Testing Process

The testing process

How Excess
testing works

An injector's dynamic performance comes down to three things: its static flow, its linear operating flow, and its opening non-linear flow. We measure all three — every injector tested to the J1832 standard, the international engineering benchmark that keeps results consistent and comparable.

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12
Duty cycles swept from 20% to 90% in the high-flow test
1,200
Flow results recorded across the high-flow sweep
4,000+
Flow tests in the low-flow, non-linear sweep
1%
Flow-slope match across every injector in a set
Controlled every time

Three parameters, locked down.

For a test to be repeatable, three things have to be held tight on every single run. If any part of a test drifts outside its window, we don't record it — the injector goes back and is retested.

01

Fuel pressure

3 bar ±0.5%

Held dead steady on every run, so each flow reading reflects the injector itself — not changing test conditions.

02

Fluid temperature

21°C ±2°C

Kept constant, because temperature shifts change the fluid's behaviour and the flow you measure.

03

Voltage

14V ±0.05V

Locked in, since supply voltage directly affects how fast the injector opens and closes.

The testing regime

Three tests per injector.

TEST 1

High-flow sweep

Linear range. 12 duty cycles from 20% to 90%, 100 samples at each — 1,200 results. The average at each point sets a line of best fit, which gives the injector's flow slope.

TEST 2

Static flow rate

The injector is held fully open, no pulsing, and total volume is measured over time. Flow rises with pressure — the nominal rating is the static flow at 3 bar.

TEST 3

Low-flow sweep

Non-linear range. Over 4,000 tests from very low duty cycles, pinpointing the offset (where fuel first flows) and the knee (where flow turns linear and predictable).

Why it matters

We match the slope, not just the flow.

Static flow is a single number — how much an injector flows held wide open. Two injectors can share the exact same static flow and still ramp up differently as they open, so matching on that one number isn't enough.

The high slope is the line through an injector's flow measured between 20% and 90% duty cycle. It describes how flow builds across that whole range, not just at a single point. We group a set so every injector's high slope sits within 1% of the others.

The result: anywhere from 20% open to 90% open, every injector in your set flows within 1% of the rest — even, predictable fuelling right across the range. Match on static flow alone and they only agree wide open, then drift apart through the mid-range.

STATICALLY MATCHED Matched at one duty point only — not how Excess does it MATCHED 80% ONLY 20 40 60 80 DUTY CYCLE · % FLOW · cc/min MATCHED AT 80% LOW THROTTLE Injector 1 Injector 2 Injector 3 Injector 4 Static matching lines the set up at one duty point — but they flow apart everywhere else, including idle and low throttle.
DYNAMICALLY MATCHED Every Excess set — dynamically matched, never statically THE EXCESS WAY 20 40 60 80 DUTY CYCLE · % FLOW · cc/min ALL WITHIN 1% · 20–90% Injector 1 Injector 2 Injector 3 Injector 4 Excess dynamically matches every injector to within 1% from 20% to 90% duty — even fuelling across the whole range.
The final step

Grouped into tight sets.

Once every injector is tested, an algorithm groups them into matched sets. First, all dynamic flow rates have to fall within 1% of each other. Then, within those groups, the dead times have to fall within 2%.

The result is a set that behaves as one — and you can log in anytime to see exactly how each injector in your set performed through the whole regime.

Dynamic flow
1%
+
Dead times
2%
Matched across the set, then logged to your serial numbers
It's all about the data

See the data behind your set

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