Why is the exhaust favored for duration

[1FSTRK]

"But as many found out those cams gave average gains until used with Kury heads"

I've used them 3 times in the last 12 years, 1 with HTCC heads, one with Dorfman's heads, and the current one with stock heads. No worse than other comparable builds with like compression, pipes etc.
Latest attached.

So we are in agreement then.

ADDED
I just looked closer at you dyno sheet and the 24 was not a great example of Rolands designs because it was actually developed to be a bolt in cam for the 110 head. All the same we still agree.

[1FSTRK]

Have any of you Dynomation users done any testing with version -6 rev13 to compare it with actual engine data?
The first version of -6 was inconsistant compared to the same data run through -5. I also wonder how the new exhaust tuning will prove out in real life as it is a bit different than pipemax.

[rigidthumper]

I just ordered version 6, so we'll see. I liked 4 better than 5, but 4 locks up in Pro-iterator mode, and 5 isn't being upgraded any more.

[Deye76]

Those 24 cams have done well in 103" (no 110 heads) as well. My point and I believe I have proved it when I used 46's with Dorfmans heads, is you don't have to use Kury heads. Are there better 113" out there, of course, but most are at 200+ccp. This was 186ccp

[Don D]

Zippers video proves that there are no good and bad cams, only good and bad combinations. The two work hand and hand. Of course the peripherals have to cooperate too. The m8 have a 1.9 port inlet, large valve and CSA and flow a lot thus they don't take as much intake duration. The exhaust a different story. This is very different from a twin cam as stated but in the twin cam family there are variants there too. I have always thought the large CSA on the exhaust side of the TC head was an EPA move to slow the flow but have no confirmation of that. But even within twin cams there are large differences of what cam will work with which heads to accomplish the goal and do so with street manors still there. I talked to Mike Roland at length about the exhaust port of the OEM TC head many years ago and he told me what to do to the ports to get them to work better with the WT cams. That is history now and we have new motors. But some of his theorys including no particular importance for high lift flow on the exhaust side I remember.

[Timinator]

 Cam selection in relation to rod/stroke ratio, engine size, and compression ratio is a BIG deal, and not figuring that into cam selection is really leaving HP on the table. Most of the peeps that call wanting cam info, or whining about what a "junk" cam that brand "X" is, have selected a profile from what they heard in somebody else's bike or car, and liked the sound, or "my neighbors, dads, friend used it back in the day in his EVO and it was bad**s."
Some of the most popular street car cams are the Comp Cams Thumper series. They don't make good power, but sound like they do. Talking to the techs and engineers there, they are bummed out (that dated me didn't it?), that they make so many different cams to have one just right for everybody, and peeps are buying 350 HP 327 clone cams and Thumpers, and crying about the results.
The problem now, is that since the M-8 is out, I know that cam development for the Twin Cam cams will grind to a halt. Pun intended. From what I have seen, the big name grinders all have some excellent cams, and a few clunkers too. Don't limit yourself to one brand only, figure out what you need and see which grinders make something close, then ask around or Google for further info. The fast guys buy several similar cams from different companies and compare them, on the dyno and Cam Analyzer to figure out what worked and why. A cam analyzer will show the nuances of area under the curve, ramp rates, symmetry or asymmetry, and overall shape. Knowing what a particular combination "likes" adds to your knowledge base for further cam selections. OK, so you don't have an analyzer, many shops do, and will profile/ graph cams for you, just like they will dyno or flow bench your heads or engines.   TIMINATOR

[Matt C]

I flowtest stuff for other people all the time. It's fun to see what the other stuff out there
actually does. And my computer stores all that stuff.

