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Mummified GTR

Discussion in 'Modifications and Projects' started by typhoon, Dec 24, 2007.

  1. DId this:
    To reduce heat under the fairing on the GTR. It made a HUGE difference, especially in slow traffic. It's reduced the bike from intolerably hot to mildly noticeable as far as heat out of the fairing goes, and I'd recommend this to anyone with a tightly faired bike.
    Not only does it protect the rider from heat, but any rubber or plastic component wil have a much longer life under the fairing.
    I used a readily available exhaust wrap (bought off Ebay) and just wrapped it up.

    Regards, Andrew.
  2. You realise that you may get colder in winter nights now?

    j/k :LOL: GTR's rock!

    I had considered that, but the GTR ain't so bad for heat as some
    touring bikes and I haven't had a real problem with it. Also I was
    sceptical as to how much difference it would really make.
    Obviously it made a real difference. Thanks for the info
  3. Andrew, you simply weren't riding fast enough!
    Good idea.
  4. What did that stuff set you back.. And does it come in black ??
  5. The downside being your exhaust header will have a much shorter life.
  6. Ah it's good to see Andrew not lagging behind with technical innovation!!!
  7. If they were mild steel, I'd agree. However, considering the GTR (and most other bikes) uses a stainles steel alloy, it' not an issue. The pipes on the GTR look like 321 or similar. You'll know non stainless headers, they'll either be painted/rusty or chromed.
    Mild steel suffers an embrittlement process ( I think something to do with the carbon in it reforming/crystalising or similar), but the higher grade stainless alloys love heat.

    Regards, Andrew.
  8. Depends on how long you keep the bike - it will still reduce the life of the headers. Only difference with stainless is it might not be enough to notice, although if the tape had been fitted when the bike was new there's a fair chance it wouldn't still be using the original pipes. Aside from the obvious potential for the tape to trap moisture there's also the issue of thermal fatigue caused by the heating/cooling of the metal - the more heat the greater the effect and 321 stainless certainly isn't immune.

    There are definitely advantages to using lagging, but like with pretty much every modification there's also a downside which people should be aware of.
  9. I'm not playing your game anymore JD, go find someone else's posts to ATTEMPT to pick holes in, it just makes you look a petty fool.
    I knew there was a reason I seldom visit these forums anymore, and it is people like you. Always trying to look like all knowing experts, when you seldom grasp much more than a basic knowledge of a subject.
    I'll stick with my 20 years knowledge and experience working with stainless steel and modifying engines.

    Regards, Andrew.
  10. Yeah whatever. I was just trying to point out to those with zero knowledge there is a downside to what your recommendation to lag the exhaust pipe of any tightly faired bike. It's for those reasons I've already mentioned, and advice from those that have used lagging before (and suffered failure even with stainless) that I've avoided using it myself.

    But what would I know, I don't have the all-knowing expertise of 20 years experience.
    But FYI although low-temperature embrittlement isn't an issue with a stabilised austenitic stainless like 321 there is the issue of sigma phase embrittlement when you go trapping the heat of combustion in the headers. At the lower end of the temp scale (about 550 degrees) this process is extremely slow - at the high end (around 900 degrees) failure can occur in a matter of weeks. Although it's unlikely a road engine is going to get quite that hot the closer you get the faster the process.
  11. Typhoon, JD does have specialist materials knowledge, but you're right, there is a tendency for him to pick holes... :p

    If you have a thermo camera or infrared thermometer (like used to measure bearing temperatures) you can see what temperature your insulated headers are at and have some idea whether the increases temperature will age the headers significantly.

    Personally, I think the fatigue issue is a non issue... unless there are some sharp weld attachments. The thermal gradient will be less with insulation than without, so who knows.

    We use 321H at work on cracker furnace outlets and it survives reasonably well... 321 a little further down the line... so I suspect MC headers will be a doddle.
  12. Looks like a hellouvajob, good one though.

    Some other guys suggested that on the 14GTR, but outside stopped traffic there's hardly a heat issue, that I find on mine atleast.

    I was up at Bells Line Rd on the way to Mudgee on Xmas Day morning, wishing for the heat - cold, wet and slippery morning it was!!

    easy way to avoid heat: stay out of cities :LOL:
  13. jd - as the lagging would insulate the headers, allowing them too heat up slower, possibly/probably run with a higher running temp (in the headers) and cool down at a slower-controlled rate, wouldnt this have a positive effect on the mechanical properties of the headers over time??
    its a genuine question, too long since civ. mat. testing for me to thoroughly remember. but i do remember that quenching a heated metal, would increase hardness, but include the risk of the material exhibiting brittle properties?
    the other point worth discussing, would be the uniformity in which the headers would heat up (as they are now insulated), no particular surface is directly exposed to airflow, therefore the overall change in mechanical properties of the entire header would have much less contrast between front and back, which is where/why failures occur?
  14. Yep, but that's a sudden process that requires a fair bit of heat to begin with.

    Probably be dredging up bad memories of phase diagrams for you but what I was referring to was the formation of the iron-carbon sigma phase which is temperature dependent and common to Cr-Fe alloys. This is a very brittle phase which has a tendency to form along grain boundaries so obviously can easily reduce the toughness of the metal. Sigma phase formation also pulls chromium out of the rest of the metal making it far more susceptible to corrosion, particularly bad if the lagging is trapping moisture.

    Not sure if lagging the engine of a GTR would be enough to push the temps that high though it is feasible. Rob's idea of an infrared thermometer is certainly a good one, as long as temps aren't too much above 600 degrees it should be okay. An unmodified car engine I think only runs at around 500 or so, but modified or high-performance engines can run a lot higher. This is why a lot of people modding cars prefer to just use a heat shield on the headers instead.

    Edit: Oh and as for thermal fatigue that's caused by different phases of the metal being unable to expand properly on heating because they're constrained by other phases of the metal (try filling a plastic bottle with water and putting it in the freezer). So rate of heating/cooling isn't an issue but the change in temperature, and amount of expansion, is.
  15. ^^^ interesting :eek:
  16. Hye cant you therma cooat headers so they keep heat in?
  17. Bloody shame that you have no soap and water. That thing is filthy.
  18. Cut them back from the exhaust headers a bit, it's apparantly really bad for them.

    I had one on my SR and recently took them off. You should see the state of the header now :(