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Pipes and Power

S

Steve in sunny Fla

Iron Butt
Industry Vendor
I've had this conversation with 3 folks recently, so I figured it would be a relevant post.

Many folks see dyno charts from aftermarket headers and they want that extra power. Often it doesn't work out as you'ld hope.

First, you need to define what the majority of your riding consists of, and what type of riding you want the increased power for. For example, are you looking for peak WOT power like what you see on a dyno chart, or are you looking for more lower - midrange rpm for better acceleration when riding 2 up? This is an important distinction to make before you spend the money on a full exhaust system.

Aftermarket exhausts are generally tuned for better peak power production. They utilized large diameter primary and midpipes, and higher flowing mufflers. All that area slows gas velocity at lower rpms, and the result is that under lighter throttle and lower to mid rpms the bike will actually feel lazier or even sluggish. Now on the other hand, give it a handful of throttle and get the rpms up, and you'll really get an exciting boost of power!

The point here is to be honest with yourself as to what the greatest majority of your riding consists of, and what concessions you're willing to make to have your bike work the way YOU want it to. Dyno charts only tell you what the performance is at WOT and it does NOT translate to light throttle / lower rpm riding equally. I know everyone wants to see dyno charts, but they just do not tell the whole story, despite the fact that they are the #1 sales method to the less than educated rider.

  Steve
 
So, a question. Is there anything to be learned by doing dyno runs at say 50% or 75%
of wide open. Would this show the difference between 2 exhaust system and how they
effect low and mid range power?
 
RWulf said:
So, a question. Is there anything to be learned by doing dyno runs at say 50% or 75%
of wide open. Would this show the difference between 2 exhaust system and how they
effect low and mid range power?
Click to expand...

Yes, and even lower, because with a c-14 you can do anything you want it terms of normal riding and never exceed 30% throttle. Steve
 
Added a Delkevic 14" slip on to my bike and instantly felt the loss of bottom end power with a lazy feel. I expected that up front as I've had that happen on other bikes/brands. No big deal to me since I'll just keep her spinning up higher in the revs now. The loss of weight was my whole goal when swapping the pipe on this big pig.
 
Steve in Sunny Fla said:
I should clarify that this was intended towards full systems with larger head pipes, not toward slipons. Steve
Click to expand...

Yes I know but a slipon will do the same thing to a certain degree. Always has on my bikes. Had a GSX-R1000 street bike turned race bike with only a slipon pipe and it was dead flat after removing the huge CAT and mufflers. Slipon killed it down low until I had my dyno tuner add a PCV and dyno tune it. He also removed the slipons baffle first thing and said "you won't be needing this".

I certainly feel the lazy behavior now on my C14 down low with slip on verses when it had the mega can on it. I won't be throwing any money towards a dyno tune on a C14 tis what it is.
 
Roy you don't need to dunno tune your c14. The guy that started this thread has a ecu flash that will wake up you're bike. Check out his link in his signature.
 
Steve, I only partially agree with what you said.
As you know I recently installed a full Area P system and it most certainly does not feel like it got lazy in the lower rpm range. Although I must admit most of my riding is between 5k - 9k rpm.
 
  Oh yeah, one other thing I did at the same time as putting on the pipes. I got your Mountain Runner flash. What a BLAST it is to ride with that! Thanks for allowing me to gain at the top end without giving up any low end power. That's an almost unheard of combination.
:) :great: :beerchug: :motonoises:
 
Deepsea said:
Steve, I only partially agree with what you said.
As you know I recently installed a full Area P system and it most certainly does not feel like it got lazy in the lower rpm range. Although I must admit most of my riding is between 5k - 9k rpm.
 
  Oh yeah, one other thing I did at the same time as putting on the pipes. I got your Mountain Runner flash. What a BLAST it is to ride with that! Thanks for allowing me to gain at the top end without giving up any low end power. That's an almost unheard of combination.
:) :great: :beerchug: :motonoises:
Click to expand...

