Diesel engine (industrial and nonroad)

01

Find the emission limits for the power band

US EPA's nonroad compression-ignition engine rule, 40 CFR 1039.101, sets Tier 4 exhaust limits by maximum engine power. In g/kWh, engines below 19 kW are limited to 0.40 PM and 7.5 NOx+NMHC; 19–56 kW to 0.03 PM and 4.7 NOx+NMHC; 56–130 kW to 0.02 PM, 0.40 NOx, 0.19 NMHC and 5.0 CO; 130–560 kW to 0.02 PM, 0.40 NOx, 0.19 NMHC and 3.5 CO; and above 560 kW to 0.03 PM and 0.67 NOx for generator sets, or 0.04 PM and 3.5 NOx for other uses. Engines above 560 kW and constant-speed engines are exempt from the transient test. [1]

Cummins' QSF3.8 brochure states that the 3.8-litre engine meets EPA Tier 4 Final / EU Stage IV with a diesel oxidation catalyst (DOC) alone at 74 hp (55 kW), and with DOC plus selective catalytic reduction (SCR) from 100 to 132 hp (75–98 kW), without a diesel particulate filter; the SCR uses diesel exhaust fluid (DEF) and the engine also uses exhaust gas recirculation. [2]

Editorial calculation: 55 kW sits just below the 56 kW boundary, where the NOx+NMHC limit is 4.7 g/kWh, while 75–98 kW falls in the 56–130 kW band with a 0.40 g/kWh NOx limit; that boundary is where the QSF3.8's aftertreatment changes from DOC only to DOC plus SCR. Ask the supplier which band and standard each offered rating is certified to. [1] [2]

Give the supplier the machine and duty cycle, required power and torque at operating speed, the markets and emission standards (for example US Tier 4 Final, EU Stage V, China), space for aftertreatment, DEF availability, fuel quality, cooling and air intake conditions, altitude and ambient temperature, starting and electrical needs, and service support required.

02

Match power and torque at operating speed

Cummins lists QSF3.8 ratings from 74 hp (55 kW) at 2,200 or 2,500 rpm with 400 N·m peak torque at 1,300 rpm, to 132 hp (99 kW) at 2,300 rpm with 488 N·m at 1,600 rpm. The engine is an in-line four-cylinder of 3.8 L with high-pressure common-rail injection, a wastegate turbocharger, electronic control, 348 kg wet weight and 34 kg of aftertreatment. [2]

Editorial calculation: power = torque × speed × 2π / 60, so 488 N·m at 1,600 rpm is about 81.8 kW, below the 97–99 kW rated at 2,200–2,300 rpm; a machine that works near peak-torque speed gets less than the rated power, so check the power and torque curve at the speeds your machine actually runs. [2]

Kubota Engine America's V3800-CR-TIEF4H, a vertical water-cooled four-cylinder of similar size, lists 130.9 HP at 2,400 rpm and 324.5 lb-ft maximum torque at 1,800 rpm (SAE J1995 gross intermittent), 3.937 × 4.724 in bore and stroke, 230.0 cu in displacement, turbocharging with after-cooling, direct injection with common rail, 882 lb dry weight, and 27.5 × 24.3 × 33.0 in without aftertreatment or 33.3 × 25.7 × 46.89 in with it. [4] Editorial calculation: that is about 97.6 kW and 440 N·m from 3.77 L, and 440 N·m at 1,800 rpm gives about 82.9 kW — again below rated power — and a gross intermittent rating should be compared with another maker's figure only on the same rating basis. [4]

Editorial note: suppliers in the linked list range from small single-cylinder engines to large engine series rated in the hundreds of kilowatts; ask each for the certified rating, curve and emission certificate rather than a series range.

03

Compare what suppliers offer

Suppliers linked to this page list diesel engines; each card links to the page reviewed.

The suppliers reviewed list vehicle, industrial, generator and small diesel engines; ask each for the rating and curve, emission certification and aftertreatment, dimensions and weight, and service network.

04

Check the EU Stage V limits, including particle number

Annex II of Regulation (EU) 2016/1628, as published on legislation.gov.uk, sets Stage V limits for nonroad engine category NRE by power band, in g/kWh. Compression-ignition engines below 8 kW are limited to 8.00 CO, 7.50 HC+NOx and 0.40 PM (0.60 for hand-startable, air-cooled direct-injection engines); 8 to below 19 kW to 6.60 CO, 7.50 HC+NOx and 0.40 PM; 19 to below 56 kW to 5.00 CO, 4.70 HC+NOx and 0.015 PM; 56 to below 130 kW to 5.00 CO, 0.19 HC, 0.40 NOx and 0.015 PM; and 130 to 560 kW to 3.50 CO, 0.19 HC, 0.40 NOx and 0.015 PM. [3]

From 19 kW up to 560 kW, Annex II also caps particle number at 1 × 10^12 particles per kWh, a limit with no counterpart in the US Tier 4 table on this page. Above 560 kW there is no particle-number limit: NRE engines are held to 3.50 CO, 0.19 HC, 3.50 NOx and 0.045 PM, while generating-set engines (category NRG) are held to 3.50 CO, 0.19 HC, 0.67 NOx and 0.035 PM. [3]

Editorial calculation: the Stage V PM mass limit of 0.015 g/kWh for 19–560 kW is half of the US Tier 4 figure of 0.03 g/kWh for 19–56 kW and three-quarters of the 0.02 g/kWh for 56–560 kW cited on this page. An engine certified only to US Tier 4 Final is therefore not automatically compliant for EU or UK machines; ask for the Stage V type-approval number and whether a particulate filter is fitted to meet the particle-number limit. [3] [1]

The aftertreatment set changes with the standard: Kubota lists the V3800-CR-TIEF4H as meeting EPA/CARB Tier 4 and EU Stage V with DOC + DPF + SCR, whereas the QSF3.8 brochure describes Tier 4 Final / Stage IV ratings without a particulate filter. [4] [2] A diesel particulate filter is the device a buyer should expect where the Stage V particle-number cap applies; ask for the Stage V type-approval number, not only the Tier 4 certificate.

05

Trace the engine and aftertreatment

This is a functional reference built from the sources cited; it is not one maker's design.

06

Fill the specification fields with values for your machine

A diesel engine quotation needs values for your machine. The table explains each field, gives published values where a reviewed source states them, and says what to obtain from the supplier.

07

Send the duty, power and emission data together

Paste it into your enquiry below or into an email to a maker, then replace every bracket.

Machine: [type; duty cycle]
Power: [kW at operating speed; torque]
Emissions: [market; standard; band]
Aftertreatment: [space; DEF]
Environment: [ambient; altitude; dust]
Installation: [cooling; intake; mounting]
Support: [service network; parts]

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