Yes you can easily get 5% bhp improvement mid winter compared to mid summer on a normally aspirated engine assuming something approaching a cold air inlet. A very rough guide is one percent improvement for every 4°C (or 7°F) reduction in intake temp.


Richard

2018 Roadster 3.7
1966 Land Rover S2a 88
2024 Royal Enfield Guerrilla 450
1945 Guzzi Airone