I have an 86 and want to change the injectors. Who knows what stock injectors are in the 5.7? I have a new set that are calabrated at #28.8. Can I use these or not?
There are a number of Fuel Injectors on the market today the following injectors have been furnished on GM OEM systems: Lucas, Bosch, Rochestor and Multec. The prices vary considerably and performance differences are hard to detect. Basically they are sized for application. The 5.0L injector is sized to deliver approximately 4.05 milligrams of fuel with a 2.5 millisecond pulse or 18.13 lbs per hr at approximately 36 PSI. The 57L injector is sized to deliver approximately 4.83 milligrams of fuel with a 2.5 millisecond pulse or 23.92 lbs per hr at approximately 43.5 PSI. This information is typical for all manufacturers and flow rates will vary slightly even between identicle injectors.
Lucas is presently pushing their new High Output Disc Injector and is referred to as a High Performance Injector. This product was introduced in March of 9l. They are competitively priced at approx $60.00 each. A wide variety of flow rates are available to include 18lb/hr, 24lb/hr,28lb/hr, 37 lb/hr. These are all 16.2 Ohms and will work well with all GM TPI ECM's Rochestor injectors are presently furnished for the 90-94 GM 5.7L engine. It has an all metal nozzle and performs well. Priced at approx $75.00 each. Bosch injectors are also an excellent choice at approx $87.00 each.
While there are significant differences between the TPI and LT1 induction systems and computers, the injectors are essentially the same. Sequentialport injectors and batch fired injectors are sized in the same manner. We regret that we have not been able to make DYNO comparisons of these products. We will be glad to share whatever we hear on this subject with you when you call. FIS stocks all of the injectors referenced.
Eagle85C4 said:I believe there needs to be more research done here. I was told and have read that stock injectors for the L-98 were 19# and that the 24# came out with the LT-1. Now according to a chart from TPIS the 19# injectors are capable of providing up to 38 HP per cylinder for a total of 304 HP. The next one up for them is the 27# injector which is capable of providing 46 HP per cylinder for a total of 368 HP. The chart is to be used as a reference to allow the user to select the proper injector for your specific application.
So as I see it (reading between the lines) it doesn't matter what size injectors you use because either the DFI or ECM control the opening and closeing of the injectors. If the DFI or ECM control the opening and closeing than its the amount of fuel that is shot dureing that opening time. ie- 30# will squirt more than 19# while the injectors are open. but if the fuel pressure regulator controles the pressure to the injectors then the opening in the injectors are what controles that amount??