New Capristo 355 Exhaust Valve

I recently purchased the new Capristo Exhaust Valve for the 355. I bought it from Nick's Forza Ferrari http://www.nicksforzaferrari.com/forzaferrariwebsite1_002.htm Took a couple weeks for delivery, but he should be stocking them now. If you are not familiar, this is a direct replacement for the factory oem Pierburg valve. It's operation is slightly different, as it's resting state (engine off) is with the valve open, where on the factory unit it would be closed. When vacuum is applied, it closes, and when removed, opens. This is the opposite of how vacuum is applied to the factory valve, so in order to do this, a replacement Pierburg solenoid is substituted for one of the factory solenoids in order to reverse the vacuum direction.

Below is a photo of the plumbing difference. Note the two vacuum lines to the left solenoid are moved to the new Pierburg solenoid mounted above. Also, the Amp Junior Timer electrical connector is also removed from the factory solenoid and plugged into the Pierburg solenoid. Note the red vacuum line would normally be plugged into the bottom vacuum line on the factory solenoid. And the black vacuum line that runs to the Exhaust Valve would normally be fitted to the upper connection on the factory solenoid.

Note this photo came from Capristo. On a North American 355, you cannot mount the solenoid in that location, as a catalytic converter ECU resides there. I ended up simply wire tying mine to some cables slightly to the left and above in this picture. If I can find a better spot, I will mount it to something in the future. I was thinking I could even mount it to one of the cat ECU mounting bolts.
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Here are a few photos to compare the two valves. Note that the Capristo exhaust valve is apparently of their own design, and also uses an unknown maker vacuum bellows. The factory oem valve and bellows are both marked "Pierburg". Pierburg I hear also makes these exhaust valves for BMW M3's (E46 series).

Notice the Capristo valve has the vacuum line attachment on the top of the bellows. This created a slight problem, as the factory hose would not reach. Had to source a longer piece of hose, keeping in mind it is pretty hot around there, so needs to be heat resistant.

Notice also that the valve has a spring at each end, keeping it under a bit of tension laterally. I assume this is to prevent the valve from rattling like the factory unit.

So, how's it work? Very nicely. What I notice immediately, is that it opens a bit sooner. My factory valve opened at around 3500 to 3700 rpm, though the WSM states it should open around 4000 rpm. This Capristo valve seems to open around 3000 rpm...perhaps even a bit sooner...it is hard to tell, as I do not hear the transition as clearly as the factory valve, which almost "popped" open rather suddenly, this is much smoother and linear.
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Here is a picture of the end of the valve, with the spring. There is a spring on each end or side of the valve.
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Along with opening slightly sooner, I noticed the Capristo valve appears to open more willingly at part throttle. The factory system is supposed to only open at wide open throttle, or at least at "spirited" throttle openings, now it will open pretty readily if I dip into the throttle, without having to punch it.

I am satisfied with the minor improvements. There is also the safety advantage that if this were to fail, it will fail in the "open" mode, rather than closed like the factory unit. Granted, if it is closed, when it should be open, it should trip a "check engine" light, and you should hear the difference, but is nice insurance, against burned exhaust valves in the heads. More importantly, this has the potential to be more durable, and remain "rattle free" during it's life. Time will tell, and I will be the "f-chat beta tester"!

 

WOW!! That looks remarkable beefier and better than the stock unit---Could not find a price on the site, what is the cost?

 

I believe the list is $999. Talk to Nick, he might be able to offer a discount off that.

 

BTW, the Capristo valve is considerably less expensive than the factory valve, which sells for anywhere from $1200 to $1800, depending on where you source it.

 

I have heard the factory piece is crazy money for what it is...

 

Like a lot of Ferrari stuff......

 

I am curious.

Doesn't the Motronic constantly evaluate specific parameters that dictate whether or not the exhaust valve should be open? My understanding has been that the 355 engine decides when the valve should be open based on gas content, temperature, etc. We know that wiring the valve to be open permanently is a huge no-no precisely because the engine's decision as to when the valve should be open must not be overridden if severe engine damage is to be avoided.

So it seems to me that opening the valve "earlier" than normal would be detrimental to the engine just as wiring it open would be.

Can you or any others comment on this?

