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E46 M3 (2001-2006) Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006.


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Old Thu, May-26-2016, 06:13:45 PM   #151
ShaikhA
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Default Re: Shock dynos, Fat Cat Motorsports and custom valved Bilstiens

This is a video I made after doing Eric's Version2 revalve. Long story short, we were able to get flatter high speed compression blow-off and also add some low speed compression to improve turn-in as he requested. The car should be more comfortable on medium to larger bumps and also handle tighter.

An added bonus point was the realization that any adjustable damper will be limited in the minimum compression high speed slope due to the minimum width of the high speed shim. With the Bilstein PSS9 or 10, that minimum width is 15mm. For a Bilstein HD or PSS (non-adjustable damping) it's 12mm or potentially even lower. That causes a measurable difference in high speed force build up which means you can get more comfort with the HD / PSS than the PSS9/PSS10. I'm not talking about KBO here, but a revalve that's "as good as you can get." KBO essentially equalizes the capabilities of all Bilstein monotubes in terms of high speed compression blow-off. So the Ohlins DFV and PCV, as I shown in the video, are not achieving the kind of reduced high speed compression force than our FCM Elite Bilstein retunes can. This adds more evidence to why I say Ohlins isn't the cat's meow some people like to think it is!


Oh, I also have a new version KBO, v1.9, which is an option to those who need more compression force than is easily generated with our KBO v1.8. The heavier C55 AMG Mercedes needed that v1.9 (necessity is the mother of invention as they say!). The v1.8 works fine on our lighter BMWs, at least the E36 and E46. A newer, heavier Bimmer might need v1.9. It's certainly a sweet and very flat blow-off!



Looking forward to your impressions, Eric6MT!

Last edited by ShaikhA; Sun, Jun-05-2016 at 08:47:08 PM.
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Old Thu, May-26-2016, 07:07:28 PM   #152
VinceSE2
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Default Re: Shock dynos, Fat Cat Motorsports and custom valved Bilstiens

Quote:
Originally Posted by ShaikhA View Post
This is a video I made after doing Eric's Version2 revalve. Long story short, we were able to get flatter high speed compression blow-off and also add some low speed compression to improve turn-in as he requested. The car should be more comfortable on medium to larger bumps and also handle tighter.

An added bonus point was the realization that any adjustable damper will be limited in the minimum compression high speed slope due to the minimum width of the high speed shim. With the Bilstein PSS9 or 10, that minimum width is 15mm. For a Bilstein HD or PSS (non-adjustable damping) it's 12mm or potentially even lower. That causes a measurable difference in high speed force build up which means you can get more comfort with the HD / PSS than the PSS9/PSS10. I'm not talking about KBO here, but a revalve that's "as good as you can get." KBO essentially equalizes the capabilities of all Bilstein monotubes in terms of high speed compression blow-off. So the Ohlins DFV and PCV, as I shown in the video, are not achieving the kind of reduced high speed compression force than our FCM Elite Bilstein retunes can. This adds more evidence to why I say Ohlins isn't the cat's meow some people like to think it is!

How Shocks Work - BMW E46 M3 compression force slope, FCM Elite vs. Ohlins DFV - YouTube

Oh, I also have a new version KBO, v1.9, which is an option to those who need more compression force than is easily generated with our KBO v1.8. The heavier C55 AMG Mercedes needed that v1.9 (necessity is the mother of invention as they say!). The v1.8 works fine on our lighter BMWs, at least the E36 and E46. A newer, heavier Bimmer might need v1.9. It's certainly a sweet and very flat blow-off!



Looking forward to your impressions, Eric6MT!

This is some real interesting stuff, thanks for sharing Shaikh!

But I don't quite understand what you mean by narrower shim and why a narrower shim can be used on a smaller stem. Perhaps because I don't really understand what else is on that stem and how it works.

Do you by any chance have a video that could enlighten me?

TIA!


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Old Thu, May-26-2016, 08:06:08 PM   #153
ShaikhA
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Default Re: Shock dynos, Fat Cat Motorsports and custom valved Bilstiens

Hi Vince, the video I linked to shows the difference in shaft diameters where the piston and valving sits on the shaft - that portion of the shaft is what I call the stem. The stem of the non-adjustable Bilstein (since no oil passage is needed) is solid and 8mm wide. The stem of the adjustable Bilstein (with oil passage) or the Ohlins (also with oil passage) is 12mm wide. That's where the 'minimum compression high speed shim' factor comes in. You need at least 2-3mm wider shim than OD to provide sufficient support for the rest of the stack. Bilstein does make a 10mm shim that could be used for a high speed but I think that's going a bit too far.

