I measured 55mm or otherwise known as 2.2" OD tubing on my 2016 Ftype R, as the pipes go into the mufflers. Measured under the car using a Mitutoyo caliper. When the car first rolled off the transport last week and I looked under it while it was on the ramp I said out loud "so THAT'S how they do it!" What I was referring to was the mid-rangey raspy bark that lacks any really deeeeeep bass, and the small diameter tubing that helps propagate that. This exhaust system is like a Trumpet, not a Trombone. I knew it sounded like that before I bought it. Now I know at least partly, how they do it. I had actually contemplated trying smaller diameter tubing for my V10 M6 for fun, just to remove some bass and see whether I could get some V10 upper harmonics to come out, without hurting power.

I looked all around the forum. Does the tubing size on the V8s not bother anyone? All the hot-rodding literature I have read, all the exhausts I have studied or modified, or fabricated for myself, on various brand cars. I have never seen such small diameter pipes on an engine that makes 550hp stock. Basically it's 2" ID pipe.

And the aftermarket makers of exhausts for the various cars I've dabbled with (Nissan 300ZXs, Mazda 3rd Gen RX7s, BMW V10s and V12s) will always lead with a declaration of tubing size (increase, almost always), but not Velocity AP, Quicksilver, and others, for the F-type. The makers of exhausts for the F-type seem to not talk about whether they have increased tubing size to unlock power. They also seem not to provide dyno sheets, which is strange, since dyno sheets are a requirement for an aftermarket exhaust for any other car.

If one is not going to try to increase the diameter to unlock some horses, why bother with an aftermarket exhaust at all?

Is there a thread somewhere that I missed where the V8s somehow lose power when you go to larger tubing?

 

We know (because VAP tried it) that headers on the V8 engine do almost nothing in terms of a performance increase. It would appear that Jaguar's design is pretty well optimized for the engine, and I would imagine that applies to the exhaust as well. Your assuming that the V8 would benefit from a bigger exhaust diameter, and that may not be true.

I haven't paid enough attention to the exhaust offerings to know if anyone is claiming performance gains from them, but i'm sure someone else could tell you. My impression was that it was a mostly sound related modification. At the end of the day, you could just ask Stuart @ VAP; he'll give you an honest answer and some of the science behind their design.

 

yeah, thanks. I did read the thread about the VAP headers. Those stock iron log manifolds look and seem nasty, but...since the motor is Supercharged, and not NA or turbo charged, I can believe that about the headers. The supercharger just stuffs air in and forces it out the manifolds. On the other side of things, turbos require all sorts of exhaust coddling and expansion cones after the exhuders to make the flow just right. In the NA arena, I myself have made bigger-tube, larger primary headers for an NA 300zx that actually lost power. But for another NA motor (the 3400 DOHC by GM), created some headers that gave the motor incredible gains --along with a shorter runner intake plenum. This engine happened to have manually adjustable cams--which helped me tune the entire engine to match what I fabbed. But, since it was old-school; no on-the-fly variable cam phasing, it's power gains were fixed in the position I locked the cams to. That engine had nothing but top-end power, but killed the lower end, which I knew might happen. But--the basic tenet of the experiment worked.

Whenever I have made a cat-back system, I have always followed the rule of "250hp or more per side?" Use 2.5"ID tubing, at least.

I will ask Stuart. (unless he hears his name and his ears are burning and he wants to chime in :-) I appreciate the droves of info on the various vendors on this forum.

The reverse of what I am asking could end up being true: I might play around with the sound of the V10 E63 M6 (and the E60 M5) by using smaller tubing for the cat-back. The holes on the exits of the tubular headers are almost 4". The cats on the M6 are two huge 3-4 foot long expansion chambers that are 3.5"- 4" in diameter each! So, almost half the exhaust on that car is two huge pipes almost 4" in diameter. On a stock M6, that necks down to 2.6" tubing. In most hot-rodding circles, it would seem counterintuitive to neck that stuff down to 2" ID pipe to exit the car, but might benefit by coming up with a cooler sound.

 

https://www.roadandtrack.com/car-cul...es-s600-sound/

If someone could make an F type sound like this, that would be amazing 😉

 

yeah, V12 sound. Not V8. I do generally like the sound of the F type V8. Never owned a V8 car with a muscly sound. So I am enjoying it.

I’ve seen that video dozens of times. I think they are using skinny tubing, as well. I also wonder if there might be some pitch shifting in the video editing process. (Cheating). Maybe not, the characteristics of that V12 might produce a high harmonic like that. I did get close with my V12 760li, but the tubing is at least 2.5” from cats back. Deeper sound. Still sounds awesome to drive. Stirs the soul when you drive it.

 

So if you promise not to make fun of my welding, here is how that V12 exhaust is routed. I’ve been suffering with a harbor freight welder for years. Sometimes it lays a nice bead, mostly not. Only recently have I bought a nice Millermatic 211. Barely touched it. So, here’s the configuration. It’s similar to the Benz video, but the BMW does not allow for exhaust to exit on both sides, so the two single pipes exit out of the drivers side.


