Cummins is taking generator orders “well into 2028” and Caterpillar closed June 2026 with $72.1 billion of firm backlog, $29.2 billion of it not shipping inside twelve months. Those two sentences come from Cummins’ fourth-quarter call on February 5, 2026 and Caterpillar’s 10-Q filed August 5, 2026, and between them they set the delivery date for every 2 MW diesel genset a factory or datacenter tries to buy this year. The Open Factory Lead-Time Monitor carries published lead times of 50 to 66 weeks for a 1,500 to 2,000 kW diesel and 90 to 110 weeks above 3,500 kW, against 16 to 24 weeks before 2020. Below: what the three listed OEMs told the SEC, the lead-time table by kW class, what used iron actually costs against a new Tier 4 unit, the emergency-engine loophole that makes used iron legal, who still has open engine capacity, and the permitting route by state.
Source: Open Factory Lead-Time Monitor (compiled from Caterpillar 10-Q and 10-K filings, Q4 2023 to Q2 2026; as of August 2026)
Caterpillar’s firm backlog sat between $27.5 billion and $28.7 billion for four straight quarters through September 2024, then added $2.4 billion in Q3 2025, $11.4 billion in Q4 2025, $11.5 billion in Q1 2026 and $9.4 billion in Q2 2026, while the slice not expected to ship within twelve months went from $6.0 billion to $29.2 billion.
What Cummins Told Investors in February
Cummins does not publish a backlog number. Asked to size it on the February 5, 2026 call, CEO Jennifer Rumsey said “we do not quantify the size of our back order” and then gave the only two datapoints that matter for a buyer: “we had record order intake in Q4 for power generation. We are taking orders now well into 2028.” Five days later the 2025 10-K put it in filing language: “We also have strong demand for our data center products extending out six to eight quarters.” Six to eight quarters from February 2026 is 78 to 104 weeks, which is the row the Lead-Time Monitor carries for the QSK95 class.
Cummins doubled its 95-liter capacity in 2025 and still sold the whole expansion through 2028. Rumsey on the same call: “we completed the doubling of our capacity of the 95-liter engine and genset that we supply, which is very popular in the data center market.” Data center revenue across the company was about $3.5 billion in 2025 per the call summary, and the guide for 2026 power generation revenue is up 10% to 20% “driven by continued high demand in the data center market and the successful execution of our capacity expansion, which was completed in 2025.” The Power Systems segment sold $2.3 billion in Q2 2026, up 19%, at a 24.5% EBITDA margin, and Q1 2026 ran a 29.5% margin on $2.0 billion. Those margins are what a sold-out factory looks like in a segment table.
Source: Open Factory Lead-Time Monitor
Cummins’ power generation product line sold $770 million in Q1 2023, $1,090 million in Q4 2024 and $1,536 million in Q2 2026, a doubling in fourteen quarters, and the segment’s own tables show why the money grew faster than the metal: high-horsepower power generation unit shipments went from 12,300 in 2023 to 12,800 in 2024, up 4%, while power generation dollars rose 19%. The mix shifted to bigger engines and higher prices, and Cummins stopped publishing the unit table in 2025. The OEM Disclosure Scorecard marks that: no backlog in dollars, no lead times, and a unit series that ended the year the market tightened.
Caterpillar Carries a Year of Sales in Backlog
Caterpillar files the number Cummins withholds. The Order Backlog paragraph in each 10-Q reads the same way every quarter, and the Book-to-Bill League Table simply lines them up: $27.9 billion at March 2024, $30.0 billion at December 2024, $39.8 billion at September 2025, $51.2 billion at December 2025, $62.7 billion at March 2026, $72.1 billion at June 2026. Every filing since Q3 2024 names Energy & Transportation, renamed Power & Energy in 2025, as the segment with “the largest increase,” and the Q1 2026 10-Q adds the sentence a genset buyer should read twice: “The backlog for large reciprocating engines and turbine products continues to grow within Power & Energy.”