P.S. You can search for videos I've made on the Bilstein PSS9 so you can see that shaft in its entirety. I've made plenty of videos showing the internals of the shock shafts so spend some time on the channel and enlighten yourself - that's the only way it'll happen anyway

Here's the first video of the How Shocks Work series, which I'm sure you already watched but just for reference

The image at the start of the top video (BMW E46 M3 compression curve and later FCM Bilstein vs. Ohlins comparison) shows the non-adjustable shaft on the left (8mm diameter stem) and adjustable PSS9 shaft on the right (12mm diameter stem). The 'working' part of the damper rests on that area - the compression high speed stop (like the end of a bookcase), the compression shims, piston, rebound shims, rebound high speed stop (other end of the bookcase), and nut to secure it all to the shaft. You can see the chrome at the bottom of that image.

Last edited by ShaikhA; Fri, May-27-2016 at 05:22:14 PM. Reason: added video link
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Old Fri, May-27-2016, 04:55:52 PM   #154
ShaikhA
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Default Re: Shock dynos, Fat Cat Motorsports and custom valved Bilstiens

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Originally Posted by Namniek View Post
Any decent coilover is valved to match the spring rate. It should be expected at this price point and above.
One would hope that's the case, and manufacturers will swear up and down it's true, but I can tell you from years of measuring other people's work that it's not true.

I agree it *should* be the case, but that's like believing a realtor who says there aren't termites because, well, it's an expensive home! So don't bother with an inspection (!). Caveat emptor.
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Old Tue, May-31-2016, 02:29:59 AM   #155
EricSMG
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Default Re: Shock dynos, Fat Cat Motorsports and custom valved Bilstiens

Rev2 is in! Only put a few miles on, but, I can feel the added low speed compression and comfort really hasn't fallen off.

I'll report back after a few more miles.
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Old Tue, May-31-2016, 01:33:16 PM   #156
elbert
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Default Re: Shock dynos, Fat Cat Motorsports and custom valved Bilstiens

Quote:
Originally Posted by ShaikhA View Post
This is a video I made after doing Eric's Version2 revalve. Long story short, we were able to get flatter high speed compression blow-off and also add some low speed compression to improve turn-in as he requested. The car should be more comfortable on medium to larger bumps and also handle tighter.

An added bonus point was the realization that any adjustable damper will be limited in the minimum compression high speed slope due to the minimum width of the high speed shim. With the Bilstein PSS9 or 10, that minimum width is 15mm. For a Bilstein HD or PSS (non-adjustable damping) it's 12mm or potentially even lower. That causes a measurable difference in high speed force build up which means you can get more comfort with the HD / PSS than the PSS9/PSS10. I'm not talking about KBO here, but a revalve that's "as good as you can get." KBO essentially equalizes the capabilities of all Bilstein monotubes in terms of high speed compression blow-off. So the Ohlins DFV and PCV, as I shown in the video, are not achieving the kind of reduced high speed compression force than our FCM Elite Bilstein retunes can. This adds more evidence to why I say Ohlins isn't the cat's meow some people like to think it is!

How Shocks Work - BMW E46 M3 compression force slope, FCM Elite vs. Ohlins DFV - YouTube

Oh, I also have a new version KBO, v1.9, which is an option to those who need more compression force than is easily generated with our KBO v1.8. The heavier C55 AMG Mercedes needed that v1.9 (necessity is the mother of invention as they say!). The v1.8 works fine on our lighter BMWs, at least the E36 and E46. A newer, heavier Bimmer might need v1.9. It's certainly a sweet and very flat blow-off!



Looking forward to your impressions, Eric6MT!
How about a shock dyno plot that looks more standard? Specifically, an x-axis that is not only more spread out, but also that is capped at 10 in/sec (or even less)?

The way your plots are done minimizes the appearance of the digression at typical velocities, and also makes the slopes appear more exaggerated.
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Old Tue, May-31-2016, 05:02:17 PM   #157
ShaikhA
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Default Re: Shock dynos, Fat Cat Motorsports and custom valved Bilstiens

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Originally Posted by elbert View Post
How about a shock dyno plot that looks more standard? Specifically, an x-axis that is not only more spread out, but also that is capped at 10 in/sec (or even less)?

The way your plots are done minimizes the appearance of the digression at typical velocities, and also makes the slopes appear more exaggerated.
Hmmm, I think you're used to seeing insufficient data on dyno graphs. The 10 in/sec region is shown in the red box. 10 in/sec is a bare minimum for a real-world damper but may not show high-speed behaviors built into the damper, like is the case with our KBO (Kerb Blow-Off) technology.

Things start getting interesting when you get to 20 in/sec or even higher but our dyno won't run past 22 in/sec. Via suspension pots, I've recorded >30 in/sec on rough city streets and pavement seams. This graph shows the full data out to about 20 in/sec and you can see the difference in high speed behaviors between Bilstein HD (in red, standard digressive piston), our KBO v1.8 (in blue, stronger high-speed compression blow-off) and newest KBO v1.9 (in green, practically FLAT high speed slope!).



The high speed behavior of the damper is very important because that's where the rough road / larger amplitude response comes into play. Do you realize that on your roads you're likely seeing >30 in / sec damper velocities on choppy sections?

It looks like you're from or in Wales. I've stayed in Conwy and Llandudno and driven some of the backroads there - gorgeous country! Has the longest proper name in the world, if I remember correctly.

