Weight savings from stock exhaust to and aftermarket


5 replies to this topic
  • oldtimemxer

Posted March 27, 2007 - 02:13 PM

#1

Hello all. I'm a 06 YZ450F owner. Does anyone know if the weight savings is significant from the stock exhaust vs. one of the lightest titanium aftermarket exhaust systems? I'd like to get one with the spark arrestor built in. Some claim as much as 3 pounds weight savings. Anyone know if this is accurate? Oh, one other question about the FMF "powerbomb". Is this a gimmick? Every aftermarket :bonk: exhaust I've ever used, I couldn't tell any difference in the power. - As if it is lacking in the first place.

  • Ga426owner

Posted March 27, 2007 - 02:23 PM

#2

Some do shave that much weight - I say stick with a alum one as CF seems to break easy on impact.....I can tell big difference with my WB on my 03 and 06

  • grayracer513

Posted March 27, 2007 - 03:29 PM

#3

... about the FMF "powerbomb". Is this a gimmick? Every aftermarket :bonk: exhaust I've ever used, I couldn't tell any difference in the power. - As if it is lacking in the first place.

The purpose of the Power Bomb is less to increase power as it is to widen the power curve and make it flatter. It does succeed in doing that.

In the most general terms, the exhaust system influences the power curve because of its length. When the exhauast valve opens, a pressure wave travels to the end of the pipe, or to the first major increase in cross section. When it hits that point, the wave is reversed, and a wave of negative pressure (vacuum) travel back up the pipe. If it gets to the exhaust valve during the overlap period, it can help purge the last of the exhaust gases, and draw more fuel and air into the combustion chamber. This effect works only within a limited range, so you have to decide whether you want the exhaust to be a high end, low end, or mid range pipe.

The Power Bomb damps the pressure waves and causes the engine to see the header as being of a non-fixed, or variable length, so that it works over a broader range. You can see this in dyno tests of PB pipes. The gain at peak is not always that impressive, but if you look at the numbers both above and below peak compared to other systems, you'll usually see that the power was increased in a greater number of points along the graph than with other headers.

On my '03, it took out the notorious "hit" at 8000 rpm, and made the bike pull harder above and below that.

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  • TexN343

Posted March 28, 2007 - 03:48 PM

#4

I have had a powerbomb since Christmas and can say the only big difference I could see was on the top end. It kept pulling longer all the way to the rev limiter. It changed the way the power hit everywhere else but not as noticeable as the top end. This is with the stock can.

  • live4speed

Posted March 28, 2007 - 04:22 PM

#5

i would only think they would drop the weight a pound or two...i know the hp gains arent all that spectacular...

  • oldtimemxer

Posted March 31, 2007 - 11:55 PM

#6

Cool. Didn't know any of that. Thanks for the informative reply. Good stuff.





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