True Duals & lowend torque
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Cruiser
Joined: May 2007
Posts: 208
Likes: 0
From: Colorado Springs, CO
True Duals & lowend torque & high altitude
Since getting rear ended on my 05 RG (see previous post) and getting my pipes tweaked I am probably looking at new exausts. I was advised against going true dual by the HD dealer due to losing bottom end torque at our higher altitude. I would also like to do this for heat control. I know the question has been beat to death but have any of you done this at HIGH ALTITUDE and did you really notice any performance loss?
Last edited by simsjam; Aug 23, 2009 at 02:08 PM.
Tourer
Joined: Mar 2008
Posts: 435
Likes: 2
From: Alberta, Canada
I live in a foothills town at approximately 4000 ft elevation. A lot (most) of my day to day riding is done higher up in the mountans to the West (Up to 7300 ft). This may or may not be considered high elevation depending on where you live.
Prior to the Andrews cam install, when my '08 RKC was still basically a stock H-D 96", I installed V&H True Duals. I also installed V&H Ovals and a Doherty intake (Current setup is Supertrapp Fatshot mufflers). I point this out because you need a good intake, mufflers and tuner or you will very likely experience lost torque regardless of the pipes (2-into-1 or duals). What I noticed with my configuration was an increase in torque across the power curve, not a loss as your dealer is telling you.
What your dealer probably should have said is the potential to build low end torque is greater with 2-into-1 pipes. But the difference in torque produced by the two types of pipes will not likely be noticeable to your butt dyno - we're only talking 1 or 2 ft/lbs difference.
I hesitate to use dyno charts for comparison because the conditions during the dyno runs vary greatly, but I have attached a copy of my dyno sheet to show how a flat torque curve (with greater than stock TQ) is possible with true duals. BTW, the dyno was done at a stealer in Calgary at 3000 ft elevation.
To answer your other question, the heat on the legs was slightly less with the duals. And as an added bonus the exhaust sound improved greatly with the duals.
Prior to the Andrews cam install, when my '08 RKC was still basically a stock H-D 96", I installed V&H True Duals. I also installed V&H Ovals and a Doherty intake (Current setup is Supertrapp Fatshot mufflers). I point this out because you need a good intake, mufflers and tuner or you will very likely experience lost torque regardless of the pipes (2-into-1 or duals). What I noticed with my configuration was an increase in torque across the power curve, not a loss as your dealer is telling you.
What your dealer probably should have said is the potential to build low end torque is greater with 2-into-1 pipes. But the difference in torque produced by the two types of pipes will not likely be noticeable to your butt dyno - we're only talking 1 or 2 ft/lbs difference.
I hesitate to use dyno charts for comparison because the conditions during the dyno runs vary greatly, but I have attached a copy of my dyno sheet to show how a flat torque curve (with greater than stock TQ) is possible with true duals. BTW, the dyno was done at a stealer in Calgary at 3000 ft elevation.
To answer your other question, the heat on the legs was slightly less with the duals. And as an added bonus the exhaust sound improved greatly with the duals.
Road Master
Joined: Apr 2009
Posts: 1,137
Likes: 0
From: Rocky Mtn High CO
+1
I have an 09 RG with Bub7 TDs, a SERT and RSD air cleaner. After the dyno tune I am running ~90 ft-lbs TQ with a pretty flat curve like the one shown above. I live in Denver and ride a lot in the mountains. Much better than the stock set-up!
I have an 09 RG with Bub7 TDs, a SERT and RSD air cleaner. After the dyno tune I am running ~90 ft-lbs TQ with a pretty flat curve like the one shown above. I live in Denver and ride a lot in the mountains. Much better than the stock set-up!
6th Gear
Joined: Aug 2009
Posts: 10
Likes: 0
simsjam,
Unlike the other two posts, you have an open loop (no O2 sensors) therfore there is a certain amount of truth to what the dealer is telling you...from '07 on the touring models all have closed loop fuel injection which allows the ecm to compensate for most altitudes. Your 05 will lose bottom end with true duals as my 06 Ultra lost bottom end. I put a Ridemaxx tuner on mine and solved all of my drivability issues. It works well for me...but I am sure others have their own opinions...the 06 and earlier ecm could adjust but not to the extent the newer systems can...so if you go TD then think of investing in a fuel tuner.