[1workinman]

Cam selection in relation to rod/stroke ratio, engine size, and compression ratio is a BIG deal, and not figuring that into cam selection is really leaving HP on the table. Most of the peeps that call wanting cam info, or whining about what a "junk" cam that brand "X" is, have selected a profile from what they heard in somebody else's bike or car, and liked the sound, or "my neighbors, dads, friend used it back in the day in his EVO and it was bad**s."
Some of the most popular street car cams are the Comp Cams Thumper series. They don't make good power, but sound like they do. Talking to the techs and engineers there, they are bummed out (that dated me didn't it?), that they make so many different cams to have one just right for everybody, and peeps are buying 350 HP 327 clone cams and Thumpers, and crying about the results.
The problem now, is that since the M-8 is out, I know that cam development for the Twin Cam cams will grind to a halt. Pun intended. From what I have seen, the big name grinders all have some excellent cams, and a few clunkers too. Don't limit yourself to one brand only, figure out what you need and see which grinders make something close, then ask around or Google for further info. The fast guys buy several similar cams from different companies and compare them, on the dyno and Cam Analyzer to figure out what worked and why. A cam analyzer will show the nuances of area under the curve, ramp rates, symmetry or asymmetry, and overall shape. Knowing what a particular combination "likes" adds to your knowledge base for further cam selections. OK, so you don't have an analyzer, many shops do, and will profile/ graph cams for you, just like they will dyno or flow bench your heads or engines.   TIMINATOR

Back in the day I tried on of those cams and pulled it I got one of there 292 solid lift , ran a lot better for me . Since your discussing camshafts why do you think SS installed the 635 in the 143 engine , Thanks Jim

[Deye76]

"Don't limit yourself to one brand only"

I never have, in my first TC I was a cam whore. Nobody I knew had a cam analyzer. I was willing to try different combinations, and not BS anybody as what I had was the best. The ones that didn't play well with the rest of the parts I  chose, were bore out when I got my ass whipped, and then I warned my friends my choices didn't work. Then dyno's became mainstream and information more readily available. What pisses me off is when theory is given more weight than actual testing, without an agenda. And contrary to some peoples beliefs, dyno sheets don't tell the whole story either.

[Timinator]

Workinman, I have a theory about the 635, I believe they used that IMHO, goofy a** cam for the same reasons that the MOCO installed the pos 211 cams in the CVO Breakout: a lot of overlap for the sound, a high lift to try to make at least  some power,because the long exhaust duration allows the engine to rev freely in the upper rpms (even if it doesn't make a lot of power), liability (big motor with big cam would make more power than the check book squids can safely handle, but they can still brag they have a big motor), and from the MOCOs standpoint, they got the sound and some power while appeasing the government smog folks. LAST BUT NOT LEAST: both the MOCO and S&S sell everything they make, including IMHO a less than wonderful cam, but hope they can get you to pay them for an upgrade at the dealer level.
Along the same lines: I truly believe the mission statement for the MOCOs exhaust division is: "design something barely nice enough to sell the bike, but ugly enough for us to sell them an upgrade." 
How many years did the MOCO shove those butt ugly Fatboy wheels down the throats of consumers? You can't go to any bike swap meet without seeing them! Next to exhausts, those wheels must be the most replaced parts ever!
The aforementioned rant was just my own personal opinion, and in no case were actual facts checked, consulted, or verified....   
  MODERATORS:  If this rant is too inflammatory for the board, please feel free to remove it. It is just my opinion.  TIMINATOR

[N-gin]

"Don't limit yourself to one brand only"

I never have, in my first TC I was a cam whore. Nobody I knew had a cam analyzer. I was willing to try different combinations, and not BS anybody as what I had was the best. The ones that didn't play well with the rest of the parts I  chose, were bore out when I got my ass whipped, and then I warned my friends my choices didn't work. Then dyno's became mainstream and information more readily available. What pisses me off is when theory is given more weight than actual testing, without an agenda. And contrary to some peoples beliefs, dyno sheets don't tell the whole story either.

I've grown quite fond of 2 cam sellers. I haven't really cared to try others in my bike. Of course I have recamended other manufactures with great results.
I just think those other cams aren't what I'm looking for as I read the specs and what I have learned, however I'm beginning to see yours and others points.
There are 2 cams I am interested in trying, one is discontinued and the other was recamended from a member. I'm chomping at the bit to try them both.

[wfolarry]

I installed a lot of those 211 cams with good results. As it is with a lot of cams it's not a bolt in but set up right it works good. Might not be my favorite but I can get them to work.
S&S always liked a lot of exhaust duration. They have their own reasons with the testing they do. I think the 635 just expanded on that idea as the cubic inches increased.
I have seen where changing one cam for another with almost identical #'s on paper made a big difference in performance.