Source: Open Factory Lead-Time Monitor
Firm backlog was 0.42 times trailing-twelve-month sales in Q1 2024 and 0.96 times in Q2 2026, so on a company-wide basis Caterpillar is booked for about twelve months of production, and since the growth is concentrated in one segment the recip engine lines are booked for far longer than that.
Caterpillar’s large reciprocating engine backlog is 3.5 times what it was in January 2024, and the company is tripling that capacity. CEO Joseph Creed said both on the April 30, 2026 call, as reported by Manufacturing Dive: the large recip backlog “has grown more than 3.5 times since January 2024,” Caterpillar “will triple its large reciprocating engine capacity from 2024 levels,” and the ProPWR framework for up to 2.1 GW of generation assets over five years was “Caterpillar’s sixth agreement with a customer seeking at least 1 gigawatt.” The Slot Economy piece covers what a 1 GW frame agreement does to the queue behind it; for a buyer of eight 2.5 MW units, it means six customers with 400 to 800 of them each are ahead in line.
Source: Open Factory Lead-Time Monitor
Power generation sales were $1,284 million in Q1 2023, $2,242 million in Q4 2024 and $3,238 million in Q4 2025, and the 10-K attributes the full-year increase from $7,756 million to $10,275 million to “large reciprocating engines, primarily data center applications,” the same clause that appears in the Q2 2026 release with turbines added.
Generac Went From Zero to $1.6 Billion in Twelve Months
Generac is the control case for what an OEM with open capacity does in this market. It entered large-megawatt datacenter gensets in Q2 2025; the July 30, 2025 release says the company “began building backlog for our new high-output diesel generator product offering.” By October 29, 2025 that backlog had “doubled over the last 90 days” with no dollar figure attached. On the February 11, 2026 call it was “$400 million,” most of it shipping in 2026. On April 29, 2026 it was “more than $700 million,” excluding a non-binding notice to proceed “for approximately $600 million in 2027 deliveries with a certain hyperscale customer.” On July 29, 2026: “approximately $1.6 billion as of today, which does not include any committed volumes from the second hyperscale customer,” after “approximately $1 billion in additional orders” in one quarter.
Source: Open Factory Book-to-Bill League Table (compiled from Generac 8-K releases and earnings calls; as of July 2026)
Generac’s disclosed datacenter backlog went $400 million, $700 million, $1,600 million across the three 2026 updates, and its C&I segment sales went from $399 million in Q1 2025 to $556 million in Q2 2026, up 29% year over year.
Generac says its domestic capacity for large-megawatt gensets will pass $1 billion a year by Q4 2026, and it has already booked 1.6 years of it. The April call also told buyers where the constraint sits: “Even if we can get great lead times on the unpackaged product, it doesn’t help us if the packaging phase is constrained,” which is why Generac bought Enercon in East Peoria and a second plant in Belvidere, Illinois “significantly expanding capacity for large megawatt generator packaging.” Engines are one queue; the enclosure, base tank, switchgear and controls are a second queue, and the Lead-Time-Adjusted Schedule tool treats them as separate rows for exactly that reason. Generac’s two hyperscaler frame agreements, one signed in June and one on June 24, 2026 with “final product specific terms for 2027 and 2028 volumes” still in negotiation, mean the third entrant’s 2027 and 2028 slots are being allocated before most colocation and industrial buyers have asked for a quote.
Published Lead Times by kW Class
Nobody publishes an OEM lead time for a 2 MW genset. The two public series the Lead-Time Monitor carries are a general contractor’s slot-reservation data and a dealer’s stock-and-order data, and they agree with each other and with the Cummins filing. Terrapin Construction Group, June 10, 2026, “from active 2026 manufacturer slot reservations”: diesel 500 to 1,000 kW at 32 to 48 weeks, 1,500 to 2,000 kW at 50 to 66, 2,500 to 3,500 kW at 62 to 82, 3,500 to 4,500 kW at 90 to 110, natural gas 1,000 to 3,000 kW at 54 to 78, ATS 24 to 40. Central States Diesel Generators, August 11, 2026: 25 to 400 kW at 12 to 26 weeks against 4 to 8 before 2020, 500 to 1,000 kW at 26 to 52 against 10 to 16, 1,250 to 3,250 kW at “52+” against 16 to 24, and a tested used unit from stock at 1 to 4 weeks.
