Why no True Dual headers from factory?
#1
05-07-2015 | 10:42 AM
Why no True Dual headers from factory?
#5
05-07-2015 | 12:21 PM
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Joined: Jun 2007
Posts: 45,429
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From: Bedford UK
There is not a new vehicle on the planet these days, with two cylinders or more, that does not have an exhaust system with all cylinders linked together. The reason is simply that by doing so the engine gives improved torque and driveability, indeed it can be much better tuned by the manufacturer. TDs are simply drag pipes with mufflers and will only work well at the revs the pipe length is optimised for, while a collector system works over a much wider rev range.
Back in the '60s IIRC BSA discovered that linking the two pipes of their parallel twins improved torque, so they adopted them across the BSA and Triumph ranges and within a few years all the major twin manufacturers had copied them. It seems to be a collective amnesia amongst Harley owners that their twins have probably been made with a 2-into-1 system for longer than any other set-up they have used!
In the case of my own Glide, I have had it dynoed by the same shop with TDs and my current SuperTrapp 2-into-1. The headline numbers for both are very similar, however the SuperTrapp gives me up to 15% more torque in the low/mid rev range, where most of us ride. A bonus is that the engine also runs much smoother and is a great deal nicer to ride. I will never use TDs again!
Back in the '60s IIRC BSA discovered that linking the two pipes of their parallel twins improved torque, so they adopted them across the BSA and Triumph ranges and within a few years all the major twin manufacturers had copied them. It seems to be a collective amnesia amongst Harley owners that their twins have probably been made with a 2-into-1 system for longer than any other set-up they have used!
In the case of my own Glide, I have had it dynoed by the same shop with TDs and my current SuperTrapp 2-into-1. The headline numbers for both are very similar, however the SuperTrapp gives me up to 15% more torque in the low/mid rev range, where most of us ride. A bonus is that the engine also runs much smoother and is a great deal nicer to ride. I will never use TDs again!
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