How much horsepower does a dirt Street Stock have?

Most dirt Street Stock race cars make roughly 350–450 horsepower, with crate-limited packages typically around 350–380 hp and more open “built” engines reaching 425–500 hp depending on the sanctioning body, carburetor limits, compression, and head/cam rules. Exact output varies widely by local rulebook and whether the class allows a GM 602 crate, a two-barrel “limited” build, or a freer four-barrel/open combination.

What “Street Stock” means on dirt ovals

Unlike national series with standardized spec engines, “Street Stock” is a rules-defined grassroots class that differs by region and sanction. Some tracks run crate-only lineups, others permit two-barrel iron-head builds with strict compression limits, and a few allow more open four-barrel engines. The horsepower spread reflects these variations as much as it reflects engine tuning or budget.

Typical horsepower by common rule packages

Crate-based Street Stocks (often GM 602)

Many tracks or series mandate the GM 602 crate engine (350-ci small-block). Factory ratings are about 350 hp and 390 lb-ft in baseline trim. In circle-track spec with headers, optimized ignition, and proper fuel, teams commonly see roughly 350–375 hp with broad torque suited to slick dirt surfaces. Some Street Stock rulebooks prohibit the higher-output GM 604 crate used in Late Models.

Limited/open two-barrel builds

Where iron-head builds with a Holley 4412-style 500 cfm two-barrel are allowed, output usually lands in the high-300s to low-400s. With 9.0–10.0:1 compression, a camshaft tailored to the restricted carb, and efficient exhaust, engines often produce about 380–420 hp with strong midrange torque—valuable for corner exit on dry-slick tracks.

Freer four-barrel/open builds

In regions where four-barrels, higher compression, and better-flowing cylinder heads are allowed, Street Stock engines can climb into the mid-400s and occasionally approach 500 hp. These combinations trade some drivability and tire management for peak output—track prep and tire rules often dictate whether that extra power is usable.

Real-world ranges by popular sanctioning styles

The following examples illustrate the ballpark power you’ll find across commonly referenced rule sets. Local tracks may use variants, so always verify your own rulebook before comparing figures.

• Crate Racin’ USA-style Street Stock (GM 602): approximately 350–375 hp with typical circle-track bolt-ons.
• WISSOTA-type Street Stock (iron heads, 2-bbl limits): commonly 360–410 hp, emphasizing torque and drivability.
• IMCA/USRA Stock Car–style builds (closest equivalent class in some markets): roughly 360–420 hp depending on compression, cam, and 2-bbl rules.
• DIRTcar/UMP-style Street Stocks where 4-bbl or less restrictive heads are permitted: often 425–475 hp, with top builds occasionally near 500 hp.

These figures reflect typical dyno ranges for legal, well-prepared engines and assume common fuels, headers, and ignition. Individual results vary with tuning, altitude, dyno calibration, and enforcement rigor.

What actually drives the horsepower number

Even within one rulebook, small choices can move an engine up or down the range. The items below are the biggest levers teams pull within legal limits.

• Carburetor restriction: Two-barrel 4412 rules cap airflow, keeping power lower but torque broad; four-barrels raise peak hp.
• Compression ratio: Tight limits (e.g., 9.0–10.0:1) restrain output; higher compression in open classes boosts hp and throttle response.
• Cylinder heads and camshaft: Iron-stock heads and flat-tappet cams keep numbers modest; better-flowing heads and aggressive cam profiles raise hp where allowed.
• Exhaust and intake: Equal-length headers, optimized collectors, and matched intakes meaningfully affect the curve, especially with restricted carbs.
• Fuel and ignition: Spec fuels, timing curves, and rev limiters can preserve parity and cap peak numbers.
• Dyno and environment: Correction standards, altitude, temperature, and test procedures can swing readings by notable margins.

Because Street Stock aims to balance cost and competition, many rulesets intentionally narrow these variables—especially carb size, compression, and head choice—to keep horsepower and budgets in check.

How to estimate your Street Stock’s horsepower

If you’re building or buying a package and want a realistic hp expectation, work through the steps below with your engine builder and tech inspector.