Last edited by ShaikhA; Sun, Jun-05-2016 at 08:46:09 PM.
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Old Wed, Jun-01-2016, 05:22:30 PM   #158
elbert
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Default Re: Shock dynos, Fat Cat Motorsports and custom valved Bilstiens

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Originally Posted by ShaikhA View Post
Hmmm, I think you're used to seeing insufficient data on dyno graphs. The 10 in/sec region is shown in the red box. 10 in/sec is a bare minimum for a real-world damper but may not show high-speed behaviors built into the damper, like is the case with our KBO (Kerb Blow-Off) technology.

Things start getting interesting when you get to 20 in/sec or even higher but our dyno won't run past 22 in/sec. Via suspension pots, I've recorded >30 in/sec on rough city streets and pavement seams. This graph shows the full data out to about 20 in/sec and you can see the difference in high speed behaviors between Bilstein HD (in red, standard digressive piston), our KBO v1.8 (in blue, stronger high-speed compression blow-off) and newest KBO v1.9 (in green, practically FLAT high speed slope!).


The high speed behavior of the damper is very important because that's where the rough road / larger amplitude response comes into play. Do you realize that on your roads you're likely seeing >30 in / sec damper velocities on choppy sections?

It looks like you're from or in Wales. I've stayed in Conwy and Llandudno and driven some of the backroads there - gorgeous country! Has the longest proper name in the world, if I remember correctly.
My personal interest is in the slow velocity behavior. There's definitely a difference between the three dampers, but when the smallest division marker is 5 in/sec (or a smooshed 2.5), that still doesn't tell me very much. But thank you for sharing that.

Sharp impact "ride" IMO is more subjective, and I'll leave it up to Eric to share his opinions. In addition, my expectation is any solid impact with a decent sized pothole will probably result in hitting the bumpstops anyway.
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Old Wed, Jun-01-2016, 06:05:55 PM   #159
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Default Re: Shock dynos, Fat Cat Motorsports and custom valved Bilstiens

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My personal interest is in the slow velocity behavior. There's definitely a difference between the three dampers, but when the smallest division marker is 5 in/sec (or a smooshed 2.5), that still doesn't tell me very much. But thank you for sharing that.

Sharp impact "ride" IMO is more subjective, and I'll leave it up to Eric to share his opinions. In addition, my expectation is any solid impact with a decent sized pothole will probably result in hitting the bumpstops anyway.
Yes, but only if the amplitude is large enough, which it generally is not. Say you're driving along on a smooth flat road and you approach probably the worst thing for 'comfort' - the 1" deep, sharp-edged manhole cover. We all know the result - you feel a nasty hit inside the cabin, but bump stops were not engaged. Why? Because the wheel first drops down into the hole and then slams the 1" lip on the other side. Total bump travel equals roughly an inch (relative to static ride height) when there's closer to 3" total bump travel available.

With relaxed high speed rebound the wheel can drop quickly rather than pulling the entire chassis down. With high speed comp blow-off the wheel can rise quickly without exerting large amounts of force into the shock towers. This means more comfort and a more stable chassis.

To your point about very slow shaft speeds. I asked FCM to increase the slow speed comp and rebound somewhat, in the 0-2 ips region. The result is crisper chassis control in general but a slight tradeoff in comfort on smooth rollers - the chassis follows the road more closely and things happen faster. This is unavoidable. That said, too much is counterproductive and feels like shit.

In addition, I also asked for a lower knee point and flatter blow-off. This makes the manhole cover, over the 1" sharp ridge running across the road, more pleasant.

I am impressed with how much control Shaikh has over the valving as he was able to make very slight adjustments exactly where I wanted them. The shape of the curves between Rev1 and Rev2 are very slight but evidient on the road. Again, Rev1 was damn good with a lean towards comfort. Rev2 is just a slightly more aggressive version in low shaft velocities and slightly relaxed in high shaft velocities. The result is more comfort on sharper hits and more control where you want it.
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Old Thu, Jun-02-2016, 02:12:47 AM   #160
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Default Re: Shock dynos, Fat Cat Motorsports and custom valved Bilstiens

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Yes, but only if the amplitude is large enough, which it generally is not.
Maybe in San Diego you'd be correct.
Anywhere there's ice (and salt), not really. You're probably not familiar with the term "frost heave"

Quote:
To your point about very slow shaft speeds. I asked FCM to increase the slow speed comp and rebound somewhat, in the 0-2 ips region. The result is crisper chassis control in general but a slight tradeoff in comfort on smooth rollers - the chassis follows the road more closely and things happen faster. This is unavoidable. That said, too much is counterproductive and feels like shit.
Yes, thank you, I already understood that. I would still be interested to see a more typical dyno plot.
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Discussing Shock dynos, Fat Cat Motorsports and custom valved Bilstiens in the E46 M3 (2001-2006) Forum - Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006. at BMW M3 Forum.com (E30 M3 | E36 M3 | E46 M3 | E92 M3 | F80/X)