The right LS fuel injector is the one sized for your power goal at the fuel pressure your system actually runs, in the length and plug your engine takes. This guide covers what came out of the factory in every LS from the LS1 to the LS9, how to work out the flow rate you need, and the fitment details that catch people out mid-swap. Three things trip people up: sizing off a forum rule of thumb, forgetting that LS fuel systems run around 400 kPa rather than the 3 bar most injectors are rated at, and ordering an injector that is the right size but the wrong length or plug. Featured in this guide: Excess 1000cc Injectors GM Holden 6.0lt / 6.2lt Set of 8, SKU X1000S8A. 1000cc, high impedance, 40mm half length (o-ring to o-ring) with a 14mm top o-ring. A direct drop-in for the Commodore 6.0 and 6.2 litre L76, L77, L98 and LS3: the factory loom plugs straight in, with no wiring or adaptors. Used as the worked example throughout this guide. Why LS injector sizing confuses people Ask five people what injector suits an LS and you will get five answers, most of them rules of thumb. Real sizing is a simple relationship: the fuel your power goal needs, divided across your injectors, with headroom left over. Your answer depends on your power target, fuel type, induction and fuel pressure, not on what worked in someone else's car. Get it wrong either way and you pay for it. Too small and the injectors run out of time at high rpm, which leans the engine out exactly when it needs fuel most. Too big and they struggle to meter the short pulses needed at idle and light load, giving a lumpy idle and flat spots. A bigger injector does not make power on its own; it only makes more fuel available. Any change of injector needs a retune. What's actually running in your LS right now Know what you have before you size anything. Holden and HSV fitted most of the LS family in Australia, and the injectors changed in flow, length and plug along the way. Factory LS Injectors by Engine LS1 5.7: VT Series II to VZ Commodore, HSV Gen III, Monaro. Bosch 0 280 155 931, ~273cc (26 lb/hr) at 3 bar. 65mm, full length. EV1. Approx. NA petrol ceiling ~380hp. LS2 6.0: VZ and VE HSV only. Bosch 0 280 158 049, ~312cc. 52mm. USCAR (EV6). Approx. NA petrol ceiling ~440hp. L76 / L77 / L98 6.0: VE and VF Commodore V8. Bosch 12639221. 40mm, half length. USCAR (EV6). Check data sheet. LS3 6.2: VE and VF HSV, VF Series II SS. Bosch 0 280 158 051, ~42 lb/hr at 58 psi. 40mm, half length. USCAR (EV6). Approx. NA petrol ceiling ~540hp. LS7 7.0: HSV W427. ~39 lb/hr. 40mm, half length. USCAR (EV6). Approx. NA petrol ceiling ~500hp. LSA 6.2 supercharged: HSV GTS. Bosch 0 280 158 187. 40mm, half length. USCAR (EV6). At or near its limit from the factory. LS9 6.2 supercharged: HSV GTSR W1. ~52 lb/hr. 40mm, half length. USCAR (EV6). At or near its limit from the factory. LS6 5.7: Not sold new in Australia (US Corvette Z06). ~28 lb/hr. 65mm, full length. EV1. Approx. NA petrol ceiling ~400hp. *Rough crank figures at the factory fuel pressure, an 80% duty cycle and a BSFC of 0.50 on pump petrol, worked out with the formula below. Treat them as a starting point, not a hard limit. Add boost or E85 and the numbers change. Two things stand out. The supercharged LSA and LS9 leave the factory with very little injector headroom, so any pulley or tune change on those engines means bigger injectors. And the LS1 and LS6 share a long body and EV1 plug, while everything from the LS2 on uses USCAR, which is where most swap headaches start. How to size an LS fuel injector for your build You need four inputs: your crank horsepower target, the number of injectors, your fuel and induction, and the fuel pressure you run. Work through the steps in order. Step 1. Set your target in crank horsepower. If your dyno sheet shows wheel horsepower, divide by about 0.85 as a rough correction for drivetrain loss. For kilowatts, multiply by 1.341. Step 2. Pick a brake specific fuel consumption (BSFC), the fuel each horsepower burns per hour: naturally aspirated on petrol 0.50; supercharged on petrol 0.60; turbocharged on petrol 0.65. On E85, multiply your figure by at least 1.3, because E85 needs roughly 30 to 40% more fuel for the same power. Methanol is its own calculation: talk to your tuner. Step 3. Work out the flow each injector needs at an 80% maximum duty cycle: Injector flow (lb/hr) = (horsepower × BSFC) ÷ (number of injectors × 0.80). Step 4. Convert to cc/min: Injector flow (cc/min) = lb/hr × 10.5. Step 5. Correct for fuel pressure. Most aftermarket injectors are rated at 3 bar (300 kPa, 43.5 psi), but factory Gen III and IV LS systems run around 400 kPa (58 psi). Flow rises with the square root of pressure: Flow at your pressure = rated flow × √(your pressure ÷ rated pressure). At 400 kPa, a 3 bar rating flows about 15.5% more (√(400 ÷ 300) = 1.155). On a factory returnless system with boost, subtract boost pressure from fuel pressure first, because the regulator does not rise with boost: 400 kPa with 70 kPa of boost gives an effective 330 kPa. Keep that 80% duty cycle. An injector at 100% duty is held open permanently and has nothing left to give when the tune asks for more. Sizing with headroom also covers the next stage of the build, so you are not pulling the intake again for the next pulley or turbo. Worked example 1: a 400hp naturally aspirated LS1 400 × 0.50 ÷ (8 × 0.80) = 31.3 lb/hr, or 328 cc/min at the 400 kPa you run. Divide by 1.155 and you need about 284cc rated at 3 bar. The factory LS1 injector is about 273cc at 3 bar, so it runs out just short of 400hp. That matches the ~380hp ceiling in the table. Worked example 2: the featured Excess 1000cc set in a supercharged LS3 