  Thanks Mike, but I wasn't going there with tuning, just trying to help folks understand that the hard part selection matters. And even comparing your setup with a stock head pipe tune for tune, The stock pipe is still sharper to throttle and pulls better at low rpm / light throttle condition.  So if my main goal was to better the two up riding, it wouldn't be by adding a large tube header. Steve
 
Deepsea said:
Steve, I only partially agree with what you said.
As you know I recently installed a full Area P system and it most certainly does not feel like it got lazy in the lower rpm range. Although I must admit most of my riding is between 5k - 9k rpm.
 
Click to expand...
Full AreaP great isn't it? I think it is the best sounding setup. I dont think  mine is  lazy either.
I have to get the tach over 7k to wake it up though. Anything below that say  from 2k to around  6k  a bone stock C14 (with Steve's Flash) will always out pull me. I have done this test with a few stock C14's and with slipons. Same result. I even swapped bikes  thinking it was my excessive weight causing the problem- nope- The stock C14 has more torque in the lower RPM'S over the big pipe AreaP header..But if I down shift a gear or two I am---> gone!!
 
Exhaust pipe design and tuning is a very precise science involving a great deal of physics. Specifically Fluid Dynamics and Sonic Pressure Waves. Things start to happen at the valve seat and get complicated from there. Much deeper than I want to go into here, suffice it to say that in this case bigger usually is not better except for WFO like drag racing. It's not just about "Back pressure" but includes rebounding wave forms. So as Steve said think carefully about how you ride before falling victim to advertising hype. Even with stock pipes his flash will surprise you and you can change to a slip-on without a re-flash for better sound and less fat.
  For me top end power is just slightly more important than low end torque. That's why I installed the Area P header and mid-pipe. If you ride like a normal sane person it may not be your best choice.
 
Mike, read what you just wrote. You demonstrated his point, perfectly.
  You sed; I don't think mine is lazy either, and then ya showed that Steve is right.

I have to get the tach over 7k to wake it up though. Anything below that {say  from 2k to around  6k} a bone stock C14 (with Steve's Flash) will always out pull me.
I have done this test with a few stock C14's and with slip-ons. Same result.
I even swapped bikes thinking it was my excessive weight causing the problem- nope- The stock C14 has more torque in the lower RPM'S over the big pipe Area P header..
But if I down shift a gear or two I am---> gone!!  :great:

Ride safe, Ted

PS: I know, that you were showing the difference, but Geez, your fun to pick on..
 
OK, a couple points:

1) I hope nobody is reading the original post as me saying your dumb for buying a big pipe. That wasn't the point at all, though some who want to be critical of me could twist it into that meaning. It was meant specifically to keep folks for falling into the advertising trap that dyno test runs have become. Since the 80's when the biker magazines changed from 1/4 mile times to dyno runs to show performance, dyno runs are the primary sales technique. It just doesn't always translate to the real world.

  2) let me relate a story that makes the point. Back when I first bought my c-10 in 2005, I started experimenting with ninja cams and carbs. Mike and Colt45 remember. I gained 13.5 hp, but when I did roll ons from 3k rpm with a STOCK c-10, he would just leave me for dead. So the horsepower gain in the real world was useless. it looked good on a dyno chart though, but I wasn't riding dyno's I was riding on the real road, and NOT doing 1/4 mile runs everwhere I went.

3) Mike and I have done a bunch of roll ons, and it's exactly as he said, my stock bike would be in front of his (with the full area p) by up to maybe 3 bike lengths early in the roll on, and at 6 k he would motor by like I had hit the brakes.

4) What needs to be remembered here is that I have laid out parameters  - lower rpm AND light throttle. Guys seem to gloss over the light throttle part. Since dyno runs are generally depicted as WOT, our brains default to thinking low rpm IS light throttle. Not so. You can go 3k rpm w/ 2% throttle, or 3k rpm with 100% throttle... there's a big difference in the flow volume, and this is where you can really see how pipe diameter / volume affects the power, just as you would see it on the other end of the spectrum, 100% throttle / high rpm (high flow volume).

