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Discussion Starter · #1 · (Edited)
There are questions now and then, so thought I could sum up what I have found so far when I had it apart.

Here is how it look, butterfly valves circled. They are normally open, and need vacuum to close.
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From below:
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Electronic valve actuator:
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Electronic valve actuator is located behind the boot:
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Actuator is letting vacuum go through(silent) when not activated. If activated, it drains butterfly valves to atmosphere, they open, and exhaust get louder.
Not verified with multimeter, but relatively sure.
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Vacuum is supplied from engine vacuum pump, therefore it barks at startup, because pump has not had time to make vaccum yet:
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This means that it should be far from impossible to retrofit, by just using a switch.
 

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So that means the valves on the 4C system are normally closed (they only open when vacuum is applied). This makes sense because I currently have two cars w/ Akra systems on and I've played around with them a bit. One is a normally aspirated V10 and the valves on that are normally open, the other one is a Twin-Turbo V8 and the valves are normally closed. My goal was to allow both to go full open all the time I wanted with the flick of a button on a remote fob (or else you would have to hard wire a switch in). I will describe both systems separately as it's easy to confuse done simultaneously.
1) This was easy to do in the normally aspirated car because boost is never a factor so they just use a normally open valve and actuate the solenoid for vacuum about 30 seconds after startup and any time the RPM's are below 3500. You can go the super easy route and just pull the vacuum lines off the valves and they will simply stay open all the time. OR, install a second (normally open) vacuum solenoid downstream from the factory solenoid that you 'close' with the remote (supply power to it) and the valves will stay open all the time. When that solenoid is off, 'open' then the computer will take over controlling the other solenoid to cut-off vacuum over 3500 rpm, factory program.
2) NOT EASY in the Turbo car with normally closed valves. It's still loud at startup but likely only because the computer allows it to pull vacuum from the vacuum reservoir that holds vacuum even when the engine is off. It also quiets down after 30 seconds. I found no easy way to bypass factory program to open and close these valves probably because you NEED the vacuum from the reservoir during boost conditions you don't want the valves to close, Right?? That would make no sense, the car would get quiet under boost...... couldn't do it. Sure, maybe there's a program you could run, or you could add another electrically controlled vacuum pump but then it gets complicated. My answer was to physically wire (with mechanics wire) the valves open. OK, so I can't do it with a switch unless I run a vacuum pump, fine, simple solution right? NOPE, took it for a test drive and was completely unsatisfied. The drama was gone, it was just loud and had drone all the time. Came home and cut the wires off and that one remains unmodified......... I suspect the same thing may occur with the 4C, but only if someone has ever attempted to wire those valves open can confirm ? ❗
 

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Actually you never said specifically as being normally open or closed. Everything made sense, it's just when mentioning the 'bark' at startup it does not necessarily mean they are normally open because they can be opened by a vacuum reservoir (this is how my ttv8 works). If it is just a short bark and closes quickly then that would make sense that they are normally open. If not sure simply disconnect the vacuum lines from the valves. If they are normally open then doing so would make it loud all the time. I was just under the impression that boosted applications used normally closed valves because that is the silly setup I'm dealing with here on this other car.
 

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Now that you got me thinking about it, the fact that they are normally open is a good thing. Like you said it makes it easier to retrofit or modify. Having to introduce vacuum to open valves rather than close them complicates things in a boosted application. Makes me wonder why they did it this way for this other car.
 

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Discussion Starter · #7 ·
Actually you never said specifically as being normally open or closed. Everything made sense, it's just when mentioning the 'bark' at startup it does not necessarily mean they are normally open because they can be opened by a vacuum reservoir (this is how my ttv8 works). If it is just a short bark and closes quickly then that would make sense that they are normally open. If not sure simply disconnect the vacuum lines from the valves. If they are normally open then doing so would make it loud all the time. I was just under the impression that boosted applications used normally closed valves because that is the silly setup I'm dealing with here on this other car.
Edited to be on the safe side, if one missed it, more will.
 

