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NCEES PE Agricultural and Biological Engineering Tractor & Automotive Engines (IC Engines): practice questions

NCEES PE Agricultural and Biological Engineering · USA · NCEES (ASABE is the content partner)

Original practice questions written to the published syllabus · not past papers
10worked here, free
17written to this exam in this subject
8syllabus units

About NCEES PE Agricultural and Biological Engineering

NCEES PE Agricultural and Biological Engineering is a licensing and registration exam run by NCEES (ASABE is the content partner), for candidates in USA. Computer-based, 85 questions, 9.5-hour appointment (8.5 hours of exam). Once a year (next: 28 Oct 2026). Closed book with the electronic NCEES handbook and supplied searchable ASABE standards; SI and US customary units.

Source: ncees.org.

Checked against the exam body's published information. Formats and fees change; confirm the current edition there before you book.

Tractor & Automotive Engines (IC Engines) in NCEES PE Agricultural and Biological Engineering

Machinery Systems: engine and tractor power, fuel consumption and efficiency calculations applied to machinery management; using supplied ASABE standards and data rather than memorised values.

How tractor engines work and how their performance is measured — the single most reliably examined farm-power topic.

Our 17 NCEES PE Agricultural and Biological Engineering questions in this subject: 2 easy, 5 medium, 10 hard, across 8 units.

10 practice questions, worked

Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.

These 10 were written to NCEES PE Agricultural and Biological Engineering and are not shown on any other exam's page.

Question 1 · medium

An ideal cycle produces 0.45 kJ of net work per cycle in a cylinder of 0.5 L swept volume. Its mean effective pressure is

  1. 0.9 bar
  2. 90 bar
  3. 4.5 bar
  4. 9.0 bar
Answer and working

D. 9.0 bar

mep = net work ÷ swept volume = 450 J ÷ 0.0005 m³ = 900,000 Pa = 9.0 bar. 0.9 bar and 90 bar are decimal-place slips in converting pascals to bar (1 bar = 10⁵ Pa); 4.5 bar halves the correct value.

Question 2 · hard

A four-stroke diesel of 4.0 L displacement at 2,000 rev/min draws 0.068 kg/s of air. Ambient air density is 1.18 kg/m³. Its volumetric efficiency is closest to

  1. 43.2%
  2. 172.9%
  3. 102.0%
  4. 86.4%
Answer and working

D. 86.4%

Ideal air flow = ρ × Vd × N/2/60 = 1.18 × 0.004 × 2000/120 = 0.0787 kg/s. ηv = 0.068/0.0787 = 86.4%. Using N instead of N/2 gives 43.2%; ignoring density gives a volume ratio above 100%. Dividing N by 4 gives 172.9%, and ignoring density gives 102.0%.

Question 3 · hard

A naturally aspirated tractor rated at 50 kW at 101.3 kPa and 25 °C works at a hill site where air is at 85 kPa and 15 °C. Assuming full-load power is proportional to air density (R = 287 J/kg K), the expected power is closest to

  1. 42.0 kW
  2. 57.6 kW
  3. 43.4 kW
  4. 25.2 kW
Answer and working

C. 43.4 kW

ρ = p/(RT): sea level 1.184 kg/m³; site 1.028 kg/m³ (T in kelvin: 298.15 K and 288.15 K). Power ≈ 50 × 1.028/1.184 = 43.4 kW. Using pressure alone gives 42.0 kW; inverting the ratio gives 57.6 kW; 25.2 kW uses Celsius temperatures and multiplies by their ratio (15/25) instead of dividing, which is doubly wrong.

Question 4 · easy

An engine delivers a torque of 200 N m at 2,100 rev/min. Its brake power is

  1. 7.0 kW
  2. 2639 kW
  3. 44.0 kW
  4. 59.0 kW
Answer and working

C. 44.0 kW

BP = 2πNT/60 = 2π × 2100 × 200/60 = 43982 W = 44.0 kW. Omitting 2π gives 7.0 kW; omitting /60 gives a per-minute figure; 59.0 is the value in horsepower, not kW. Omitting /60 gives 2639 kW.

Question 5 · hard

Heat-balance test on a diesel: fuel 12 kg/h (CV 42 MJ/kg); BP 45 kW; cooling water 1.0 kg/s heated by 9 °C (c = 4.187 kJ/kg K); air 300 kg/h; exhaust 420 °C, ambient 30 °C, cp of exhaust 1.1 kJ/kg K. The unaccounted heat as a percentage of heat supplied is closest to

  1. 15.4%
  2. 12.3%
  3. 14.4%
  4. 40.9%
Answer and working

C. 14.4%

Supplied = 12 × 42,000/3600 = 140.0 kW. Coolant = 1.0 × 4.187 × 9 = 37.68 kW. Exhaust = (300 + 12)/3600 × 1.1 × (420 − 30) = 37.18 kW. Unaccounted = 140.0 − 45 − 37.68 − 37.18 = 20.14 kW = 14.4%. Leaving out the fuel mass in the exhaust gives 15.4%; using 420 °C without subtracting ambient gives 12.3%. Ignoring the exhaust loss gives (140.0 − 45 − 37.68)/140 = 40.9%.

