JFR Equal Length Y-Pipe for 2nd Gen Tacoma, T4R, & FJ Cruisers

Sorry. Wife and dogs were ready to hit the road. Been a long 12 days. From snow at Silverton to Moab.

 

I've been doing things in exhaust land..... In a follow up to my earlier post regarding the use of exhaust bleed holes for resonance control in exhaust piping, I have some findings.



First this execution is far from scientific and is really more for general experimentation than anything else. Ideally I would have only made one modification at a time to see which had the largest effect, but I was running shy on time.

General overview: After installing the URD headers and JFR Y pipe, I had a little bit of resonance in the cab that I attribute to having a full length Cab running the length of the exhaust versus a partial cab, longer exhaust and bed configuration. I couldn't hear the resonance outside the cab, but more inside.

Muffler:
After doing some research and talking to Roost, it was clear a reactive muffler was going to be helpful. I liked Roost's idea of the chambered muffler, but was worried that even the largest Flowmaster won't give me what I'm looking for. I found out that Magnaflow offers a "3 Chamber" turbo muffler in various lengths 14-36" case lengths. The largest I can fit without cutting off the cat in my transition pipe is the 30" over all length. But you can get them all the way up to 40" in overall length. Obviously, length corresponds to exhaust volume and resonance cancellation. Price is about $90 for a stainless steel offering, so not too shabby. I also saw it on Amazon for $63 after I purchased it!

Link to muffler:https://www.summitracing.com/parts/mpe-13742

Resonance Free Pipe Theory:

In addition to the muffler design, I researched various methods for attenuating resonance. Both side branch resonators and Helmholtz resonators are very popular for this, with Side branches being more effective for a wider spectrum of frequencies. During my research I came across a new technology that was recently utilized on the 2019 Chevy silverado. They are essentially holes in the exhaust piping that are covered in micro mesh screens that allow some gas (and noise) escape while keeping a majority of the noise and gas in the pipe. The patches are installed at specific locations on the exhaust piping to target certain frequencies. The results are supposed to be surprisingly good. Data from the patent filing show that certain frequencies are reduced by a significant decibel level. The Chevy guys seem to be surprised by them as well. Here's some light reading material for you: https://patentimages.storage.googleapis.com/85/d2/bc/90ffb6616650e0/WO2014126548A1.pdf

So.....I picked up 3 cheap exhaust butt clamps: https://www.summitracing.com/parts/wlk-33278

AND.......I picked up a sampler pack of stainless mesh screens: https://www.utahbiodieselsupply.com/stainlessmesh.php#6x6sheets

Due to the very limited run of straight pipe that I had available to strap on a 3" butt clamp, I was only really able to get 1 location in, which will not produce the full results. Ideally, I would have 1 at the 25% distance, 3 at 50% and 1 at the 75% distance as measured from the point in the muffler where the perforations end, and the tailpipe. My only location I hit was spot on at 50%.

I hole sawed a 1.25" hole in the stainless exhaust tube (yeah that was fun, nothing like drilling heat treated stainless steel) and a 2" hole in the clamp. Out of my sampler pack, the finest mesh was a 74 micron mesh. I used a layer of that along with the thicker, 100 micron mesh as a backer. Clamped it on the tube and threw it all back together.

Results:
Wow! Between the muffler and the hole in the pipe, idle is surprisingly VERY quiet. Cruising on the freeway is also way, way, way more quiet. There is still resonance present during modest acceleration, but its very different. It's almost complete gone at light acceleration or WOT. Speaking of WOT, it sounds amazing. Seriously good. I'm trying to think of a way of describing that doesn't sound like a hyperbole, but it tough. Think high end European sports car. I've never heard a 1grfe sound this way.
Inside the cab, the exhaust note is relatively loud despite my extensive sound deadening efforts (CLD, MLV, Melamine, Thermal barriers, the whole shebang). I think there's two reasons for this:
1) I put a fat hole in my exhaust directly below the cab. It's going to leak noise and increase cab volumes.
2) the muffler design. While it's a chamber muffler, I got a center to center version. This means you can see straight through the muffler, versus the split flow straight through Magnaflow I used to have. At higher exhaust velocities and pressures, it's hard not to think more noise bypasses the chambers and makes it straight on through. It kinda gives most people what they're looking for. It's quite when you want it to be and loud when romp on it.


Conclusion:

There's absolutely something to the resonance free pipe idea. I would not necessary recommend it for a full cab vehicle like my FJ, although I do plan on trialing a 5 micron mesh next along with the possibility of closing the hole up a little bit with the clamp rotation. If I had a Tacoma, I'd certainly try out the 4 or 5 ideal locations for this along with a fine mesh like the 5 or 15 micron mesh. I also might use a field of smaller holes, instead of the 1.25" hole saw, as it was pretty much toast after one hole.

I like the magnaflow muffler. I think the sound is very good. Ultimately, if I could fit the longer version of it I would. I'd also try and fit up an offset inlet-outlet if space and misalignment permit. I feel like this would further help to keep noise down while under acceleration.

