2,000HP, 441CI LS2
Mark Koehler, Cincinnati, OH
Walking through the pits at Holley's LS Fest last September, we were drawn to Mark Koehler's engine like zombies to a fresh skull of brains. Dunno about you, but this is one of the biggest turbochargers we've seen. However, don't make the mistake of overlooking the other components under the hood, like the awesome engine, for instance. We liked hearing that Mark built this car at home, beginning with a lowly six-cylinder stripper model. It's come a long way from its plebeian roots. This Outlaw Firebird makes more than 2,000 hp and runs mid-7s at the track. Let's take a closer look.
So far: 7.50 at 194 mph on 32-psi boost. Mark is looking to get into the 7.40s before the end of the '10 season.
Squint at the picture and you can make out the Daily Engineering three-stage dry-sump oiling system.
These are stock, off-the-shelf Trick Flow 245 cylinder heads. Mark told us no work was done to the intake runners or combustion chambers. They were only modified to fit the bigger-diameter head studs.
C. EFI and ECM
Twin Weldon 1,100 fuel pumps are plumbed inline from the fuel tank and feed the octet of Bosch 160-lb/hour fuel injectors. Stock ignition coils are tucked up under the base of the windshield, and a BigStuff3 Gen III Pro SEFI controller runs the show.
Believe it or not, the foundation for this incredible powerplant is a production LS2 block. It was, however, thoroughly gutted, sleeved, and fitted with a six-bolt head stud kit by ERL Performance in New Albany, Indiana. We've seen the company's work firsthand and were very impressed. The new iron sleeves allow a final bore size of 4.125 inches, and the six head bolt conversion kit allows for a much greater clamping load over the production block's four bolts per cylinder. More clamping load means you can turn up the boost. Way up. The block houses a 4.125-inch-stroke Callies crank, Oliver rods, and Wiseco pistons set up to deliver a boost-friendly 9:1 compression ratio. Engine builder Kurt Urban also added some cool tricks to the bottom end. He added oil squirters that direct a stream of oil to the bottom of the piston. This greatly improves piston cooling, vitally important in a boosted application. He also modified the thrust bearing, adding eight oiling holes to the thrust surface. "Boosted LS engines tend to push the crank forward. This wipes out the thrust surface," Urban told us. Force-feeding the thrust bearing prevents this. Keeping the crankshaft inside the engine block is a good thing.
E. Cam and Valvetrain
The cam is a hydraulic roller from Comp that specs 254/248 at 0.050 and 0.646-inch lift. Manton pushrods actuate pedestal-mount Harland Sharp rocker arms to which Urban added his own girdle to keep everything in place. There is a lot activity going on in there, too. Mark normally shifts at 7,600 rpm but has on occasion run this combination up to 8,100, depending on track conditions.
Mark built this car at home in his garage over three years. Initially, he had a business partner who helped with some of the bills. He bought his partner out after a couple of years. It was an amicable parting, and Mark has been the man since then. He started with a running but really ugly looking '00 Firebird with a six-cylinder engine, stripped it down to nothing, and built this stunning-looking and blindingly quick race car working nights and on weekends.
It is shocking to see this 106mm Precision Turbo & Engine turbocharger in person. It occupies a lot of real estate under the hood yet looks as if it just belongs there-probably because of Mark's elegant and simple routing. Stock 6.0L truck manifolds run up to the turbine and then duct into a pair of Burns Stainless race mufflers and into tubing in the fenders that ducts out to tidy exhaust openings just behind the front wheels. On the cold side, air is ingested directly in the front of the hood and routed efficiently to a heat exchanger behind the left headlight. The question everyone asks: "How much boost?" Though it varies from race to race, Mark generally runs around 30 psi-the same as 2 atmospheres.