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The Simple Approach to 8.40 Passes in a Nitrous-Fed 572ci Camaro

Eight and Change

Jeff Smith Oct 27, 2016
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It is among the most brutal form of sports in America. A young cowboy tightly wraps his right hand around the handle strapped to the body of a 1,700-pound bull with attitude. Once he leaves the gate, it’s a violent, eight-second contest to remain on the bull’s back.

Troy LaCrone’s quarter-mile ride is not all that different, except that he exerts a little more control over the 1,200-plus horsepower beast that he straps himself into on a regular basis. His steed is an attractive pearl blue ’68 Camaro that could pass for a typical street car. There’s no major betrayal—no giant rear tires—but there is a crispness to the engine noises emanating from the exhaust. It hints at the car’s potential.

Troy has a thing for fast street cars. Awhile back, he owned a similarly-hued ’71 Camaro with a nitroused small-block wrapped around a pair of plain-Jane traction bars. That car would consistently slap the timers deep into the 9s, with a 9.19 best. After a series of disappointments with newer age cars that Troy says “are less fun to wrench on,” he longed for the consistency and simplicity of his first Camaro. That’s when he spied this F-body for sale on Craigslist. The ’68 had originally been stuffed with a Chevrolet Performance 572 as a bucket list race car by a man who contracted cancer and eventually sold it to a friend. It sat inside for a few years in the proverbial Midwestern barn until the friend decided the Camaro needed a new home. That’s how it ended up in Troy’s School for Upwardly Mobile Camaros.

Typical of other cars from his past, his latest adventure was suffering from “a really crappy red paintjob,” rust, dents, dings, neglect, and other issues. “It was a typical race car,” Troy says. First they attacked the body and interior to bring it up to Troy’s street standards with bodywork and paint by friend Tom Monehan of Monehan’s Autobody, whom Troy describes as “the very best there is.” Troy also removed the rattle-ratty old aluminum door panels and other race car accoutrements to return the interior back to ’68 Camaro chic. Along the way they updated the safety equipment to give the Camaro the ability to run the planned sub-9 second runs.

The Camaro ran OK when it first hit the road, Troy estimates mid 11s and on the chassis dyno it produced a lackluster 424 hp, which would stand as simply a starting point for what was to come. This was with the as-delivered Chevrolet Performance 620hp 572. That package delivers 645 lb-ft of torque at 4,200 rpm at the flywheel using a 254/264 degree hydraulic roller with 0.632-inch lift combined with 9.6:1 compression and rectangle-port Chevrolet Performance aluminum heads. “Over the next couple of years, I tinkered with the combination,” Troy says. This included additions including a new carburetor, a fully built Hutch’s Turbo 400 trans, Circle D torque converter, 3-inch exhaust, and an Induction Solutions single-stage nitrous system. Several suspension tweaks to the Chassis Engineering ladder bars and AFCO double-adjustable rear shocks were done as well as new springs and shocks for the front.

Troy’s buddy Scott Lowery added a braced Ford 9-inch rearend with a Strange Pro centersection, 35-spline axles, and 3.50:1 gears. Lowery also added the near requisite antiroll bar in the rear to keep the car launching straight.

The result of all these changes was the car was now running 10.50s at 128 mph on the engine and a startling 8.90 at 150 mph on the Edelbrock-controlled nitrous. “Yeah, that was like the perfect pass. The air was cool and everything was working really well.” For some, that might have been enough just to say you’d done it. But, not surprisingly, Troy wanted to go quicker. “I knew there was no way that that factory 572 was gonna go any quicker!” It was time for the engine to come out.

Troy made the call to Chris Straub at Straub Technologies in Piney Flats, Tennessee, and together with Scott Foxwell, they dialed in the 572. The biggest change to the short-block was a set of Diamond forged custom nitrous pistons along with a set of Total Seal rings and a set of superior ARP 2000 rod bolts. This, along with the selection of a set of milled 335cc AFR rectangle port cylinder heads, increased the compression to a solid 10:1. The combination of a set of 2.35-inch intake valves and some mild port work pushed the flow numbers to or tickling 400 cfm, so the airflow potential is certainly there.