Source: Open Factory Lead-Time Monitor (compiled from Terrapin Construction Group slot reservations, June 2026; Central States Diesel Generators, August 2026; Cummins 10-K and Q4 2025 call, February 2026)
The 1,500 to 2,000 kW class that hyperscalers standardize on sits at 50 to 66 weeks, the 2,500 to 3,500 kW class at 62 to 82, and the largest units at 90 to 110, so a PO placed this month for a 3 MW unit lands between Q4 2027 and Q3 2028.
| Class | Fuel | 2026 lead time | Pre-2020 | Published by | Date |
|---|---|---|---|---|---|
| 25 to 400 kW standby | Diesel | 12 to 26 wk | 4 to 8 wk | Central States Diesel (dealer) | Aug 2026 |
| 500 to 1,000 kW | Diesel | 32 to 48 wk | n/a | Terrapin CG (GC slot reservations) | Jun 2026 |
| 500 to 1,000 kW standby | Diesel | 26 to 52 wk | 10 to 16 wk | Central States Diesel (dealer) | Aug 2026 |
| 1,500 to 2,000 kW | Diesel | 50 to 66 wk | n/a | Terrapin CG | Jun 2026 |
| 1,250 to 3,250 kW standby | Diesel | 52+ wk | 16 to 24 wk | Central States Diesel (dealer) | Aug 2026 |
| 2,500 to 3,500 kW | Diesel | 62 to 82 wk | n/a | Terrapin CG | Jun 2026 |
| 3,500 to 4,500 kW | Diesel | 90 to 110 wk | n/a | Terrapin CG | Jun 2026 |
| 1,000 to 3,000 kW | Natural gas | 54 to 78 wk | n/a | Terrapin CG | Jun 2026 |
| High-horsepower DC gensets (QSK95 class) | Diesel | 78 to 104 wk (six to eight quarters) | n/a | Cummins 10-K FY2025 | Feb 2026 |
| High-horsepower DC gensets (QSK95 class) | Diesel | orders taken well into 2028 | n/a | Cummins Q4 2025 call | Feb 2026 |
| Automatic transfer switch, large | n/a | 20 to 40 wk | 6 to 12 wk | Terrapin CG; Central States Diesel | Jun to Aug 2026 |
| Tested used or surplus, dealer stock | Diesel or gas | 1 to 4 wk | 1 to 4 wk | Central States Diesel (dealer) | Aug 2026 |
Source: Open Factory Lead-Time Monitor. Data: genset-lead-times.csv
Twelve rows, three publishers, and the pre-2020 column shows the multiple: 3x at the small end, 2.5 to 3x at 500 to 1,000 kW, and a floor of 52 weeks against a 16 to 24 week norm at 1,250 kW and above.
Two things in this table matter more than the numbers. First, the contractor’s ranges are tighter than the dealer’s because Terrapin is quoting reserved slots, meaning the buyer paid a 10 to 30% deposit to hold a production date, which is the mechanism the Slot Economy piece priced at $60 million for a hyperscale campus. Second, the dealer’s floor for 1,250 kW and up is open-ended at “52+” because dealers are quoting allocation, not a schedule: Central States Diesel describes “allocation language that didn’t exist in 2019,” and that language is how a 52-week quote becomes 80 weeks without anyone breaching a contract. The RFQ for capital equipment template handles this with a firm ship date plus liquidated damages at 0.5% a week, and in this market a vendor who accepts LDs on a genset is telling you it has a real slot.
