V-Twin Forum banner
1 - 6 of 6 Posts

·
Premium Member
Joined
·
48 Posts
Discussion Starter · #1 ·
Much controversy (and apparent confusion) surrounds the issue of exhaust "back-pressure". Many performance-minded people who are otherwise knowledgeable still cling tenaciously to the old school concept.... "You need more back-pressure for better performance."
For virtually all high performance purposes, backpressure in an exhaust system increases engine-pumping losses and decreases available engine power. It is true that some engines are mechanically tuned to "X" amount of backpressure and can show a loss of low-end torque when that backpressure is reduced. It is also true that the same engine that lost low-end torque with reduced back-pressure can be mechanically re-tuned to show an increase of low-end torque with the same reduction of back-pressure. More importantly, maximum mid-to-high RPM power will be achieved with the lowest possible backpressure. Period!

The correct choices and combinations of carburetor or EFI, air cleaner, cam shaft, ignition, and exhaust used in the proper relationship to each other for the intended riding application will always produce the finest quality results. Most important of all, is to do your research prior to purchasing the combination of products and equipment best suited to your individual style of riding.
 

·
I'm gonna powder his nose
Joined
·
537 Posts
"""Many performance-minded people who are otherwise knowledgeable still cling tenaciously to the old school concept.... "You need more back-pressure for better performance""""


Glad I'n not one of THOSE exhaust pipe designers.

Good answer on the last paragraph though, right on the button !
 

·
Registered
Joined
·
4 Posts
Amen to that! Do the research and get good advice. Ask yourself what ur looking for. Get a proper tune for your components by a quality tuner.
 

·
XLIII
Joined
·
10,078 Posts
chas2379 said:
More importantly, maximum mid-to-high RPM power will be achieved with the lowest possible backpressure. Period!
Please explain over-scavenging, then.
I just picked up 8 HP by going to a LESS free-flowing muffler, with the low-end unchanged.
If "mechanically re-tuned" means changing cams or heads, it's not the same engine now, is it?

Honestly not trying to be difficult, just don't understand how this aspect I just worked through relates to your statement.

Thanks!:cheers:
 
1 - 6 of 6 Posts
Top