Y-pipe, muffler-resonator

[Guest Thurem]

Been thinking that instead of using a Y-pipe to connect the pipes coming from the headers, I could use a dual inlet single outlet spintech muffler. And then run a single 3 or 3.5" pipe to another muffler in the back. This way the first muffler would also act as a resonator. while reducing noise and still flow really well. What are your thoughts on the effects on topend power and midrange torque? Has anybody done anything similar to this?

SO, am I way off or do you think this would work well?

I do want my car to be as quiet as possible, so they don't know what just hit them, and so the cops won't have time to put the donut down and reach for the radargun.

Thure

[ZROSSA]

I would actually run a resonator instead off a muffler. Then put the muffler at the back. If you want to do it right then the y-pipe need to be a certain distance fron the collecter and then the resonater needs to be a calculated distance back from that. On a dual system this distance is usually a multiple of the primary exhuast lenght. I dont know how to figure it out with a y- pipe. I read once that to figure out how long you want your collecters do some full throttle runs and then cut the pipe of where it starts to discolour. This is where you need to mount the resonater as well. Once the exhaust hits the resonater it behaves as though its the atmosphere and what you do behind doesnt really matter.

 

If any one out there knows how to propery configure a single pipe system on a v8 i would love to know more. I am going to have to make my own exhuast and figure It may as well be a good as i can get it. I keep hereing that there is a H.P./ torque advantage in the single pipe, but a lot of v8 race cars still run duals with or without a x-over. Why dont you ever see drag cars with single pipes?

 

Cheers

 

Douglas

[ZROSSA]

I finally found a photo of a Transam car with single exhaust last night. The y pipe looks to be mounted at a distance thats the same distance as the primary pipe length of the header. The muffler is mounted that same distance from the y pipe. These exhausts are huge. They can run a 4.5 or 5 inch single or dual 3.5 inch pipes. I cant emagine that anyone would go to the lenghts that they do to get the exhuast into a single pipe if it wasnt worth some H.P.

 

Douglas

[Mike C]

In David Vizard's "How to build HP, Vol One (I think...) he talks about using an expansion chamber just past the collector. This effectively takes the tailpipe out of the picture allowing you to do as you please past the expansion chamber without affecting power output due to pipe length. Flow volume a different story.

 

It would be interesting to merge the two collectors into this expansion chamber, shape it like a triangle with the two coming in the top and a single larger pipe exiting the bottom to the rear of the car. It would have to be pretty big however and in a Z that is virtually impossible...

 

The next best solution seems to be 2 1/2" primary pipes into the Flowmaster Y-pipe with 3" exit. Then run 3" to the diff. Here are a couple of scenarios at that point" First, get a pair of 3" mandrel bends and run into a single Dynomax 3" muffler. This is for most power in a milder motor. The second option would be to take the 3" and reduce it to 2 1/2", then use a pair of 2 1/2" mandrel bends and a single 2 1/2" Dynomax muffler. This would be for most sound control.

 

You could still replace part of the 3" pipe with some sort of a tube muffler, but most have only a 2 1/2" core for a 3-3.5" case diameter. Dynomax does make a race muffler that has a 3" core with 4" case, but it is tough to fit.

[ZROSSA]

Mike,

I always seem to get a little confused on where the collecter finishs and the exhuast pipe starts. I always thought the collecter finished where the piped stoped diverging. It would seem that in drag racing circles (open pipes) that the pipe straight pipe after the diverging pipe is called the collecter as well. This obviously would make a difference to where you put your resonater. If your collecter is like a drag racing one with a tuned straight length after it and then goes into the resonater i can see that working. I cant see it working straight of the back of some headers though.

 

Douglas

[Mike C]

In my mind, the collector is the pipe where all of the primary tubes come together. The end of the collector is the point at which the tubing reduces to become the pipe. If the pipe is the same size as the "collector", it is really just a long collector! The waisted collector that is found on the Dynotech headers can skew that definition, however. Vizard explains much better than I how the expansion chamber can effectively remove the LENGTH of the exhaust pipe from the exhaust equation and how length can be effectively changed using a straight-through type muffler which is perceived as a pipe extension. He also suggests that a modified Flowmaster style muffler (ie one without baffles and an enlarged "cone" for exhaust to exit) can make a good expansion chamber.

 

While it would be nice to fab such a trick exhaust on a Z, the only way I can envision a suitable ex chamber is ground clearance un-friendly. In that case, the best you can do is minimize the power loss by using appropriately sized tubing and flow-friendly y-pipes and mandrel bends.

[ZROSSA]

Looks like I will have to go to the shed and pull out my Vizard books. I dont really remember that part with any great detail.

 

Cheers

 

Douglas

[Guest Want aZ]

Expansion Chambers are actually quite simple really, goes back to my old dirt bike racin days...and the design of them isnt too complicated. Normally the head pipe is a standard diameter, that emptys into a Chamber that is conical in shape that often tapers down after a set distance. As the Exhaust emptys into the Cone it expands, hence the term. now on the back side (exhaust port) pressure is reduced creating a semi-vacuum therefore increasing the scavenging of the cylinder as the exhaust valve is opened. although this works much better in 2 strokes. Reason being as the exhaust is being pulled out the intake charge is being pulled in. not sure how it would work on a 4 stroke though. You would have to time the exhaust pulses for it to work effeciently...Just soomething to think about, Grumpy could probably add much more as he is a full engineer (retired), and the physics related there of.

[Guest Anonymous]

while on the topic of y-pipes...where can i get a good deal on one? flowmaster y-pipes seem to be the popular?

[jeromio]

I will be deaf after a few weeks of driving this car. My ears ring for about 20minutes after I get out.

 

I am going to have to tweak my exhaust. I have 2.5 Y'd into 3 and then to a MAC muffler.

 

It is LOUD. I said LOUD. And cruising in 6th is the worst - it kind of resonates at 65mph in a low, mind-scrambling way.

 

So, the only idea I have is to add a resonator after the Y. Something like this:

 

3 in 3 out 12in long. That's about all I think I can fit. My question is, for $45 and a Saturday spent, will I notice a big improvement?

[ZROSSA]

I put in a 3 inch resonater on my wifes turbo legacy. It was the difference between her complaining and then not. It wont be as noticeable on a n/a set up but its will stop the resonating for a start. Any way you can get a muffler in there?

 

Douglas