2into1 vs true duals
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2into1 vs true duals
It seems like most of you guys think 2into1 makes a little more hp and tq than T Ds. If this is true not saying just asking can someone tell me why. And would not the type mufflers used on T Ds make a big dif. on the tq or hp. Has someone posted dyno# T Ds vs 2into1 on same bike I have looked a lot and not seen one. If someone can tell me it would save me a lot of time and maybe $ . I am talking about 09 r k.
Club Member
Joined: Jun 2007
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From: Bedford UK
Take a look at a Buell. They use equal length pipes (and a butt ugly muffler, but that comes with getting the pipes the same length) which enables them to use a much higher state of tune than say a Sportster. The entire engine is built to make the best use of the exhaust. My XB12R gives the same HP as my 1750 S&S 107.
So if the two pipes of a 2-into-1 on a big twin are the same length, theoretically the engine will be better off. However I have never seen the evidence, except in these sorts of discussion, or people like S&S saying it is so!
I have true duals on my S&S 107 and it gives slightly better figures than S&S quotes in their catalogue. I am happy with that! It may be able to give slightly better numbers with a 2-into-1, but I have other things to spend my cash on than finding out.
So if the two pipes of a 2-into-1 on a big twin are the same length, theoretically the engine will be better off. However I have never seen the evidence, except in these sorts of discussion, or people like S&S saying it is so!
I have true duals on my S&S 107 and it gives slightly better figures than S&S quotes in their catalogue. I am happy with that! It may be able to give slightly better numbers with a 2-into-1, but I have other things to spend my cash on than finding out.
Grand HDF Member
Joined: May 2008
Posts: 4,624
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From: Newcastle, Ca.
One important thing about numbers, its not all about peak numbers, its more about the area under the curve. Also, ask tuners what pipes they recommend.
Basic tutorial.
http://www.youtube.com/watch?v=zwjpwC0ZM44
http://www.youtube.com/watch?v=YfSOthdE6lU
http://www.hotbikeweb.com/tech/0306h.../photo_10.html
Despite all this, if you like TD's, you should get them.
Basic tutorial.
http://www.youtube.com/watch?v=zwjpwC0ZM44
http://www.youtube.com/watch?v=YfSOthdE6lU
http://www.hotbikeweb.com/tech/0306h.../photo_10.html
Despite all this, if you like TD's, you should get them.
Club Member
Joined: Jun 2007
Posts: 45,429
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From: Bedford UK
Lets take a look at what happens in a real engine with true duals, my S&S V107T, fitted with Samson TD pipes and S&S oval mufflers. Except for a few minor adjustments on the dyno it is straight out of the box from S&S, with Super G carb and 585 cam. See the curves attached Ive stretched them vertically a bit, to show them better. At the time my motor had only a few hundred miles on it, hence it was not run up to peak rpm. It has done over 8k now and it feels stronger and runs smoother.
On first glance you might think we can see the double torque curve referred to in the video, which is supposed to be typical of TDs, but there are two things to consider. One is that from around 2,600rpm right through to 5,700rpm it is making 90 ft.lbs or more (peak of 103). So that apparent dip is just 3 ft.lbs and is not detectable on the road. The other point is the air/fuel ratio, which looks pretty awful! What we can see is transition between jets, typical of a simple carb. It may be possible to improve on that and if the bike had EFI the mixture would be near perfect, in which case the very slight dip around 3,500rpm would not be there.
So while the double bump may happen in some motors, it isnt there in mine. It wont be there in many other motors either. Engines in a very different state of tune may well behave differently. I might someday invest in some development work to see if I can improve my air/fuel ratio, but I would then expect to see a perfect torque curve, like a 2-into-1 is supposed to give. In fact I already have one.
Discuss!
Stellar HDF Member
Joined: Feb 2010
Posts: 3,121
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From: sunny florida
I agree with Graham, you can say this or that and make an argument for or against 2 into 1 or 2 into 2 but all I will tell you is on my 01 FLHTCI it was an 88ci bored out to a 95ci , head work, cams , ported , polished ,power commander etc. and I run true duals, I have over 100hp and over 100 lbs. of torque and my bike pulls so hard and never levels off if you are on it hard you better be watching the tach to shift so the rev limiter doesn't shut it off and make you look stupid, I watched the youtube videos that were attached and all I will say is you cannot prove by me 2 into 1 out perform true duals
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From: Bedford UK
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Thanks Graham and tj316 I think what we are seeing here is that if everthing matches up and tuned right you can make a great preforming ride out of T Ds or 2into1s. I raced drag cars years ago and I found that if you change one thing you allways had to change something else to match what you were trying to do. Thanks for the great info. Remember its all about the ride and I love it. Bill
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Joined: Jun 2007
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From: Bedford UK
Thanks Graham and tj316 I think what we are seeing here is that if everthing matches up and tuned right you can make a great preforming ride out of T Ds or 2into1s. I raced drag cars years ago and I found that if you change one thing you allways had to change something else to match what you were trying to do. Thanks for the great info. Remember its all about the ride and I love it. Bill