Supercharged K20A Exige
I just completed the first supercharged K20A Exige conversion after trying it out on my Exige a couple of months ago.
I weighed the car with the Rover and then with the Honda, and here are the figures. Rover 1,771 lbs [805 Kg] Honda 1809 lbs [822 Kg]. The supercharger adds 20 lbs [9 Kg], so a naturally aspirated K20A Powered car only weighs 18 lbs [8 Kg] more, and the weight balance is .75% more toward the front. I didn't get a chance to check the C.G. difference, but the K20A is mounted 35 mm lower in the chassis than the Rover, measured at the crank centerline.
This particular engine made 283.4 HP at the wheel flanges on a Dynapack chassis dyno, where my engine made 292.4 HP. Looks like my engine runs a little stronger than some, but Doug Macmillan from Hondata saw 293 HP from a DC-5 Integra Type R with the same supercharger setup in England last month on Abbey Motorsport's Dynapack, so the output is fairly consistent. We can't reasonably expect to see the same HP output from every engine within a family, now can we?
The torque delivery is extremely linear, with 4 pounds of boost at just 2,000 RPM rising to a maximum of 7.5 pounds [.5 bar] at 8,000 and above. I've made some smaller diameter pulleys we'll be testing next week on Doug's RSX-S to see how well his engine performs at higher boost levels, and I've made an intercooler setup we'll be testing on my engine soon as well. Derek from Hondata has put a bit of laughing gas into his engine recently, and will be installing a turbosystem to work in conjunction with it very soon.
For superior performance in an Elise the K20A Honda is the only choice.