For decades, drag racing has had a foothold on American motorsports passions. The ground-pounding power and sound of an NHRA dragster screaming down the strip is an awesome sight. For the Average Joe, the barrier for entry into drag racing is very low, and as a result, there are a lot of drag racers around. As such, there is a lot of knowledge about what makes a good drag race engine. In more recent years the tire-smoking and adept sliding of Formula DRIFT cars have begun to excite fans and inspire grassroots builders to get into the drift game. As more and more people start to build their own drift cars, the question that regularly comes up is, “will the same concepts put into a drag racing engine work for drift?” The answer, of course, is yes and no.
These Are Race Engines
The first thing to recognize about a drift engine or a drag race engine is that neither are street engines. The engine for your street car lives its life between 3,000 and 6,000 rpm, going to the grocery store and taking you to the job you hate. Most street car engines rarely see north of 6,000 rpm (unless, of course, they are in a rental car, which are abused daily).
By contrast, a race engine lives its life at high RPM and rarely sees street engine speeds. The engine package needs to be optimized for what it is used for. That means if you try to use a valvetrain system optimized for one environment, it will be a complete disappointment in the other realm. Short answer: there is a difference.
Drift vs. Drag Differences
To understand some of the differences between drift and drag engine builds, we spoke with Billy Godbold, COMP Cams’ Valvetrain Engineering Manager. Godbold explained that a racing engine is continually pushed to its maximum ability for performance, which requires constant maintenance and refreshing. “People would be amazed at just how few cycles occur in a drag race event. Fifty thousand cycles might be considered a full life on a Sportsman drag race valvespring, where even a single pass at Bonneville might run twice that many cycles. An then a Pro Stock drag racer might expect as few as 5,000 valve spring cycles. While I do not believe many of the Formula DRIFT racers expect a NASCAR style five hours between rebuilds, I am sure almost everyone in that series would want two-plus hours before freshening the valvetrain.”
Dangers Of All-Out Competition
Godbold detailed how things can go wrong for some race engines, saying, “There is often a harsh similarity of doom between drift and some drag race engines (especially in turbocharged drag race classes). The harshest thing for a valvetrain system is sitting on an ignition cut. When you cut spark without cutting fuel, not only do you get the negative effect from the unloaded crank springing forward, you also allow a fresh fuel and air charge through the chamber and out the exhaust.
“When the ignition is brought back in subsequent cycles, you reload the crank, and also provide an ignition source for the fuel-air charge (or tiny bomb) in the exhaust header. For turbo drag racers, this explosion and pressure spike excites the exhaust turbine side of the turbo system, allowing boost to build more quickly. For drifters, the same type of explosions can excite a turbo (and the sound excites the fans and the series’ judges) to keep turbine speed up in transitions.
A Look Inside Of A Formula DRIFT Pro-Level LS
|Engine: LS7||Port Work: Jon Kaase Racing Engines|
|Builder: Jon Kaase||Valves: Titanium Comp|
|Total Displacement: 427 cubic inches||Valvesprings: Comp dual spring|
|Bore x Stroke: 4.125 x 4.000||Rockers: Comp shaft mount|
|Block: RHS||Pushrods: Comp|
|Crankshaft: Callies forged steel||EFI System: FuelTech|
|Rods: Callies 6.125-inch forged steel||Injectors: FAST 2000cc|
|Pistons: JE 10.8:1||Throttle Body: Fast 102mm|
|Oil Pump: Melling||Power Adder: Edelbrock E-Force supercharger, 18psi|
|Oil Pan: Canton||Ignition System: FuelTech|
|Timing Set: COMP||Fuel Type: Ignite E98|
|Cylinder Heads: RHS LS7||HP/TQ: 991 horsepower, 1180 lb-ft (Hub Dyno)|
“However, that excitement comes at a cost. The same pressure that pushes out a sound wave or spins a turbine can also lift an exhaust valve off the seat. When the camshaft comes around, a lifted exhaust valve can act exactly like you were running 0.100-inch-plus lash or clearance. No camshaft profile is designed around that type of running start.” To summarize what Godbold said above: big turbo, plus ignition cut-off, plus ignition back on, can equal instantaneous disassembly of the engine.
