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True advantage of 4-into-1 versus 4-into-2 silencers

  • Thread starter Thread starter anikmankar
  • Start date Start date
A

anikmankar

Guest
I have been trying to find out whats the true advantage / disadvantage of having 4-t-1 it 4-t-2 silencers.

1) performance
2) noise
3) mileage
.....

thanks
 
i believe the answer is performance, due to the process of scavaging
 
4 into 1 exhausts flow more at higher rpm's. This allows the engine to breathe better thus making more power. They are also lighter than your typical OEM exhaust systems. This weight savings will help the bike accelarate a little faster.
The downside of 4 ino 1's is that most will cause you to actually lose power in the lower to mid rpm ranges which is where street engines spend most of their time. It's a classic tradeoff. You'll probably see more older bikes with 4 into 1's just because the original exhausts have long since rotted away and there simply are no good quality 4 into 2 replacements out there (the selection of 4 into 1's has dwindled quite a bit over the years for our older bikes too). Yeah, Jardine makes a 4 into 2 but I've never been impressed with the quality of their stuff.
As far as mileage goes, any difference is probably negligible. Noise wise a properly packed 4 into 1 isn't that much louder than a stock exhaust. My Vance and Hines header on my 1100E isn't loud at all.
 
Jetting can fix it

Jetting can fix it

RJ said:
4 into 1 exhausts flow more at higher rpm's. This allows the engine to breathe better thus making more power. They are also lighter than your typical OEM exhaust systems. This weight savings will help the bike accelarate a little faster.
The downside of 4 ino 1's is that most will cause you to actually lose power in the lower to mid rpm ranges which is where street engines spend most of their time. It's a classic tradeoff. You'll probably see more older bikes with 4 into 1's just because the original exhausts have long since rotted away and there simply are no good quality 4 into 2 replacements out there (the selection of 4 into 1's has dwindled quite a bit over the years for our older bikes too). Yeah, Jardine makes a 4 into 2 but I've never been impressed with the quality of their stuff.
As far as mileage goes, any difference is probably negligible. Noise wise a properly packed 4 into 1 isn't that much louder than a stock exhaust. My Vance and Hines header on my 1100E isn't loud at all.
Click to expand...

The low and mid-range losses can be usually be overcome with attention to the right jetting, etc. The 4 into 1 usually provides much better ground clearance, for steeper turning into the curves...
 
Unclesol said:
The low and mid-range losses can be usually be overcome with attention to the right jetting, etc. The 4 into 1 usually provides much better ground clearance, for steeper turning into the curves...
Click to expand...

If you still have the centerstand installed, it will hit before the stock pipes ever will.
 
I did not lose any performance on my 850 changing from stock 4 into 2 to a Vance and Hines street 4 into 1. Its quicker, faster topend and didnt lose any fuel economy. It is a little loud when your "digging into it". If I drive moderately the noise is not obnoxious but definately louder than stock.
Like Unclesol says proper jetting is the main key to getting a freer flowing exhaust to perform.
The V&H pipes are alot lighter. I liked the original dual exhaust look, but the 4-1 header looks cool too.
 
I lost at least 8mpg when I had a 4-1 pipe, and it was Dyno tuned. But that doesn't nessecarily mean it was jetted right.
 
When my GLZ was stock I got any where from 32 to 40 miles to the gallon. I depended first on the weather and second on how I drove.
When I put the V&H pipes on I get 36 to 37 mile to the gallon all the time and have more horsepower and more consistant horspower. It could probly lean it out and get a couple more mpgs and still be safe- but it would probly loose some hps.
The stock setup in the carbs was really lean keeping the engine from performing to its full potential.
When I put the pipes on I also opened up the airbox to flow alot more.
I feel the feer flowing airbox and the more accurate jetting are the main contributors to the extra performance I found. Im sure I could have had similar performance improvements with stock exhaust.
The stock airbox on my GLZ is the main thing holding that motor back. I would have used pods but I like the looks of the chrome side covers on the airbox.
I am going to used pods on the 1000 motor Im putting in.
 
A well designed 4-1 will scavenge very well - however, the problem with most of the 4-1's sold is they are not designed well - most (with the exception of some of the race pipes) do not have equal length headers, and many have collectors tha are too large for normal street use. The lack of back pressure in these pipes causes the lower rpm performance to be very tame.

Ground clearance is a problem on many of the 4-1 pipes - most have a 'square' collector with the pipes stacked 2 over 2 - this causes the pipes to hang down a couple of inches more than most of the stock pipes. Combine this with a trend of owners lowering the bikes and you often see dinged and crushed collectors or lower header pipes.

Some of the 4-1's have to be removed to change filters and oil - not fun. For someone like me, I change oil every 500 miles - and that could mean pulling pipes off 3-4 times a year.

Factory pipes tend to have a double skinned header pipe - a pipe within a pipe. This is why the chrome on the factory pipes tends to avoid going blue or yellow.
 
Last edited:
Jethro said:
I lost at least 8mpg when I had a 4-1 pipe, and it was Dyno tuned. But that doesn't nessecarily mean it was jetted right.
Click to expand...

How come? I thought the main reason behind springing for dyno-tuning was to ensure optimum jetting/performance.:confused:

Tony.
 
performance and economy are two different things...

you tune differently for ultimate performance versus streetability.
 
jeff.saunders said:
performance and economy are two different things...

you tune differently for ultimate performance versus streetability.
Click to expand...


Especially in a free air cooled engine such as the GS engines.
 
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