Exhaust size

[superbird03]

So I am hoping for some feedback on how big peoples exhaust are.... I put a side burner exhaust on my truck. I ended up with about 30 feet of pipe (including the muffler). I went with 5" because that is what the down pipe was. Anyone think that will be too restrictive for the length of pipe? I have a couple thousand miles on it and haven't seen any ill effects of this but was wondering what others have for exhaust pipe diameter size?

Thanks,
Steve

[jasong]

On a pipe that long it's important to keep the velocity up.
I probably would've done the same.

[Mntom]

Do you by chance have a pyrometer? That will tell you if the pipe is large enough.

[hot rod]

surely there is a resource somewhere to figure exhaust size. I like mntom's idea. If you are building too much heat at the engine end of the exhaust, there is too much restriction. Also, any elbows make a difference. I know when we used to use a chart to figure line sizing for propane/natural gas (same theory, gas flowing through a pipe under pressure) we had to figure in for elbows at the equivalent of 5' of straight pipe for every 90 degree elbow (larger radius elbows had a lower factor). So if that same rule of thumb applies here if you have 30' of pipe and two 90 degree elbows that would equal 40' of pipe.

[superbird03]

Thanks guys... I don't have a pyrometer but makes sense that would be the easiest way to tell if there is a problem or not. I will have to look at getting one hooked up.

Thanks!