Head to head
Generac GP8000E COsense vs Generac GP18000EFI COsense
Generac · Portable Generator
Generac GP8000E COsense
~$979
8,000 W / 10,000 W surge · up to well pump or a small central AC
Generac · Portable Generator
Generac GP18000EFI COsense
~$4,399
18,000 W / 22,500 W surge · up to whole home with central air
Quick takeThe Generac GP8000E COsense lists about $3,420 lower; the Generac GP18000EFI COsense puts out more sustained power (18,000 W).
| Spec | Generac GP8000E COsense | Generac GP18000EFI COsense |
|---|---|---|
| Approx. price | ~$979 | ~$4,399 |
| Type | Portable Generator | Portable Generator |
| Fuel | Gasoline | Gasoline |
| Running / output watts | 8,000 W | 18,000 W |
| Starting / surge watts | 10,000 W | 22,500 W |
| Battery capacity | — | — |
| Expandable to | — | — |
| Noise | — | — |
| Runtime | up to 11 hrs @ 50% load (7.9 gal) | 9 hrs at 50% load on 14.2 gal |
| Outlets | 4x 120V 20A (5-20R), 1x 120/240V 30A (L14-30R) | 2x 120V 20A (5-20R duplex), 1x 120V 30A (L5-30R), 1x 120/240V 30A (L14-30R), 1x 120/240V 50A (14-50R) |
| Fuel tank | 7.9 gal | 14.2 gal |
| Weight | 198 lbs | 442.8 lbs |
| Transfer-switch ready | Yes | Yes |
| Warranty | 3-year limited | 3-year residential, 2-year commercial |
Highlighted cell is the better figure for that row.
Owner pros and cons
Generac GP8000E COsense
- +8,000 running watts under $1,000 with electric start
- +PowerRush 10,000W surge starts well pumps and AC
- +L14-30R 240V ready for an interlock
- +COsense CO shutdown standard
- +11-hour half-load runtime on the 7.9-gal steel tank
- −Loud open-frame operation; no published dB spec
- −Non-inverter power — keep sensitive electronics buffered
- −Gasoline only; no propane option in this SKU
- −Recall history (2022 handle, 2026 carb leak) requires serial checks
- −198 lbs with a narrow wheelbase on rough ground
Generac GP18000EFI COsense
- +14-50R outlet feeds a 50-amp transfer switch
- +22,500 W starting capacity handles a 5-ton AC
- +THD under 5% protects electronics
- +COsense CO shutdown, electric start and battery included
- +12-inch never-flat wheels for a 443 lb machine
- −Around 443 lbs, so it needs a ramp and two people
- −About 9 hrs at half load means refueling through the night
- −No noise figure published, and an 816cc twin is loud
- −$4,399 buys a Guardian 14kW standby before install
- −Gasoline only, with fuel that needs stabilizer if stored