TORS

[Ransom]

GPM wrote:

So, do you think that the sole, or at least primary function of that box is to further dampen the sound? I do know that my R3T with the D&Ds is by no means loud. I can't imagine that it would take much to design a Y type pipe to replace the small box. I would like to get a look at the Jardine system for the R3T and see how they handled that area.

I think the primary purpose is sound control. I think a y pipe would lean out the motor and add volume/sound to exhaust.

 

[nico]

The exhaust pipes actually educt spent gases out of the combustion chamber when the intake valve overlap occurs (intake and exhaust valves open at the same time). This provides a more complete evacuation of spent gases from the combustion chamber and a better fresh charge of air for the next combustion cycle. Changing the diameter and length of the exhaust pipes changes the point at which the super-sonic flow occurs and changes the timing required for the overlap. So changing from stock pipes to TORs (which are shorter) changes where the eduction occurs. If you put a restiction in the stock pipes, the engine would run rich with stock settings. Increasing the flow rate through the pipe (TOR) means more fresh air is available in the combustion chamber. With a stock tune the engine is already running on the leanest possible settings. Increasing exhaust flow leans it even more and you get the Orville Redenbacher exhaust note (pop-pop-pop) as expending gases hit super-sonic velocity early in the overlap.

I was not aware that the opening of the intake valves occurs before the exhaust valves are completely shut. My understanding is that the intake and exhaust valves are never open at the same time. The way I understand it, during the exhaust stroke the piston is coming up pushing exhaust through the open exhaust valves. By the time the piston has reached TDC, the exhaust valves have shut and the intake valves begin to open so that when the piston travels down, the resulting vacuum sucks air and fuel into the cylinder through the open intake valves from the intake manifold. If the intake valves were to open before the piston reaches TDC, then some exhaust would be forced into the intake manifold, which would be a bad thing. Or if the exhaust valves stay open after the piston reaches TDC and begins going back down, exhaust would get sucked back into the cylinder, also a bad thing.

Maybe I'm totally missing something. Perhaps you tell me where I'm wrong?

 

[GPMAZ]

I think the primary purpose is sound control. I think a y pipe would lean out the motor and add volume/sound to exhaust.

It would be interesting to find out. Do you have a local muffler shop that would be willing to bend some pipes?

On the other hand I think my D&Ds are getting louder. I just got back from a quick run up along the Rim to check out the fall colors. Coming back down 87 running 85-90 much of the way and it seems that the exhaust is a bit louder than when I left. I have about 8000 miles on the D&Ds, I wonder if the packing would start to deteriorate that fast. Or, it could just be my imagination.