Page 2 of 27 FirstFirst 123412 ... LastLast
Results 11 to 20 of 270

Thread: messy ZX6R project

  1. #11
    Join Date
    Mar 2008
    Location
    Southington, CT
    Posts
    9,693

    Default

    Quote Originally Posted by Nuar View Post
    Can someone explain the reasoning behind heat wrapping motorcycle exhaust?
    Technical explanation:

    - As the exhaust pulses travel through the exhaust piping they cool.
    - As the pulses cool, they loose velocity.

    Exhaust flow is very complicated because the flow consists of pulses, not constant flow. Because of this, especially on 4 or 2 into 1 setups, it's important to use the pipe lengths to get the pulses in the "Y" to be timed properly to help prevent the colliding of these pulses. Here's an explanation that was given to me a long time ago. It pretty accurately what happens to each pulse:

    Picture two small pipes mounted vertically and filled with water. They combine, using a "Y" fitting, into a single piece of pipe the same size in diameter as the pipes above.

    - If only one side is allowed to drain, it would drain at the rate of flow for that size pipe.
    - If both upper pipes are allowed to drain at the same time, it will take 2x the amount of time.

    The same thing happens in exhausts. This is a very simplistic example, but it does demonstrate what happens when exhaust pulses collide, or slow down.

    Why does heat wrap apply to this situation? It helps keeps the exhaust pipes from being heat radiators, and transferring exhaust heat to the air, therefore keeping more heat in the exhaust and the pulses at a higher velocity. As the pulses cool and slow down, it causes two reactions - one being a slower exhaust flow, the other is "scavenging". Scavenging is a result of each pulse creating a small pocket of lower pressure behind them when leaving the cylinder. This pocket of low pressure is strongest between the closed exhaust valve, and the first pulse traveling down the primary tube. This pocket helps the exhaust in the cylinder to flow out - both by giving room for the hot gasses to go, AND by having an area of lower pressure to help it move along. The advantage to a more complete evacuation of the compression chamber during the exhaust stroke is a cooler, more complete charge that is not diluted by left over exhaust in the cylinder as the intake valves open and the exhaust valves close.

    This scavenging effect can be greatly reduced by the exhaust design, and the cooling of the exhaust gasses in the system.

    So what does this mean for HP? Well, when all is said and done, it really depends on the motor and how well the stock exhaust is designed to begin with. As an example, there was a guy @ Stafford speedway with a SK Modified race car. Those cars are allowed to run any long tube header with a specified max primary tube length, a specified set of mufflers and exit point on the car. This person took the car down to Hooker's R&D house, and spent supposedly over 15k to have them develop a set of headers that made more power. The guesses given by people with hear-say information were that they found over 15hp... that’s significant and I'd say it was a pretty good guess based on the amount of pull he had on even the top of the class cars down the straight-aways. But that’s an example of scavenging and how it can effect power. Heat and pulse velocities are only 2 of many factors in gaining HP through exhaust efficiency. On a 500hp motor however, that’s still only 3% gain.

    On a bike, I'm sure it helps, but I'd doubt anyone would see anything more then 1-2%, which at the HP bikes put down is well within the margin of error/repeatability of the dyno.

    - - - - - - - - - -

    I hope this sheds some light on this for you guys - I know it's a bit of an overkill type post, but this is some of the things I have learned about it from racing, and helping build engines as a part time job. In this case with the bike, I think the look of it with being painted black will be great - but without doing the entire system, including the header, there will be no performance gains. I'm sure that the rider will feel significantly more heat off the exhaust however!

  2. #12
    Join Date
    May 2009
    Location
    NY
    Posts
    326

    Default

    haha what is messy about this,

    that is one sexy bike!
    Pardon my driving, I am reloading.

  3. #13
    Join Date
    May 2008
    Location
    Danbury, CT
    Posts
    2,534

    Default

    ^the room it's in is messy, doesn't that count?

    Quote Originally Posted by scubasteve View Post
    there will be no performance gains. I'm sure that the rider will feel significantly more heat off the exhaust however!
    no way man. if my stickers give 4hp each, this will see AT LEAST 10hp.

    but yeah, it's to keep the heat down. had a few things starting to melt.
    i've had my car's downpipe and manifold wrapped for 2 years now, still doing great.

  4. #14
    Join Date
    Mar 2008
    Location
    Southington, CT
    Posts
    9,693

    Default

    yeah in undertail exhausts like that one it's gotta get warm under there. The wrapping should survive no problem - I had it on my old cars headers for years. I think the clamp bands rusted and broke before the wrap ever showed any signs of wear and tear.

