So, what's the final verdict re exhaust valve?

What we know for sure, disconnected:

-- Much louder at idle and low rpm;

-- Less heat buildup in engine bay;

-- Resonance in cabin circa 3500 rpm, smack within freeway cruise rev range.

What has been surmised but not sure:

-- Loss (slight?) of low rpm torque due to reduced back pressure?

Mine came with hose disconnected by 1st owner.

Informed opinions, please!

 

I connect, disconnect, re-connect all the time... depending on what my mood is

I agree with all your comments.

When disconnected, off-the-line performance does feel more sluggish. Also, from a standing start... unless you pull-away aggressively, the noise when you start off is not all that good. Sounds like a truck with a bad muffler. If you take off more aggressively, all is well again.

My car is a coupe, so I can escape the noise if needed by rolling up the windows, but sometimes the resonance can be annoying.

I actually keep the car with the valves connected most of the time. I like it stock... go figure.

 

I haven't tried it disconnected. I guess I like it just the way it is as well.

 

+1

 

Get a valved Capristo or Kreissieg with remote controlled solenoid for the valves for the best of both worlds. Or just buy the Capristo solenoid with remote control for your OEM exhaust. Then you can change sound and not get your hands dirty.

Taz
Terry Phillips

 

- back pressure is no good. period!
- it is louder at low rpm, but it is unhealthy sound.
- lose low rpm power.
- makes your car shiver.

I can not think of a single advantage, you will probably leave it alone too if you understand the physics behind.

exhaust system are designed to make gas flow out in steady rhythm, smooth waves of pulses. you will hear beautiful rhythm of pulses if you play them back in slow motion. speed of air flow is important, each pulse of gas coming out carrying enough momentum to suck out the next wave . The thickness, the length, the bend, the valves, everything are tuned to optimize the speed of the air flow. if the pipes are too wide, speed will be too slow, the wave can not from.
the shivering and the bad sound is the result of erratic turbulent air inside the system. but of course some people like that kind of sound. but as a musician I prefer rhythm and solid pulses.

 

I drive my F430 always with unplugged valves and wouldn't plug them again. The results are all the opposite as written before:

Much better sound, just incomparable
Much better engine and throttle response
Better torque at low revs, yes, really makes a difference
Right before the valves open, there is a lost of power due to the inertia of the vacuum line.
There is indeed a resonance between 3500-4000 rpm but I like it
Less pressure on the exhaust brackets which is real weakness on the F430 and can brake the headers due to the strain on the entire exhaust line
The engine has already enough to deal with backpressure with the precats and cats
The exhaust valves are there only for one reason: noice regulations

So, I see only advantages in keeping it open all time ;-)

 

As expected, disagreement re low end torque -- less, same or more? I question how it can be more. My sense is that there is a slight but noticeable loss of giddyup, tho' not as much as I remember re my poor student car days in Boston, where every couple yrs the exhaust would rust thru and there would be a distinct gain in power every time after I have that fixed. Surely someone with connections to the factory can answer whether the valve is there merely to pass noise regs, or to regulate gas flow? Even for that slight gain (I think), I am inclined to go back to stock.

As to the quality (not quantity) of the sound, obviously one man's music is another man's earful. My opinion is: impressive to the bystander, but not exactly musical or, for that matter, Ferrari-like. So on that alone, I'd go back to stock.

But then there is that tangible benefit of reducing heat in the engine bay...

 

http://www.capristoexhaust.us/Remote-control-to-open-or-close-exhaust-valves-p/rm.htm


the adove is a link to a remote that at a press of a bottom you can drive with the valves open or closed .This is for any Ferrari with a valved exhaust system .
Some info on the topic can be read .

 

He is right, I have the capristo twin sound and it is amazing. It's super loud and when you press the button, it really quiets it down. Most times I keep the valves open as my intention was to have the loudest 430 possible. The exhaust system with test pipes also reduced the weight of the car about 54 pounds after weighing everything that was taken off. That's always a plus. Talk to Andrea, he'll give you the run down.

 

Slightly less torque but I do mean slightly.
It does sound a little rough at idle but yes, noise level is quite a bid louder.
I have my valves wired back to the cabin with a wee switch beside the petrol cap so I can open and close at will. I leave them open half the time and closed the other half!

Vive la difference!

 

i'm sure this has been done, why not put the loss of torque question to rest and someone dyno with it unplugged and plugged?

 

Good one

 

Yeah. Someone should but who's gonna bother? From my experience, there will be slight loss of low end torque but for a car that has over 400nm of torque, it's not like you're going to feel a masive difference. Unless you're driving a 200-300nm car, then a loss of low end torque would be a real killer. I guess were splitting hairs here. The tiny loss will be over compensated by the gains in improved throttle response, mid to higg end gains in torque and most importantly aural enjoyment.

Andrea from Capristo can help.

 

Improved throttle response at the low end? I feel the opposite (slight). Above 4000 rpm should make no difference, since valve is in bypass mode anyways.

Sound is a matter of personal taste. My guess is after I drive it awhile in one state, I would get bored and want to switch to the other. The Capristo switch is intriguing, not that I would use it on an ad hoc basis.

But there is noticeably more heat in the engine bay.

 

Thanks, Andrea. Interesting solution!

 

I do own a remotes for my capristo and I don't use it. Think about it, the factory setup is just perfect! You have a euc that opens and close those valves for you. When the car most need the valves ia at start and low rpms. The car starts better and you have the low end torque and when you need free flow exhaust to achive full flow at high rpms the euc just open up the system!
I bet that if the stock systems comes with remotes a lot of tuners will make a automatized system to control the valves! Lol ;-)

 

Agree 90%. Only tangible benefit of disabling the valve is to reduce heat buildup for in-town driving.

 

Is there a write up or pictures that show how to disconnect
valves? I would like to try it for myself. I hit the search button
But could not find any info.

 

On each side of the muffler there is a small valve that sits on top of a exhaust pipe, with actuators underneath it and a vacuum hose attached to it (pointing to the rear). The hose should have a tiny clamp on it. This assembly is very visible with lots of space around it. Pull that hose off, put a suitably sized screw into it to cap it. Secure it with a high-temp zip tie to another wire/conduit (it's obvious which one, if you look since they run together). Meantime find a rubber cap of the right size (or high temp foil tape) to seal off the fitting in the valve (to keep dust/dirt out).

If still have trouble, I can take a pic.

 

What I did is to screw a small screw (see picture, allen type) directly into the vacuum line, deep enough, and plugged the vacuum line back on the exhaust valve. With the right screw size, it's easy to reverse and unscrew it out without damaging the vacuum line. Did this for a long time and works perfectly well
Image Unavailable, Please Login

 

Thanks for the info. I just got home and looked. Mine are
already disconnected and the two hoses have a screw in the end
with a clam on it and they are neatly zip tied to the rear facia.
I've only had the car for two weeks and like the sound. Maybe
I'll return back to stock to see the difference.

 

Let us know what you think re the difference.

 

Stef- Please explain to me what you mean by inertia of the vacuum line. The vacuum comes from a vacuum accumulator also used to power the servo for the brake system.

Taz
Terry Phillips

 

I'm not sure about that Taz.
The brake systems feeds directly from the back of the intake manifold. The drepresor tank feeds from the front of the intake manifold ant it serves the exhaust valves, the intake manifold upper and under vacuum actuators. The socondary air system which serves the fuel vapor system also feeds directly from the intake manifold.
Correct me if I'm wrong.