• Welcome to the BMW R18 Forums. Member registration disables ads and allows you to post and share. Register Here.

Any idea of what kind of exhaust is this one?

  • <i class="fa--xf fal fa-check "><svg xmlns="http://www.w3.org/2000/svg" role="img" aria-hidden="true" ><use href="/data/local/icons/light.svg?v=1789222567#check"></use></svg></i> Discussion starter Discussion starter JC_CASIRAGHI
  • Start date Start date

Attachments

  • IMG_1153.jpeg
    IMG_1153.jpeg
    1 MB · Views: 51
I like it! I've been keeping a eye out for a attractive transition from the stock header heat shields to a shorty like that. If anyone knows if those are being sold or something similar, please post and let us know
 
They are made to order as opposed to a production line. He is a bike builder and I guess that if you ask him to replicate the exhaust he did for the show bike he will build one for you . When I was talking to him about bike building etc, he did say that the possibility are endless and the real limit was my wallet, i.e, how much one is prepared to spend on a project.
 
I think the most torque you can get out of an exhaust system is a 2 into 1. None of the R18 s have that available even aftermarket that I know of.

Keep in mind that the longer pipes generate a reverb and back pressure needed for the most torque. When you start swapping out pipes you change the torque curve. What I have found is besides the looks and sound, you actually lose power with the shorter "cooler" looking pipes. Or, your off the line might improve very slightly, then at 2000 rpms or so it fizzles out. Seems like with a motor this size you want the max torque around 3500-3800 rpms.
And the only way to know for sure unless it's really obvious is on a reliable Dyno.
 
Randy Kahn said:
I think the most torque you can get out of an exhaust system is a 2 into 1. None of the R18 s have that available even aftermarket that I know of.

Keep in mind that the longer pipes generate a reverb and back pressure needed for the most torque. When you start swapping out pipes you change the torque curve. What I have found is besides the looks and sound, you actually lose power with the shorter "cooler" looking pipes. Or, your off the line might improve very slightly, then at 2000 rpms or so it fizzles out. Seems like with a motor this size you want the max torque around 3500-3800 rpms.
And the only way to know for sure unless it's really obvious is on a reliable Dyno.
Click to expand...
Bla bla bla …. “And the only way to know for sure unless it's really obvious is on a reliable Dyno.”

😂
 
Randy Kahn said:
I think the most torque you can get out of an exhaust system is a 2 into 1. None of the R18 s have that available even aftermarket that I know of.

Keep in mind that the longer pipes generate a reverb and back pressure needed for the most torque. When you start swapping out pipes you change the torque curve. What I have found is besides the looks and sound, you actually lose power with the shorter "cooler" looking pipes. Or, your off the line might improve very slightly, then at 2000 rpms or so it fizzles out. Seems like with a motor this size you want the max torque around 3500-3800 rpms.
And the only way to know for sure unless it's really obvious is on a reliable Dyno.
Click to expand...
I agree. Most of us are cruiser type guys and don't actually care about a little bit of power loss in a certain rpm range.i always say I don't care and after I do it I usually think Damn why did I do that?? Lol
 
Longshot said:
I agree. Most of us are cruiser type guys and don't actually care about a little bit of power loss in a certain rpm range.i always say I don't care and after I do it I usually think Damn why did I do that?? Lol
Click to expand...
Years ago I didn't realize that the pipes can effect acceleration and overall how the bike runs. Then I got to be friends with a mechanic with a lot of experience who also had a Dyno that he made sure was calibrated to give accurate results. Then I started on a journey of having motors built, experimenting with lifters, cams, heads, exhausts.et.et.

My goal with this R18 is to try and NOT modify it......but I spent a lot of $$$ on very cool pipes that were just that, very cool, but didn't do jack shit....
 
Randy Kahn said:
This comes from maybe 100 hours over 10 years with various exhausts on a Dyno. But you find that funny???
Click to expand...
Yup.

All the experience in the world means nothing without knowing the science of how something works.

Back pressure is a myth as it relates to modern engine performance; so 1970.
Back pressure is just additional work the engine has to overcome.

A little homework can go a long way if someone really wants to learn. Folks should google “ back pressure myths”. And/or “scavenging velocity” .

Everyday is a school day.
 
Last edited:
Gr8adv said:
Yup.

All the experience in the world means nothing without knowing the science of how something works.

Back pressure is a myth as it relates to modern engine performance; so 1970.
Back pressure is just additional work the engine has to overcome.

A little homework can go a long way if someone really wants to learn. Folks should google “ back pressure myths”. And/or “scouring velocity” .

Everyday is a school day.
Click to expand...
Respectfully, I have found experience to be FAR superior to opinions. You of course believe what you like...I have thousands and thousands of dollars and hundreds of hours screwing around with bikes that tells me different...
BTW if you notice at some airports that have huge backwalls placed where the jets take off....why??? Back pressure. It's a different dynamic....but a related principle.

But anyway....no matter....I'm sure your right.....
 
Randy Kahn said:
Respectfully, I have found experience to be FAR superior to opinions. You of course believe what you like...I have thousands and thousands of dollars and hundreds of hours screwing around with bikes that tells me different...
BTW if you notice at some airports that have huge backwalls placed where the jets take off....why??? Back pressure. It's a different dynamic....but a related principle.

But anyway....no matter....I'm sure you’re right.....
Click to expand...
I guess everyday is not a school day. 😂

Here is a link with some basic language knowledge of the science behind engine exhausts. There are a great many more technical discussions available.


Even though I continue to be amazed at some peoples disregard for science and knowledge, we must remember this thread is about a cool looking exhaust! Especially (for me) about someone who has apparently finally built a heat shield that fits and looks good on the shorties.

Ride on.
 
Randy Kahn said:
I think the most torque you can get out of an exhaust system is a 2 into 1. None of the R18 s have that available even aftermarket that I know of.

Keep in mind that the longer pipes generate a reverb and back pressure needed for the most torque. When you start swapping out pipes you change the torque curve. What I have found is besides the looks and sound, you actually lose power with the shorter "cooler" looking pipes. Or, your off the line might improve very slightly, then at 2000 rpms or so it fizzles out. Seems like with a motor this size you want the max torque around 3500-3800 rpms.
And the only way to know for sure unless it's really obvious is on a reliable Dyno.
Click to expand...
2 into 1 was always the best. At least when I had Harley-Davidsons. And they bark!
 
Last edited:
emgarciax said:
2 into 1 was always the best. At least when I had Harley-Davidsons. And they bark!
Click to expand...
2 into 1 ‘generally’ increases scavenging and increases exhaust flows. (The exact opposite of back pressure). But it’s not always the case. And many times the gains are not material. Some people really like the look.

Anything one can do to get more high velocity airflow out of the engine with the correct air/fuel ratio, gains can be had.

To not make this post too long, here is a good link by Dennis Kirk that describes the idea with the needed healthy does of “it’s not that simple”.

https://www.denniskirk.com/blog/2018/09/19/2-into-1-system-vs-true-dual-exhaust-a-comparison/
 
Fwiw I did send him a message yesterday. Still have not heard back. I’ll keep folks posted when I learn something/anything
 
You must log in or register to reply here.
Back
Top