please teach a young guy about cross overs and x,y,&h pipes

 

I'm no expert, but the way I understand it is that it compensates for the firing order. Baascially, if you use dual exhaust, the exhaust pulses arn't in sequence with respect to one side. By adding any type of crossover, you wind up with the pulses from all 8 cylinders in sequence at that point.

The pulses that would normally be missing from one side are now there from the other side. This helps exhaust scavenging as those missing pulses, which are now there with a crossover, help pull exhaust through the header pipes.

With valve overlap, the exhaust helps pull some fuel/air mixture into the cylinder when both valves are open and hence, more power.

 

A cross over pipe, whether "H" or "X" lets each bank of the engine see the other pipe, hence balancing the exhaust flow. The pipe whether "H" or "X" enhances low end torque and throttle response. It also mellows the exhaust sound. The "X" pipe helps top end more than the "H" pipe because of the angles involved. A "Y" pipe is not technically a cross over pipe even though it does cross over, it just ties the right and left banks together and lets them flow out a single exhaust pipe. A "Y" system is usually thought of as a cheap way to get the exhaust out. Even though I have a "Y" system on my 1984 F250 with a 460 which has the two pipes from the manifolds flow into a single 3" pipe and muffler, it has not helped the top end, it did help mpg.

 

I was told the "H" pipe will only help at 1,500 rpm and below rpm as above that speed the exhaust gases get sheared and can not make that 90 degree turn.
My muffler shop told me they are ok for those that want or need that even exhaust sound only. He mentioned a tight angle designed "X" cross one between 30 to 35 degrees maximun angle to allow for a high syphoning effect of the previous exhaust power pulse to pull the next cylinders primary pipes exhaust creating a strong vacuum. This I was told will not only help off idle but up to your redline plus need to be rejetted allowing for the exhaust change. Headers a must with free flowing mufflers also.

 

on a v8 i honestly like the different sounds out of each pipe. any crossover is benificial in a certain rpm range, but you just can't get that sound with a crossover or a y and single pipe with dual outlets. it's just my taste, even true duals on an efi motor don't have that distinct sound that i love