do anyone knows what the exhaust collector looks like?

[Pat Conlon]

Another consideration is the firing order.
The more even the pulse spacing and the longer spacing distance within the tubes, the better the scavenging.
I say should but it's hard to do on a 4 into 2 into 1 header system on a I-4 cylinder engine with the FJ's firing order of 1-2-4-3.
Instead of connecting cylinder #1 to cylinder #2 and on the other side connecting cylinder #3 to cylinder #4 theoretically with 1-2-4-3 firing order, cylinders #1 should be connected with #4 and #2 connected to #3, again, like the coils. Hard to connect #1 with #4 and keep the tubes equal length.

Several years ago there was a 4-2-1 FJ header for sale on FleaBay that had header tube #1 crossed over 2/3 and merged with #4.  It sure looked weird.


A 4-1 system has no such concerns.

[mtc]

Another consideration is the firing order.
The more even the pulse spacing and the longer spacing distance within the tubes, the better the scavenging.
I say should but it's hard to do on a 4 into 2 into 1 header system on a I-4 cylinder engine with the FJ's firing order of 1-2-4-3.
Instead of connecting cylinder #1 to cylinder #2 and on the other side connecting cylinder #3 to cylinder #4 theoretically with 1-2-4-3 firing order, cylinders #1 should be connected with #4 and #2 connected to #3, again, like the coils. Hard to connect #1 with #4 and keep the tubes equal length.

Several years ago there was a 4-2-1 FJ header for sale on FleaBay that had header tube #1 crossed over 2/3 and merged with #4.  It sure looked weird.




A 4-1 system has no such concerns.

yes for optimization

i see what you are saying

https://pantera.infopop.cc/fileSendAction/fcType/0/fcOid/1598208421242774/filePointer/1598208421571197/fodoid/1598208421571195/imageType/LARGE/inlineImage/true/bundle_of_snakes.JPG

i think that is why the stock "expansion chamber" works so well, it roomy, directs flow, commingles all pulsation to 2 outlets, and tuned for the fj's factory power-band, (with none of the 4 to 1 flat spot) so maybe the first response  could be doable, block one outlet on the manifold and enlarge the remaining, but curve the left side not unlike the famed Dynomax super turbo internal half pipe redirecting flow

https://www.google.com/search?q=dynomax+super+turbo+muffler&tbm=isch&chips=q:dynomax+super+turbo+muffler,g_1:cutaway:aJ3AnECPNqY%3D&client=firefox-b-1-d&hl=en&ved=2ahUKEwiCwvnJu63pAhVSWKwKHZ2mDD0Q4lYoAXoECAEQFw&biw=1041&bih=598

call our mid-pipe a resonator

https://nascargallery2019.blogspot.com/2019/02/nascar-boom-tube-exhaust.html

[FJ1200W]

Another consideration is the firing order.
The more even the pulse spacing and the longer spacing distance within the tubes, the better the scavenging.
I say should but it's hard to do on a 4 into 2 into 1 header system on a I-4 cylinder engine with the FJ's firing order of 1-2-4-3.
Instead of connecting cylinder #1 to cylinder #2 and on the other side connecting cylinder #3 to cylinder #4 theoretically with 1-2-4-3 firing order, cylinders #1 should be connected with #4 and #2 connected to #3, again, like the coils. Hard to connect #1 with #4 and keep the tubes equal length.

Several years ago there was a 4-2-1 FJ header for sale on FleaBay that had header tube #1 crossed over 2/3 and merged with #4.  It sure looked weird.


A 4-1 system has no such concerns.

Kawasaki's KZ650SR had a similar setup.

Supposedly it put out more midrange power than the "normal" setup.

Looks really good IMO

[FJ1200W]

Cosmetic appearance  IMO, is WAY better with symmetry ( Toucans ) but it's what YOU perceive as best appearance, ( I prefer sheilas with both cans) 


Cheers
Alan

That's good stuff

[FJ_Hooligan]

The EXUP exhaust valve on the FZ1 changes the exhaust pairing at higher RPMs for better performance.