 

The valve opens, based on a signal to the solenoid from the Motronic ECU. The only way it can trip a CE light is if the valve is open when the ECU thinks it should be closed, and vice versa. It confirms this through the temperature probe off the Y pipe to the ECU. I can only surmise that the reason the Capristo valve opens faster, is it is simply responding faster. Remember, it is only opening and closing based on the signal from the Motronic ECU. It also seems to have slightly less resistance to opening and closing force...so requires less vacuum to operate. Again, I am only guessing. But the bottom line, is the Capristo valve should not trip a CE light, because it is only open and closed when signaled by the Motronic ECU, there is no way around that.


The reason wiring the factory valve open sets off the CE light on a Motronic 5.2 F355 (1996 to 1999) is because now it is always open, and yet the Motronic ECU is sending a signal at idle (for example) and the thermo probe is hot, telling the ECU the valve is open when it shouldn't be. Got it?

 

the parameters are rigid, not changed for any market or condition.

1st gear: open at 2760 rpm and fill throttle
2nd gear: open at 2760 rpm and fill throttle
3rd gear: open at 4000 rpm and fill throttle
4th gear: open at 2760 rpm and fill throttle
5th gear: open at 2760 rpm and fill throttle
6th gear: open at 2760 rpm and fill throttle

From the workshop manual.

Jay

 

Actually, that answer is not correct.

Those rpm specs are not specified in the 5.2 Motronic section, but only mentioned that specific rpms exist. It would be interesting to confirm they are the same. In the 5.2 section it goes on to say for USA cars only: It will also open under very high throttle opening (ie high load), accelerating over 100 mph, or constant over 150 mph.

 

Hey, I'm just the messenger!

I thought you had a 1995. I have had to buy both the owners manuals, because the 1995 says things that the 96 doesnt, even in terms of the body and especially the spider top. The 1995 also has extra stuff, mostly more detailed in the chassis, but not limited to the OBD1 differences.

So here it is from the Prancing Horses mouth:
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Hey JM3, no problem, but we must have different copies or something. What you printed was in the "2.7" section of my WSM (though formatted differently), and slightly different stuff written in the "5.2" section, though with a reference to rpm settings. If I could figure out how to copy and past from a pdf, I would...

 

I am not a computer guy, but I don't think you can cut/paste from most pdf, what you are looking at is:

get pdf on screen

click [print screen]

open "paint shop pro"

left click

[paste as new image]

[crop] all gay porn and Lambo links from the browser toolbar that show with "print screen"

[save image] as a .jpg in Ferrari Pictures Folder

[manage attachments] in Ferrarichat to upload picture to message.


Jay

 

LOL .............

 

There must be a misprint. Unless the car is an F1 the motronic unit has no input for gear. There cannot be a different RPM opening specification based on gear selection. The spec should be 2760 for all gears.

 

Can someone please help me understand this stuff; I must be having a bad brain day.

On my car the exhaust valve opens via throttle position, I am gauging this based on the change of pitch from the exhaust, when the valve opens in my car it gets very loud.
Are these rpm levels listed when the valve "may" open, or is it open once the engine revs past this point?

Sorry for my lack of understanding, it just seems the 2 355's I have owned have not operated in they way suggested here.

 

I hooked up a vacuum gauge to the bypass valve vacuum line on a 1995 2.7 and noted: (tested both w/ vacuum gauge and physically watching the bypass valve hooked up to a vacuum line inside the car while driving).

-the bypass valve opens on WIDE OPEN THROTTLE ONLY (once the min rpm requirements are achieved as controlled by the ecu).

-the bypass valve is opened by strong vacuum and this only occurs on wide open throttle . If you accelerate slowly to 7 or 8 thousand rpm the valve will not open.....there must be wide open throttle to create the vacuum to open the valve.

-regardless of rpm the bypass valve will close once you 'coast' (no longer wide open throttle)....ie you can be coasting at 7000 rpm and when who are coasting (no longer at wide open throttle)...the vacuum drops and the bypass valve closes.

 

Thank you Chris, this is my experience also.

 

+1

LMAO!!

 

Just one question about this - at WOT isn't vacuum at it's weakest?

 

No, at wide open throttle the vacuum goes right off the scale (max's out).

Note:I'm planning to do some more testing on the bypass valve (see if its possible to modify the opening duration) and will note the vacuum readings during coast and wide open throttle phase