You’d certainly expect that conventional wisdom would demand a mechanical roller for this big Rat, but Straub and company instead suggested a custom Straub hydraulic roller with 272/274 degrees duration at 0.050 with 0.731/0.714 lift (with a 1.7:1 rocker ratio) and a lobe separation angle of 109. All that lift and duration is followed with a set of Morel lifters, Smith Brothers pushrods, 1.72:1 GM rockers and an AFR girdle—a very conservative and therefore durable valvetrain.

Topping it off is a Straub/Foxwell-ported Edelbrock Super Victor intake and an AED 1,050-cfm Dominator carburetor and a simple MSD 6 ignition. The exhaust relies on a set of Dan Lemon’s 2 1/4-inch primaries stepped to 2 3/8-inch using a 4-inch collector. The rest of the exhaust consists of 3 1/2-inch mandrel-bent tubing and a pair of DynoMax bullet mufflers. The entire engine was machined, balanced, and assembled by Chris Calkins, whom according to Troy “did an amazing job for me.”

On the dyno, Troy says naturally aspirated it makes 816 hp on straight BP 93 octane. But the real excitement begins when they hit the Induction Solutions nitrous. With the “conservative” 350-shot on race fuel, the dyno sheet revealed 1,202 hp at only 6,200 rpm. With this kind of power, Troy knew that the biggest problem would be planting all that power without spinning the tires.

This brings us to a relatively simple device that Troy had been experimenting with even before the engine upgrade. Nitrous is a simple on/off power-adder unless you devise some way of controlling it. Instead of a complex array of multiple mechanical nitrous stages, Troy instead relies on an Edelbrock progressive nitrous controller. There are easily over a dozen different progressive controllers to choose from—some complex and some fairly simple. Troy decided simple might be better and landed with the Edelbrock.

Progressive nitrous controllers have become an ideal way to manage nitrous. Most controllers manipulate the nitrous and fuel solenoids by interrupting the ground side of the solenoids through high-quality relays. Managing the solenoids comes down to using something called pulse-width modulation (PWM). This is exactly how every electronic fuel injector is controlled. Within a one-second period of time, for example, if the controller turns the solenoids “on” for one-half second, then this would represent a 50 percent on-time. The process is more complex that this, but this is basically how the system works. Essentially going down the track, the nitrous and fuel solenoids are turning on an off multiple times per second, leading to at a 100 percent on at a specified time point.

The Edelbrock controller offers inputs down to as finite as 0.001-second, so precise control is there. Plus, it offers some relatively complex stepped control parameters yet does so without the need for a laptop. All inputs are generated through a palm-sized control box with only six wires leading from it and a minimalistic six tiny buttons that allow all this control.

Troy is constantly experimenting with his control matrix, but as an example, he can create an incredibly “soft” curve for a no-prep race surface where potentially as little as 10 percent of the total 350hp shot is available to the engine at launch. The Edelbrock allows the creation of this light initial stage followed by control over the maximum amount of flow later in the pass. As Troy says, “I always work with very small changes so I don’t hurt anything.” That requires patience and attention to detail, and this approach has been rewarded with no broken parts.

“So far, I’ve only launched it with the foot brake. I have a trans brake that I will start using next year after I travel-limit the frontend. For now, I’m just worried about putting it on the bumper!”

But this conservatism doesn’t mean that Troy is not shooting for even quicker heroic times. First changes to the current system involve adding an MSD Power Grid system to the car to take advantage of the data logging and its even greater ignition control and accuracy. He also plans to lighten the Camaro since its 3,450-pound girth with driver is certainly a factor. His current target is to push the Camaro into the 8.20s at 167 mph. But he’s not stopping there. “I think it can run in the 7s if I lighten it and throw more nitrous in it.” It’s always good to have a goal.

