about two years ago, and it's in line right now for a bigger exhaust and a few other subtle changes to make even more power. The old package made a mere 1,200, and Duttweiler thinks the tune-up will pump out 1,400 big ones. All of this is stuffed into a tubbed black Buick Grand National that is going to need traction control to hook all the power to the pavement. Amazingly, all this plumbing fits into the stock Buick engine compartment with the air-to-air intercoolers wedged between the front bumper and the radiator.

A. Cam And Valvetrain
The 18-degree heads use a Crower rocker system, but the cam is little more than a Comp Cams Street Roller spec'd to deliver 230 degrees of duration with a wide 115-degree lobe separation angle. Valve lift is 0.589 inch.

B. Electronics
Duttweiler designed this engine around an ACCEL Gen VII EFI package that drives eight very large 83-lb/hr ACCEL injectors. The ACCEL ignition has more than enough amperage to light off all that cylinder pressure.

C. Heads
A normally aspirated 400ci small-block Chevy is formidable enough when it sports a set of TFS 18-degree high-port heads. The heads breathe through monstrous 2.18- and 1.600-inch intake and exhaust valves and can flow upward of 335 cfm on the intake side. Lord have mercy. The 18-degree heads also require a dedicated 18-degree GM Performance Parts single-plane intake with a Keith Wilson 90mm throttle-body using a Hogan fabricated 90-degree adapter.

D. Short-Block
It's a moral imperative to use an iron Dart block when you're pumping out over 1,200 hp from a small-block Chevy. Spinning inside is a Crower billet crank, Oliver rods, and forged JE pistons that only squeeze out 8.5:1 compression. That's so when the engine's just cruisin', 91 octane works just fine.

E. Lubrication
Despite the massive power, you can see this is still very much a wet-sump oiling system with a Billet Fabrication 7-quart pan and a CarQuest oil filter. Duttweiler uses Lucas street oil and doesn't run much more than 60 psi of oil pressure.

F. Turbos
Those are a pair of Precision Turbo GT4067S pinwheels that according to Duttweiler are capable of generating 700 hp apiece. That's on top of what the engine can make on its own. Those are Steve Watt custom-fabbed 1 3/4-inch stainless steel headers that feed the hot side of the turbos.

Fuel System
What you can't see in the photo is a Pro Series Aeromotive fuel pump capable of delivering a bazillion gallons of fuel per hour at as much as 75 psi. With 20 psi of turbo boost, the boost-referenced fuel system must deliver at least 20 psi more than base fuel pressure.