on E85 Assuming a 3 bar rating and a boost-referenced regulator holding 400 kPa over manifold pressure, 1000cc flows about 1,155cc, or 110 lb/hr. Run the formula backwards: Maximum horsepower = flow (lb/hr) × number of injectors × 0.80 ÷ BSFC. 110 × 8 × 0.80 ÷ (0.60 × 1.3) = about 900hp on E85, and well over 1,000hp on petrol. That is plenty for a big supercharged LS3 on E85. It is far more than a mild naturally aspirated 6.2 needs, and on that build a smaller injector will idle and cruise more cleanly. Connectors, lengths and adapters: the fitment trap between generations Getting the flow rate right does not guarantee a plug-and-play fit. Check three things before you order. Length. LS injectors come in three common lengths: about 65mm for the LS1 and LS6, about 52mm for the LS2, and about 40mm for the LS3, L76, L77, L98, LS7, LSA and LS9. The wrong length either will not seal in the rail or will not let it bolt down. Injector extensions and fuel rail spacers solve some combinations, such as a shorter injector in a longer manifold. Connector. The LS1 and LS6 use EV1; everything from the LS2 on uses USCAR (EV6). They are not interchangeable without an adaptor harness. See our injector wiring range. O-rings. The top o-ring is 14mm across the LS family, but some LS2 and LS3 manifolds use a larger lower bore and need a matching lower o-ring. Fit new seals and filters every time the injectors come out. None of this is a problem if you know it going in. It becomes one when an injector sized for an LS3 arrives for your LS1 and neither the length nor the plug matches. Installing new injectors on your LS Two rules matter above all others. Get the data and the tune right before you drive it hard. The ECU only knows how much fuel it is delivering if it has the correct flow rate and dead times for your injectors. Load the correct injector data file into Haltech, HP Tuners, MoTeC or your ECU of choice, then have the car tuned. Rated flow and real flow are rarely identical, which is why flow-matched sets come with measured data. Confirm length, plug and o-rings before the intake comes off. Lay the new injector beside an old one and compare length and connector. Lubricate the o-rings with clean engine oil or o-ring lube, fit them square, and check for leaks with the key on and the pump primed before you start the engine. A flow-matched set matters more than a big number on the box. A set that flows unevenly cylinder to cylinder shows up as a rough idle or a misfire under load, even when the size on paper was right. If you are not sure whether your loom and ECU suit high or low impedance injectors, check before you buy; every LS factory injector is high impedance. The Excess 1000cc injectors for GM Holden 6.0 and 6.2 The Excess 1000cc set is a direct drop-in for the 6.0 and 6.2 litre Commodore engines: the factory loom plugs straight into the injectors, with no wiring or adaptors. It is a high impedance, 40mm half-length injector with a 14mm top o-ring, sold as a set of 8 (SKU X1000S8A), with a separate set for HSV 6.2 litre engines (SKU X1000S8A_1). It ties straight back to the sizing steps above. At 1000cc, the set suits a boosted or E85 6.2 that has outgrown the factory LS3 or L98 injectors, with headroom for the next stage. For a mild naturally aspirated engine, run the formula first; you may need far less. Vehicle applications Holden Commodore 6.0 litre L76, L77 and L98 V8. Holden Commodore 6.2 litre LS3 V8. HSV 6.2 litre LSA, LS9 and LS3, using the HSV version (SKU X1000S8A_1). Not suited to the 5.7 litre LS1 or the 6.0 litre LS2, which use longer bodies. Frequently asked questions about LS fuel injector sizing What is the correct size injector for an LS engine? The correct size injector for an LS engine depends on your power goal, fuel, induction and fuel pressure. As a guide, a 500hp naturally aspirated LS on petrol needs about 39 lb/hr, or roughly 410cc/min at the factory 400 kPa (about 355cc rated at 3 bar). On E85 that rises to about 535cc/min at 400 kPa (about 460cc rated at 3 bar). Run your own numbers through the five sizing steps above. What are the stock injectors on an LS1, and how much power can they handle? The stock injectors on an LS1 are the Bosch 0 280 155 931, rated about 273cc (26 lb/hr) at 3 bar. At the factory fuel pressure they are good for roughly 380hp at the crank on petrol before they run out of headroom, as worked example 1 shows. Past that, or on E85, size up. What happens if fuel injectors are too big? If fuel injectors are too big, they struggle to meter the short pulses needed at idle and light load. The result is a lumpy idle, flat spots at low throttle and a tune that is harder to settle. Size for your goal with 20% headroom rather than going as large as possible. Are LS1 and LS3 injectors the same? LS1 and LS3 injectors are not the same. The LS1 injector is about 273cc at 3 bar, 65mm long with an EV1 plug; the LS3 injector is about 42 lb/hr at 58 psi, 40mm long with a USCAR plug. Swapping between them needs an adaptor harness and spacers or extensions at minimum, plus a retune. Are LS1 and LS2 injectors the same? LS1 and LS2 injectors are not the same, though they are closer than the LS1 and LS3. The LS2 injector is about 312cc, 52mm long, with a USCAR plug, so the plug and length both rule out a direct swap. Treat them as different starting points for sizing. What fuel pressure are LS injectors rated at? The fuel pressure LS injectors are rated at varies: most aftermarket injectors are rated at 3 bar (43.5 psi), while GM figures are often quoted at the factory 58 psi. Always check the rating pressure on the data sheet, then correct to the pressure you run using Step 5 above.
