Engine builders, Dyno guru's
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From: Vermont
Engine builders, Dyno guru's
I'm in the process of changing out my Vance and Hines Pro Pipe for either a Cobra Power Port head pipe with Bub mufflers or a complete Bub 7 TDX system, which also has the cross over port. I'm leaning more toward the Cobra head pipe because I just plain like the look a little more than the Bub head pipe. The thing that is turning me off from the Bub is the plate that they use to hide the cross over. The questions I have for those in the know is what difference if any, the stepped 1 3/4 to 2 inch header on the Bub head pipe will have as opposed to the more simple 1 3/4 non stepped Cobra header on my plain old stage 1. ( I'm only running an exhaust, free breathing air cleaner and PCV tuner and nothing more.) I am aware that Fuel Moto has a PCV map for the Bub system with my current free breathing Fuel Moto air cleaner but none for the Cobra pipe as they said they haven't worked with the Cobra pipe before. Would'nt the same map work ok for either or would that stepped header make that much of a difference? In regard to the stepped verses non stepped header, I have so many opinions from everybody and their brother and don't know which is correct. Some say the
1 3/4 is the same as the stock head pipe size and works better than stepped on a stock stage 1 only motor. Others say the stepped will increase torque on any motor and still others say it makes no difference on a stock motor...both the same. The opinions are all coming from average Joe back yard mechanics like myself. Any builders or Dyno techs out there have the facts on this? Thanks Rick
1 3/4 is the same as the stock head pipe size and works better than stepped on a stock stage 1 only motor. Others say the stepped will increase torque on any motor and still others say it makes no difference on a stock motor...both the same. The opinions are all coming from average Joe back yard mechanics like myself. Any builders or Dyno techs out there have the facts on this? Thanks Rick
Last edited by Rickr01; Oct 4, 2011 at 01:26 PM.
HDF Community Team
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From: san antonio
It would help if you specified the bike and model year. The simple fact is that, in most cases, the stock head pipe is more than adequate for a Stage I upgrade. The power boost is in the mufflers.
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Oh Man yeah your right, sorry about that. Its a 2010 FLHX Street Glide, with a Stage 1 Screaming Eagle / Fuel Moto air cleaner a PCV with a pre programmed map from Fuel Moto and currently a Vance and Hines Pro Pipe. Thanks
Road Warrior
Joined: Dec 2008
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From: Australia
DJL is right, at stage 1 there is not a hell of a lot to be gained in the head pipe.
The stepped pipe will definitely cost power. Basic fluid dynamics says that a stepped expansion is actually worse for pressure drop than a stepped contraction.
At stage 1 you should go for what you like the look of, because you aint gonna set the world on fire performance wise...
The stepped pipe will definitely cost power. Basic fluid dynamics says that a stepped expansion is actually worse for pressure drop than a stepped contraction.
At stage 1 you should go for what you like the look of, because you aint gonna set the world on fire performance wise...
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I'm not overly concerned about the stock performance, it's more than adequate for my needs. Obviously I don't want to lose whats there. So the stepped will actually cost me a little, but the straight 1/3/4 pipe will not? Thanks for the professional advice! It felt like I lost the seat of the pants lower RPM grunt after I installed the stepped header Pro Pipe?
DJL is right, at stage 1 there is not a hell of a lot to be gained in the head pipe.
The stepped pipe will definitely cost power. Basic fluid dynamics says that a stepped expansion is actually worse for pressure drop than a stepped contraction.
At stage 1 you should go for what you like the look of, because you aint gonna set the world on fire performance wise...
The stepped pipe will definitely cost power. Basic fluid dynamics says that a stepped expansion is actually worse for pressure drop than a stepped contraction.
At stage 1 you should go for what you like the look of, because you aint gonna set the world on fire performance wise...
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