Steve
 
The saying I always remember is...

"People buy horsepower and drive torque" :motonoises:

HP numbers are nice for bench racing, but generally are not what everyone is looking for in their butt dyno.
 
I'm sure Steve is correct, he almost always is.  But, one of my first bikes was a CB400F Super Sport (rode it to Canada and back).  The next one was a VF500F Interceptor and took a couple of 1000 mile trips on it.  I *like* high revving engines.  I have never ridden a stock C14, so I wouldn't know lazy from food stamps.  But, really, just how lazy could 1352cc be? 
 
In 1979 I put Kerker headers on my 1100 XS Yamaha with ignition advance by dealer , from a low rpm press  I  lost ground to my friends stock header 1100xs with ignition advance mod.  the only thing I gained was the attention  cops  :'(
 
Colt45 said:
But, really, just how lazy could 1352cc be?
Click to expand...

That's the best way to frame the question. the point is that it's 1352cc lazy vs 750cc, it's comparing  1352cc with one pipe, vs 1352cc with a different, larger pipe.

  Also keep in mind I've been mentioning 2 up riding. that makes a difference.

  Here's another way to look at it, in terms of what I mean "lazy" ... with the small head pipe, my bike is perfectly comfortable at 40 mph in 4th or even 5th gear. With the large pipe, at the same speed, I'd be in 3rd just to have more rpm's on the engine, or there's nothing left for accelerations.

  Steve

 
 
Steve in Sunny Fla said:
Colt45 said:
But, really, just how lazy could 1352cc be?
Click to expand...

That's the best way to frame the question. the point is that it's 1352cc lazy vs 750cc, it's comparing  1352cc with one pipe, vs 1352cc with a different, larger pipe.

  Also keep in mind I've been mentioning 2 up riding. that makes a difference.

  Here's another way to look at it, in terms of what I mean "lazy" ... with the small head pipe, my bike is perfectly comfortable at 40 mph in 4th or even 5th gear. With the large pipe, at the same speed, I'd be in 3rd just to have more rpm's on the engine, or there's nothing left for accelerations.

Good real world example!

  Steve
Click to expand...
 
"perfectly comfortable at 40 mph in 4th or even 5th gear"

Sheesh, at 40 I'm just gettin' out of 1st. :-[ :-[  Maybe that's why I only get 25 mpg.
 
Deepsea said:
"perfectly comfortable at 40 mph in 4th or even 5th gear"

Sheesh, at 40 I'm just gettin' out of 1st. :-[ :-[  Maybe that's why I only get 25 mpg.
Click to expand...

yeah, I'm talking droning the 2 lane residential roads. the speed limit is less than 40. I often do stuff like that just to see if the bike will do it, how it will react to throttle input. etc. I never actually just "ride"a motorcycle, my brain is always clickin' on what's going on inside there. Steve
 
Deepsea said:
"perfectly comfortable at 40 mph in 4th or even 5th gear"

Sheesh, at 40 I'm just gettin' out of 1st. :-[ :-[  Maybe that's why I only get 25 mpg.
Click to expand...

last week I wanted to see what the fuel economy would be if I rode the speed limit on the roads I was on. highest limit of 65. I went for a 30 mile ride. My mileage when I got back was 48.4 and climbing. I only kinda got on it 3 times. The bike was perfectly happy going the speed limit, but man... that's slow.  ::)

Steve
 
last week I wanted to see what the fuel economy would be if I rode the speed limit on the roads I was on. highest limit of 65. I went for a 30 mile ride. My mileage when I got back was 48.4 and climbing. I only kinda got on it 3 times.
Click to expand...

I don't know who the he11 you are but please give SiSF's computer back to him.

:motonoises: :beerchug:
 
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