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Yes, several members here have swapped in the SPD Y pipe and other local built ones, I installed a set of Banks headers which come with a full flow Y pipe, mine breathes a little better with the changes, glad I did it. You should expect slightly better throttle response and a small improvement in power output under high loads, that factory T pipe is an abomination but the big restriction is the factory exhaust manifolds.
I installed the SPD y-pipe on mine a few months ago. I did notice slightly better throttle response. No noticeable power increase felt with 3.73 gears, but about a 1mpg gain when cruising in OD.
I made a call to friend who is an exhaust engineer at one of the big aftermarket companies.
Look at the restriction on each pipe from the L and R cylinder bank.
it necks down for a short distance, this creates a low pressure zone, then opens up to a slightly larger chamber than the entry pipe, By using the Bernoulli effect Ford engineers are using a “scavenger chamber” Because exhaust gases come in bursts as the valves open and closes they can use these pulses combined with the effects created by pressure differentials to actually “suck” the exhaust out of the manifolds and cylinders.
that crappy LOOKING stock exhaust is using science to not just flow more but evacuate the gases quicker that the pretty aftermarket exhaust.
bottom line is all of our years looking at race cars with headers has trained us to visually identify the smooth tubular header as better, data, aka a flow bench and dyno proves otherwise.
technically the most restrictive part of the exhaust system valve opening.
True, but those factory logs are tiny inside.
And I am a faithful science believer and understand some of how flows behave but I did the headers and Y pipe at the same time and there was a real difference that was obvious when pulling a highway grade with the TT on the hitch, the EX was still pulling at 50% throttle where it had been asking for more in the same scenario when all stock.
The "Ram's horn" style Y pipe shown above in MasterX's post was the EX's original design but supposedly it was redesigned to the T shaped pipe to counter the exhaust flutter some owners reported. I ran the T pipe and now the Banks headers and Y, the latter with the stock muffler, an Aeroturbine 3030XL and a straight pipe and still haven't heard anything I would call a "flutter".
.... The "Ram's horn" style Y pipe shown above in MasterX's post was the EX's original design but supposedly it was redesigned to the T shaped pipe to counter the exhaust flutter some owners reported. ....
I wouldn't be surprised if the "redesign" was done the way it was because it could be done on the existing assembly equipment without adding a part.
Add a couple of crimps and 1 weld, all done.
The Y-connector would be a new part with 3 welds.
1. Didnt get the 3V V10 or 3V V8
2. Didnt get a 5 or 6 speed transmission.
3. Exhaust is funky.
BTW, my 2000 has a completely different Y pipe than his, interestingly.
This one
My Super Duty came with the Ramhorn style in your picture. I changed to the SPD Y-pipe and regret it. I also have a 4" catback, in my opinion it's to free flowing. Later I'll install my Doug Thorley headers with new Y and see what happens.
Cliff notes: keep the Ramhorns if you have them. If you have the T and don't plan on header's it's likely worth it, based on consensus across the board.
My Super Duty came with the Ramhorn style in your picture. I changed to the SPD Y-pipe and regret it. I also have a 4" catback, in my opinion it's to free flowing.
Bently,
Which engine do you have, and did you install the catback and the SPD Y at the same time?
I made a call to friend who is an exhaust engineer at one of the big aftermarket companies.
Look at the restriction on each pipe from the L and R cylinder bank.
it necks down for a short distance, this creates a low pressure zone, then opens up to a slightly larger chamber than the entry pipe, By using the Bernoulli effect Ford engineers are using a “scavenger chamber” Because exhaust gases come in bursts as the valves open and closes they can use these pulses combined with the effects created by pressure differentials to actually “suck” the exhaust out of the manifolds and cylinders.
that crappy LOOKING stock exhaust is using science to not just flow more but evacuate the gases quicker that the pretty aftermarket exhaust.
bottom line is all of our years looking at race cars with headers has trained us to visually identify the smooth tubular header as better, data, aka a flow bench and dyno proves otherwise.