Troy felt it important to mention some of the people that helped make these great results possible. Tom Monehan, Steve Johnson, Chris Straub, Scott Foxwell, Chris Sehorn, John Hutchinson, Chris Calkins, Scott Lowery, Mick Boyer, Brian Raymond and Larry Busse. “All of these people have gone above and beyond to help me.”

572ci Camaro 2/12

01. There’s a cable TV show where three guys try to guess a car’s e.t. in the quarter-mile. As a 572ci Camaro you might think it’s worth mid 9s—but that would be way off the mark.

572ci Camaro Gm Crate Engine 3/12

02. Opening the hood doesn’t tell you much. Yes, it’s a GM crate 572 enhanced with a few goodies, including AFR heads, a Straub custom hydraulic roller cam, and that 4500 AED Dominator is hard to miss. Even the Induction Solutions nitrous system doesn’t really stand out unless you know the power this simple plate is capable of producing.

572ci Camaro Nitrous Progressive Controller 4/12

03. Look closer and this is an Induction Solutions single-stage Sledgehammer nitrous system using the Trashcan nitrous solenoid. Troy says those budget looking Holley fuel pressure regulators are the only ones he will use on a nitrous system.

1968 Chevrolet Camaro Interior 5/12

04. The interior looks downright underwhelming, which is a big part of the Camaro’s charm. Auto Meter tach and gauges and a B&M shifter are hardly indicators of 8-second potential.

Edelbrock Progressive Nitrous Controller 6/12

05. A clue is this Edlebrock progressive nitrous controller. If you think about it, this is essentially no different than a turbo guy using a digital controller to manage boost. The controller is on the dash to make it easy to access for minor tuning changes. No laptop required.

Nitrous Percentage Results 7/12

06. Most simple progressive controllers can only create a simple straight progressive curve. The Edlebrock controller is designed to be able to create more complex curves like the one illustrated here.

572ci Big Block 350 Hp Dyno Run 8/12

07. This is a graph of the dyno run with a 350hp shot on top of the upgraded Straub Technologies 572ci big-block. The curve is odd shaped because they waited until 5,400 rpm to hit the nitrous button with the full 350hp shot. The result was 1,202 hp at 6,400 rpm. Let that settle in for a moment before you move on—1,202 hp.

1968 Chevrolet Camaro Nitrous 9/12

08. This is no trailer queen race car. Troy is one of those guys who expend a ton of effort into building a very nice car that is quick but is also driven on the street. That’s one reason for the hydraulic roller cam—less maintenance on the valvetrain. On the street, Troy runs nothing more than pump-fed 93 octane and, he reports, it’s completely happy thanks to the mild 10.0:1 compression ratio. This shot was at the Street Machine Nationals in Du Quoin, Illinois.

1968 Chevrolet Camaro Nitrous 10/12

09. Just in case you think that the 8.439 at 162 might have been a fluke hero run, Troy showed us these three back-to-back passes – all within 0.05-second at 162+ mph. Do you think Troy has a handle on this beast?

1968 Chevrolet Camaro Nitrous 11/12

10. Traction comes from a pair of Hoosier 31x14x15 slicks at the track and 31x16.50 Hoosier Quick Time Pros mounted on 14x15 American Racing Track rear wheels for the street. Plans for the future include pushing into the 7s if he can get the car light enough. Of course, it will still be a street car.

Knocking on Seven’s door

Nitrous Progressive Controller Testing 12/12

Just before this story went to the press, LaCrone pumped a 500-shot into the system, changed the controller—and nearly put it on the bumper! After that aborted pass, he tied the front-end down and went for it. The timeslip tells the story: 8.259 at 166.07 mph, almost exactly his goal. This was despite what LaCrone described as an ugly “85-degree night that was humid as hell.” Can the 7s be far behind?

Sources

Air Flow Research (AFR)
Valencia, CA 91355
877-892-8844
AirFlowResearch.com
Holley
Bowling Green, KY 42101
866-388-5120
www.Holley.com
American Racing Custom Wheels
Rancho Dominguez, CA 90221
www.americanracing.com
Edelbrock
Torrance, CA 90503
310-781-2222
www.edelbrock.com

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