help with capristo bypass valve

If you put an inline tap and close it, you are not stopping the vaccum, since you have not relieved the pressure, you have basically sealed it at whatever the present vacuum is at. From that stand point, the oem valve would do the same thing, it would hold the exhaust valve open or closed at whatever setting it was at.

With the Capristo valve, you have to release all vacuum, for the valve to stay open. As an example, with my car running at idle, I can open the engine lid and see the valve position; that the valve is closed, and when I shut off the engine, the valve does not immediately open...it take several seconds for it to lose the vacuum, then it opens.

Try it and see.

 

It works similarly to the factory oem valve. It might be me, but it appears to open slightly sooner, by a couple hundred rpm, and seems to open a bit more willingly to throttle inputs. Meaning I don't have to press the throttle quite as agressively to get it to open...but it maybe that is just in my mind.

 

You know that the capi valve works opposite to the oe valve......no vacuum = open valve.

Put a 't' in the vacuum line and temporarily run a vacuum line (through the passenger window if you like) and a vacuum gauge into the passenger cabin. Watch the gauge as you accelerate and when vacuum drops the valve should open....and the power come on. You should be able to hear the difference when the vacuum flat lines. If you don't feel and hear the difference then something is wrong.

I played with my oe valve last summer (although I routed the vacuum line through the rear bulkhead to the cabin as my tests were more prolonged than a single run)

 

Did u not get the new solenoid from Capristo with the Bypassvalve? They should also have sent u the mounting instruction with the valve.

Kimmo /// Sweden.

 

The installation instructions are basically non-existant. If you ask the seller Nick at Nick's Forza Ferrari, he will provide you with a plumbing photo, but that is all he gets from Capristo. Capristo really should make a formal set of instructions with clearer diagrams/photos. If you search my thread, you can find it, and I posted the photo, along with my own, and some basic instructions.

BTW, Darren PM'd me, and said his Capristo valve was incorrectly plumbed by his mechanic and is now working correctly once the vacuum lines were correctly situated.

 

How much did you pay for the Capristo Bypass valve? Is it 63 mm inside the valve or bigger?

Kimmo / Sweden.

 

Be good if you can take some photos and post up the correct installation for future reference!

 

If you can find my thread, it is here on this site in the archives from my installation.

(edit) Here ya go: http://www.ferrarichat.com/forum/showthread.php?t=201300&highlight=capristo+valve

Also, the Capristo valve is sold by Nicks Forza Ferrari (site sponsor) for around $950 or so. Ping him for an exact price.

 

Go down to repco and buy one of the cheap gauges, it will probably come with a peice of vacuum line in the box. This is all you will need for these tests

 

Actually, I don't think this is right. Both valves are vacuum OPERATED, but they are not controlled by the presence of vacuum in the manifold. They are controlled by the Motronic. There is a vacuum canister that maintains a vacuum, and this force is used to operate the valve, like a vacuum operated accessory (such as power brakes). The solenoid actually triggers the opening/closing of the valve, and this gets its signal from the ECU.

The difference between the OEM and the Cappy is that the default position (no action applied to it) of the OEM valve is closed, and the default Cappy position is open. This does not mean anything about when they open and close, only that if there is a failure, the Cappy fails open, the OEM fails closed.

You should be able to hear the difference on startup. The OEM valve is closed when you start the car. The Cappy valve is open, so when you crank it, the sound will be louder and then quickly quiet down as the vacuum comes up and provides power to close off the valve.

It also behaves differently. I agree that it seems to open faster. But more than that, it seems to stay open longer. Try this: blip the throttle sitting still, once. If I do this and watch the valve, it opens as the engine is settling back down - and the sound is no different. Now blip it three times. Here the valve opens as the engine is spooling down from the first blip, but it will stay open meaning the next two blips are noticably louder.

All of this is VERY apparent if you have a Cappy level 1, because the difference between closed and open is fairly significant.