One thing I ponder is the effect of backpressure generated by the constriction. I see where you compress any fluid which includes gasses, the speed generated by the constriction is due to increased pressure(backpressure)-like sticking your thumb over the end of a garden hose thus decreasing the allowable volume of the flow(you feel the backpressure on your thumb) The pulsations of the flow created by an engine running from two sides into a common area(dual heads into a single pipe) must be timed correctly so that flow from one side of the engine exhaust doesn't combine with the flow from the other side creating a high pressure area which would impede exhaust flow from the engine. I think in terms of the constrictions as increasing back pressure which allows for timing of the flow into the common area. If the flow was not timed from each bank of headers into the common area, you could build up enough backpressure to severely diminish flow -essentially more flow pressure into the common area than that which can be accommodated by the exit side of the common area. The only reason we have any exhaust constrictions to begin with is to create a differential pressure gradient to allow a directed flow of gases away from the passenger compartment-correct? So..high pressure in the cylinders-->valves open-->flow into ambient air would generate the least amount of backpressure. In this system, the valves become not only the most constrictive source but the only source on the exhaust side of the cylinder . The next most efficient path would be piping each cylinder into its own exhaust pipe followed by the use of headers using an outlet pipe for either side(dual exhaust) followed by the most constrictive arrangement of 2 headers into two pipes going into a common junction and using 1 pipe as the final exhaust path. To me, the concern is about the effect of backpressure generated by the constriction. I see where you compress any fluid which includes gasses, the speed generated by the constriction is due to increased pressure(backpressure)-like sticking your thumb over the end of a garden hose thus decreasing the allowable volume of the flow(you feel the backpressure on your thumb) The pulsations of the flow created by an engine running from two sides into a common area(dual heads into a single pipe) must be timed correctly so that flow from one side of the engine exhaust doesn't combine with the flow from the other side creating a high pressure area which would impede exhaust flow from the engine. I think in terms of the constrictions as increasing back pressure which allows for timing of the flow into the common area. If the flow was not timed from each bank of headers into the common area, you could build up enough backpressure to severely diminish flow -essentially more flow pressure into the common area than that which can be accommodated by the exit side of the common area. The only reason we have any exhaust constrictions to begin with is to create a differential pressure gradient to allow a directed flow of gases away from the passenger compartment-correct? So..high pressure in the cylinders-->valves open-->flow into ambient air would generate the least amount of backpressure. In this system, the valves become not only the most constrictive source but the only source on the exhaust side of the cylinder . The next most efficient path would be piping each cylinder into its own exhaust pipe followed by the use of headers using an outlet pipe for either side(dual exhaust) followed by the most constrictive arrangement of 2 headers into two pipes going into a common junction and using 1 pipe as the final exhaust path. When you converge 2 separate flows into one, you then introduce a potential traffic jam at the intersection. The only way you can efficiently move traffic through an intersection is by controlling the flow into the intersection. In this case, the use of constrictions in concert with the properly tuned pulsatile flow of the exhaust relative to the constriction of a common area are what is used to manage the flow from 8 or 10 cylinders into the flow of 4 or 5 separate sources per engine side into 2 headers, into a common area into a single pipe and out. Notice that the constrictions from each side are located at different distances from the common area. I would like to think sophisticated calculations were done to determine the best location for those constrictions from either side into the common area to coincide with the timed pulsatile flow of exhaust gases from 2 cylinder banks Given the fact that we don't have race cars that can accommodate an exhaust pipe per cylinder 2 separate flows into one, you then introduce a potential traffic jam at the intersection. The only way you can efficiently move traffic through an intersection is by controlling the flow into the intersection. In this case, the use of constrictions in concert with the properly tuned pulsatile flow of the exhaust relative to the constriction of a common area are what is used to manage the flow from 8 or 10 cylinders into the flow of 4 or 5 separate sources per engine side into 2 headers, into a common area into a single pipe and out. Notice that on the factory pipe the constrictions from each side are located at different distances from the common area. I would like to think sophisticated calculations were done to determine the best location for those constrictions from either side into the common area to coincide with the timed pulsatile flow of exhaust gases from 2 headers. I think in terms of alternating traffic flow like traffic leaving a football game where lines are stopped and started as directed by a state trooper. The Y pipe seems to be designed with the idea of traffic merging on their own accord -being like this lane ends -merge. Obviously we don't have the specifics to determine which one is most efficient and creates the least resistance. In general Valves would be the most constrictive prior to exhaust flow whereas the headers would be the next most constrictive point as the first common area of multiple flow sources. Bottom line, While the ram shaped pipe may or may not be superior to the aftermarket I do think it was purposely designed with intent of efficiency and not just throwing a cross pipe out there to worm it's way through the chaos of wires, hoses and pipes. However, it is a constriction none the less so whatever you do on the front side of that constriction has it's effects limited by it. Lets just cut off the CATs and straight pipe it.
PS I was really sleepy when writing this and I hope it makes sense
PSS-I was too sleepy to proof read it
The purpose of his post was to say that you can use smaller geometry to increase the speed of the flow, to increase the flow to a degree, however you know what else increases flow, a bigger pipe......
07-06-2021, 05:27 PM