Order the Transformer the Same Month
The genset is no longer the longest line on the electrical schedule, and that is the trap: a 66-week genset arriving before a 95-week substation transformer is a $1.4 million asset sitting on a pad with nothing to feed. Terrapin’s same June 2026 sheet puts a 5 to 25 MVA substation transformer at 65 to 95 weeks, 15 kV metal-clad switchgear at 60 to 80 weeks and a large ATS at 24 to 40, so the genset order, the transformer order and the paralleling switchgear order have to be placed in the same month for the plant to energize in the same quarter. The buyers who are getting 2027 dates are ordering all three at land close and reserving the slot with the deposit; the buyers who wait for construction documents are ordering a genset for a building whose transformer arrives six months later. Natural gas is the one class where the queue is shorter than diesel at the same kW, 54 to 78 weeks against 62 to 82 for 2,500 to 3,500 kW diesel, and the Recips vs Turbines vs Fuel Cells TCO shows why: gas prime-power sets are sold by engine houses whose factories were built for gas compression and CHP, not by the two diesel OEMs whose high-horsepower lines the hyperscalers have booked.
The Used Market Is Pricing Time, Not Iron
The dealer consensus, in Central States Diesel’s words, is that “low-hour large gensets that once sold at 40 to 50% of new now command 60 to 75% when new delivery is a year away.” That is true on the dealer’s own terms and misleading for a datacenter or plant buyer, so we pulled the dated listings and checked. Four listings from one dealer’s yard in Waukesha, Wisconsin, between June 23 and August 11, 2026, and the price bands from Power Generation Enterprises’ May 2, 2026 guide are in used-vs-new-prices.csv; asking prices, n=1 per listing, FOB dealer.
| Unit | kW | Year / hours | Tier | Asking price | New reference | Ratio | Listed |
|---|---|---|---|---|---|---|---|
| Used Cummins DQKC (QSK60), open skid | 2,000 | 2002 / 406 h | not stated | $249,900 | New 2,000 kW Tier 4: over $1.4M | 0.18 | Aug 5 2026 |
| Used Kohler 2000REOZMD (Mitsubishi S16R) | 2,000 | 2018 / 223 h | Tier 2 | $449,900 | New 2,000 kW Tier 4: over $1.4M | 0.32 | Aug 11 2026 |
| Used 2,000 kW band (3516B/C, QSK60) | 2,000 | various | mostly Tier 2 | $280k to $650k | New 2,000 kW Tier 4: over $1.4M | 0.20 to 0.46 | May 2 2026 |
| Used 1,000 kW band (3508B, QST30) | 1,000 | various | mixed | $90k to $250k | New 1,000 kW Tier 4 all-in: ~$810k | 0.11 to 0.31 | May 2 2026 |
| New Cummins DQFAD (QST30), emergency-only | 1,000 | 2024 / 0 h | Tier 2 | $269,900 | New 1,000 kW Tier 4 all-in: ~$810k | 0.33 | Jun 23 2026 |
| Used Cummins DQFAA (QST30) | 750 | 2007 / 792 h | not stated | $135,900 | Same dealer’s new Tier 2 at $270/kW | 0.67 per kW | Jul 20 2026 |
Source: Open Factory Public Bid-Tab Price Book (compiled from Central States Diesel Generators listings, June to August 2026, and Power Generation Enterprises pricing guide, May 2026; asking prices, n=1 per listing). Data: used-vs-new-prices.csv
A 2018 Kohler 2,000 kW Tier 2 unit with 223 hours asks $449,900, or $225/kW, against “north of $1.4M” for a new 2,000 kW CAT 3516 with Tier 4 aftertreatment, a ratio of 0.32; the 2002 Cummins QSK60 at $249,900 is 0.18; and the only row that reaches the dealers’ 60 to 75% is a used 750 kW unit at $181/kW against the same dealer’s new Tier 2 1,000 kW at $270/kW.
