It's 1:30 a.m. and we're mere blocks from home when a local cop yanks a U-turn and comes blasting after the bright yellow '67 Camaro. We idle through neighborhood side streets with the cop following, lights flashing and the spotlight drilled into the interior. All we need now is the local news chopper to make this a real media circus. "I'm not stoppin' til I get home," David Welker says, and it's clear he means it. But it's not about running. "I don't want anything to happen to the car." It sounds like the voice of experience. We pull into David's driveway and it turns out the cop used to live in the same neighborhood and knows David. There's no harm, no foul, and best of all, no ticket-this time.
While the cop didn't recognize the car, every other street rat in the greater Phoenix area certainly does. The kamikaze bikers who made an entrance at the Sonic burger earlier that evening talked big but didn't want to race when they saw the parachute on the back of the Camaro. Oddly, they missed the two turbos peeking out from under the fiberglass hood. The bike dudes got off easy.
What's impressive isn't that this is an 8-second street car. That game is becoming more familiar every day. But most times, that performance comes with a high-tech price tag-expensive turbos, an incomprehensible EFI package, and lots of custom-fabbed plumbing. So what makes the naysayers a bit flustered is when David and his son James (he calls himself RJ) pop the hood and a lone carburetor sits atop a single-plane intake manifold.
The Camaro started out as a father-son project. James wanted to take on the 1,320, so David bought the old Super Street racer from his friend Billy Carroll. Carburetors and turbos have always been the combination, with the first attempt to hide them down low stuffed behind the headlights in a twin-carb draw-through configuration. "They said it wouldn't even start," David says. "It ended up running a best of 9.30." The problem wasn't power, but rather a struggle to pump oil away from the turbos. "We tried all kinds of stuff, but the engine would always blow smoke when we first started it up. Carburetor cleaner is your best friend when you work with pull-through turbos." There were other, equally vexing problems as well. In a draw-through system, the intake manifold and the long runners leading up to the manifold are full of air and fuel. If (or more appropriately, when) the motor sneezes, all that fuel and air contribute to a big bang.
The next step in the learning curve was to dump the massive 211/44-inch-primary-pipe headers and trim them down to much more conservative 131/44-inch primary pipes to put more energy into the turbos. Combined with a pair of budget 58mm TO4B turbos from Joel Britt at Arizona Turbo, the package began to take shape with new homebuilt headers that positioned the turbos up high and right through the hood. According to David, "They're just $250-apiece industrial turbos. They're not ball bearings and they aren't ceramic. They're not even off-center turbos. They're old school, but they work."
David also hits it with a 150hp plate shot of nitrous on the starting line. "We use the nitrous to spool up the turbos, but we've also used it down track." While this might seem like wretched excess, David's plan is actually quite sane: "We use the nitrous to help cool the incoming charge." The nitrous comes out of the plate at something like -65 degrees F, which does wonders for turbo discharge temperatures that easily see the high side of 200 degrees F.
All this romantic turbo stuff is built around a "very tired" four-bolt main 454 iron block that's currently 0.070-over. "We got one hole that's got something like 0.010-inch piston-to-wall," he says, yet the Camaro still makes plenty of power. There are very few exotic parts on the car except for eight precious metal pieces. David has learned that Inconel exhaust valves are a must when paired with turbo exhaust heat. "We popped the head off an exhaust valve in our boat once and found it stuck all the way up in the turbine housing." After that, David spent the money for the best exhaust valves he could find.
So how much power does this monster make? "I don't know," David opines. "You can't race a dyno, so it really doesn't matter." He will tell you that the Camaro has run 8.62 at 162 mph-hence the need for the rollcage and parachute. He'll also admit that the engine would run much quicker in a better car, a lament we hear quite a bit now that horsepower has become so easy to make. "It makes gobs of torque. The biggest problem is the motor makes more power than the chassis can hold. You can hear the tires squeakin' all the way down the track."
