MotorSports Digest

Fuel Injector Chart

The following chart is set up to show the absolute maximum horsepower possible with supercharged, eight cylinder applications. However, with normally asperated cars these numbers will be much more conservative. That being said, the higher pressures aren't really practical without some form of forced induction, so most of the chart is geared toward supercharged applications. Also, even though the chart represents eight cylinder applications, with other combinations you can divide the hp number by eight and multiply by the number of cylinders you have.

Maximum Horsepower Potential

	19 lb	24 lb	30 lb	36 lb	42 lb	55 lb	83 lb
40 psi 50 psi 60 psi 70 psi 80 psi 90 psi 100 psi	285 hp 317 hp 347 hp 375 hp 401 hp 425 hp 448 hp	358 hp 400 hp 439 hp 474 hp 507 hp 537 hp 566 hp	448 hp 501 hp 548 hp 592 hp 633 hp 672 hp 708 hp	537 hp 601 hp 658 hp 711 hp 760 hp 806 hp 849 hp	627 hp 701 hp 768 hp 829 hp 886 hp 940 hp 991 hp	821 hp 918 hp 1005 hp 1096 hp n/a n/a n/a	1239 hp 1385 hp 1517 hp n/a n/a n/a n/a

To get a better idea of what is really going on, this chart shows the effects of fuel pressure on injector size. It gives a good idea of just how much of a gain you get from increasing pressure with a Fuel Management Unit (FMU).

Effective Injector Size

	19 lb	24 lb	30 lb	36 lb	42 lb	55 lb	83 lb
40 psi 50 psi 60 psi 70 psi 80 psi 90 psi 100 psi	19.0 lbs 21.8 lbs 23.9 lbs 25.8 lbs 27.6 lbs 29.2 lbs 30.8 lbs	24.0 lbs 27.5 lbs 30.2 lbs 32.6 lbs 34.8 lbs 36.9 lbs 38.9 lbs	30.0 lbs 34.4 lbs 37.7 lbs 40.7 lbs 43.5 lbs 46.2 lbs 48.7 lbs	36.0 lbs 41.3 lbs 45.2 lbs 48.9 lbs 52.2 lbs 58.4 lbs 58.4 lbs	42.0 lbs 48.2 lbs 52.8 lbs 57.0 lbs 60.9 lbs 64.6 lbs 68.1 lbs	55.0 lbs 63.1 lbs 69.1 lbs 74.6 lbs n/a n/a n/a	83.0 lbs 95.2 lbs 104.3 lbs n/a n/a n/a n/a

With both of these charts it's important to keep in mind that not all injectors work well under higher pressures. Also, you can't rely on additional fuel pressure to solve all your problems. The purpose of the charts is simply to show the potiential that each size of injector has. Many people will jump straight to a set of 42 lb injectors on applications that could work just as well with a set 24's. While it's important to have a large enough injector to stay safe, it's also a good idea to keep in mind that the larger the injector, the more difficult it can be to tune. A custom chip or tuneable computer can solve these problems, but so can an FMU and a more reasonably sized injector.