1299S home made slip on w/RB and Ducati map

40% better driveability not power gain.

Is driveability actually measurable.

Raptor 88 said:

40% better driveability not power gain.

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I could see how you could claim driveability improved..but I am a little baffled by how you claim you can quantify it.....

he meant 38.65% improved.. unlike his welds, which are 99.99% ....... .

Shervin???? Is that you???

I remember Shervin! Hahaha, what a plum.

Raptor 88 said:

40% better driveability.

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80shilling said:

Shervin???? Is that you???

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Maybe so....He is not on the Kawasaki Forums anymore apparently...

Shervin and his ZX10R - KawiForums - Kawasaki Motorcycle Forums

Lets take a moment to remind ourselves



And of course "that" frame mod

I'm a BAD man.....

Buwahaha I forgot about skirvin!!! Frame hole zx10.. that poor bike git the bad end of a ...... owner

Damn I try and stick up for ya and you go and claim a 40% increase in power. Now I look stupid lol!!

Mr C said:

Lets take a moment to remind ourselves

And of course "that" frame mod

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.... that dude is suicidal!

Chaotic said:

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It's not easy being "green"....

I did notice with the weather change from mid 80's/90's to 60/70's that 2-4k rpm smoothed out a lot on cruising. That is with no changes.
I would figure with 2 big cylinders pushing air and the rpm range of these motor's that the cams have to be designed for more top end charge. This will give up low end drivability. Then add in emissions. To smooth out that area I would normally ( in cars) richen up the area to smooth out the overlap on the cam. This will affect gas mileage though. Another way can be restricting exhaust.

Now, being an engineer I'm surprised with using a tuner that intercept's computer output's and changes them. (not knocking it) Instead of actually reprogramming the computer.

Raptor 88 said:

40% better driveability not power gain.

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I increased my driveability by 60% by adding a comfort seat. For under $300 it can't be beat!

Many thanks for clearing up that "pulses" disappear somewhere in the primaries after scavenging has occurred and that exhaust gas velocity has nothing to do with proper exhaust design. Things like drag, material properties, and sudden changes of cross section all influence back-pressure which can increase reversion.

However, I am still impressed that you can determine your performance improvements without any objective standard to compare against because of your 40 years of experience of guessing.

"The astute exhaust designer knows that you must balance flow capacity with velocity. You want the exhaust gases to exit the chamber and speed along at the highest velocity possible - you want a FAST exhaust stream. If you have two exhaust pulses of equal volume, one in a 2" pipe and one in a 3" pipe, the pulse in the 2" pipe will be travelling considerably FASTER than the pulse in the 3" pipe. While it is true that the narrower the pipe, the higher the velocity of the exiting gases, you also want make sure the pipe is wide enough so that there is as little back pressure as possible while maintaining suitable exhaust gas velocity.

Back pressure at it's most extreme form can lead to reversion of the exhaust stream - that is to say the exhaust will flow backwards, which is...er... is not good. The trick is to have a pipe that that is as narrow as possible while having as close to zero back pressure as possible at the RPM range you want your power band to be located at. Exhaust pipe diameters are best suited to a particular RPM range (remember the pulses!). A smaller pipe diameter will produce higher exhaust velocities at a lower RPM but create unacceptably high amounts of back pressure at high rpm. Thus if your power band is located 2000-3000 RPM you'd want a narrower pipe than if your power band is located at 8000-9000 RPM.
Many engineers try to work around the RPM specific nature of pipe diameters by using set-ups that are capable of creating a similar effect as a change in pipe diameter on the fly. The most advanced is Ferrari's which consists of two exhaust paths after the header - at low RPM only one path is open to maintain exhaust velocity, but as RPM climbs and exhaust volume increases, the second path is opened to curb back pressure - since there is greater exhaust volume there is no loss in flow velocity. BMW and Nissan use a simpler and less effective method - there is a single exhaust path to the muffler; the muffler has two paths; one path is closed at low RPM but both are open at high RPM. High technology snowmobiles have also used a variable exhaust that increases or decreases back pressure as required for maximum performance at different rpm." exhaustbackpressure

Exhaust system design is very straight forward.

"Neil Spalding, Race Engine Technology's in-house expert on motorcycles, provided me with a gallery of detailed photos showing the varied strategies employed in Moto-GP (the F-1 of motorcycle racing) to shape the engine power curves with exhaust tuning finesse, along with a wealth of information on these machines, including the fact that the use of Inconel tubing is fairly common.
In several RET articles, Neil has discussed the difficulty in getting the available power to the ground in Moto-GP, and the efforts which the manufacturers have taken to improve the available traction, including implementation of uneven firing orders so as to affect the tire contact patch in a beneficial way. The uneven spacing of exhaust pulses requires some out-of-the-box thinking to gain benefit from exhaust tuning. In order to linearize the engine power curve (flatten the torque curve) there has been widespread usage of the 4-2-1 design described above in the Cup section.
These systems use various techniques specific to the particular engine, including diverging tapers in the primary tubes just past the flange, steps in the primary tubes, converging-diverging collectors, straight collectors, diverging tapered collectors, and more."
Exhaust System Technology: Science and Implementation of High Performance Exhaust Systems

so now I finally understand the relationship between pipe diameter and exhaust gas flow velocity!

So now why is longer better? WSBK exhausts have continued to grow in length. And I'm convinced that my front-exit Termi, which has the shortest exhaust path available for purchase for a Panigale as far as I know, gives up a little on the very top end, even if the dyno curves don't show it.

"The lengths of both the primary and main section of pipes strongly influence the location of the torque peak(s) within the power band. In street and track performance engines with longer pipes typically produce more low-to-mid range torque than shorter pipes and it is torque that moves a car. The question is... Where in the power band do you want to maximize the torque?
Longer pipes tend to increase power below the engine’s torque peak and shorter pipes tend to increase power above the torque peak.
Large diameter pipes tend to limit low-range power and increase high range power.
Small diameter pipes tend to increase low-range power and to some degree limit high-range power.
"Balance" or "equalizer" chambers between the exhaust pipes tend to flatten the torque peak(s) and widen the power band."
Performance and road car exhaust

If you want a good exhaust primer, read the whole article its a quick easy read.

I haven't studied Termi's front exhaust design but it appears to remove at least one 90 degree bend which is ideal when trying to maintain flow velocity and peak power.

WSBK - A broader/flatter torque curve could improve traction and drive out of the bends which may suit the Panigale better over race distance. Its all about compromising towards the strengths of your platform.