8CH vs 8CR Weight Characteristics?

supercharged111

supercharged111

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Sep 12, 2011
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Da U.P.
I'm just wondering what the diff is between the 8CH and 8CR weights? 8CH being stock for my 98 700SX with 13.9 rivets in and out vs. the 8CR SLP calls for with their triple pipes with a single 13.3 on the inside. I understand that rivet selection and placement adds an element of "it depends" here, but what is it about the profile itself that's so different? Why not just run different rivets in the 8CH weights? I get the impression this comes down to an extent to rider preference. I do like the way this sled will cruise when you back out of it. I've ridden other modded clutched sleds that seemed to hold RPM higher and were ready to just jump at a moment's notice. I've always thought this sled was quite responsive, and if I'm riding it hard the RPMs stay plenty high and I don't seem to lack for a snappy response so I'd like to try to retain that cruising capability to the extent that I can with the pipes.
 
Can you describe how the sled reacts to them? I have an unknown multi-angle helix on the sled right now, will remove it to verify what it is when I do the pipes. I also have the stock helix with new buttons ready to go, but will likely stick with that mystery helix initially.
 
supercharged111 said:
Can you describe how the sled reacts to them? I have an unknown multi-angle helix on the sled right now, will remove it to verify what it is when I do the pipes. I also have the stock helix with new buttons ready to go, but will likely stick with that mystery helix initially.
Click to expand...
All you can really do is test. The only way to get a straight shift from the 8ch weight is with a progressive helix. The helix from the apex or rx-1 is a 51-43 factory, which wouldn't be too far off with the 8ch.
The 8ch with a straight helix will over-rev by about 500+ rpm in the low to mid speed, then come back to desired rpm at top speed.
 
74Nitro said:
All you can really do is test. The only way to get a straight shift from the 8ch weight is with a progressive helix. The helix from the apex or rx-1 is a 51-43 factory, which wouldn't be too far off with the 8ch.
The 8ch with a straight helix will over-rev by about 500+ rpm in the low to mid speed, then come back to desired rpm at top speed.
Click to expand...

Now that you've described it that way, it makes way more sense. Mine has a straight shift as is, so whatever helix I put in 20+ years ago (and then didn't ride the sled forever) must be about right (but I do need to ID the thing so I know what's what). Though I am over-revving by a couple hundred RPM with the single pipe. I didn't pay as much attention back then, tuned a lot of cars since then, and have a different perspective than I did back then. So the 8DN-20 must have a straight shift with a straight helix then. What's the diff between an 8DN-20 and the 8DN-00 the SRX came with? Or does the 20 just mean it's the new version of that same part?
 
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