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This is one of the most common dilemmas for enthusiasts. You don’t want to buy injectors that are too small and limit your power, but you’ve heard the horror stories of "too big" injectors causing a terrible idle and poor fuel economy.
The choice between 1000cc (roughly 95 lb/hr) and 1500cc (roughly 142 lb/hr) isn't just about the numbers, it's about your fuel type, your power goals, and how you use the car. Here is the breakdown to help you choose.
The "E85" Factor
The single biggest deciding factor in this comparison is the fuel you intend to run. As we’ve discussed in our E85 vs. Pump Gas guide, ethanol requires roughly 30-35% more volume than gasoline to produce the same power.
- If you are staying on 98 Octane: A 1000cc injector is massive. It can support over 600hp on most 6-cylinder engines with room to spare.
- If you are moving to E85: That same 1000cc injector is now only capable of supporting around 400-450hp before it reaches a high duty cycle. If your goal is 500hp+ on E85, the 1500cc is the logical choice.
Horsepower Capacity
To make the choice easier, look at these "safe" horsepower limits (assuming an 80% duty cycle and a 6-cylinder engine):
|
Fuel Type |
1000cc (100lb) Capacity |
1500cc (145lb) Capacity |
|
98 Octane |
~650 hp |
~950 hp |
|
E85 (Ethanol) |
~450 hp |
~700 hp |
Note: For V8 engines (LS, Coyote), you can increase these numbers by roughly 33% because you have two extra injectors sharing the load.
The Myth of "Bigger is Worse"
In the past, 1500cc injectors were notorious for being difficult to tune. Because they were so large, they struggled to spray the tiny amount of fuel needed for a smooth idle. They would "dribble" fuel rather than atomizing it, leading to a shaky idle and "sooty" spark plugs.
The Reality with Excess Injectors
Modern injector technology has changed the game. Our Excess 1100cc and 1500cc injectors use advanced internal geometry that allows them to remain incredibly fast and precise even at very low pulse widths.
With our Exact Match Data, a 1500cc injector can be tuned to idle as smoothly as a factory 300cc injector. This means the "penalty" for going larger is now virtually non-existent.
Why You Might Choose 1000cc
If your goal is a 350hp street car that will never see E85, the 1000cc is the "Goldilocks" choice.
- Pros: Lower cost, incredible resolution for fine-tuning fuel economy, and zero risk of ever being "too big" for the ECU to control.
- Cons: You may have to buy new injectors if you decide to go for a "big turbo" and E85 later.
Why You Might Choose 1500cc
If you are building a car with a "future-proof" mindset.
- Pros: You will likely never "outgrow" this injector. It handles E85 with ease and has enough headroom for high-boost "track mode" settings.
- Cons: Slightly higher initial cost.
The "Safety Margin" Argument
As we covered in our article on Maxing Out Injectors, you never want to run an injector at 100% duty cycle. If your power goal puts a 1000cc injector at 90% duty cycle, you are better off stepping up to the 1500cc. This keeps the injectors cooler, ensures more consistent fueling, and gives the ECU room to add more fuel if it detects a lean condition.