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Zhast Mods – Heat wrap, Volume, Baffles, Tuning WTF mate?

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by brownyy, Nov 6, 2009.

  1. Hey all;

    While I love my Daytona to bits (gawd forbid) I do not like the abundance of heat coming from the underseat pipe which is pretty damn close to my right leg. While speaking to a retired rider about dealing with the heat I explained I intended to put heat wrap around the pipe to try and keep my leg cool.

    He said this might mess up the performance.

    He explained something about pipes been a certain length for tuning and resonant frequency, volume and heat expansion, etc etc. Now personally, I have no idea about any of this. Can someone please explain roughly how it works??

    All I know is I have a 3 into 1 pipe with exup valve in there somewhere. The stock pipe also still has its baffles in, and I was keen to remove them (gotta break some welds first). Any advice how to deal with all this stuff??

    I’m not keen on buying a slip on either for multiple reasons.

    Thanks for any help you can give.


    Below; The pipe is pretty close to the RHS but still passes through the swing arm.

  2. I would have thought heat wrap actually improves performance as the air velocity is fastest if kept hot, because as it cools it expands and it moves slower.

    It was something i was planning on doing to my wrx as i was going to chase some big power and with more power comes more heat so among some other reasons such as keeping all the heat away from things that need to be cold aka intercooler, it would actually improve the flow of things so i would have done the headers, and exhaust as a result to get the best performance possible.
  3. wrapping that section of pipe won't make much difference to the performance at all.

    what will happen is the amount of heat that can escape from the overall system will be reduced because you're reducing the effective cooling surface area. The result will be that the rest of the exhaust will be hotter (but only slightly) and since metal is an excellent thermal conductor your engine will become hotter (only very slightly) making your radiator work harder (well, you wont even notice it).

    conclusion: if you've got something to wrap the pipe that can handle the exhaust's skin-melting temperatures without looking crap, then wrap it...
  4. completely the opposite is true.

    air / exhaust gas contracts as it cools.

    I'm not sure what you're saying otherwise.

    edit: bloody hell there is a lot of just plain wrong information flowing around about exhaust systems... almost as much as church-spread misinformation about condoms in Africa.
  5. Ask QuarterWit about his heat wrap experience (and the replacement of his head!). Mind you, he had the whole header wrapped, and pushed the bike on long hot runs that melted the exhaust.

  6. o_O wow, that is some impressive heat buildup.
  7. Or an unimpressive exhaust!

    (But an excellent head, so....)
  8. oh sweat ****, that's not cool... I just wanna wrap the part visible under the seat between the riders pegs and pillion pegs in the photo above...

    Thanks all for the replies... any more word on this tuning stuff??

    I know when a mate got a slip on on his Daytona he needed a new map...
  9. Just the wrap the ****er with the stuff I gave you or give it back ;-)
  10. Well thats what i first thought, but then why would there be a performance increase after wrapping stuff? :-s
  11. just leave it as is. the 675 doesn't cook the rider that bad, compared to other bikes i've ridden.

    tough it up princess, and ride the dam bike! :)

    lastly, if you play around with the exhaust (or intake, cams, head work, etc), get the thing on the dyno and check the air fuel ratios. it's the ONLY way to know what's going on. simply taking someone's word for it that "ah she'll be right, no need to change the mapping" is all well and good until you pop a motor from it being too lean.
  12. What if you got someone to create a stainless steel piece that goes around that bit of exhaust like lots of other bikes have as a heatshield?

    Would still look nice and shiny and not look too much out of place i would think.
  13. Sheppo; cheers mate, I like to tough it up regularly, but gawd dammmmmmmmmmm!!! its hot... lol... there's hotter then this thing?? fook me!

    dimi, I've thought about that a little but some website was commenting on a CF built thingo that apparently did nothing... might need to look into it more...

    Thanks all for your help and advice. :)
  14. I wouldn't expect CF to do much. I'd experiment with something like a space blanket (not sure if they can handle extreme heat) or the heat-reflective stuff sold for car firewalls. Attach it temporarily and go for a decent ride - if it makes a difference then explore making something pretty.
  15. Hmm. Sounds like you will be standing up during the Tassie trek.

    If you can't get more air between the pipe and the seat to dissipate the heat, what about getting more air through your pants? Or insulate a tank bag and fill it full of ice cubes, giving you a ready supply which you can stuff down your pants.
  16. Do you have an aftermarket slip on?, if it's the factory one the cat is what gets hot and retains a lot of heat, ditching the factory pipe gets ride of the cat and also the weight that goes with it.

    If you want to minimise temps further you can get the whole exhaust HPC or ceramic coated inside and out
  17. Nah stock as a rock Bamm Bamm. No ice cubes Grey, they won't last long with this heat...!
  18. Hot air will flow more freely. (however the increase in power gained by keeping the gasses hot will not be huge)

    Hot air will be greater in volume than cold air at the same pressure. If your exhaust gasses cool quickly the mass of gas in the exhaust will be greater. It may take more work to push the denser air through a catalytic converter or complex exhaust silencer.

    However, changing the temperature before your header junction could cause the pulse-timing of the exhaust to be different from the 'tuned' range. Hot air would be better for high-revs, cool air better for low-revs.

    But the heat has to dissipate somewhere. You may end up setting fire to your muffler's packing material or melting the pipe, seat, or other componentry in the area.

  19. This is what I was worried about, doing damage by heat wrapping the pipe after the cat... it's an undertail unit, so the duct tail, seat and battery might cop it hard...

    thanks all for your responses...
  20. Do you take a pillion frequently? If not you could do this. If so, you could get some longer pillion peg bolts and then.... do this.

    Get somone to machine a bit of aluminum that'll reach from the rear passenger peg mount, along that frame line and then down to block the radiant heat from the exhaust. You should be able to fit it so that it doesn't interfere with the operation of the swing arm, watching out for contact with the rear brake reseviour and actuator in particular.


    This picture is a rough sketch, the pillion bolts are the green dots and the red outline is what you're after. Might not be the most aesthetically pleasing solution, but it won't cost much and is easily reversible. You could even rib the rear of the plate with shallow saw cuts to help heat dissipation.

    Cheers - boingk