When it comes to how much horsepower NASCAR cars have, you may think that to reach and maintain such high speeds it must be very high. However, you may not know that multiple factors other than speed go into how NASCAR decides how much horsepower NASCAR cars have.
NASCAR cars have 670 horsepower in their primary Next Gen package. This package also features 4” spoilers. However, a second package, used for superspeedways, offers about 510 horsepower with 7” spoilers. This is a significant increase over the Generation 6 cars, but not the most they’ve ever had.
Below, we will reveal why NASCAR’s Next Gen cars have more horsepower than their Generation 6 counterparts. We will also touch on how improved downforce, coupled with more horsepower, has made the cars both safer and more exciting to watch.
Next Gen NASCAR Cup Cars have 510 horsepower on the superspeedway package and 670 horsepower on the intermediate and road course package. The different packages are designed to keep racing as fast and exciting as possible while also improving safety for drivers and fans.
Generation 5 And Generation 6
NASCAR’s older Generation 5 (Car of Tomorrow) and Generation 6 cars drew criticism. Fans, teams, and manufacturers did not like the fact that the cars looked generic in comparison to street legal counterparts. Especially the Generation 5 cars and their infamous raised, winged spoilers. The Generation 6 cars did not fare much better. Both generations also drew criticism for lack of downforce.
However, more downforce meant slower speeds. So, to keep races interesting, NASCAR needed to find a way to increase the downforce and to keep the cars racing at higher speeds. The solution was more powerful engines.
Theoretically, the old NASCAR engines could reach 850 horsepower. However, NASCAR added restrictor plates to the vehicles at superspeedways like Daytona and Talladega. This limited the cars to just 410 horsepower. NASCAR has used the same 1/8” restrictor plates since they mandated them following Bobby Allison’s crash at Talladega.
With improved downforce and aerodynamic packages, NASCAR was able to create 2 packages for their “specs.” The first spec was for the 2 superspeedways and it called for 7” spoilers and 510 horsepower, far more than the older cars possessed under the restrictor plate.
This increased horsepower allowed the cars to maintain additional downforce without sacrificing a lot of speed. The same thing went for the other aerodynamic/downforce package, intended for the intermediate tracks and road courses, but they came with 670 horsepower and 4” spoilers.
With the intermediate track/road course package came the tapered spacer, which look like restrictor plates, except they are roughly 1” thick instead of ⅛” thick.
They also have tapered holes, which differs from the restrictor plate’s straight holes. This lets the engine get more gas and air than what the restrictor plate allowed, and it is responsible for the Next Gen cars’ increased engine power, even with the cars containing more downforce.
Restrictor plates are no longer used in NASCAR. They have been replaced by tapered spacers for the Next Gen cars. The restrictor plates failed to prevent the type of crashes they were initially brought in to stop. The tapered spacer gives NASCAR more control over power outputs at each track.
History Of Restrictor Plates
Starting in 1988, NASCAR mandated all teams use restrictor plates following Bobby Allison’s crash at the 1987 Winston 500 at Talladega. Allison, said to be traveling at 210 mph, blew a right rear tire. This caused his car to spin and fly into the catch fence, injuring several fans. While Allison’s car did not go into the stands, it was too close of a call for NASCAR.
The restrictor plate limited the air and gas pumping into the engine, which kept the cars driving at reasonable speeds. And while you saw numerous accounts of cars going airborne and into the catch fence, the slower speeds kept these incidents few and far in between.
Yet throughout the decades, NASCAR realized they still had work to do. During the 2009Aaron’s 499 at Talladega, Carl Edwards flew into the catch fence on the final lap in a crash reminiscent of Allison’s. And if you noticed anything, the crash occurred at the same track, almost in the same spot.
Fast-forward to 2015 at Daytona, when Austin Dillon had a similar wreck. Edwards and Dillon both walked away unharmed, but for NASCAR, it was another wake-up call. The restrictor plates needed to be replaced as Edwards’ wreck occurred in the Gen 5 car while Dillon’s occurred in the Gen 6.
If restrictor plates were designed to keep cars safer, why were they still going airborne and getting mangled at superspeedways? The major drawback with restrictor plates was the fact they caused cars to race too close to one another.
Just watch any race at Daytona and Talladega and you will discover quickly just the slightest bump could set off a pileup, nicknamed The Big One. This is what happened with Austin Dillon toward the end of the summer Daytona race. And about a dozen more cars crashed during that final lap.
Tony Stewart’s flip at the 2001 Daytona 500 is another example of just how debilitating The Big One was for its drivers. And if you go back through the decades, you will recall seeing The Big One occurring at just about every race on superspeedways.
