Karl Schello, Palmdale, CA A couple of months ago we were invited to attend a private test and tune session at Auto Club Speedway in Fontana, California. Our host was Adam Montague, owner of ST Motorsports in San Bernardino, who rented the track so he and some of his customers could run their cars and work out any tuning issues they had. What made this event unique was that all the cars were less than 6 years old, and all 10 of them were able to click off 10-second quarter-mile passes.
We will cover those cars, among others, in an in-depth article on late-model performance in a couple of months. But as a teaser, check out the Hemi in Karl Schello’s ’09 Challenger SRT8. With a Kenne Bell supercharger on an otherwise stock engine, Karl is putting 533 hp to the ground. After a couple of warm-up passes at 11.28 and 128, he siphoned the premium unleaded out of his tank and replaced it with C16 race gas, did a quick pulley change, and reflashed the ECM. Now he’s making that 757hp figure noted above. That’s 757 at the wheels, folks.
At Karl’s request, Montague piloted the no-holds-barred pass, returning with a 10.87 at 119.7. That’s a big improvement in e.t., but notice the huge drop in mph? That’s because the engine broke during the pass. We spoke to Karl recently and got the postmortem report: broken ring lands on five pistons. He said they also discovered a bent valve but determined that he did that during his burnout, when he bounced the engine off the rev limiter. What’s important to note is just how much potential is lurking within the confines of this engine. Montague is reassembling the engine with a little more compression, a 3.6L Kenne Bell, and some nitrous. Karl wants to go 200 mph in the standing mile. As outrageous as that sounds in a stock-body Challenger, we suspect he will pull it off.
What’s remarkable is that just one power- adder was able to motivate this bone-stock engine into the 10s. The new Hemi is a great platform, with a deep-skirt block and cross-bolted main bearing caps, but the 6.1 SRT8 version is especially good with a forged crank, improved pistons and rods and the addition of piston oil squirters. The compression ratio is 10.3:1, and this combination is rated at 425 hp at the crank from the factory. In these heavy LX-platform Chryslers, the combination is generally good for 0 to 60 times of about 4.7 seconds and quarter-mile times in the low 13s.
This 2.8L Kenne Bell Mammoth supercharger is an efficient twin-screw design, rather than a Roots-type blower. It operates in a range of 8 to 24 psi of boost and will support up to 1,000 hp. The one on Karl’s Hemi is the newest version, sporting an internal coolant passage to help keep the case cool. The intake charge still runs through an air-to-water aftercooler just below the supercharger case. Karl keeps the charge cooler full of cold water plumbed from a tank in his spare tire well. Normally, he runs the car on 10 psi of boost on 91-octane gasoline, and that is good for 535 hp at the wheels, a nice jump from stock. Raising the octane allows him to crank the boost up to about 20 psi and make an impressive 737 hp. That translates to low 10s at the dragstrip.