Used gensets trade at 60 to 75% of new only when the new unit is also Tier 2, which is a unit you can only run 100 hours a year. Against the Tier 4 unit a non-emergency application must buy, used iron is 18 to 46 cents on the dollar, and the gap is the aftertreatment: Power Generation Enterprises prices a new 1,000 kW Tier 4 Final base unit at $580,000 to $720,000 “plus $130,000 to $185,000 for the aftertreatment package,” puts a 2026 CAT 3512B HD Tier 4 Final at $850,000 to $1,050,000, and says a used Tier 4 Final unit “commands $35,000 to $80,000 more than the same kW Tier 2 unit, because the buyer doesn’t have to navigate emissions paperwork.” The 2024-model-year Cummins DQFAD in the table is the clearest case: a brand-new 1,000 kW unit at $269,900 is a third of a new Tier 4 unit because it is certified to Tier 2 and can only be sold for emergency duty. The Used and Refurbished Market piece covers what “load-bank tested, documented hours” is worth on these units; the Genset TCO tool carries the Tier 4 aftertreatment line and the run-hour cap as separate inputs so the two routes can be compared on ten-year cost rather than sticker.
Tier 2 Is the Loophole That Makes Used Iron Legal
The reason a 2018 Tier 2 engine is still a legal datacenter generator is written into 40 CFR 60.4202. Manufacturers must certify emergency stationary CI engines of 37 kW and up to “the Tier 2 or Tier 3 emission standards for new nonroad CI engines” from model year 2007, and engines above 3,000 HP to “the Tier 2 emission standards” from model year 2011. Non-emergency engines are different: 60.4201 sends them to the current 40 CFR part 1039 standards for their model year, which for a new engine means Tier 4 Final, and 60.4204 puts the same duty on the owner. A datacenter genset is an emergency engine because its owner promises it will behave like one.
The promise is 100 hours a year, and under 60.4211(f) only 50 of them can be anything other than testing. The text: emergency engines may run “for maintenance checks and readiness testing” for “a maximum of 100 hours per calendar year,” of which “up to 50 hours per calendar year in non-emergency situations” is allowed, and “the 50 hours per calendar year for non-emergency situations cannot be used for peak shaving or non-emergency demand response, or to generate income for a facility to an electric grid,” unless the engine is dispatched by the balancing authority to avert “voltage collapse or line overloads.” There is “no time limit on the use of emergency stationary ICE in emergency situations.” An owner who runs a Tier 2 unit outside those limits “must meet all requirements for non-emergency engines,” which is Tier 4, which is the $1.4 million unit with the 90-week lead time.
Source: Better Data Center Project, as reported by Latitude Media, March 2026; split derived by Open Factory
Virginia had permitted about 10,500 generator units and 27 GW of diesel capacity at datacenters by the end of 2025, “over 70%” of it Tier 2 per the Better Data Center Project report as covered by Latitude Media, which works out to roughly 19 GW of Tier 2 iron against 8 GW of everything else, while “over half of the newly permitted capacity is Tier 4.”
The national numbers in the same report explain the backlog charts above: US datacenter diesel generator capacity went from about 20 GW in 2018 to about 55 GW in 2024, and one Amazon site in Manassas runs 93 generators of 2.5 MW each. Texas is now doing the same at higher speed and under minor permits. A Floodlight analysis reported by Latitude Media on July 13, 2026 counted “at least 38 data centers across Texas” that “received minor permits to operate on-site power sources” since 2024, covering “more than 2,100 backup diesel generators,” with one Vantage site permitted at “99.8 tons per year” of NOx “barely below the area’s 100 ton-per-year threshold” that would trigger public review. The emergency route is not a Virginia habit. It is how 55 GW of engines got permitted in six years, and it is why the Large-Load Policy Tracker now carries generator permitting alongside interconnection rules for every state where a 100 MW load is being built.