I make stuff out of mild steel (can rust) because I usually only own a car for a few years and just put the stock exhaust back on anyway, it’s not meant to be permanent. Plus, what if it did not work, and I spent $1000s on stainless tubing?

 

Well if your willing to experiment on your car, I would be happy to throw some $$ your way to come up with something special.. A design that allows removal of the stock system and instillation of a new design that allows the car to be returned to stock.
Sounds like your going to be tinkering anyway, I am just offering some R&D dollars in exchange for a design I can take to the local exhaust guy and have built for my car.
PM me if your interested.

 

That’s an interesting offer. I don’t mind sharing whatever I come up with other people can take it to a local shop and have it replicated. My biggest drawback is a Mr.FirstWorld issue where I retired in November, expecting to have tons of fun project time on my hands. But of course, like everybody else I find myself doing stuff that was not previously on the agenda.

what objectives would you want to achieve with this exhaust? In my case instead of necessarily changing the sound—especially— I’m not interested in making it louder, I’m interested in seeing if there’s a way to unlock some horsepower. But unfortunately if you did go with larger tubing it’s going to get louder. I do like what I see with the aftermarket treatments where the sport mode exhaust is basically like a straight pipe out and the quiet mode is a valve that knocks the exhaust off to the side so it can be muffled. I think that’s a great idea. The diagrams that I have seen of the stock V8 muffler put a sort of hard jog into the sport mode channel of the exhaust. But that jog might be one of the things that keeps it from being even louder than it already is. Another thing I might want to do is put a perforated tubular resonator on the sport mode side so that it sounds a little bit less metallic and raspy.

 

Keeping in mind that you are trying to improve one of the best sounding factory exhaust systems ever.
I would think weight reduction and less restrictions would be appealing fore sure. Increasing the pitch without becoming raspy would also appeal to me. The worst possible outcome would be for it to sound like all the mustangs and camero’s around here with extremely loud and obnoxious exhausts.

 

You guys are the first ones I've seen asking about, and even knowing about the tubing diameter on these cars. I've been trying to figure out what the difference between the XF and the XFR-S exhausts are supposed to be... they, Jaguar, claim they are different, but I can find no proof other than engine tuning. My 2014 E63 S model has somewhere between 2.6 and 2.75 inch OD pipe on it, and it isn't loud, but has a low tone that I'm looking for in the XF. Now a little larger engine 5.5 L vs 5 liter, yeah moves a little more gas volume, and yeah the E is making almost 600 HP to my almost 500, will account for something, but sitting at an idle, neither of them are doing any work. In a previous life i had shoehorned a 351W into an 81 Capri, and it had 2.5 inch exhaust, with shorty headers, and it sounded good. Deep tone, but wouldn't shatter windows.

I have a very hard time believing that adding headers to the 5 liter wouldn't improve anything, unless A, the headers are of garbage design and just too small (which i doubt), or B, the restriction in the rest of the exhaust, namely the catalytic converters, is so high it really doesn't matter what you do (unless you remove them).

I do not know what the spring baffle things in the mufflers would do or sound like if they were to be modified to be permanently actuated, dunno if anybody ever tried that.

In the end for me, I'm more interesting in a lower exhaust note, and decel crackle can take a back seat, though I'd like that too.

 

did you use any muffling? was the muffler chambered--like a Flowmaster, instead of a straight-thru perf-tube glass pack, like a Magnaflow? Chambers and baffles can cut out a lot of bass, and a lot of volume, without necessarily destroying all the power you are making.

Flowmasters, which I am sure would make at least a few members of this forum barf, are really cool.They are tunable, like a wind instrument--or a big pipe organ. The length of the exit tube you place on them can literally be played with until you get the desired higher overtone (if its there--if there is no overtone, you are screwed). With no tube, they are bass-ey as heck. With a super long tube, they just sound like "a Flowmaster" that everyone is used to hearing. If you fart around with exit tubing in the 1' to 2' range and --everything in between, you might grab all these cool harmonics that are surprising. Again, the engine has to be making them in the first place. I learned that by talking to a Flowmaster rep on the phone, and tried it myself.

watch this test video I made for myself when I was playing with Flowmasters on my V12 BMW 760Li.--where one of the exit tubes, which was just clamped on for a quick audio test, flew off. The sound goes from high-pitched F1-wannabe Limousine to a deep burble-- instantly. It IS dramatic! Right then and there I realized the guy at Flowmaster was NOT kidding, and I started to futz with the length to get the exit tubes just right, and of course, I had to deal with whether the whole mess fit under the car in the exhaust cavity. The final ones had bends in them which did slightly change things as well. Everything is a compromise.


