A few days ago, I did what I thought would be one of the most stupid things I've done in my life. I duct taped my Zoom H2n microphone into my car's engine bay. I wanted an authentic engine sound, but couldn't afford the right mics and equipment to record the exhaust.
Don't try this at home (or do!)
Several questions ran through my mind before doing this - among those include why anyone would do this - but the main one was finding a place to put my mic. To address this problem, I drove around my neighborhood once until my car was just under operating temperature, where it was still hot to the touch, but not too hot where you could burn yourself. This is so I could figure out a safe spot to attach my mic so that it won't melt.
The hood liner really didn't give me much to work with, as most of the parts under the hood were flush with it, so I had to put the mic under something to avoid crushing it with the hood. I narrowed it down to underneath the strut bar and positioning it behind the air box. In hindsight, it was a bad place to put it because even though the mic captured the sound of the engine as well as it could, it also captured the vacuum suction of the intake, adding more noise around the 6k to 15k frequencies.
I also did not drive as aggressively as I should have to capture the engine really revving up, because I was afraid the mic would fall, so most of the engine captures were pretty quiet with its low RPMs. The end result was not fruitless, however, after playing around with the capture in Reaper, I found out that with the sound slowed down and the frequencies from the airbox were left untouched, It made for a decent diesel engine sound for the rigs in B.O.O.M.'s level "The Chase." All is well!
Now I just need to summon the courage to put my mic closer to the engine and really floor it!