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Jan 3, 2012 | 01:53 PM

#51

iclick

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Joined: Sep 2005

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From: Baton Rouge, LA

Quote:

Originally Posted by boogaloodude

No, you didn't, Iclick did. Keep up

I did indeed--but to clarify a bit, I think if you have maybe 6-8 charts to look at the chances of being somewhere in that realm is reasonable given a good tune. No guarantees, of course.

Jan 3, 2012 | 01:58 PM

#52

iclick

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Joined: Sep 2005

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From: Baton Rouge, LA

Quote:

Originally Posted by Twinrider

Lots of people are saying that the 255s are strong from the bottom but I find they don't start pulling hard till I hit 4,000 rpm and beyond. I would like more power everywhere on the rpm scale.

That's the first time I've seen this description of 255 cams, and is indeed quite the opposite of the norm. I would suspect more than a tune issue, but maybe the cam-timing retarded a tooth or two.

Jan 3, 2012 | 02:16 PM

#53

Mike

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Joined: Jun 2009

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From: Centralia, Wa

Quote:

Originally Posted by iclick

I think it safe to assume that one might expect to be somewhere between those two extremes given a good tune.

You're assuming the two charts represents two extremes. The problem is, with only two charts to look at (posted in the thread at the time), and with no build data for either one, there was no way anyone else can draw any conclusions whatsoever. I can post up two examples of a build and tell you that they represent the two extremes, and they may be or they may not. Even if I believe they are, they may not be. That's the only point I was trying to make. And as usual, I must not have been very clear. Mostly, I was just trying to have a little fun with the thread.

Jan 3, 2012 | 02:17 PM

#54

Mike

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Joined: Jun 2009

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From: Centralia, Wa

Quote:

Originally Posted by djl

You quoted me, so I thought you were referring to something I said. Maybe we do agree.

dude, we were in complete agreement.....

Jan 3, 2012 | 02:35 PM

#55

Mike

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Joined: Jun 2009

Posts: 6,786

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From: Centralia, Wa

Quote:

Originally Posted by iclick

That's a fair statement and I would like to see the numbers on my setup too, but it probably ain't going to happen. You see, I don't care what the numbers are

I don't care what the numbers are, either. However, (as you frequently say), I'm more interested in the shape of the torque curve.

we know the 255s fall off after 4000 rpm. They have a short intake duration, and physics pretty much dictate a short duration means less time to fill the cylinders at higher rpms, so it makes sense that the shortest cams would fall off the soonest. However, on your bike, that apparantly does not happen, or at least you keep claiming it doesn't, so I'd just like to see something to back up statements like the one you made earlier in the thread. You've got all these dyno charts, but not the one I'm most interested in seeing. Maybe your bike is an anomoly? That would be interesting to see.

Quote:

Originally Posted by iclick

FWIW, I hate to continually dispel rumors to the contrary, but the TC96/SE255 combo in my 96" SG does not "fall on its face above 4k rpm." What constitutes a "fall on its face" sensation is obviously up to the individual butt dyno, but mine says it ain't so.

Jan 3, 2012 | 05:15 PM

#56

bklynbob

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Joined: Mar 2008

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From: bklyn,ny

click

Ok,we get it,the 255 is the best,enough already.....................

Jan 3, 2012 | 08:41 PM

#57

iclick

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Joined: Sep 2005

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From: Baton Rouge, LA

Quote:

Originally Posted by boogaloodude

The Herko chart was posted and described by the tuner himself on HTT, which was a TC96/255 with Bub 7 TD's. I have to take his word that the description is accurate, especially given his good reputation as a tuner. It might be worth noting that had he used a more performance-oriented exhaust he likely would've gotten even better results, particularly in the low-end of the chart.

Quote:

I can post up two examples of a build and tell you that they represent the two extremes, and they may be or they may not. Even if I believe they are, they may not be. That's the only point I was trying to make.

I originally said that "I would expect any given result to be somewhere between the two," considering I have seen several others that fit in between the two. I didn't say they represented any global extremes, but were the high and low among the small sample of charts that I had seen. Or at least that's what I was trying to say.

Jan 3, 2012 | 08:56 PM

#58

TheGrandPoohBah

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Joined: Jun 2011

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From: Mountain Top, Alabama

Wow - you guys still going at it... zzz....

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Jan 3, 2012 | 09:12 PM

#59

iclick

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Joined: Sep 2005

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From: Baton Rouge, LA

Quote:

Originally Posted by boogaloodude

I don't care what the numbers are, either. However, (as you frequently say), I'm more interested in the shape of the torque curve.

I agree. I like flat, and when the curve starts looking like a bell I lose interest.

Quote:

We know the 255s fall off after 4000 rpm. They have a short intake duration, and physics pretty much dictate a short duration means less time to fill the cylinders at higher rpms, so it makes sense that the shortest cams would fall off the soonest. However, on your bike, that apparantly does not happen, or at least you keep claiming it doesn't, so I'd just like to see something to back up statements like the one you made earlier in the thread. You've got all these dyno charts, but not the one I'm most interested in seeing. Maybe your bike is an anomoly? That would be interesting to see.

I'm definitely not making myself clear. I think it's fair to say that most (all?) bolt-in cams for Harleys have their TQ peak below 4000 rpm, so you might say all of these "fall-off after 4000 rpm." I won't challenge that at all, especially for the SE255's, but that's not what I've been reacting to. I've challenged those that insinuate that the sensation is like the engine almost turning off at some point, like "run out of steam" or "fall flat on their face" as in the current example. I don't think this is representative of the way these cams feel in my bike or any other that is blessed with a proper installation and tune.

I think it's also fair to say that above 4000 rpms the 255 cams are probably among the weakest of all performance cams on the market, but although their design goal isn't to excel in that range, IMO "fall flat on their face" is not an accurate description for them. Would you not agree? My challenge is the extreme choice of words that may unfairly influence someone, that's all.