I know the cats are being blamed for a lot of the performance hits, and I am sure the 200-cel ones are nice for flow, but I am thinking along your lines, that the rest of the exhaust could use sizing up, as well. I have no idea,, but I have to imagine VAP tried their new header design with their hi-flow cats, and their exhaust System. If they used stock-sized tubing, then your logic is sound. That said, headers are not "that" important in a supercharged application. If it was NA, and you got the length and tubing size right, and then modify the intake runners as well, then its a different story. I am willing to bet the opposite: that if you size up the rest of the exhaust, using stock manifolds, you will see some gains with no tuning. THEN, headers might help, but still, since it's supercharged, so.... not by much.

isn't that what you get in dynamic mode? Open on both the muffled and the "sport" mode side all the time? bear in mind, that once you open that valve, its a mix of the sport side, PLUS the muffled side. The muffled side is doing something to the sound. Acting as a resonating chamber.




lower exhaust note may come from larger tubing and some baffling to reduce drone caused by larger tubing, and resonating-- to reduce the sharp edges. Reducing the sharp edges would be like tuning the treble down, leaving the lower mids and bass. Deceleration crackle is in the ECU programming, not the exhaust, AFAIK. Spraying fuel when the exhaust valves are open, and retarding timing like crazy.

explained here

"Two things are necessary to create pops and bangs. First of all, we need to change the software in your ECU so that it does not cut off fuel immediately after you lift your foot off the throttle pedal. This means that some fuel is injected even when you are not pressing the pedal.Secondly, we retard ignition timing during deceleration. The change causes the flame front to spread later than it normally would. This means that a part of combustion happens as the exhaust valves open and the cylinder is no longer the only location where the flame front spreads."

some people on Hellcat forums claim it goes away when they remove some of their stock exhaust.... Not sure. Others say it gets louder doing the same removal...?

 

I just thought of something. If the quiet side is operating at the same time as the Sport side, it "might": be canceling or attenuating some frequencies of the sport side as the two mix. Might be cutting out some low mids.... So, In order to get what you want, you would need straight pipes out. No quiet side mixed in. You'd have to build something. Or, there are a couple aftermarket exhaust out there that do not have valvetronic. Check them out on YouTube.

 

I’ve been lurking on BAT looking at all the exotic car exhausts and am amazed at both the similarities and the differences. It’s great because they almost always have under car pics.
Good thing I don’t have a bigger garage because there are some nice deals on there.

 

It is indeed likely that a true long tube header might improve performance somewhat, but we determined that there is barely enough room to fit a short-medium length header next to the V6 engine, and even less room in the V8 engine compartment. On the V6, the short-medium length headers produced an unbearable raspiness.

BTW, the exhaust switch holds those valves open full time (at least on the V6 MT)

 

That's interesting, on the V8 it seems that if you're in Dynamic (i.e. switch on by default) the valves are open all the time, but if you turn the switch on in non-dynamic the valves only open around 1500 rpm. It's definitely noticeable at tickover.

 

here's my observations about the exhaust modes on my R. If you drive in normal mode with no dynamic mode and exhaust switch off, it goes only thru the curvy part of this diagram. It's always "quiet". The snap crackle and pop seems less drastic, although that might be my imagination. According to the below diagram, it hits the valve on the outer tubes, and is blocked entirely, (the flow is not real great) If you drive in sport-auto mode, NOT in dynamic mode, with the exhaust switch flipped off, the exhaust valves open only at higher RPMS and WOT, then, it goes thru both sets of tubes, and closes back up as you decelerate, . Kinda nice.

If you go into dynamic mode, or flip the exhaust switch ON, the valves are open completely, and it always goes thru both sets of tubes, and the ECU turns up the deceleration "snap crackle and pop" and the pops and the exhaust noise happens all the time, and--while I always get a kick out of it-- the exhaust sound would be too much if it were constant (to me). Its good you can modulate it. I love the switch!

 

Nope, not in my MY18 V8. Above about 3,500 (maybe 4,000) rpm the valves open, regardless of mode. So only "always quiet" below 3,500 rpm.

Again, not in my MY18. with the exhaust switch on with dynamic mode off the valves are definitely closed at low rpm (below 1,500) - I can clearly hear the difference between that and dynamic mode at tickover.

 

I'm probably mistaken. Anyone on this forum has obviously had more seat time with it than I. I thought I had it sussed out. Give me some time with it this weekend, and I'll try all the scenarios you mention and get back to the thread.

 

The behaviour may vary with model year, so I'm interested if yours is different. Which MY is yours?

BTW, I've had mine over two years and have only recently figured this out.

 

2016. Sooooo. Went to the grocery store with it. I was totally wrong, as most of you surmised. Sorry.

Dynamic mode, or exhaust button on= exhaust open and loud all the time, of course.

All other modes: non-sport or sport, without the exhaust button on: it is closed until you go to WOT, and then it opens up around 3500 room or so. closed back up as you decelerate. I mistook it, because you can stay in a gear and go up around 4000 rpm and not hear much exhaust, if you are feathering the gas pedal, but eventually, even a light gas pedal will open the exhaust valve at higher RPMs.