4200 - Valved Exhaust Upgrade

FIFTY

Member
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3,100
4200 - Valved Exhaust control kit

Hello good SM people

This is one of the collective's favorite type of thread - exhaust fettling!

I would like to call on experience of upgrading a non-valved 4200 to GS back boxes with operating valves, I understand that I need to install a remote kit, some sort of pneumatic pump to control the valves. The Larini kit comes with a sensor that taps into the throttle to open the valves over 3500rpm, is that needed for the GS backboxes too? Guess it's a safety feature for the engine temps

Do not care about wiring the valves into the SPORTS button, I don't even want to know the feasibility... a simple key fob manual control will suffice

So in short do I have to buy Larini's kit or is there any more "competitive" options?

Thank you!
 

FIFTY

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3,100
Yeah he mentioned that to me Mark

Interestingly the FD kit is no longer listed on their website unless I'm totally missing it!

Larini have a kit circa 500 quid
 

jasst

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2,313
There is a thread covering this subject, (don't know how to post link to thread) search sports maserati exhaust modification guide.
 

CatmanV2

Member
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48,547
Hi shogi. I noticed the FD kit seems to have dropped as well :(

Still no real issue. We can make something up easily enough, although it would be worth giving them a call tonight or tomorrow. All we need is a remote control relay, solenoid valve and some piping. I can see where to take the vacuum feed from.

If you bring it round here, I reckon we can do it in an afternoon

C
 

FIFTY

Member
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3,100
Alright thanks sounds like a plan... the GS boxes land next week

Here I was thinking there would be a kit on amazon/ebay


Just another question to GS owners... do the valves stay closed through to redline or do they open at 3500-4500?
 

namaste

Member
Messages
212
I have a guide for the GT in my sig, not sure how much different it will be for a 4200. Sourced parts off ebay for about £20 total.
 

FIFTY

Member
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3,100
Cheers Namaste. C explained it to me so I have to splice into the secondary air system for the vacuum feed and run the hose to the rear in order to supply the valves.

I'll get it done in February no doubt and post an update on how I get on
 

safrane

Member
Messages
16,748
The GS system is basic as it is on when the button is pressed thus using the engine vacume to close the valves.

When you start there is no vacuum from the engine for a moment or so hence the slight bark when starting.

If you disconnect the vacume lines the box's stay in sport mode.

However as the sports button also changes the engine and gear box settings you cant get all the joys of sport just having the vacuum line disconnected.
 

F456M

Member
Messages
124
I have been thinking about putting GS boxes on my 4200 too. But I want to be able start the engine with open flaps to get that sound and it is possible with a manual switch if I have a vacuum accumulator so there is vacuum even when the engine is off. Then when the switch is off, it will start and be closed with no vacuum. My 550 maranello mufflers are closed with no vacuum. Are the GS boxes like that or opposite? So how to make them open when neccesary? I don't want to have to push a button every time I get above 4000 rpms..... I know the powersteering ECU gets a signal with varying voltage depending on speed, so my idea would be to make a device that open the valves when above 40-50 kph as the road noise will overtake the drone and exhaust noise. That way the system would work perfectly as go go from always open to auto when the manual switch is in off position, and you get a loud Maserati which is quiet when going home slow at night or in stop and go traffic, but if you step on the gas, the car is loud over 40-50kph. which is what I want. What do you think? Thanks
 

safrane

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16,748
F456M

As per my previous post. The GS boxs need the vacume to close the valves to be in normal mode. No vacuum = constant sports mode.
 

CatmanV2

Member
Messages
48,547
I have been thinking about putting GS boxes on my 4200 too. But I want to be able start the engine with open flaps to get that sound and it is possible with a manual switch if I have a vacuum accumulator so there is vacuum even when the engine is off.

Not there isn't. At least not for very long. It's exactly the same system as used on the GTS and Strad (at least in operation, the parts are different)

Having said that, even when there *is* vacuum you can set a switch to make the valves open. But then you'll need to close them manually as well.

Standard GS boxes are open at atmospheric pressure. You could (relatively) easily swap the actuators for closed ones.

To do what you want you'd need to get some kind of signal either from the speedo, or tachometer. Then program some kind of device to act on the valves as needed. You might be able to use the PAS signal but I rather doubt it's as simple as varying voltage.

C
 

FIFTY

Member
Messages
3,100
I have been thinking about putting GS boxes on my 4200 too. But I want to be able start the engine with open flaps to get that sound and it is possible with a manual switch if I have a vacuum accumulator so there is vacuum even when the engine is off. Then when the switch is off, it will start and be closed with no vacuum. My 550 maranello mufflers are closed with no vacuum. Are the GS boxes like that or opposite? So how to make them open when neccesary? I don't want to have to push a button every time I get above 4000 rpms..... I know the powersteering ECU gets a signal with varying voltage depending on speed, so my idea would be to make a device that open the valves when above 40-50 kph as the road noise will overtake the drone and exhaust noise. That way the system would work perfectly as go go from always open to auto when the manual switch is in off position, and you get a loud Maserati which is quiet when going home slow at night or in stop and go traffic, but if you step on the gas, the car is loud over 40-50kph. which is what I want. What do you think? Thanks

From what you are saying I think the larini kit will fulfill your needs on this https://www.larinisystems.com/collection/maserati/4200/larini-auto-valve-control-remote-exhaust-kits

"Allows valves to open and shut at a predetermined RPM load via throttle input"