Want to Buy Exhaust for Roadster

[Claviger]

If true - HOW MUCH HP diff and please show comparative dynos.

A good summary. I know you know this already Steve.

For the benefit of those that don't, the Carp pipe has shorter, slightly larger diameter primaries after the head flange (all the same size), so theory dictates the Carp pipe will make more power up top, but less total area under the curve. Pretty much reflected in the dyno's I've seen of them.

 

[1olbull]

A good summary. I know you know this already Steve.

For the benefit of those that don't, the Carp pipe has shorter, slightly larger diameter primaries after the head flange (all the same size), so theory dictates the Carp pipe will make more power up top, but less total area under the curve. Pretty much reflected in the dyno's I've seen of them.

I follow the math but be far from a header expert! What is the formula for determining the primary header length?
Vids were very interesting and I would up watching several more.
Kewl science!!!

 

[leatal]

A good summary. I know you know this already Steve.

For the benefit of those that don't, the Carp pipe has shorter, slightly larger diameter primaries after the head flange (all the same size), so theory dictates the Carp pipe will make more power up top, but less total area under the curve. Pretty much reflected in the dyno's I've seen of them.

I seem to remember someone here had a discussion a while back about the ideal primary length being as close to 30" as possible, and diameter of 1.75". This keeps to torque down low with very little horsepower loss at the top (on stock or lightly nodded engines). If you go highly modified with higher RPM for maximum horsepower, short and large diameter are the way to go. Sooooo the CARPENTER pipe works very well for the Carp engines, max horsepower on top, slight loss on bottom end torque. The CES and the Reband seem to closely match the the ideal length and diameter for those of use who like torque down low, and operate the engine RPM within OEM design limits. I'm sure Art will chime in and mention you won't win drag races or achieve blistering top speeds with longer, smaller primaries, but most of us will never go there anyway. Now for a fly in the ointment, FORKLIFT bought the Carp Sidewinder system and did an extensive writeup with pictures. He did state the pipes seem to lose nothing on the bottom but gave him an engine that was eager to accelerate to top RPM. Go figure! Anyone with a Carp Sidewinder system want to chiime in?

 

[Paul Bryant]

I follow the math but be far from a header expert! What is the formula for determining the primary header length?
Vids were very interesting and I would up watching several more.
Kewl science!!!

The formula for the length of a primary tube is based on the Exhaust Cam timing and the RPM that you want the power at, multiplied by a specific magic figure. (fact)
This then gives you the over all length of the pipe measured from the center of the piston at BDC.
There are a lot of variables that come into play, one being the rider/driver of the Vehicle as different riding/driving styles can have different effects.

 

[1olbull]

The formula for the length of a primary tube is based on the Exhaust Cam timing and the RPM that you want the power at, multiplied by a specific magic figure. (fact)
This then gives you the over all length of the pipe measured from the center of the piston at BDC.
There are a lot of variables that come into play, one being the rider/driver of the Vehicle as different riding/driving styles can have different effects.

THANK YOU!!!
Do you also happen to have the exhaust valve diameter, opening degree, duration and centerline for the Rocket Roadster?
Trying to learn more about this stuff . . .

 

[sleeves]

THANK YOU!!!
Do you also happen to have the exhaust valve diameter, opening degree, duration and centerline for the Rocket Roadster?
Trying to learn more about this stuff . . .

Hi Bull

Think this is what your after? was building my own headers a while back before I caught up with Paul down the road, had done all the above maths. Sorry its in metric but that's how we roll here.

 

[Claviger]

Its listed in the service manual

30" primary @ 1.75 is a very good primary size/length for the stock motor. The diameter targets a peak torque boost right around 4600 RPM, and the length targets about 3900, a good point that helps extend the upper power band, coincidentally the CES exhaust is very close to these numbers.

The collector and post collector length will pivot the curve around that 4600 number, so shorter will tilt to to increase upper/decrease lower and vice versa. Paul's systems look like they will, guessing here, target something like 4800/5000 for peak pulse tune, also a very good spot, I expect they make power graphs similar to CES.

Carps pipes do indeed have bigger primaries, moving power up to 5900, shorter primaries, moving power up, BUT, they use the megaphone collector style that's fairly long, this will increase exhaust gas velocity, improving bottom end, so it will make a good "everywhere" power curve. What you will find, is as exhaust flow increases, primary diameter will matter more, so yes, on the built motors the non-carp exhuasts using 1.75 "may" cause a reduction in ultimate top end power, but should be trading that off for an increased area under the curve, BUT, if 1.75 just becomes straight up undersized, they would lead to a reduction everywhere in the RPM band vs the 2.0 primaries.

I should qualify that I am of the opinion the Carp pipes will make notably less power at part throttle conditions than any other R3 system out there.


If you look at cam timing, it creates peak power low down, so having the exhaust create power higher up extends the torque curve giving a longer, broader power band, something reflected in all the dyno graphs of aftermarket headers (besides zard's garbage).

Someday when my **** dealer gets off their asses and gets my 265 head/cams put on, we'll find out, I plan on going sidewinder at some point, so there can be a back to back apples to apples ces vs carp header on the 2wdw dyno when I get to WA.

 

[BigKel]

Its listed in the service manual

30" primary @ 1.75 is a very good primary size/length for the stock motor. The diameter targets a peak torque boost right around 4600 RPM, and the length targets about 3900, a good point that helps extend the upper power band, coincidentally the CES exhaust is very close to these numbers.

The collector and post collector length will pivot the curve around that 4600 number, so shorter will tilt to to increase upper/decrease lower and vice versa. Paul's systems look like they will, guessing here, target something like 4800/5000 for peak pulse tune, also a very good spot, I expect they make power graphs similar to CES.

Carps pipes do indeed have bigger primaries, moving power up to 5900, shorter primaries, moving power up, BUT, they use the megaphone collector style that's fairly long, this will increase exhaust gas velocity, improving bottom end, so it will make a good "everywhere" power curve. What you will find, is as exhaust flow increases, primary diameter will matter more, so yes, on the built motors the non-carp exhuasts using 1.75 "may" cause a reduction in ultimate top end power, but should be trading that off for an increased area under the curve, BUT, if 1.75 just becomes straight up undersized, they would lead to a reduction everywhere in the RPM band vs the 2.0 primaries.

I should qualify that I am of the opinion the Carp pipes will make notably less power at part throttle conditions than any other R3 system out there.


If you look at cam timing, it creates peak power low down, so having the exhaust create power higher up extends the torque curve giving a longer, broader power band, something reflected in all the dyno graphs of aftermarket headers (besides zard's garbage).

Someday when my **** dealer gets off their asses and gets my 265 head/cams put on, we'll find out, I plan on going sidewinder at some point, so there can be a back to back apples to apples ces vs carp header on the 2wdw dyno when I get to WA.

My CES makes power thru to 8000 rpm. Can you post the dyno graph when you get your Carp system on as I have never seen a Carp graph going past 8000.

 

[Claviger]

They will make power anywhere, but will they make more with a Sidewinder? That's really the question. Yes, I'll post graphs as it all comes along, will be over a few months though, need head/cam first, then move to WA, then get sidewinders.

Edit: won't go over 7000 on my bike, new roadster = no 9000 RPM map

 

[Fourfive]

What header is this? Amazing bike man.