Topic: 4 into 1 or 4 into 2 exhaust?

[75 super sport]

Just wondering if anyone had any helpful advice in helping me make a decision on which exhaust system to go with. I have been looking at a mac 4 into 2 exhaust and was curious as to if there are any significant power losses in going with the 4 into 2 instead of 4 into 1. Thanks in advance for the advice.

[cougar]

Well, this is an opinion from all that I've read. 4 into 1 is the best exhaust that you can use for performance. 2nd paragraph here,http://www.satanicmechanic.org/exhaust.shtml . And here is a Quote from Ken at "CycleX" > "In my opinion, any 4 into 1 system is better than drag pipes and most other cool looking systems."  I can't find any other links at this time but more should chime in. Hope this helps.   ...cougar...

[trueblue]

What performance aspect are you looking to improve peak power at or near red line?  Or, cruise power,  low end grunt, etc?
Or, is it primarily all about how it looks and sounds?

A 4 into 1 "can" improve peak power at high RPM if the pipe size (diameter) is selected carefully and the header tubes are all equal/tuned length for the engine's breathing and RPM parameters.  That same exhaust will be inefficient and actually lose power capability in the low and mid range operation.  It is why this is a popular race option.

A "crossover" 4 into 2 can improve the low and midrange RPMs.  The crossover (2&3 share a muffler -1&4 shares the other) makes each exhaust outlet have a 180 degree timing and exhaust note, while improving scavenging.  It won't make as much peak power at High RPMs as a properly designed 4 into 1.
Most 4 into 2's have 90 degree pulses as they tie together 1&2 or 3&4.  And, these don't really provide much if any performance boost, but you may like the sound they provide.  They are usually pretty cheap, too.

The 4 into 4 discounts or eliminates any scavenging aid from any other cylinder.  However, joined exhaust pulses (as in other systems) don't foul the scavenging of any cylinder, making the exhaust very straight forward to tune, and works well at pretty much all RPMs.  The drawback here, of course, is the weight of four separate exhaust systems.  But for street use, it gives good power at low, mid range, AND high RPM, but will not get the "scavenge boost " effect at RPMs where a 4 into 1 system can be "tuned" to provide benefit.

Cheers,

Edit: corrected the crossover pairing reference.

[Flying J]

All the old honda race bikes were 4-4.

[Greggo]

Just wondering if anyone had any helpful advice in helping me make a decision on which exhaust system to go with. I have been looking at a mac 4 into 2 exhaust and was curious as to if there are any significant power losses in going with the 4 into 2 instead of 4 into 1. Thanks in advance for the advice.

Run what you think looks good, and no there won't be significant power loss either way.