I'd rather have a good dyno tune than a good dyno sheet.

[Matt C]

Workinman, I have a theory about the 635, I believe they used that IMHO, goofy a** cam for the same reasons that the MOCO installed the pos 211 cams in the CVO Breakout: a lot of overlap for the sound, a high lift to try to make at least  some power,because the long exhaust duration allows the engine to rev freely in the upper rpms (even if it doesn't make a lot of power), liability (big motor with big cam would make more power than the check book squids can safely handle, but they can still brag they have a big motor), and from the MOCOs standpoint, they got the sound and some power while appeasing the government smog folks. LAST BUT NOT LEAST: both the MOCO and S&S sell everything they make, including IMHO a less than wonderful cam, but hope they can get you to pay them for an upgrade at the dealer level.
Along the same lines: I truly believe the mission statement for the MOCOs exhaust division is: "design something barely nice enough to sell the bike, but ugly enough for us to sell them an upgrade." 
How many years did the MOCO shove those butt ugly Fatboy wheels down the throats of consumers? You can't go to any bike swap meet without seeing them! Next to exhausts, those wheels must be the most replaced parts ever!
The aforementioned rant was just my own personal opinion, and in no case were actual facts checked, consulted, or verified....   
  MODERATORS:  If this rant is too inflammatory for the board, please feel free to remove it. It is just my opinion.  TIMINATOR

[Don D]

The S&S 635 cam was designed to enhance and work well with their b2 and b3 heads. The combination again. First motor they appeared in was the 126 I believe. Their wonky timing make for a tuners cussing session and are a challenge when trying to get v to v clearance on oem and other heads.
Read the literature on a 143. They warn about raunchy manors. He'll a 143 with a little more squeeze and their 675 would probably be a lot more fun and comfortable too

[gordonr]

Have any of you Dynomation users done any testing with version -6 rev13 to compare it with actual engine data?
The first version of -6 was inconsistant compared to the same data run through -5. I also wonder how the new exhaust tuning will prove out in real life as it is a bit different than pipemax.

  With regards to Pipe Max I choose one cylinder to test with with. Then with the results I input the data into D5 and I start from there. I still have issues in getting an accurate @ the wheel tq. HP is always close to real dyno results though. As a note: Reading Tq @ the crank resembles something better but... But in end I do get good trend intel. Also I find  primary exhaust lengths (2-1 only) I figure off single cylinder models because of the 315 degree issue.

[1workinman]

The S&S 635 cam was designed to enhance and work well with their b2 and b3 heads. The combination again. First motor they appeared in was the 126 I believe. Their wonky timing make for a tuners cussing session and are a challenge when trying to get v to v clearance on oem and other heads.
Read the literature on a 143. They warn about raunchy manors. He'll a 143 with a little more squeeze and their 675 would probably be a lot more fun and comfortable too

I appreciate the information , I spoke to SS a while back about the 640 and they even said that they had tried the 670 in it . I asked why not the 640 , it did not make the power , but they did not increase the compression ,  I think most of the reason the 143 acts the way it does is the 635 , I guess we shall see 

[Timinator]

Right on! Gordonr! You can learn different things with the Dynomation and pipemax with a single cylinder example. I also experiment on single cylinder engines because it is easier and quicker to have to only change one thing to see the results. When I was learning porting, after the singles, I ran a 2300 4 cyl Pinto for a few years. The changes to one head and ease of pulling one head or intake manifold made the learning curve quicker.  TIMINATOR

[Matt C]

Right on! Gordonr! You can learn different things with the Dynomation and pipemax with a single cylinder example. I also experiment on single cylinder engines because it is easier and quicker to have to only change one thing to see the results. When I was learning porting, after the singles, I ran a 2300 4 cyl Pinto for a few years. The changes to one head and ease of pulling one head or intake manifold made the learning curve quicker.  TIMINATOR

Singles are fun to experiment on. When I was in school, we had a little water brake dyno, and a mini flow bench.
Those little engines were fun to blow up!