Question 6 · medium

A tractor works at 35 kW with a BSFC of 260 g/kWh; diesel density is 0.835 kg/L. Its fuel consumption is closest to

  1. 9.1 L/h
  2. 7.6 L/h
  3. 10.9 L/h
  4. 109 L/h
Answer and working

C. 10.9 L/h

Mass rate = 0.26 × 35 = 9.1 kg/h. Volume = 9.1/0.835 = 10.9 L/h. Quoting kg/h as litres, or multiplying by density instead of dividing, are the usual errors. 109 L/h is a decimal slip.

Question 7 · medium

For any one tractor, which ordering of power figures is normally correct?

  1. Drawbar power > PTO power > net engine power > gross engine power
  2. Gross engine power > net engine power > PTO power > drawbar power
  3. PTO power > gross engine power > drawbar power > net engine power
  4. Net engine power > gross engine power > drawbar power > PTO power
Answer and working

B. Gross engine power > net engine power > PTO power > drawbar power

Each step loses power: installed accessories (net), transmission to the PTO, and at the drawbar wheel slip and rolling resistance as well.

Question 8 · medium

During a test mode an engine delivering 45 kW emits 180 g of NOx per hour. The brake-specific NOx emission is

  1. 0.25 g/kWh
  2. 8100 g/kWh
  3. 1.11 g/kWh
  4. 4.0 g/kWh
Answer and working

D. 4.0 g/kWh

Brake-specific emission = mass rate ÷ power = 180 g/h ÷ 45 kW = 4.0 g/kWh, the unit in which non-road limits are written. Inverting gives 0.25; dividing by 3.6 wrongly converts to g/MJ-style units. Multiplying gives 8100 g/kWh.

Question 9 · hard

An engine with DOC, DPF and SCR after-treatment must run on ultra-low-sulphur diesel mainly because

  1. sulphur lowers the cetane number
  2. sulphur poisons the catalysts and forms sulphate particulate
  3. sulphur freezes the diesel exhaust fluid
  4. sulphur raises the fuel's flash point
Answer and working

B. sulphur poisons the catalysts and forms sulphate particulate

Sulphur compounds deactivate catalyst sites and add sulphate to the particulate; high-sulphur fuel quickly degrades after-treatment. Low-ash oil is also needed to avoid clogging the DPF.

Question 10 · hard

Emission limits for agricultural tractor engines in the US, EU and India are expressed and tested in which way?

  1. As grams per kilometre on a road driving cycle
  2. As a single smoke opacity value (in Bosch units) at rated speed
  3. As brake-specific limits (g/kWh) by power band, tested on steady-state multi-mode and later transient cycles
  4. As a percentage of the fuel mass burnt over a field duty cycle, with the same limit applied to all engine sizes
Answer and working

C. As brake-specific limits (g/kWh) by power band, tested on steady-state multi-mode and later transient cycles

Non-road rules set g/kWh limits by power band, measured on dynamometer cycles such as the ISO 8178 C1 eight-mode cycle, with a transient cycle added in later stages. Road vehicles use g/km; smoke opacity is only one test. Limit values differ by country and stage.

A study plan for Tractor & Automotive Engines (IC Engines) in NCEES PE Agricultural and Biological Engineering

This plan follows where our questions actually fall, so the time goes where the marks are likely to be. It is our reading of the syllabus, not the exam body's weighting.

  1. First, the heavy units (59% of the 17 questions): BSFC and heat balance (5, 29%); Emission norms (3, 18%); Air intake and turbocharging (2, 12%).

    Read the manual chapters for these first and do every worked question you can find on them.

  2. Then the middle band: Engine performance: IP, BP, FP and efficiencies (2, 12%); Otto, Diesel and dual cycles (2, 12%); Cooling system (1, 6%).

    Aim for one sitting per unit, then mixed questions across them.

  3. Then the lighter units: Diesel fuel system: injection pump and injector (1, 6%); Engine testing (1, 6%).

    Learn the definitions, classifications and standard numbers; these units are more often recalled than worked.

  4. Leave time for the hard ones: Air intake and turbocharging (2 hard of 2), Cooling system (1 hard of 1), Diesel fuel system: injection pump and injector (1 hard of 1).

    Come back to these after a first pass, untimed, and read every explanation, including for the options you rejected.

  5. Bank the easy marks: Engine performance: IP, BP, FP and efficiencies (1 easy of 2); BSFC and heat balance (1 easy of 5).

    Do these early in revision so they are fast on the day.

  6. Finish timed. Sit the subject as a timed set without notes, mark it, and send each wrong answer back to its unit above.

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