Speciale exhaust

Oh no. My HS is on the way, that doesn't sound like fun. Ferrari dealership say anything about this?

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Describe "drone". I have a 2015 California T. No issues at all. The car sounds bad till its warmed up. I leave in automatic till its warm. I do get a strange sound from exhaust until its warm. The sound is around 2K RPM slower, no sound, fast no sound, but a almost rattling noise at 2K rpm till the engine is warm.

 

Yes... Definetly drone created by the valve issue that open at any RPM. Ask the dealer to have the flap automatically open/close as the RPM controlled accordingly.

Good Lucks.

 

My dealer warned me about drone when I asked him about a post market switch to keep the valves open, for my 2016 Cali T. He said it could be very unpleasant. The valves open at 3000 rpm anyway so I elected to not do the modification. You have the HS package so this should not be a problem for you and yes, your dealer will fix it if you ask.

 

I'm a bit concerned and confused by this.
Can somebody explain please ?
When are the valves supposed to open, when you switch from comfort to sport, or at a certain engine revs?
Or is there a switch for open/closed?
What is the speed alert and what has that to do with exhaust valve position?
We ordered our HS car for long distance driving, i don't want an annoying drone !

 

I think it has to do with the engine rev speed matching the resonant frequency of the exhaust system.

There's usually a component of the exhaust system called the resonator, which prevents the exhaust from resonating when the exhaust gas vibrated by the engine reaches the resonant frequency of the exhaust system. The resonant frequency is the frequency at which an object (e.g. exhaust system) will vibrate in a sympathetic amplified manner when an external vibrator (exhaust gas vibrated by the engine) vibrates it at that "sweet spot". The result with an exhaust system is that you will experience unusually loud exhaust noises at the resonant frequency... i.e. the drone.

However, exhaust systems usually have a muffler, which in effect increases the length of the vibrating exhaust system and so in effect the whole system is normally tuned to prevent resonance when you cruise at around 1900 rpm. In the case of sport exhaust systems, if they open the valve and allow most of the exhaust to bypass the muffler, the effective length of the exhaust is shortened, which messes up the tuning of the exhaust system for cruising speed (usually around 1900-2000 rpm). This isn't a problem if you rev past the resonant frequency but if the valve stays open all the time and you keep your engine revs at around 1900 rpm, your exhaust will drone.

So if your sports muffler system somehow keeps the exhaust valve open full-time you should rev the engine past 2000 rpm when in SPORT or CST-OFF mode or try to close the valve to activate the muffler when you are on "autopilot" (AUTO in COMFORT mode) tooling around at 2000 rpm.

I use a remote valve controller with my Capristo muffler which has 2 valve control settings: 1) valve always open and 2) valve opening automatically controlled by the car's ECU (i.e. only open after 3000 rpm). It's possible the installer of the OP's HS muffler set the exhaust valve to be always open.

 

I'm glad about that for you, though secretly disappointed we didn't get a full scientific explanation !
Otherwise enjoying the car ?

 

New exhaust systems have of course, completely clean interior surfaces (the OP said his new car's mileage was at 100 miles). The structure will vibrate more readily as the exhaust gas impacts the surfaces directly.

As the new exhaust system collects soot over the first few hundred kms, depending on how naughty you are with the throttle, the soot sticking to the interior surface of the exhaust plumbing will dampen the transfer of vibrations from the exhaust gases.

This is most likely the reason for the disappearance (or reduction) of the droning.

 

I had the same issue with the full electric seats when I was ordering my car. I found it impossible to get a comfortable configuration with those seats. Perhaps it was an issue where some of the myriad settings somehow conflicted with each other. Many people had already played with the settings on their test drives.

It may help if you return all the adjustments to their "lowest" settings and then carefully re-calibrate each one until that particular adjustment is comfortable. I guess, sometimes it's better to keep it simple.

 

Hey, I guess a few more miles on the clock, how is the exhaust sounding now ?

 

Not sure why you bring up discussing "blurb/pop". I thought we were discussing droning, which is a loud constant resonating harsh-sounding exhaust note that happens at specific engine speeds.

