![Question. Is the general rule is 15cc per 1hp, 420cc=28hp. So why is this 420cc engine 13hp? I assume it has to do with displacement or something. But 15hp (half) difference seems Question. Is the general rule is 15cc per 1hp, 420cc=28hp. So why is this 420cc engine 13hp? I assume it has to do with displacement or something. But 15hp (half) difference seems](https://preview.redd.it/question-is-the-general-rule-is-15cc-per-1hp-420cc-28hp-so-v0-n4ue4nrb1in81.jpg?auto=webp&s=b5346ed6c5fe6326d1d8a8616dbacf33a407400e)
Question. Is the general rule is 15cc per 1hp, 420cc=28hp. So why is this 420cc engine 13hp? I assume it has to do with displacement or something. But 15hp (half) difference seems
![Source BISON 18Hp Vertical Shaft Engine For Lawn Mower 190F 420Cc Ohv 16Hp Single Cylinder Engine 192 F on m.alibaba.com Source BISON 18Hp Vertical Shaft Engine For Lawn Mower 190F 420Cc Ohv 16Hp Single Cylinder Engine 192 F on m.alibaba.com](https://sc04.alicdn.com/kf/H113bce19e37944399fa1205a79d31716G.jpg)
Source BISON 18Hp Vertical Shaft Engine For Lawn Mower 190F 420Cc Ohv 16Hp Single Cylinder Engine 192 F on m.alibaba.com
![Powerease Gas Engine 420cc 15Hp 1" Shaft - ATPRO Powerclean Equipment Inc. - Pressure Washers Online Canada Powerease Gas Engine 420cc 15Hp 1" Shaft - ATPRO Powerclean Equipment Inc. - Pressure Washers Online Canada](https://www.pressurewashersonline.ca/cdn/shop/products/RATO_15hp_2000x.png?v=1455568800)
Powerease Gas Engine 420cc 15Hp 1" Shaft - ATPRO Powerclean Equipment Inc. - Pressure Washers Online Canada
![Amazon.com : BILT HARD 420cc 15HP Gas Engine with Electric Start, Horizontal Shaft 4 Stroke OHV Gas Motor, Gas Powered Multi-Use Engine : Patio, Lawn & Garden Amazon.com : BILT HARD 420cc 15HP Gas Engine with Electric Start, Horizontal Shaft 4 Stroke OHV Gas Motor, Gas Powered Multi-Use Engine : Patio, Lawn & Garden](https://m.media-amazon.com/images/I/71rUXSRHVxL.jpg)
Amazon.com : BILT HARD 420cc 15HP Gas Engine with Electric Start, Horizontal Shaft 4 Stroke OHV Gas Motor, Gas Powered Multi-Use Engine : Patio, Lawn & Garden
![Bison Loncin 420cc Engine 15 HP 4 Stroke Gasoline Motor Chinese Ohv New Engine - China Engine 420cc 15 HP 4 Stroke Gasoline Motor, Loncin 420cc Engine | Made-in-China.com Bison Loncin 420cc Engine 15 HP 4 Stroke Gasoline Motor Chinese Ohv New Engine - China Engine 420cc 15 HP 4 Stroke Gasoline Motor, Loncin 420cc Engine | Made-in-China.com](https://image.made-in-china.com/2f0j00ZitoOknKQbqe/Bison-Loncin-420cc-Engine-15-HP-4-Stroke-Gasoline-Motor-Chinese-Ohv-New-Engine.webp)
Bison Loncin 420cc Engine 15 HP 4 Stroke Gasoline Motor Chinese Ohv New Engine - China Engine 420cc 15 HP 4 Stroke Gasoline Motor, Loncin 420cc Engine | Made-in-China.com
![LIFAN 1 in. 15 HP 420cc OHV Electric Start Horizontal Keyway Shaft Gas Engine LF190F-BDQ - The Home Depot LIFAN 1 in. 15 HP 420cc OHV Electric Start Horizontal Keyway Shaft Gas Engine LF190F-BDQ - The Home Depot](https://images.thdstatic.com/productImages/17ea2a10-1e53-4dcd-9668-503cdfe1151f/svn/lifan-replacement-engines-lf190f-bdq-40_600.jpg)
LIFAN 1 in. 15 HP 420cc OHV Electric Start Horizontal Keyway Shaft Gas Engine LF190F-BDQ - The Home Depot
![LIFAN 1 in. 15 HP 420cc OHV Electric Start Horizontal Keyway Shaft Gas Engine LF190F-BDQ - The Home Depot LIFAN 1 in. 15 HP 420cc OHV Electric Start Horizontal Keyway Shaft Gas Engine LF190F-BDQ - The Home Depot](https://images.thdstatic.com/productImages/d0c08a5e-52f9-47f8-a256-f4c499058b04/svn/lifan-replacement-engines-lf190f-bdq-e1_600.jpg)
LIFAN 1 in. 15 HP 420cc OHV Electric Start Horizontal Keyway Shaft Gas Engine LF190F-BDQ - The Home Depot
![Engine Assembly - Electric Start series - DEK Yellow - 15 hp, 420cc - Generators: 5650EL, 6500EL, 7550EL Pro - GXI Parts & Service Engine Assembly - Electric Start series - DEK Yellow - 15 hp, 420cc - Generators: 5650EL, 6500EL, 7550EL Pro - GXI Parts & Service](https://cdn11.bigcommerce.com/s-mnfnydhoql/images/stencil/1280x1280/products/1842/5540/G04211__58469.1512614933.jpg?c=2)
Engine Assembly - Electric Start series - DEK Yellow - 15 hp, 420cc - Generators: 5650EL, 6500EL, 7550EL Pro - GXI Parts & Service
![DuroMax 420-cc 16-HP Replacement Engine for Multi-purpose in the Replacement Engines department at Lowes.com DuroMax 420-cc 16-HP Replacement Engine for Multi-purpose in the Replacement Engines department at Lowes.com](https://mobileimages.lowes.com/productimages/7f01fe62-7a02-43f7-a126-fe4fc34bbfd7/12244609.jpg)
DuroMax 420-cc 16-HP Replacement Engine for Multi-purpose in the Replacement Engines department at Lowes.com
![Amazon.com: Tool Tuff New 420cc 15 hp Gas Engine - Elecrtric Start, 6-Month Warranty, Reliable : Automotive Amazon.com: Tool Tuff New 420cc 15 hp Gas Engine - Elecrtric Start, 6-Month Warranty, Reliable : Automotive](https://m.media-amazon.com/images/I/71-shyXWN4L._AC_UF894,1000_QL80_.jpg)