  5. #15
    Join Date
    Jun 2007
    Location
    Newington
    Posts
    355

    Default

    Thanks Steve, that was a really good explanation!
    Makes a lot more sense now, but raises more questions lol. Not gonna post them in this thread though. I already feel like I thread jacked the guy lol
    Sorry

  6. #16
    Join Date
    Oct 2006
    Location
    midway CT
    Posts
    6,224

    Default

    Quote Originally Posted by Nuar View Post
    Can someone explain the reasoning behind heat wrapping motorcycle exhaust?
    I understand a turbo car but why on a bike?
    Is it simply to make it more comfortable on hot summer days?
    I wrapped mine because it started to burn right through the fiberglass.....
    R.I.P. - Reed - 3-23-2008
    Matty V you are missed.

    LRRS/CCS #76 TTD Instructor
    #5/ RSP Racing MTAG Pirelli / StradaFab / / Dyno Solutions / Tony's Track Days /Woodcraft /Armor Bodies /
    MOTUL / Sport Bike Track Gear / Brunetto T-Shirts /



  7. #17
    Join Date
    Oct 2006
    Location
    Boston
    Posts
    13,184

    Default

    Damn Scott, that's an explanation. I'm gonna bookmark it and read it again later - too late and too detailed to comprehend now...
    LRRS/CCS EX #47 -RSP Racing / Tony's Track Days / MTAG-Pirelli / Woodcraft / Dyno Solutions / Sport Bike Track Gear / Knox / Brunetto T-Shirts / 434 Racer Parts / GMD CompuTrack

    2012 LRRS Champion, AM Thunderbike
    2018 LRRS Double Backup Champions, GTL and ULSB

    RIP Reed 8/16/84 - 3/23/08
    RIP Vaughan 11/18/66 - 9/19/10


  8. #18
    Join Date
    Oct 2006
    Location
    Meriden
    Posts
    18,210

    Default

    Quote Originally Posted by weld View Post

    don't care. random adjective. messy =/= crazy. i wasn't aware, nor do i care, if messy is associated with the word "customization"
    Oh cool... And you're a bitch too?



    Quote Originally Posted by Mustang View Post
    Damn Scott, that's an explanation. I'm gonna bookmark it and read it again later - too late and too detailed to comprehend now...

    Pssssttt... Hey Bill... His name is Steve...
    LRRS/CCS Amateur #514 / RSP Racing / Woodcraft / MTAG Pirelli / Dyno Solutions / Tony's Track Days / Sport Bike Track Gear / 434racer / Brunetto T-Shirts / Knox / GMD Computrack

    Quote Originally Posted by Mr. Kurtz View Post
    This place is about as family friendly as donkey porn.
    Quote Originally Posted by nhbubba View Post
    Noel is my hero

  9. #19
    Join Date
    Oct 2006
    Location
    Naugatuck, CT
    Posts
    25,291

    Default

    Quote Originally Posted by GixerJockey View Post
    Oh cool... And you're a bitch too?

    Pssssttt... Hey Bill... His name is Steve...

  10. #20
    Join Date
    May 2008
    Location
    Danbury, CT
    Posts
    2,534

    Default

    i just got outbid on 2 sets of 07/08 nissin calipers. lame. 3rd set ending today. might just go for CBR1000 calipers.

    Quote Originally Posted by GixerJockey View Post
    Oh cool... And you're a bitch too?
    .
    o shit e-thug, i don't wanna fight, sir. don't take my lunch money

Similar Threads

  1. Wtb: '99-'02 zx6r
    By Ituen in forum I Want/Need
    Replies: 16
    Last Post: 10-11-2009, 06:52 AM
  2. 98-02 zx6r wheels
    By The Magician in forum Gear, Parts or Accessories
    Replies: 4
    Last Post: 11-22-2008, 10:17 AM
  3. 1st new mod for the ZX6r
    By Just_Jeff in forum Everything Bike
    Replies: 10
    Last Post: 06-09-2008, 12:06 PM
  4. Least Messy Way To Change Brake lines
    By jimmycapp in forum The Garage
    Replies: 11
    Last Post: 02-18-2008, 08:54 AM
  5. zx6r fighter project
    By The Magician in forum Everything Bike
    Replies: 28
    Last Post: 02-13-2008, 09:25 AM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •