Bottman
4️⃣ Gold
I was watching a video on small ways to improve performance and in the video it recommended removing the engine cover as it is "purely cosmetic" and it makes your intake manifold hotter.
As an engineer I always want to see the proof and none was presented so I decided to try it and see if it is true. I took six temperature readings (each intake runner) on two days immediately after my commute in the Phoenix area. I got an average with the cover on of 166.9 degrees and with it off I had an average of 160.9 degrees. The ambient temperature was within one degree of each other during the test. It was one degree cooler on the day I had the cover on. I then performed a statistical test to see if the difference was statistically significant and it is. The probability of this happening by chance is essentially zero (P-Value)
Test
Null hypothesis H₀: μ_difference = 0
Alternative hypothesis H₁: μ_difference < 0
T-Value P-Value
-8.42 0.000
Test
So yes, removing the engine cover does result in a lower outside temperature of the intake manifold. However, this is the outside of the intake not the actual temperature of the air inside the intake. I highly suspect that inside the intake the difference is smaller. Even if you got the full six-degree change in the intake air temperature it would be estimated at a 1% HP improvement so less than three horsepower improvement. So, from a practically significant improvement perspective not so much.
I still found the results interesting and thought I would share.
As an engineer I always want to see the proof and none was presented so I decided to try it and see if it is true. I took six temperature readings (each intake runner) on two days immediately after my commute in the Phoenix area. I got an average with the cover on of 166.9 degrees and with it off I had an average of 160.9 degrees. The ambient temperature was within one degree of each other during the test. It was one degree cooler on the day I had the cover on. I then performed a statistical test to see if the difference was statistically significant and it is. The probability of this happening by chance is essentially zero (P-Value)
Test
Null hypothesis H₀: μ_difference = 0
Alternative hypothesis H₁: μ_difference < 0
T-Value P-Value
-8.42 0.000
Test
So yes, removing the engine cover does result in a lower outside temperature of the intake manifold. However, this is the outside of the intake not the actual temperature of the air inside the intake. I highly suspect that inside the intake the difference is smaller. Even if you got the full six-degree change in the intake air temperature it would be estimated at a 1% HP improvement so less than three horsepower improvement. So, from a practically significant improvement perspective not so much.
I still found the results interesting and thought I would share.
