Raceland Dyno Test Results
12-05-2010, 02:27 PM
#62
I think what Bernie's saying here is that without shims or some other way of differentiating between low and high speed damping you're stuck with a single and mostly linear damping rate. Damping still occurs as the fluid moves past the ports/holes, but you can't set up a different damping rate (the slope of the graph) for low speed.
Those shims can be tuned to open and blow off pressure by the tuner. At low speeds they can be set to stay put, forcing the shock fluid through the bleed hole. When a large hit occurs (high speed event), the pressure spike forces the shims to deflect which opens additional ports. The damping curve now follows a different slope.
More or less bleed, and how it is combined with the control provided by the shim stack and piston ports, can sometimes mean shocks will have roughly similar plots but will arrive at those plots using different components.
Those shims can be tuned to open and blow off pressure by the tuner. At low speeds they can be set to stay put, forcing the shock fluid through the bleed hole. When a large hit occurs (high speed event), the pressure spike forces the shims to deflect which opens additional ports. The damping curve now follows a different slope.
More or less bleed, and how it is combined with the control provided by the shim stack and piston ports, can sometimes mean shocks will have roughly similar plots but will arrive at those plots using different components.
The rate is fine. The question is the diameter. Is it the same?
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12-05-2010, 02:32 PM
#63
Not to offend anyone, but it's pure comedy to read guys rationalizing how a $250 set of no-name Chinese steel twintubes inside a mock coilover's dyno "look like Xida's". If you look closely and understand what a FvS plot represents (reading between the lines so to speak), they are quite different. As Bernie has mentioned several times on the forum, dyno's don't tell the whole story anyway. There are a very few here that have driven on Raceland's and Xida's on the same track that would probably share the laugh.
They are no more alike that a Chevy Aveo is a like BMW M5 because they both have four wheels (look the same) and have the similar shape speed vs time acceleration curve. We're literally comparing something equivalent to $9.99 Pep Boys OEM replacement shock mechanism to AST/JRZ/Moton's. Naturally, after all the work I put into getting the Xida's made for you guys, I bristle and the ill-informed inferring that these $10 shocks are "similar".
They are no more alike that a Chevy Aveo is a like BMW M5 because they both have four wheels (look the same) and have the similar shape speed vs time acceleration curve. We're literally comparing something equivalent to $9.99 Pep Boys OEM replacement shock mechanism to AST/JRZ/Moton's. Naturally, after all the work I put into getting the Xida's made for you guys, I bristle and the ill-informed inferring that these $10 shocks are "similar".
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12-05-2010, 02:46 PM
#64
Not to offend anyone, but it's pure comedy to read guys rationalizing how a $250 set of no-name Chinese steel twintubes inside a mock coilover's dyno "look like Xida's". If you look closely and understand what a FvS plot represents (reading between the lines so to speak), they are quite different. As Bernie has mentioned several times on the forum, dyno's don't tell the whole story anyway. There are a very few here that have driven on Raceland's and Xida's on the same track that would probably share the laugh.
They are no more alike that a Chevy Aveo is a like BMW M5 because they both have four wheels (look the same) and have the similar shape speed vs time acceleration curve. We're literally comparing something equivalent to $9.99 Pep Boys OEM replacement shock mechanism to AST/JRZ/Moton's. Naturally, after all the work I put into getting the Xida's made for you guys, I bristle and the ill-informed inferring that these $10 shocks are "similar".
They are no more alike that a Chevy Aveo is a like BMW M5 because they both have four wheels (look the same) and have the similar shape speed vs time acceleration curve. We're literally comparing something equivalent to $9.99 Pep Boys OEM replacement shock mechanism to AST/JRZ/Moton's. Naturally, after all the work I put into getting the Xida's made for you guys, I bristle and the ill-informed inferring that these $10 shocks are "similar".
I was just trying to understand one particular criticism regarding the curves being too linear by showing how your Xida's are quite linear after the transition as well.
It sounds like the devil is in the details...particularly around that transition area and at low speeds. Also, as is often mentioned, monotubes are a bit like big brakes in their ability to dissipate heat. I wonder the Raceland twintubes would be better or worse with the big external tube cover (would it act as an insulator or a heat sink?)
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12-05-2010, 03:41 PM
#66
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I'd need the dimensions of the raceland inserts. Knowing my luck upgraded inserts don't exist for whatever the size is.
I'm thinking more along the lines of using the raceland housings instead of something like a ground control sleeve.
I'm thinking more along the lines of using the raceland housings instead of something like a ground control sleeve.
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12-05-2010, 07:40 PM
#72
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12-05-2010, 07:46 PM
#73
You guestimated points from the Raceland shock dyno and then stuck them into a Subaru STI "damper rate calculator." Explain to me what your thought process was? Did you update it with Miata wheel rates and the like? This chart doesn't seem to differentiate between compression and rebound damping. Is it suggesting compression and rebound should both be 70% critically damped?
I'd be careful about reading the low end points off Bernie's dyno run. He suggested he might need to do something to highlight that area better which suggest resolution might be an issue.
I'd be careful about reading the low end points off Bernie's dyno run. He suggested he might need to do something to highlight that area better which suggest resolution might be an issue.
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12-05-2010, 08:00 PM
#75
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I wanted to express the shock dyno in terms of critical damping % relative to my car and springrates.
Yes, all of the items were updated to reflect my Miata. *sigh* Give me a little credit here.
I think that is just a guideline/suggesion, it is up to the end-user to interpret the chart properly. Perhaps someone with a bit better knowledge of shock forces could explain how bump / rebound should relate when configured properly.
Yes, all of the items were updated to reflect my Miata. *sigh* Give me a little credit here.
I think that is just a guideline/suggesion, it is up to the end-user to interpret the chart properly. Perhaps someone with a bit better knowledge of shock forces could explain how bump / rebound should relate when configured properly.
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12-05-2010, 10:22 PM
#76
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The full data files for the shocks are below. This contains all four shocks dynoed at both 5ips and 10ips.
Please read my previous post on how to view the files in the Roehrig program.
RaceLand.zip
Please read my previous post on how to view the files in the Roehrig program.
RaceLand.zip
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