Model family · 4BT Cummins
Cummins 4BT — the 4BTA3.9 family
The smallest Cummins family in this catalogue, and one of the most completely listed: machine variants from 60 to 97 kW and two genset-drive variants at 1,800 rpm.
The 4BT page of the catalogue is the 4BTA3.9 table. It lists the family from the 4BTA3.9-C80-II at 60 kW to the C130-II at 97 kW, on bore and stroke of 102 × 120 mm and a displacement of 3.9 litres, at speeds of 2,200–2,500 rpm for the machine variants. Alongside them sit the generator-drive variants that make this family a genset staple: the 4BTA3.9-G2 listed at 58 kW at 1,800 rpm and the G11 at 80 kW at 1,800 rpm.
That spread — one engine family, machine ratings and genset ratings side by side — is exactly why the variant suffix matters. A C-variant quote and a G-variant quote are different products at different rating points. This page reproduces the listed figures so you can identify the variant you need, then confirm it in the enquiry.
Listed range at a glance
| Model / line | Details on record |
|---|---|
| 4BTA3.9-C80-II | 60 kW · machine variant, family table at 2,200–2,500 rpm |
| 4BTA3.9-C130-II | 97 kW · top of the listed machine-variant range |
| Family dimensions | Bore × stroke 102 × 120 mm · displacement 3.9 L |
| 4BTA3.9-G2 (genset) | 58 kW at 1,800 rpm |
| 4BTA3.9-G11 (genset) | 80 kW at 1,800 rpm |
| Marine versions | GM47 / GM55 / GM65 marine generation ratings — see the marine page |
Choosing a 4BT variant
Decide the duty first. For a machine or industrial drive, work in the C-variant rows and note that their ratings are quoted at 2,200–2,500 rpm. For a 60 Hz genset, the G rows at 1,800 rpm are the starting point: 58 kW (G2) or 80 kW (G11) of engine rating, from which your alternator output follows. For a 50 Hz set or a marine set, do not transpose these rows by guesswork — the marine GM rows for this engine are listed separately (47, 55 and 65 kW), and the correct procedure is to state your frequency in the enquiry and have the variant and rating confirmed against the listing for that duty.
When replacing an existing 4BT, record the full designation from the plate including the suffix and the rating code (for example C130-II). The family spans 60–97 kW in machine form, so 'a 4BT' does not specify an engine; the designation does.
How buyers spec this line
- Quote the full designation including suffix (C, G or GM) and rating code.
- Genset rows here are 1,800 rpm rows; confirm 50 Hz requirements separately.
- Marine GM ratings for this engine are 47/55/65 kW — see the marine engines page.
- Confirm scope of supply for the variant before you order.
Terms on record
Listed terms on record: complete engines and power units carry a delivery window of 15–30 days and a warranty of 1 year or 1,200 hours, whichever comes first, as published in the supplier's FAQ. Confirm the exact rating, scope of supply and delivery window for your model before you order.
Buyer questions
What is the difference between the C and G variants?
The listed table quotes C variants as machine ratings at 2,200–2,500 rpm and G variants as generator-drive ratings at 1,800 rpm. They are different rating points for different duties — state your duty in the enquiry.
Can the 4BT drive a 50 Hz generator?
The G rows on record are 1,800 rpm rows. For 50 Hz service, state the frequency in your enquiry and have the correct variant and rating confirmed rather than assuming a transposed figure.
Is the 4BT available as a marine genset engine?
Yes — the marine table lists 4BTA3.9-GM47, GM55 and GM65 ratings. See the marine diesel engines page.
Related lines
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