Unlike the other two posts, you have an open loop (no O2 sensors) therfore there is a certain amount of truth to what the dealer is telling you...from '07 on the touring models all have closed loop fuel injection which allows the ecm to compensate for most altitudes. Your 05 will lose bottom end with true duals as my 06 Ultra lost bottom end. I put a Ridemaxx tuner on mine and solved all of my drivability issues. It works well for me...but I am sure others have their own opinions...the 06 and earlier ecm could adjust but not to the extent the newer systems can...so if you go TD then think of investing in a fuel tuner.
Road Master
Joined: Feb 2008
Posts: 1,179
Likes: 1
From: NH
Can't say that I can feel any loss in bottom end torque when I ride in the mountains. My dyno showed that I slightly gained torque from the stock pipes. A good dyno tuner may be the key to performance.
Thread Starter
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Cruiser
Joined: May 2007
Posts: 208
Likes: 0
From: Colorado Springs, CO
simsjam,
Unlike the other two posts, you have an open loop (no O2 sensors) therfore there is a certain amount of truth to what the dealer is telling you...from '07 on the touring models all have closed loop fuel injection which allows the ecm to compensate for most altitudes. Your 05 will lose bottom end with true duals as my 06 Ultra lost bottom end. I put a Ridemaxx tuner on mine and solved all of my drivability issues. It works well for me...but I am sure others have their own opinions...the 06 and earlier ecm could adjust but not to the extent the newer systems can...so if you go TD then think of investing in a fuel tuner.
Unlike the other two posts, you have an open loop (no O2 sensors) therfore there is a certain amount of truth to what the dealer is telling you...from '07 on the touring models all have closed loop fuel injection which allows the ecm to compensate for most altitudes. Your 05 will lose bottom end with true duals as my 06 Ultra lost bottom end. I put a Ridemaxx tuner on mine and solved all of my drivability issues. It works well for me...but I am sure others have their own opinions...the 06 and earlier ecm could adjust but not to the extent the newer systems can...so if you go TD then think of investing in a fuel tuner.
Club Member
Joined: Jun 2007
Posts: 45,429
Likes: 2,898
From: Bedford UK
I also have true duals, on my S&S 107. I wrote to S&S before buying my new motor and asked what their recommended systems are and they include true duals. It is said a good 2-into-1 system is better than all others, but I have yet to see any convincing evidence. These things get repeated time and again and the internet makes that worst. I am pleased with my exhaust and the performance it gives, but I have had it set up by an S&S specialist on his dyno.
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Road Captain
Joined: Mar 2008
Posts: 724
Likes: 2
From: Cincinnati Ohio
With a race tuner, the 2 into one can give ever slightly better performance, and is usually less expensive than true duals. More performance, less cost, makes sense. That being said, I have true duals. Why? Looks better, sounds better, performs more than good enough for my non drag racing butt.
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Outstanding HDF Member
Joined: Jan 2008
Posts: 3,328
Likes: 15
From: Pacific Northwest
"You'll lose low end" seems to be the mantra of the "gotta have a 2-1" crowd. That was never my experience with my 88" ('06) motor at any altitude. I put on Rinehart TD's when they still could be had for $600 and found nothing but power gains across the board - a slight gain in low end and a real sweet mid-range. Put a set of V&H Softail Duals on the wife's 96" Heritage ('07) with the same results. Both now have a PCIII along with a Big Sucker and a dyno tune. The grin factor just keeps getting bigger.
Tourer
Joined: Sep 2007
Posts: 383
Likes: 1
Leftcoaster could not have said it any better. All of this low end torque loss nonsence has to be bad tunes on fi bikes. My carbed 04 rk custom with duals, se heavy breather and thunderheader slipons runs great and sounds awsome. Definitly runs better than it did with stock head pipes.