The Rental Fleet Is the Only Thing Shipping This Quarter
Aggreko filed to list on the NYSE on August 24, 2026, and its Form F-1 is the first audited look at what the bridge-power market is worth. The fleet is “approximately 120,000 assets” and “17 GW, including 6.3 GW of diesel/HVO power generation, 2.1 GW of gas power generation,” with “average physical utilization for the year ended January 3, 2026” of 54%. Data center net revenue went from $96 million in 2023 to $196 million in 2024 to $391 million in fiscal 2025, and $362 million in the first half of 2026 alone against $160 million a year earlier, on a total of $1,918 million. The filing names “two large (135 MW and 86 MW), multi-year contracts recently won with a blue-chip data center developer in the United States” and describes a bridging job of “48 times 1,200 kW (or equivalent) Tier 4 Final generators totaling 48 MW of continuous operational bridging power.”
Source: Aggreko Inc., Form F-1, August 2026
Data centers were 3.8% of Aggreko’s revenue in 2023, 11.4% in fiscal 2025 and 18.9% in the first half of 2026, and the sector added $202 million of revenue growth in the latest year, more than utilities, building services and events combined.
A 6.3 GW diesel rental fleet at 54% utilization is about 2.9 GW of idle Tier 4 Final engines, which is more than the entire US behind-the-meter fleet actually running. The Behind the Meter forecast counted about 2 GW operating against 90 GW announced. Rental is not cheap; Central States Diesel’s advice is to “budget it as insurance, not as the plan,” and the 48 MW Tier 4 Final bridging job in the F-1 was run for a hyperscaler waiting on grid power, not on gensets. But the arithmetic for a plant that needs 4 MW of standby in 2027 is simple: a 24-month rental of Tier 4 units while a new-build slot matures, priced through the Genset TCO tool against a used Tier 2 purchase, is the only path that does not depend on an OEM quoting a date. Generac’s April call adds a second reason rental fleets have iron: “many of our rental customers have begun to invest in new equipment as part of a refleeting cycle,” which puts the rental houses in the same OEM queue as everyone else, buying now what they will rent to you in 2027.
The gas side of the rental and bridge market is where the OEMs themselves are now selling prime power, not standby. Cummins’ Q2 2026 release lists a June agreement with Circe Energy “to provide a series of natural gas generator sets to support a scalable, behind-the-meter, prime power microgrid solution” for an HPC datacenter in Texas, and describes “natural gas-fueled generator sets and integrated microgrid controls designed to address power grid constraints.” That is a diesel standby company selling gas prime power into the same Texas minor-permit route described above, and it is the clearest sign that the 100-hour emergency engine and the 8,000-hour prime mover are converging on the same order book. A plant buyer competing for a 2 MW slot in 2027 is now behind hyperscale standby fleets, behind-the-meter gas campuses and rental refleeting, in that order; the Datacenter MEP Cost Table carries the carrying cost of each month of that delay per MW.
What to Do Monday
The Cummins and Caterpillar queue is not going to shorten before 2028, because both companies have told the SEC as much: six to eight quarters of demand on the 95-liter line after a capacity doubling, and $29.2 billion of Caterpillar backlog that will not ship within twelve months. The buyer’s job is to stop waiting for a quote and pick a route. For emergency standby under 100 hours a year, buy the tested used Tier 2 unit this month at 18 to 46 cents on the Tier 4 dollar and put the savings into the ATS and paralleling gear that also runs 20 to 40 weeks. For anything that will run more than 50 non-emergency hours, order the Tier 4 unit now with a firm date and LDs, and bridge with rental. Either way, run the Lead-Time-Adjusted Schedule with the genset row at 62 to 82 weeks and the ATS row at 24 to 40, and put the Quote Check band next to whatever the dealer says; a quote inside 40 weeks for anything above 1,500 kW is either a cancelled order, which you want, or a slot the dealer does not hold, which you do not.
Behind the paywall: the ten suppliers with open or committed engine and packaging capacity, dated, including the 1.1 GW INNIO order and the 1.25 GW Rehlko allocation that show where prime-power gas slots still exist, and the Tier 2 versus Tier 4 permitting route in Virginia, Texas and Georgia, with the hour limits and thresholds on one page. The Lead-Time Monitor carries the genset rows monthly; the Genset TCO tool prices the two routes side by side.