What size are the stock m50 injectors?
The stock M50 injectors are typically in the low- to mid-20s pounds per hour (lb/hr) range, with the 2.0-liter variant commonly around 19–21 lb/hr and the 2.5-liter variant around 21–23 lb/hr at standard fuel pressure. Exact sizing can vary by model year, market, and production revision, so verifying the specific part numbers is important.
In this article, we break down the usual factory injector sizes for M50 engines, explain how the sizes differ between variants, and outline practical ways to identify your exact injector rating for tuning or upgrades.
Stock injector sizes by M50 variant
These figures refer to standard factory injectors calibrated for the M50 family at the common fuel rail pressure used in BMWs of that era (about 3 bar / 43.5 psi). Real-world numbers can vary slightly by market and production run.
- M50B20 (2.0 L) — typically around 19–21 lb/hr
- M50B25 (2.5 L) — typically around 21–23 lb/hr
The size differences align with engine displacement: larger pots generally require slightly larger injectors to meet fueling targets under load, though the exact rating can still vary by year and market.
How to verify your exact injector size
Because production changes and market calibrations exist, the definitive way to know your stock injector size is to read the labeling on the injector itself or consult official specifications for your vehicle’s build date and market.
- Inspect the injector body for stamped flow rating (for example, 19 lb/hr, 21 lb/hr, or 23 lb/hr) and a part number.
- Cross-check the stamped numbers with BMW’s parts catalog or a trusted OEM/aftermarket source for your exact model year and market.
- If labeling is unreadable, use your VIN to pull the OE specification from a dealer or professional source, or arrange a flow test to determine the exact rating.
Knowing your exact size is essential for accurate tuning, fuel delivery planning, and choosing appropriate upgrades or replacements.
Summary
For most M50 engines, stock injectors sit in the low- to mid-20s lb/hr range. A typical guideline is 19–21 lb/hr for the 2.0 L M50B20 and 21–23 lb/hr for the 2.5 L M50B25, though variations by year and market mean you should verify the exact rating on your vehicle. Always check the injector labeling or dealer documentation to confirm the precise size.
What cc are 36lb injectors?
380 cc/
Bosch 36 lb/hr (380 cc/min) Fuel Injector.
How much HP can 52lb injectors handle?
A 52 lb/hr injector can handle approximately 610-775 horsepower for a naturally aspirated engine and 510-650 horsepower for a turbocharged or supercharged engine. These are estimates, as the actual horsepower capacity depends on factors like the specific engine, fuel type, and other components like fuel pressure and duty cycle.
Naturally aspirated engines
- Estimated HP: 610-775 hp
- Note: This range assumes a lower brake-specific fuel consumption (BSFC) compared to forced induction applications.
Turbocharged or supercharged engines
- Estimated HP: 510-650 hp
- Note: This range is lower due to the higher BSFC of forced induction engines, which require more fuel to produce the same amount of horsepower.
Other factors to consider
- Fuel type: Injectors may perform differently with various fuels, such as E85 or race gas, compared to gasoline.
- Duty cycle: For reliability, it is recommended to not exceed a 90% injector duty cycle, which is a measure of how often the injector is opening and closing.
- Fuel pressure: Higher fuel pressure increases the injector's flow rate, meaning a 52 lb/hr injector can support more horsepower at a higher PSI.
What LS came with 42lb injectors?
LS Injector Size and Identification Guide
| ENGINE | LS INJECTORS TYPE | LS INJECTOR SIZE |
|---|---|---|
| L76 | EV6 / USCAR | 42 lb/hr @ 58 psi |
| L77 | EV6 / USCAR | 42 lb/hr @ 58 psi |
| LS3 | EV6 / USCAR | 42 lb/hr @ 58 psi |
| L99 | EV6 / USCAR | 42 lb/hr @ 58 psi |
What size injectors for 500hp?
For 500 horsepower, you'll likely need 32 lb/hr injectors on a gas engine with a power adder, but 42 lb/hr injectors or larger are a safer bet for most setups to provide headroom and avoid running them at their absolute limit. If using a different fuel like E85, you will need much larger injectors, and for diesel applications, the size will depend on the specific engine and tuning.
For gasoline engines
- Safe bet: A set of 42 lb/hr injectors is a good starting point for 500hp, as it provides enough flow and some headroom for future tuning.
- In-the-ballpark: Based on the rule of thumb that 111 horsepower needs about 0.50.50.5 lb/hr of fuel, a 500500500 hp engine would require 250250250 lb/hr of total fuel flow. Divided by eight injectors (31.2531.2531.25 lb/hr each), a 32 lb/hr injector would be the theoretical minimum, but it's not recommended to run injectors at their absolute limit.
- Larger options: If you plan on forced induction or running a more aggressive setup, a higher-flow injector like 46 lb/hr or larger would be a better choice.
For diesel and E85 applications
- E85: With E85, you will need significantly larger injectors. For example, a 1000cc (which is roughly 95 lb/hr) injector set may only support 420-440 wheel horsepower on E85.
- Diesel: For diesel engines, injector size is a much more complex topic and depends on the specific engine and modifications. For a 500hp Cummins, you might need injectors like 5x18s or 5x20s for smaller setups or larger injectors, depending on the injection pump and overall modifications, YouTube.
