Loud engine noise is usually a result of a hole or disconnection in the exhaust manifold or muffler.
Check the heat shield.
depends on what car it is and what engine ur running under your hood
It sounds like it is overheating. Remove fluff from the fan and vent. Check the heatsink on the processor.
A NASCAR race car is measured to be about 125-130 decibels. So they are pretty loud. I have been to 5 NASCAR races and the sound doesn't bother me. It is still pretty loud even if you are sitting 20 to 25 rows from the track.
You'll have to isolate where the noise is coming from before you can do a diagnostic.
very loud
Your car battery could be running low so what you could do is get jumpleeds and get an other and jumpwire it
Possible it is reverberation in the exhaust system if it occurs when vehicle is stationary.
Super loud they have be that loud in case a a jerk in front of you is not paying atttenion.
Often when a vehicle air conditioner gets loud, the problem is due to a belt. You should take the car in to have the belt checked.
So you look cool, and play your music so LOUD, that old people hate you.
Running a straight pipe will improve the engines performance, but at a cost. You will have a very loud car with not pollution controls for the exhaust. This may cause CO2 fumes to build in your car without you knowing it and cause you to pass out at the wheel.