Over the last week ive done lots of testing with this theory of taking the lid off the airbox. A total of 516 miles of testing!
Now some of you are going to read it and think ‘well i knew that’ but i just wanted to test it for myself.
Doing runs at motorway speed with the speed limiter set at XXmph (keeping my foot to the floor in 6th gear) i would wait until i went over a fixed ‘bump’ in the tarmac and knock the limiter off, the car would then start accelerating hard until i hit another bump some ¼ mile down the road which is when i check the speed (on the GPS)
This test was done countless times with the lid on and with the lid off, also several times a day over the last week.
Result =
With the lid on it accelerated better/quicker, upto 12mph was the best difference.
I then had another look at the airbox set up on the 200 and decided i would do away with the 2nd air feed that ends next to the battery pulling in the warm air from the engine bay. I put my own pipe on this and ran it down to the lower grill near to the fog light. As ive only done a few runs with it like this i can only give the results so far which is same test as above with the lid on (OEM setup) then putting my CAF on gives another 3mph. Based on the results im going to be running mine with the lid on and with the 2nd CAF.
Plus side to having the airbox lid off, it sounds loads better, and thats it really as far as my tests found.