dusman59
Well-Known Member
I drove semis for 12 years with Jake brakes. Its the jacked up pickup trucks which seems like almost strait headers. I do like a nice sounding exhaust even if its loud but some are very obnoxious and sound bad.Most likely what your hearing is Jake Brakes. It's an option you can order on trucks that turns the engine into a compressor by changing the valve timing when braking. It provides quite a bit of braking without wearing out the friction brakes. They are loud and there are restrictions as to where they can use them. If you live near a hill or the pitch drops over time, your probably hearing a Jake Brake.
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