Engines used in Generac generators

Generac generators use two main engine types: OHV (Overhead Valve) and OHVI (Overhead Valve Industrial).

• OHV: A common small-engine design used across many products. These engines are typically light-duty with splash lubrication and no automotive spin-on oil filter, which makes them well-suited for intermittent use and regular maintenance intervals.
• OHVI: Generac’s proprietary “industrial” engine family, purpose-built for generator duty and longer runtimes. Key upgrades include full-pressure lubrication and an automotive-style spin-on oil filter for longer life and heavier-duty operation. Many OHVI engines have been produced in Wisconsin.

Environment

This article focuses on engines found in residential air-cooled home standby and portable generators. Liquid-cooled commercial standby generators have more variation, so check your specific model’s owner’s manual on the product lookup page. See this article for help with industrial models.

Which engines are paired with which generators?

• All air-cooled home standby generators (except the 7.5 kW PowerPact) use OHVI engines.
• Most portable generators use OHV engines. Larger portable models, such as the GP15500 EFI, use the OHVI engine.
• To confirm which engine your generator uses, review the spec sheet and owner’s manual on the product lookup page.

OHV (Overhead Valve)

• Generac-designed and assembled overseas.
• No oil filter, which requires more frequent maintenance.
• Splash lubrication, internal engine motion splashes oil on moving parts.
• Mechanical governor, slower response than an isochronous governor.

OHVI G-Force (Overhead Valve Industrial)

• Manufactured in Whitewater, WI.
• Used on all 9–28 kW air-cooled units (engine size matches generator power rating, see below).
• Pressurized lubrication, oil is pumped directly to critical areas.
• Includes both an air filter and a spin-on automotive-style oil filter.
• Electronic (isochronous) governor, fastest responding governor available. Maximizes engine performance and helps prevent stalling.
• Next Generation air-cooled standby models (459 cc, 817 cc, 997 cc) feature hydraulic lifters, which eliminates the need for valve adjustments.

Engines used in the Next Generation air-cooled standby generator

kW size	HSB model number	Engine size
10 kW	G0072570	459 cc
10 kW	G0073210	459 cc
14 kW	G0072580	817 cc
14 kW	G0073230	817 cc
18 kW	G0072590	817 cc
18 kW	G0073240	817 cc
22 kW	G0072600	997 cc
22 kW	G0073250	997 cc
24 kW	G0072610	997 cc
24 kW	G0073260	997 cc
26 kW	G0073270	997 cc
26 kW	G0073280	997 cc
28 kW	G0072820	997 cc
28 kW	G0073290	997 cc
20 kW (3-phase)	G0072710	997 cc

Guardian series engines

kW size	HSB model number	Engine size
10 kW	G0071710	460 cc
10 kW	G0071720	460 cc
14 kW	G00722310	826 cc
14 kW	G00722510	826 cc
18 kW	G00722610	826 cc
18 kW	G00722810	826 cc
22 kW	G00704211	999 cc
22 kW	G00704311	999 cc
24 kW	G00720910	999 cc
24 kW	G00721010	999 cc
26 kW	G0072900	999 cc
26 kW	G0072910	999 cc
20 kW (3-phase)	G0070771	999 cc

Guardian series, liquid-cooled, and portable engines

The OHVI 460 cc engine is used in 9 kW and 10 kW liquid propane (LP) and natural gas (NG) generators.

The OHVI 816 cc engine is used in 14 kW and 18 kW natural gas (NG) and liquid propane (LP) generators.

The OHVI 999 cc engine is used in 22 kW LP/19.5 kW NG, 24 kW LP/21 kW NG, and 26 kW LP/22.5 kW NG generators.

OHV engines are used in most portable generators and are available in a range of sizes.

Where can I get parts for my Generac generator engine?

• Generator parts are available on Generac’s OrderTree site.
• Parts manuals can be found by searching your generator’s model or serial number on the product lookup page.
• If you cannot find the part you are looking for, use the dealer locator to contact a local Independent Authorized Service Dealer (IASD), or review How can I find a Generac service dealer in my area?.