Next steps. I'd still like more muffle. I might try a Flowmaster DBx in place of my ultra quiet resonator. Or possibly a stainless super turbo muffler...Can't wait to hear Roost's custom Borla Dual Flowmaster combo!

 

I saw the first picture, and my immediate thought was, "Hmm. What's he going to do with those firecrackers? " Lol.

Great idea! Now what if you were to add a deflection shield over the mesh? To direct its flow away from directly at the cab? Direct it to flow out but in line with the flow of the rest of the exhaust.

 

That’s some really interesting stuff, more ideas to steal! Thanks!

 

Ha! That firecracker looking log ended up being the perfect size to clamp onto while drilling a hole into the clamp. Saved me from having to buy an entire post.

That’s funny actually, Roost said the same thing about the deflector. I’m going to try and reduce the open area available in the mesh first to see if I can cut down on the volume from it. A deflector would probably work, but it would need to be rigid enough not too vibrate and exacerbate the resonance issue.

 

Awesome on the firecracker!

Do you have a welder or no? If no, you could basically cut a reducer to fit. Make tabs at the two corners, and one at the rear. Then rivet the tabs down.

 

Yep I got a welder for just such an occasion! And you're right that would be just about perfect .

 

@DocME Definitely interested in your results! @Roostfactor welded up my cat and resonator from the v-band to the connection of the Magnaflow of my hi-clearance cat back and
still have some 2-3k rpm accelerating noise in the 4r that is a bit louder than I want. I won't have the room to do what you are doing in the front but may look again to change my perspective. I love the sound with the exception of that area accelerating.

 

That’s interesting. Seems to be more common with us short bus people.

Not sure if you’re talking about patches or muffler change, but I think it’s more important for the resonance patches to go after the muffler so that the noise is already reduced. That way exhaust leaks are already muffled AND more importantly the patches are tuning the long pipe that runs from muffler to tailpipe. Unfortunately for me, my cab is so short the distance of contorted tube from muffler to tailpipe is 55”. That section I put my patch on was the longest straight section in that system.

 

Actually I am willing to do both if necessary. Looking more closely at your pic I see that indeed you hole is after the muffler. The URD hi-clearance is just a pipe all the way back from the muffler and actually have room to put more than one mesh....

 

I've ordered some 5 micron mesh to test out. Hopefully it can help reduce the noise level under the cab a bit. I'll also try a deflector as previously suggested. I'm still ultimately concerned that this may not be perfect for under cab applications, but I'll let you know what I find out. Either way I think you'll benefit from chambered or reactive muffler versus the Magnaflow straight through. Don't know how much room for activities you have around your muffler location, but here's some thoughts:

- Quietest would be Walker Quiet Flow SS. This is a three tube chamber design like factory mufflers. my only concern is there is a neck down internally and I was hoping to keep it more free flowing. There may not be an appreciable loss, but in theory there is.
- If you could fit a 40" overall length magnaflow 3 chamber, that would be worth a shot.
- I still kinda want to try a Flowmaster 70 series under there. Its designed for big flow from big block, so the two Helmholtz chambers that it has may not be tuned for our resonance frequency that we want to drop out, but I'm sure its bound to help.

I don't think you and I will have the space available to do the setup that Roost is working on unfortunately. But keep in mind you do have some space available after the axle. My ultra quiet resonator is after the axle right before the tail pipe.

 

WOW!!! This is one of the most detailed and well written posts I have seen on this forum!

Thanks for sharing!

 

I'm not super happy with the dual flowmasters, at least not yet. Testing continues

 

Wow is right! I love all this exhaust quieting experimenting!

 

It's Christmas in June boys! Got a JFR y-pipe
and modified cam gears in the mail today. The pipe looks amazing as always @Roostfactor.
Opening the box I felt like the dad in A Christmas Story when he's opening the leg lamp. My girlfriend didn't understand what all the giddiness was about but I sure knew

 

Two header legs that must be going on the Harley, LOL.

 

This is copied from a pm I have going with @DocME. Kind of funny so I will share with y'all.


So I stopped by an exhaust shop yesterday in search of a takeoff rfp. They hadn't even heard of it. When I showed him my exhaust and explained what we are trying to do it was WAY over his head. He thought I should be an engineer.

So I went to the local Chevy dealer to see it in person and the first salesman had no idea what it even is! I said I know it's on the dual exhaust models so he told me where the 1/2 ton trucks were.

As soon as I got down to look two more salesman came up curiously (total of 3 now) and as I was taking pics I was teaching the salesmen about their new tech they know nothing about!

Pretty funny how 4 people, 3 that sell the damn trucks and a muffler shop who does it for a living got schooled by a backyard mech!

Here are a few pics from yesterday.

 

Yeah buddy!

 

Good engineering. Poor choice of filler wire. Ugh.

 

Did they weld carbon to stainless?