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About Sam@TDi

  • Birthday 14/07/1980

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    Jaguar XJ8

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  • Interests
    Motorsport and Science, mixed!

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  1. Absolutely correct, in fact it's near impossible to model accurately even if you are privy to all the required information. It's for that reason that you'll find tyre testing rigs at all of the tyre manufacturers research bases, whats more tyre testing rigs are being carted about by all the top NASCAR, F1, ALMS teams etc. The chassis engineers simply test the tyres on a simulated appropriate surface and then map out the force responses in the form of an industry standard carpet graph, they map out the tyre as completely as possible, THEN they decide how best to exploit the tyre to achieve their goals. Working without accurate tyre data necessitates extensive real world experience (and/or data) with the tyre, or at least tyres of similar design and chemistry. If you find yourself with neither accurate tyre data or any real world experience with the tyre then you'll find you need a great deal of luck.
  2. Sagitar that's spot on, as usual As Sagitar has eluded to, the chemical make up of the tyre is a huge variable determining the exact exchange mechanisms by which "grip" is generated, and without factoring it in whilst you're thinking you can't really work with this subject.
  3. you'd be right in thinking that, it's impossible to change one aspect without influencing the rest to some degree
  4. Ok I understand, the science related to this transient situation is just about as complex as chassis dynamics ever gets! The variables effecting the eventual perfect solution fall in to the fields of geometry, weight distribution, sprung vs unsprung mass ratio, force transfers pathways, roll centres, specific tyre dynamics, net roll resistance (springs plus arb's), low speed compression damping forces and chassis preload. In short the answer to the "to squat or not to squat" question is the motorsport holy grail, I've got my own opinions on the subject as have other chassis dynamisist's and the one thing we've got in common is that we've all come up with different conclusions
  5. I'm not understanding "squat corner out" Tony can you describe what you mean?
  6. No probs ..... but hey 11sec's to 100mph is serious stuff no matter which way you look at it
  7. MR2 turbo's punch well above there weight off the line, in Japan they're often forced to race with the 4wd classes at the drag strip
  8. http://www.youtube.com/watch?v=G5oFCpIW_ds
  9. Yes you absolutely could but the level of heat energy involved would soon heat the ceramic and you'd be back to radiating heat, the simplest way to address the issue is to isolate the turbo and heavily lag sensitive components in the proximity. We use a special Goodrich lagging that is designed to protect wiring in foundry machines from molten metal strikes it cost's around £60per meter
  10. Indeed welcome to WIM Personally I've found it extremely difficult to gain access to good quality scientific information on the subject of vehicle dynamics. I'm my opinion the academic land scape in this field is clogged with authors offering their opinions often passing them off as fact or worse still preaching as an expert based solely on their own trail and error experience without any real understanding of the true mechanisms at play. I would recommend that you cast a skeptical eye over as much material as possible, then perhaps mentally attempt to sort the wheat from the worryingly large amount of chaff. I've been lucky enough to work with some talented people in this area and I've certainly gleaned far more from my discussions with these people then from any of the books I've ever read on the subject.
  11. Wizard of Nos equipment works extremely well even if they don't look like the most flashy, direct port is ALWAYS better for even nitrous distribution than a single injector but it's around double the price for the hardware and almost four times the work to fit. I would recommend a single injector if you planning a power hike up to 50bhp, over 50bhp then it's worth thinking about direct port. I would also heavily recommend a bottle pressure gauge, fuel pressure gauge and if the budgets there a progressive controller.
  12. Ok, Honda's vtec system uses completely different cam lobes pre and post the change over point, that is pretty unique and was actually patented by Honda for a long time. The intake cam advance and retard function that puts the "I" in "IVTEC" is a tuners dream, it can advance or retard the cam +/- 25deg so that's 50deg of overall swing! it can reposition the cam at a typical rate of 10deg per 10msec which is fantastically fast. Mapping the the H' B' and K' series Honda engines accurately is as you say very tricky but for reasons that go way beyond the control and subsequent dynamic influence of the cam shaft control systems, these engines are unique in many ways, personally I absolutely love working with them
  13. I prefer regular compressed air and wd-40, and a good ultra high pressure PTFE joint to start with.
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