Initially, NASCAR sought for the Gen 6 car to have enough downforce to prevent these types of crashes seen from Stewart (Gen 4), and Edwards (Gen 5). However, Dillon’s crash (Gen 6) proved it wasn’t enough. Even with restrictor plates.
NASCAR had used the tapered spacer at other tracks, so when the time came to make more changes to the cars, they implemented their use in Daytona and Talladega following the 2019 Daytona 500.
NASCAR’s goal was to keep the cars’ speeds under control. Yet at the same time, they wanted to give the cars a bit more space on the track. It was something the tapered spacer helped with at Daytona and Talladega. When the Next Gen car arrived, the added downforce and improved aerodynamics would further keep the cars safer, regardless of the engine’s more powerful horsepower.
NASCAR’s most powerful engine was the Chevrolet R07, which debuted in 2007. This engine was built specifically for NASCAR. It was thought to be the most refined small block engine of its generation with over 900 horsepower being generated from the V8, much higher than the current 670 HP.
Overall, NASCAR’s Next Gen engines feature a great deal more power than their predecessors. But they still aren’t the most powerful engines. Through the years, NASCAR has seen some strong engines, which slowly forced the organization into mandating certain specifications to keep the playing field level. Of the most powerful engines in NASCAR, 2 stick out: The Hemi and the Chevrolet R07.
The Dodge Daytona and its sister car, the Plymouth Superbird, dominated NASCAR in the late 1960s and in 1970. They set track records all over the NASCAR circuit, and with the powerful engine, the Superbird won 8 races in 1970. Their engine of choice? The Hemi.
The Dodge Daytona was known for reaching 200 mph. This feat caught NASCAR’s attention, and they later banned the engine from its events. The story begins, however, in 1964, with Dodge’s “Doomsday Machine,” featuring a 426 cubic D.O.H.C. V8. At 425 horsepower.
However, although the engine was the most powerful for its time, NASCAR’s ban will leave us wondering how powerful this engine could have become. How powerful was it? In 1964, it won 26 of the season’s 62 races, 9 of which belonged to Richard Petty, who also recorded 43 top 10s that year.
The Chevrolet R07 was the most powerful NASCAR engine. Built specifically for NASCAR, the engine debuted in 2007 and it was believed to be the most refined small block engine of the time.
Dubbed the Engine of the Future, the R07 was capable of reaching 10,000 revolutions per minute (RPM). It was a V8, per NASCAR specs, and it featured 4.5” between cylinder bores, which was wider than its predecessor, the SB2. This allowed better circulation around the cylinders.
NASCAR Xfinity cars have between 650-700 horsepower, making them quite similar to their Cup Series counterparts. They still call for an engine displacement of 358 cubic inches with a V8 pushrod. When it comes to speed, this means there is little difference between them.
You may initially think there aren’t many differences between the NASCAR Cup and Xfinity Series cars. If you flip on an Xfinity Race on Saturday and watch a few laps, you probably couldn’t tell that a difference exists unless you are well-versed in the world of stock cars.
However, there are slight differences between the NASCAR Cup and Xfinity cars. Xfinity cars have slightly smaller wheelbases and are about 100 pounds lighter than their Cup counterparts. But the power and speeds are quite similar.
For example, in 2022, pole sitters at Daytona had similar speeds. Daniel Hemric won the pole at the 2022 Beef. It’s What’s For Dinner 300 with a qualifying speed of 49.221 seconds. Kyle Larson recorded a time of 49.680 seconds. Similar to his Xfinity Series counterpart.
NASCAR trucks have similar horsepower to the Xfinity and Cup cars, between 650 and 700. Restricted, these engines run at 450 horsepower, like the Xfinity cars. The trucks also feature an engine displacement of 358 cubic inches and pushrod V8s, similar to those used in the Cup Series.
Unlike the NASCAR Cup and Xfinity series, you will notice more significant differences in the trucks’ aesthetics. They are also slightly wider than both NASCAR Cup cars and Xfinity cars at the wheelbase.
Despite featuring similar engines that also include 12:1 compression ratios and natural aspiration, the major differences between the 3 series are their schedules and the length of their races.
The NASCAR Xfinity Series runs a slightly shorter schedule featuring 33 events instead of NASCAR’s 36 events (not counting exhibition races). The Truck Series features an even smaller schedule of just 23 races.
Further, Xfinity Series races are roughly 60 to 70 percent the length of their Cup Series counterparts. Truck Series races run for about half the length of the Cup races. For example, when compared to the Daytona 500, the Xfinity event lasts 300 miles and the Truck Series event, 200 miles.
Next Gen NASCAR cars have 670 horsepower for their intermediate track and road course track packages and 510 horsepower for the superspeedway. These are more powerful than the Gen 6 engines to compensate for more downforce. Xfinity and Truck Series feature similar power to the Cup Series cars.