1. Identify your exact rulebook and any local clarifications (carb model, head casting, compression method, rev limiter).
2. Choose the engine path (crate vs. built) and confirm seals or verification processes required by tech.
3. Discuss cam, heads, and compression targets that optimize midrange torque for your track’s usual surface.
4. Plan supporting components—headers, fuel, ignition, cooling—and confirm they’re legal and dyno-proven together.
5. Dyno with the carb and exhaust you’ll race, using consistent correction and fuel to get an apples-to-apples number.

This process gives you a credible horsepower figure while ensuring the combination is legal, durable, and matched to your track conditions.

Why peak horsepower isn’t everything on dirt

On quarter- to three-eighths-mile dirt ovals, tire grip, gearing, and throttle control often trump peak horsepower. Many winners run midrange-focused engines that are easier on tires and more forgiving in slick conditions. Balance, repeatability, and drivability can decide races more often than an extra 20–30 hp at the top of the curve.

Bottom line

A dirt Street Stock typically makes 350–450 horsepower, with crate-limited combinations near 350–380 hp and more open builds ranging from about 425 up to roughly 500 hp under permissive rules. Check your specific rulebook to pinpoint where your class falls on that spectrum, and prioritize a broad, usable powerband over sheer peak output for dirt-track success.

How much horsepower does a Chevy 292 inline 6 have?

The Chevrolet 292 inline-six engine produced around 165 gross horsepower and 260 lb-ft of torque in its stock form, but GM intentionally underrated it, with actual figures sometimes exceeding these ratings. This engine was designed for strength and low-end torque, with features like a forged steel crankshaft and seven main bearings. Its robust design allowed for significant performance upgrades, with enthusiasts achieving over 600 horsepower in turbocharged builds.
 
You can watch this video to learn more about the power of the 292 engine: 47sEngine LegendsYouTube · Apr 30, 2025
Factory Output and Intent:

• Horsepower: Approximately 165 gross horsepower at 3,800 rpm. 
• Torque: Around 260 lb-ft at low RPM. 
• GM’s Strategy: GM deliberately limited the 292’s performance through components like a mild camshaft and restrictive exhaust to protect V8 sales. 

Key Features:

• Seven Main Bearings: Provided exceptional crankshaft stability and reduced flex, a significant advantage in a high-torque engine. 
• Forged Steel Crankshaft: Made the engine highly durable and capable of handling heavy loads and high RPMs. 
• Long Stroke: The 4.125-inch stroke created substantial low-end torque, making the engine excellent for heavy-duty applications. 
• Strong Construction: The thick cylinder walls, strong block, and heavy-duty connecting rods made it incredibly resistant to wear and failure. 

Performance Potential: 

• Hot Rodders: Enthusiasts modified the 292 for racing and discovered its considerable hidden performance potential.
• Turbocharging: With modifications, the 292 became a prime candidate for turbocharging, with some builds exceeding 600 horsepower.

In Summary:
The Chevy 292 was a powerful and overbuilt engine that offered impressive low-end torque in its stock form. While officially underrated, its true potential for performance was realized by hot rodders and racers who understood its strong, durable design.

How much horsepower does a street stock have?

375 to 450 hp
Street Stocks tend to fall in the 375 to 450 hp range, while IMCA Stock Cars can produce anywhere from 400 to 475 hp, depending on whether it’s a crate engine or built motor. In open classes, you’ll often see cars making 500 horsepower or more.

How fast do factory stock dirt cars go?

Factory Stock
During a race, Factory Stocks average 60 MPH in the corners and 75 on the straight-a-ways. Factory Stocks use a Hoosier Asphalt Slick Pull off 8″-10″ wide racing tire. Rear tires can last around 8 weeks and front tires can last longer. Factory Stocks use 110 octane or 98 octane pump gas fuel.

Do all nascars have the same horsepower?

For most tracks on the NASCAR calendar, the cars are tuned to produce about 670 horsepower. But this may vary from year to year based on rules changes. On higher-speed tracks, NASCAR uses varying restrictor plates atop the fuel injection ports to reduce the amount of fuel and air entering the engine.