Over time, competitors have learned what works and doesn’t work, according to Godbold. “In drag racing, our customers are doing a much better job of staying on the chip for less time and finding other ways to build boost. Likewise, professionals in Formula DRIFT see far less aggressive popping today and have learned other tricks (reduced throttle, more timing, excessively rich) to reduce pressure spikes in the header that can destroy a valvetrain system.
However, these changes have taken some time to catch on throughout the worlds of either drift or drag.” Godbold and his team at COMP Cams work directly with Formula DRIFT driver Taylor Hull to develop the perfect package for getting “slideways” for the crowd.
Taylor Hull runs in the Pro class of Formula DRIFT in a 2015 Cadillac ATS-V. You can see him destroying the rear tires of his Cadillac all across the country at different events. According to Hull, they didn’t design their LS engine to rev directly to redline like you would a drag racing engine, “We have actually designed this engine to not really get to redline.” Hull explained this is accomplished in two different ways.
First, they tuned the car to not hit redline. However, that was really a back-up to their initial method. “We put so much grip into the car that even at full throttle, the grip i is enough to keep it from reaching redline.” Taylor added, “The failsafe is to simply let out of the throttle slightly and modulate. The redline on our engine is currently 8,600 rpm. If we ever get close to it on a course, we typically just turn the rev-limiter up higher. We would rather see more RPM than have the engine bouncing off the limiter.” This method is consistent with the warning about ignition cut-off from Godbold.
Drag Racing Brain
Since the camshaft dictates the opening and closing of the valves, which directly controls the flow of the air-fuel mixture to the cylinders, most people consider the camshaft to be the “brain” of an engine. Drag racers have been upgrading that brain for years to find more performance. To grasp maximum power from any cam, it must work in unison with the entire vehicle combination, from induction to displacement to gearing and even the vehicle’s weight.
Bigger doesn’t always mean better. You can increase torque by advancing the cam or you can get more horsepower at higher RPM by retarding the cam. To fine-tune the engine, you need to take advantage of generating the best volumetric efficiency by timing the cam with the crankshaft. This will help you move the power band up or down. A good drag racing engine wants to rev quickly, putting huge power down as it gets ready for the next shift of the transmission. Drift engines aren’t seeking the next shift.
The Formula for Drift
Drifting is different than drag racing. It isn’t simply a straight-line run for a quarter of a mile. In drifting, there is an enormous amount of modulation of the throttle to carry a drift. These drifts are done within millimeters of a concrete wall at high speeds. The commitment is big for a driver. They need an engine that can provide torque everywhere and make around 1,000 horsepower. The LS engine in Taylor Hull’s Cadillac is a Racing Head Service (RHS) aluminum block and heads, with a COMP Cams solid roller valvetrain, titanium valves, and an Edelbrock supercharger. That package provides Taylor with 991 horsepower and 1,180 lb-ft torque. Not too shabby.
COMP Cams developed a cam specifically for the needs of drifters after working with Hull. Godbold talked about what they came up with. “We developed a couple of packages expressly for the grassroots drift crowd. Our 54-777-11 and 54-778-11 camshafts were made just for the customer wanting to take a junkyard GM 4.8, 5.3, or 5.7-liter Gen-III LS engine and use that for drifting. Really, that camshaft, our 26906KIT spring kit, our upgraded timing chain, along with the RHS sheetmetal intake and TB kit would be a great, low-budget combination to get started in these type of competitions. Clearly, we have numerous great cams and parts for drag racing, but have not forgotten about our friends sliding around while smoking the rear tires.”
And The Final Answer Is…
So, the final answer is drag racing engines and drift engines are different and they aren’t. Clear as mud? Both competitors want as much power as they can get. However, where they want that power band to hit can be different. What should be taken from this discussion is that it’s a carefully put together package that will make the difference at the track.
Simply bolting on random parts from the internet will rarely provide success. This sentiment is shared by Tony Bischoff, renowned engine builder and owner of Bischoff Racing Engines. According to him, building a good racing engine requires an entire package that will, “optimize the engine to generate more torque at higher RPM.”
Whether you are creating a drag racing engine for straight-line speeds or a drift engine to decimate rear tires and slide sideways, you need to ensure all of the engine’s parts are paired with the rest of the vehicle to provide optimal torque at the exact RPM range to ensure you get to the finish line first or wow the judges at a drift event.