UncleDude

Thanks to @SpyderSenseOC for sharing his spare collars. I’ll be trying this mod soon - question, do you guys notice much difference in sound when the collar keeps the valve almost open and / or almost closed? I read earlier in the thread about a little going a long way etc. - just wondering how much finesse there is available.

SpyderSenseOC

That collar looks to be about 9 mm or so away from the bracket. Mine are placed in the same location. The collars themselves are approximately 9 mm thick and that collar and the gap in your pic appear to be very close dimensionally.

One of these days I'll crawl under the car with the engine running and operate the valves manually to see just how much difference, if any, closing the valves slightly makes.

slilley

Correct, a little goes a surprisingly long way! What @Avera shows is about the highest I'd ever recommend (keeping the exhaust from closing more than about 1/4 way) - it does have a benefit vs. keeping them fully-open all the time. But I think the "sweet spot" is with the collar positioned farther down on the plunger, so that the exhaust can still close between 1/2 and 3/4 of the way. I eventually settled on keeping the plunger a little less than 1/4" from the bottom (so the valve could close ~75% of the way), and found that to be a good way to eliminate a lot of the drone while still delivering the beautiful sound when you got on the throttle.

I eventually added a Softronic tune to my car, so I ended up removing the collars entirely since the tune gives me fully-manual control over the exhaust valve via the PSE button. Now I leave it in quiet mode, except when I want to sound like a hooligan!

UncleDude

So I played around with this mod this weekend. The collars I have are not wide, but they do hit the nut so I first started mouthing them as low to the ground as I could (more valves closed) until they didn’t hit the nut on the valve housing. I could not have done this (spyder) without the ramps because of the diffusers. I used tape (scotch tape, mistake!) to hold them together as suggested above, then once you get one threaded it is easy - but I found it really fiddly and a good test of patience.

The sound with the collars mounted mid shaft (to clear the nut) was IMO almost full valves open. I couldn’t tell a difference between valves open or closed, which I’m sure some would like but I was still looking for a difference and just wanted a bit more grumble valves closed.

So this morning I slide them all the way down as low to the ground as I could and simply let them hit the nut. I suspect I might have to tighten them once in a while leaving them like this but I do like the sound in this position. It is 15-20% more loud, and there is a slight difference valves open to closed. I could not hear them clink, or vibrate or make any annoying noise and they seem to hit the nut firmly and seem rigid in that position. In the video it looks like they don’t hit the nut, but I checked it about 5 times and they do hit on both sides. I suppose I could grind off part of the collar, but that would mean putting them on again lol.





Also, I used rare earth magnets for shims when I was positioning the collars mid way, they worked great. After I moved the collars all they way down I also tried them on the collar surface that hits the valve housing, and they stayed in place on a spirited drive.


small magnet spacers

981KMAN

Really happy to see lots of folks using this Collar Modification. Every now and then I have a good idea

Avera

@981KMAN

Do not sell yourself short . . . it was an AMAZING idea

Avera

jayper

your contribution is much appreciated good sir

Richardkun

I have been using this mod now for several months now on my '22 Spyder. So simple, but yet so elegant. I have the collar set at about 2/3 open at minimum. This mod was exactly what I was looking for. I don't mind the OEM exhaust and sound when it's open/partially open. Ideas like yours is why I enjoy reading these forums daily. Thank you for your contribution.

Avera

Removed JCR Race Pipe

Replaced OEM rear box with shaft collars positioned an estimated 15mm from top (yellow)

Going from Race Pipe to OEM rear box . . . lost JCR tone (obviously); lost some decibels; and lost the insane drone associated with Race Pipe

Out of curiosity, I removed shaft collars and I was quite surprised to appreciate just how much the collars were accomplishing. WAY more apparent after removing the collars than when first applying them

Decibels: With valves closed, the exhaust decibels seemed like zero. With valves open, it still screamed (due to Dundon headers/OAPs)

The ‘quiet’ with valves closed was almost shocking and (for ME) completely undesirable. Before installing the Race Pipe, I knew the transition from valves closed to valves open was abrupt and undesirable. However, it was not until I went full circle – back to OEM rear box without shaft collars – that I realized just how quiet the exhaust is with valves closed.

