Go to the app store for any of the major cell phone companies and you’ll surely find plenty of apps. Apps for running, apps for walking, apps for music, TV, games and even apps for telling you what time to use the bathroom in the middle of a movie. But as someone who generally prefers a night of carb cleaning to a night at the movies, you don’t care much for these things. But what about a car building app?

Speedmaster, a performance parts manufacturer/supplier, has designed a useful app that takes some of the math and guesswork out of build planning. Called Speedmaster Tools, the app consolidates many of the mathematical equations normally used in build planning, and keeps them in one convenient app that does the work for you. After entering relevant build specs into the provided fields, the app will calculate basic figures like compression ratio, rod-stroke ratio, gear ratios and 1/4-mile times. The app can even do more advanced calculations, like carburetor size needed and horsepower gains from turbos/supercharging. Check out the images for the complete list of features.

Best of all it’s a free app, so skip the weird dating and bathroom apps and checkout Speedmaster Tools.