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It's pretty easy to retrofit the valved system if your heart isn't set on using the DNA switch to engage. I used a kit similar to this from ebay to retrofit the Akra valved system into my LE

2pcs Vacuum Actuator Exhaust Electric Valve Wireless Remote Control Switch Kit | eBay

Along with the exhaust, I had the factory vacuum line with the built in "T" to run a vacuum line to the exhaust. It was nice to have but it wouldn't have been difficult to install even without that. The exhaust I found didn't come with the exhaust tip surround piece, so I used some other tips I found on ebay, wish, or someplace like that.
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The nice thing with the ebay controller is that I can switch to open or closed regardless of my drive mode where the factory setup is open (loud) only in Dynamic mode.
 

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The nice thing with the ebay controller is that I can switch to open or closed regardless of my drive mode where the factory setup is open (loud) only in Dynamic mode.
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That's EXACTLY what I was using for my N/A application where the valves are 'normally open'..... too bad I did Not know at the time there was such a 'kit' available ❗ All in all cost me about the same but I spent much time in researching the proper solenoid, remotes, wiring, etc. where this is all one Nice little kit
 

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Discussion Starter · #11 ·
It's pretty easy to retrofit the valved system if your heart isn't set on using the DNA switch to engage. I used a kit similar to this from ebay to retrofit the Akra valved system into my LE

2pcs Vacuum Actuator Exhaust Electric Valve Wireless Remote Control Switch Kit | eBay

Along with the exhaust, I had the factory vacuum line with the built in "T" to run a vacuum line to the exhaust. It was nice to have but it wouldn't have been difficult to install even without that. The exhaust I found didn't come with the exhaust tip surround piece, so I used some other tips I found on ebay, wish, or someplace like that.
View attachment 123281
The nice thing with the ebay controller is that I can switch to open or closed regardless of my drive mode where the factory setup is open (loud) only in Dynamic mode.
Personally, having the OEM solution, I'd prefer to operate it independent of DNA switch. So I'd say your setup is better than OEM.
 

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Plus, for owners not fortunate enough to get the 'dual mode' system aka akra, it IS the ticket to building your own system. (y)
 

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I also wish it were independent of the DNA system, attached to one of the stupid dummy switches on the dash please, with the other going to a garage door opener. :geek:
That has been my plan, eventually. I bought some extra switch parts so I can try to cobble something together at some point in the future.
 

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Discussion Starter · #15 ·
That has been my plan, eventually. I bought some extra switch parts so I can try to cobble something together at some point in the future.
You should be a bit careful before trying, if you plan to connect together with output from TCM. Depending how current is applied from output of TCM, you risk burning internals around TCM output stage, if voltage/current from extra switch hit it in reverse. If you disconnect TCM, then no worries. By the way, I have not managed to get an alarm, so it does not look like there are monitoring in TCM to check if valve actually does what its supposed to.

If button in dash is momentary(only provides 12V as long as button is activated), to keep it as simple as possible, you can use a bi stable pulse relay to supply actuator.

The real job is pulling the wire.
 

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The valves are in different locations in the first and second photos (post #1). Is there more than one version of the Akrapovic exhaust?
 

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Added to the Technical Reference thread.

There is another (much older) thread on this - I haven’t compared the two but anyone inerested might want to look here also.

 

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Very Good reference. See part# 68334269AA is the actual AK shroud w/ tailpipes..... BUT, looks NLA unfortunately. USAspareparts.com has it listed as 'available' but for a mere 3,459 Euros and hasn't been updated since August of 2019..... pretty much time to give up unless you get lucky and find a dismantler who is clueless, otherwise watch eBay auctions. Originally the Akra was a must-have option on my list, but now I've reconsidered and am planning my own valved system inspired by the 458 w/ 3 tips.......hmmmm
 
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Very Good reference. See part# 68334269AA is the actual AK shroud w/ tailpipes..... BUT, looks NLA unfortunately. USAspareparts.com has it listed as 'available' but for a mere 3,459 Euros and hasn't been updated since August of 2019..... pretty much time to give up unless you get lucky and find a dismantler who is clueless, otherwise watch eBay auctions. Originally the Akra was a must-have option on my list, but now I've reconsidered and am planning my own valved system inspired by the 458 w/ 3 tips.......hmmmm
I actually got the tips and cover on eBay for $500 then made an Akra copy 3” Ti. Thinking about adding a muffler on one side, and a valve on the other. Pair with Scara 200cells cat. Sound just like another 4banger.
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