What became even MORE apparent, and even more undesirable, were downshifts. Almost no exhaust decibels unless you REALLY ‘blip’ the sh*t out of it. I do have PDK and drive in manual mode, so I say ‘blip’ to relate AGGRESSIVE downshifts.

Drone: Coming from Race Pipe with the most insane drone I have ever experienced, I did not find the drone associated with OEM rear box and shaft collars to be intrusive AT ALL. That said, when I removed the shaft collars, the drone appeared to go to zero.

I say ‘appeared’ to go to zero because the fully stock exhaust setup is known to have a little drone. Add the Dundon components and you get a LITTLE more. Add the shaft collars and you get a more on top of that. Point being, even though completely non-troubling for ME, the shaft collars do accentuate baseline drone, which is to be expected and most apparent to me upon removing the shaft collars.

Overall, even with Dundon components, the OEM rear box with functional PSE (valve) control is EERILY QUIET. For ME intolerably quiet. MOST apparent is how uneventful downshifts are with functional PSE control.

Collar Position: Prior to placing Race Pipe I had collars placed at about 9mm (red). Again, it was not clearly apparent what the collars were accomplishing until going full circle and removing them from OEM rear box.

9mm vs 15mm might not seem like a lot, but I can confirm 9mm is essentially valves fully open all the time. 15mm is noticeably different, where I estimate the valves close some 50-75%. Even though the latter is MUCH better than no collars, I prefer the valves open all the time and replaced the collars at 9mm.

Final Note: I think most all of us relate the stock valve control as simply opening/closing at 5K RPM (1st and 2nd gears) and 3800 RPM (3rd- plus gears). However, after having played with my exhaust setup more than one man should, it has become apparent stock valve control is far more intricate than an open/closed proposition.

Yes, the valves open/close according to RPM. However, it is not just RPMs. For example, throttle intensity seems important in how ‘open’ the valves remain once RPMs are achieved. Valve control with downshifts seems to be similarly more complicated than a simple open/closed proposition. Hard to put into words, but you can tell what the computer is trying to do with the valves, but the valve collars are preventing (if clamped fully open) or attenuating (if held partially open).

SpyderSenseOC

I'm curious to know whether the computer does anything except keep the valves fully open or fully closed. Is there some middle ground in the stock configuration wherein the computer modulates the valves at all? I think the answer is the computer does nothing except open or close. But like I've said before in the Akra OAP thread, there sounds like there's some crazy stuff going on at times that I cannot jibe with just open or just closed. Maybe that damn symposer is the source of the weirdness.

UncleDude

I think it is open or closed. The 992 cars have a variable setting for the valves and they use a small motor for that, so I would assume to achieve a partial open they'd have done the same here. I wonder what the Porsche engineers think of the collar mod LOL. I'm quite pleased with the placement I have (right at bottom of plunger, collar hits the bolts). I can *just* hear the valves open or close now - perfect.

Soul Performance

It could also be the cylinder deactivation, that also sounds very strange when that engages

SpyderSenseOC

I turn that off IMMEDIATELY upon starting the engine. Not only do I dislike the noise it makes, I personally feel cylinder deactivation is not good for the engine.

SpyderSenseOC

I think it's smart to either place the collar where it squarely hits the nuts and doesn't travel any further (and probably allows 50% or so closure) or close to the actuator (where it probably only allows 15-20% closure). Otherwise you run the risk of them just glancing off the nuts and making audible clanking sounds when they do it. Either place them at 9mm (where they clear the nuts) or at the other end of the spectrum like you have so they slam squarely onto them. That's my two cents.

Avera

If you look at the COBB AP threads recently released, they identified NUMEROUS files and suspect there are many more are unknown to them involved in valve control.

It is not a simple matter of valves being open or closed at a particular RPM. What I tried to share - others as well in prior posts - is in keeping with the complexity.

It might very well be the valve activity is a matter of open or closed - not partial - but when all this activity occurs seems to be far more complex than simply occurring at a particular RPM.

Avera