So this is for anyone with an electric cutout or dumped exhaust after the y-pipe. I got some work done at a shop and the tech recommended not using an electric cutout due to a lack of backpressure. He was telling me the lack of back pressure could cause catastrophic engine failure with the valves. He said he personally has seen multiple engines fail because of this issue(not specifically RAMs). I have been using a cutout for almost 3 years without any issues relating to my engine, I use it just almost every day. The main reason I got it was so I wouldn't wake up my kids or my neighbors. I am just wondering if anyone has seen or heard of any issues like this.
Not my area of expertise, but here's what I think I understood from fluid dynamics.
When an exhaust valve opens, you get a rush of hot gas, and also an acoustic pulse that propagates down the exhaust system. When this pulse encounters obstructions or changes in tube size, a reflection occurs which travels back up the system. In general if the tube gets smaller, the reflection will be positive i.e. try to push gas back in, if the tube gets bigger, the reflection is inverted i.e. tries to suck more gas out. In the case of a cutout, the change in size from tube to free air is pretty large, so it will be be a strong pulse. Depending on engine speed, if this big sucking pulse gets back to a valve just as it is closing, it can try to suck more gas through at the worst possible time and increase seat erosion.
With racing engines that have lots of valve overlap, you can also suck additional air/fuel through the cylinder which burns in the exhaust port and heats the exhaust valve up more than normal. With our sedately tuned street engines and timed fuel injection, I tend to discount that scenario for most of us.
Anyway, I don't think lack of backpressure (static) has as much potential to damage valves as the dynamic stuff that goes on in the exhaust system. That's my theory, anyone else want to chime in?
