| There was a day when finding inexpensive | | | | can also be modified to flow 47lbs. This method |
| aftermarket injectors to support 500-600rwhp | | | | of modifying certain Ford/Bosch style injectors will |
| were tough. There were few options for high | | | | dramatically increase fuel delivery without |
| impedance style injectors, other than the Ford | | | | significantly compromising the injector spray |
| Motorsport 42lbs or MSD 50lb units. The | | | | pattern or vehicle emissions. From a very high |
| aftermarket fuel injector industry has progressed | | | | level, here are the steps to modify fuel injectors; |
| rapidly over the past several years and as a | | | | |
| result there are many brands and sizes available | | | | 1. Remove the pintle cap, o-ring and insulator. |
| for most performance enthusiasts. Larger | | | | 2. Remove the difusser plate by filing around the |
| injectors are necessary to support higher | | | | weld. |
| horsepower levels on modified cars. As a rule of | | | | 3. Install new pintle caps, o-rings and insulator. |
| thumb the following equations are useful when | | | | 4. Have theunits flow tested and ultrasonically |
| selecting the right size injector to support the | | | | cleaned by a professional service shop. |
| required horsepower level. | | | | The problem is that the actual procedure is not |
| To calculate the size for a particular application: | | | | well known and it is very easy to destroy a fuel |
| - Injector Flow Rate (lb/hr) = Engine HP(1) x | | | | injector if done improperly. Care needs to be |
| BSFC(2) - Number of Injectors x Injector duty | | | | taken when removing the difusser plate, and the |
| cycle(3) | | | | injectors must be flow tested and ultrasonically |
| Or | | | | cleaned (a good practice for used injectors) to |
| - Injector Flow Rate (cc/min) = Engine HP(1) x | | | | verify the flow rate. Once the injector size is |
| BSFC(2) x 10.5 - Number of Injectors x Injector | | | | known the computer/maf can be calibrated to |
| duty cycle(3) | | | | match the new flow rate to ensure proper air to |
| An old trick that some of the "Tuners" used to | | | | fuel ratio (this is something that needs to be done |
| do was modify the 30lb/36lb Ford Motorsport | | | | regardless of what aftermarket fuel injector is |
| units to increase the flow rate. There are still | | | | used). |
| street/strip racers using these modified injectors | | | | When this procedure is properly performed, these |
| today with great results for the intended purpose. | | | | modified fuel injectors work very well and will |
| Generally, 30lb injectors becom 47lb injectors and | | | | easily support street/strip cars easily generating |
| 36lb injectors may become 66lb / 72lb / 77lb | | | | 400-600 horsepower. There are many still being |
| injectors. | | | | used today. It is still an economical way to obtain |
| Furthermore, there are some original equipment | | | | larger units for those car owners on a limited |
| manufacturer bosch style units used by Ford that | | | | budget. |