I do like the idea of a valve in the vacuum line. This would be a very easy way to quickly switch between regular function of the valve and open all the time. I may have to try this

 

I have the Cappy valve too, so what I am describing is what I have noticed with the new valve. I don't remember the OEM valve staying open like that, it shut almost instantly. It almost seems to me like there is some lag in both systems when applying the vacuum, like the vacuum action is lazy. For the OEM valve, the lag is in opening. The Cappy valve seems to be slower to close. I can't back that up with data, it's just my perception.

For the sake of argument, let's say the vacuum system takes a full second to do its thing, but the reverse action is almost instantaneous in either system...

OEM: You floor the gas at 2500 rpm. The engine starts to spool up. At 4500 rpm, the Motronic says "Open!" A full second later - now at near to 6000 rpm, the valve makes its way open. Then you let off the gas to shift, and the valve snaps shut. Back on the gas, the sequence repeats as the Motronic signals the valve to open but there is a lag before it responds.

Cappy: You floor the gas at 2500 rpm. The engine again spools up. At 4500 rpm, the Motronic says "Open!". Near to instantly, the valve snaps open, say by 4800 rpm. Then you let off the gas, but there is a full second lag, so the valve stays open. With a manual you can complete a shift in a second or so, and the F1 only takes 1/4 second. And then you are back on the gas with the Motronic saying "Open!" before the valve ever got closed.

The result is that you have the same signal timing, but the Cappy valve physically opens quicker/sooner and closes slower/later. I believe this is what is going on.

Right or wrong, you will not get my Cappy muffler - or Cappy valve - out of my car while I own it!

 

Are you certain you know what is happening? Solenoids are full-on, full-off valves where an electro-magnet opens (or closes) a valve, they are not proportional devices. On Ferraris they are full-off devices until current is applied by the Motronic ECU. Attached is how the 355 WSM describes operation for the OEM system. The bypass valve linkages have a spring pressure to close them. No vacuum, valves are closed. My personal opinion is the Capristo solenoid valve works like the OEM valves. Makes no sense otherwise. The OEM solenoid is designed to interrupt the vacuum, so should the Capristo's be. If you bypass the solenoid, the bypass valves are open whenever the engine is running and vacuum is present, and close when the engine is shut off. If you wanted to change how that worked, you would need a change to the Motronic engine ECU.

On the 550 and 575M the valves open above 2720 rpm and 64% engine loading. The 355 at 2760 rpm is similar, but no idea why it schedules at 4000 rpm in 3rd gear only. Note on the 355 parts catalog pages the vacuum accumulator 6 on the air injection device page, and the vacuum operated bypass valve 12 on the exhaust page. Vacuum opens the bypass valve as scheduled by the ECU/solenoid valve, and spring pressure closes it when the Motronic ECU/solenoid determines the rpm/load are below the mapped value.

If you can explain how it works differently, I would be very interested.

Taz
Terry Phillips
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Darren- I did some more thinking on the bypass valve and your explanation makes perfect sense. The stock bypass valve is spring loaded to close and the Capristo bypass valve is spring loaded to open. The stock solenoid valve is closed until it receives power from the ECU, the Capristo solenoid valve is open until it receives power. In the stock system, vacuum opens the bypass valve, in the Capristo system vacuum closes the bypass valve. There is only one ECU signal, and it can be used for either.

The 4000 rpm in 3rd gear had me puzzled, but one of our European readers explains there is a full throttle noise test from 50-60 kph the cars must pass in Europe. Extending the valve closed period to 4000 rpm in that gear most likely gets the car past that test.

Taz
Terry Phillips

 

The inline valve is great! I am going shopping this weekend

 

Be careful with running the valve open all the time. Brian Crall (Rifledriver) says it can cause engine damage on 355s. Hopefully he will explain why soon. About 2/3 down this thread.

http://www.ferrarichat.com/forum/showthread.php?t=236340

Taz
Terry Phillips

 

Here is Brian's answer. Running with those valves open all the time can cause some real problems on a 355.

http://www.ferrarichat.com/forum/showpost.php?p=138506346&postcount=18

Taz
Terry Phillips