Great results, Congratulations!!!! Do you mind sharing the engine build and other details related to power performance?
Cheers,
Charles
The engine is nothing special. It's a basic 3.8L with a good set of ported heads. The cam is aggressive but not much different than a lot of other people are running. We haven't flowed the heads, but I'm guessing somewhere around 220/170cfm. The cam is a solid roller design but it's not a high rpm profile. It's solid roller for reliability reasons only. I feel that valve float and bounce at higher rpms and higher boost levels is a big problem with these motors so we wanted to be sure and run ample valve spring pressure to avoid that.
Other than a responsibly built motor, the rest of the performance recipe is a 3 legged stool.
1) Supercharger. The blower itself is of major importance here, and the abradive coated rotors are even more so. This is an out of the box MPX with the new rotor pack properly clearanced and broken in to where the blower runs smooth and quiet (relatively speaking). With that, the ability to make nearly 20psi of boost with 20% OD is one of the most important factors in this build. We could have made the same boost with the MPX at 30% OD, but in our experience increases in boost without an increase in OD results in approximately double the HP gain per pound of boost. We feel that this boost level and OD level represent a more or less ideal balance for this engine and this supercharger. This is particularly relevant when you consider that this motor sees 6800rpm at the track and has no signs of belt slip. The belt speeds that would be encountered at that rpm and 30% OD would make belt control very difficult. In a whole season of racing and dyno, etc., we are still using all the same set of belts so we are comfortable with this OD level.
2) Cooling. We use a very large front mounted intercooler along with alcohol injection to keep air charge temps under 100degF throughout an entire 1/4 mile pass. We initially used a large 3" core but found that to be insufficient so we are currently using a 4"x24"x12" core mounted outside the engine bay (right behind the bumper).
3) Tuning. There is no magic here, but having 20psi on tap from 2500rpm on up means that you must be aware of the engine's detonation tendencies and have fuel and an ignition advance curve that match that requirement. You can't just throw xx deg of timing in and expect xxx results. Each motor is different and at 20psi your margin of error (especially on pump gas) is small. We tune specifically to avoid detonation in the mid range then bring in our more aggressive tune on the top end for more HP when it is safer to do so.
That is the three legged stool that supports this power level.
The only other thing I will add, is that it is no small thing to be aware that this motor does this with stock exhaust manifolds, emissions legal cats, and a full rear exit, quiet exhaust system. The car is fully streetable, is daily driven, and passes OH E-check with flying colors.