So with all this power, the misconception would be that this is a beast with neanderthal table manners. But cruising down the freeway or even down a deserted two-lane blacktop north of Glendale, Arizona, we quickly discover from the right seat that this car is as comfortable on the road as it is on the track. With 3.42:1 gears, 33-inch-tall tires, and a tight converter, the Rat loafs at around 2,300 rpm at 60 mph.
The streetability question extends even to David's choice of fuel. For a mild night out, the 8.0:1 compression easily supports a pump-gas routine, but David doesn't like the fumes. "We run Av-Gas for a little better octane and because it smells better," he says. That statement made more sense after gaining some seat time. With the turbos sticking through the hood, you still smell the fuel even though it's a blow-through system. By the end of the night, your eyes sting a little from the fuel-rich atmosphere that wafts back past the windshield. As for trackside duties, that's strictly race-fuel territory. He runs Sunoco Supreme NOS fuel, which at an amazing 117 is the highest-octane fuel you can buy. Remember, there's no intercooler on this package, so 16 psi worth of heat stuffed past that carburetor is an excellent reason to run the good stuff.
The Camaro is clean, functional, and eyeball-flattening quick when he applies the turbo boost. The regimen is almost always the same-run it hard, break it, fix it, and run it hard again. To some, that may seem like work. But David does it for the fun, and because he prefers two turbos and no waiting.
What: '67 Chevrolet Camaro
Owner: David Welker, long-time turbo guy
Hometown: Glendale, Arizona, a suburb of Phoenix where there are tons of very straight stretches of two-lane blacktop.
Techs: David gives credit to Joel Britt at Arizona Turbo (602/253-9953) and Billy Carroll at B&B Automotive Machine.
Short-block: A very tired two-bolt-main 454 with a hardened GM steel crank, Eagle H-beam rods, 0.070-over SRP 8.0:1 compression pistons, and Moroso oil pan and pump. David does all his own machine work at B&B.
Camshaft: Turbos don't need a radical cam-it's an Engle 253/ 253 at 0.050 with 0.580-inch lift and 114-degree lobe spread.
Heads: Pro Topline aluminum 360cc rectangle-port castings with 2.30/1.88-inch valves with Comp dual springs measuring 360 pounds over the nose.
Headers: This started out as an owner-fabricated 131/44-inch primary tube Jeg's weld-up kit, coated inside and out.
Turbos: Schwitzer hybrid T04B with a 58mm compressor wheel and a 0.96 I/R turbine housing. All of David's turbochargers and parts come from Arizona Turbo.
Intake: Weiand Team G single plane
Carburetor: Carburetor Solutions Unlimited (CSU) 950 cfm with custom annular-discharge boosters designed for blow-through applications.
Fuel System: David uses an Aeromotive A2000 carbureted bypass return-style regulator that increases fuel pressure 1:1 to boost pressure to prevent leaning out the air/fuel ratio. Fuel pressure is maintained by a massive Aeromotive electric fuel pump.
Nitrous: Used Top Gun single-stage plate tuned for a 150 shot.
Ignition: David just tried a hotter 7AL3 MSD unit but says that his trusty 6AL with boost retard worked just as well.
Transmission: Owner-built TH400 with a 10-inch Coan 3,500-stall converter.
Suspension: Your basic back-halved Camaro with a Jegster ladder-bar rear suspension and single adjustable Koni coilover shocks hooked to a gusseted 12-bolt with 3.42 Richmond gears and Strange 35-spline spool and axles. For traction, David runs Hoosier 32x14-15 slicks mounted on 14x15 Weld wheels. On the street, he runs 33x19.5-15 M/T Sportsman "rock hards." Up front is a stock front clip with Moroso front springs, Competition Engineering shocks, and a stock steering box and brakes.
Performance: The Camaro's best pass to date is an 8.62 at 162, while his best 60-foot is 1.30.