Everybody knows Hennessey and what they do. Everybody. This time Mr John took both Hellcats and upgraded their stock 6.2 liter V8s that pump 707 HP up to 805HP for the HPE800 and 852 HP for the HPE850 model. To achieve this Hennessey

upgraded ECU, installed less restrictive air filter, upgraded lower pulley that increases boost by 1-2 psi and port-matched throttle body. The HPE850 has all of these upgrades and ads one more – ported supercharger housing.