The momentary noise which you may hear when lifting off the throttle is probably a slight backfire. I guess you may not be familiar with the desirable sound effects of sport exhausts. Backfires are intentional. The non-turbo Cali also makes a loud cracking exhaust sound on hard up shifts and downshifts (the latter when simultaneously braking) which are also caused by the momentary lifting of the throttle so you shouldn't worry about the blurb/pop you mentioned. Cars with sports exhausts are meant to feel a bit raw or less smooth than non-sports exhaust cars. The idea is to not feel like your regular smooth German sports sedan. Anyway backfires would be a topic for a different discussion.

 

Just looking at the reviews of the HS in the press, no journalist has mentioned an annoying sound on throttle lift off. I don't recall any during my, admittedly brief and urban, test drive. How mysterious. It would help if other HS owners would weigh in here with their experiences?

 

I think you're taking an overly superficial view of the exhaust behaviour of your cars, the CaliT, GT3, GT4 and Evora 400. The burp/pop sounds are almost certainly due to unburnt fuel being ignited outside the combustion chambers, in the exhaust system. The normal effects for this is known as backfire or as some technical people appear to prefer, "after-fire". Engine overrun is the primary cause of back-fires, burps/pops.

When you lift throttle, both the ignition system and fuel supply are cut off or are at least reduced depending on how abruptly and completely you lift. You should also experience engine-braking when you suddenly lift off throttle. However, with a unrestrictive high-flow exhaust, there will be less back pressure from the exhaust system, therefore a bit less engine braking as the wider exhaust piping is less restrictive to the engine pushing gases out the exhaust. At the same time. the faster exhaust flow will "messes up" the timing of the ignition cut-off vs. fuel cut-off. The net effect is that some extra unburnt fuel will get into the exhaust, more than before. This fuel is then ignited within the exhaust system by the high temperatures in there and you will hear and/or feel a little rumble or burble as a result.

You mention the CaliT exhaust burps/pops sound nothing like the backfire in your GT3, GT4 and Evora 400. Well, of course they don't. What do you think causes the loud backfires in your GT3, GT4 and Evora 400? It's certainly not just thin air. Noise comes from the release of energy, resulting in the vibration of the surrounding air and structures. The noise is from the combustion of unburnt petrol outside the combustion chambers of the engine. How loud the burps/pops are depends mainly on the amount of unburnt petrol let into the exhaust system, and that depends on how much throttle you were applying before you lifted. Drive your CaliT harder and upshift, downshift or suddenly lift throttle. If your CaliT HS is anything like my Capristo Cali30 HS, it will backfire as loud or louder than the GT3, GT4 and Evora 400.

While we're on the subject of exhaust sounds, I thought I would also explain the reason why the sound of our cars depend a great deal on their mufflers, EVEN WHEN THE VALVES ARE OPEN. Here is a photo comparison between my Capristo muffler and one of the actual OE mufflers from my Cali30.

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What you want to take away from this comparison is that both MUFFLERS ARE ALWAYS VENTING EXHAUST EVEN WHEN THE VALVES ARE OPENED. The reason is the muffler is responsible for creating some of the qualities of the exhaust sound. These mufflers with exhaust valves open ARE NOT THE SAME AS STRAIGHT PIPES. So the "exhaust bypass" shown in my comparison photos are not really a complete bypass as much as they are "additional exhaust outlet".

What you will also notice from the comparison is that that Capristo muffler is much smaller than the OE muffler and the emerging section of the pipe conducting the "muffled" exhaust gases through the Capristo muffler is also much bigger than the one in the OE muffler.

Another curious observation is that the valve on the Capristo muffler is POST-MUFFLER while that of the OE muffler is before the pipe reaches the muffler. I suspect this may mean all of the exhaust travels through the Capristo muffler regardless of whether the valve is opened or closed. Opening the valve just results in a bigger aggregate exhaust outlet and an extra exit pipe of larger bore. Since the Capristo muffler is very small, having all of the exhaust travel through it would not be very restrictive, especially when the valve is opened. If you study the Capristo muffler you will see that it actually involves more design effort to place the valve in the post-muffler position (i.e. it would have been much easier to just make a smaller copy of the OE muffler with bigger pipes). So placing the valve post-muffler was important to Capristo and thus supports my theory.

Finally, I also want to point out that air traveling down pipes of different lengths and bore diameters result in sounds with different pitches. You can see this when you consider the sound from a bugle vs the various sounds from a trombone. These mufflers essentially exhibit a blend of sounds derived from 2 different pipes.

The design considerations of these exhaust components are fairly complex.