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Truenotch

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Everything posted by Truenotch

  1. Good progress! Venturi collectors look like a cool idea. I've never seen inside one before.
  2. I might bring my FA50 as a backup bike. It'll do 80kph on the flat, but is geared pretty high so could be punishing up hills. It's got a 2 litre fuel tank, terrible lights and the brakes almost work.
  3. Sheeit, this is next week. This month is going fast! Next meet is Thursday July 18th at 7pm. See you at Burgerfuel! Here's the facebook event: https://www.facebook.com/events/348168292782181/
  4. Hopefully the MX100... Will get started in September once the Racecar is back on its feet.
  5. I’ve made good progress on the right hand tub now. Got most of the finishing and a coat of primer onto it. Then @Rhyscar came around with his tube bender and we started on the new radiator support: This bolts in place on the sides and will have a couple of vertical stays for the radiator and ducting mounts. Popped the guards and bumper back on for a visual inspection: And the new radiator will mount like this: With ducting to take the flow out the bonnet. Woohoo! Now back to body work in the engine bay.
  6. Do it anyway! Bring the ragtop.
  7. Haha, cheers man. I’ve never been much good at bogging, so half the fun was learning how to mix and lay it again... The stuff I’m using doesn’t change colour when you add hardener, so I doubled down on hardener the first time and ended up with a streaky mess to deal with. Recent applications have been much nicer! Plus the sanding is basically cardio . Its getting there now - bit of filler primer and seam sealer done. Now it’s time to start applying filler to the other side and get the rest of the bay cleaned, sanded and primed for paint.
  8. September will be two years since I've driven this car... So I've decided that I should get it going and try to race it at the final round of the Manfeild winter series. I've not done a whole lot since 2017 due to general slackness, but have cleaned up a bunch of welds around the tubs. This was about a year ago: Fast forward to this week and I've started doing things again. More weld removal, a few holes welded up, paint removal etc. A bit of filler and the first coat of etch this evening to see how it looks: The underside is still a bit wrinkly, but it's good enough for an inner arch. Now to get the other side. to this level.. I always forget how long it takes to sand filler! It's a pretty painful job . Once both sides are in primer I can give the rest of the bay a good clean up, sand and start thinking about paint.
  9. 16 Valve club for lyfe. @Stu
  10. Yep. And the speed of sound changes with temperature, so it's important to know the rough temperature of your pipes too.
  11. Hmm I don't know. The scavenging isn't necessarily done by sonic waves. As I understand it, when a the gas pressure runs down a the pipe and out the megaphone (diffusion cone) it creates an expansion wave and the gas behind it accelerates. This creates a vacuum that heads up the pipe (negative pressure wave). I starts from the small end of the diffusion cone and works its way back up towards the exhaust port. So the positive gas pressure wave effectively "falls away" as the gas in the diffusion cone expands, which creates a draw in the exhaust port. In two stroke tuning, the sonic wave(s) play a key part in creating resonance, but it only works because there is no exhaust valve in the way and you can get an almost direct connection between the inlet and exhaust sides of the engine. Sonic waves can build up into multiples which is what 2 stroke tuners are trying to achieve (true resonance). Here's quick video that might help: And a not-so-quick one that explains the sonic vs gas pressure waves and resonance in more detail: There's another video somewhere that has good high-speed photos of the gas pressure wave entering a chamber that makes it slightly easier to understand, but I'll have to search around again to find the video.
  12. I’m curious about whether reversion/reflection cone would ever be beneficial on a 4 stroke. The diversion cone makes sense to me - the taper creates expansion waves heading out and at the same time creates a negative pressure wave that heads back up the pipe to aid scavenging IF the wave is timed correctly. I don’t see why adding reversion would work on a 4 stroke because there’s minimal fresh fuel/air in the pipes to shove back into the cylinder.
  13. Have you done any reading about anti reversion chambers on headers / after headers? I know you tested an expansion chamber at one point, but I'm not sure if you've given these puppies a go. It sounds like the theory around stepped headers could serve a similar purpose to these anti-reversion chambers. They look like they could be fiddly to make though... There's quite a few open wheeler headers with these bits in them (high level like F2 and old F3 cars) and lots of chat in the big block speedway world too.
  14. You got me started... Now you receive homework... Some systems have them after the header, some have them on the header: Here's a reading list about anti-reversion chambers: https://crateinsider.com/using-anti-reversion-to-create-free-power/ https://thumpertalk.com/forums/topic/1075515-megabomb-header-explanation/ https://forums.seatcupra.net/index.php?threads/exhaust-design-and-anti-reversion.319359/ https://nasaspeed.news/tech/engine/the-art-of-scavenging-myths-and-methods-of-getting-burned-gases-out-of-an-engine/ https://nasaspeed.news/tech/engine/the-art-of-scavenging-myths-and-methods-of-getting-burned-gases-out-of-an-engine/ A bit about megaphones: https://www.hotrod.com/articles/post-collector-exhaust-add-ons-can-affect-exhaust-tuning/ ... This hole is almost as deep and weird as the black magic of 2 stroke expansion chambers...
  15. I'd be keen for a copy. If you want some interesting header data, go over to KPR's starlet thread. He has a dyno now and has been testing a couple of different 4-1 headers (38 and 44mm) and tried a 4-2-1 and an expansion chamber a while ago too. Here's the link:
  16. @kpr - have you done a side by side comparison of your 151kw tune with the filter installed/removed? I'd be keen to see if there's any difference with the filter on. Also keen to know how much room you have inside that filter between the top of the trumpets and the inside of the filter element - it looks spacious compared to a domed pipercross/ITG. I also lolled at the way those silicone joiners jiggle in the high RPM. There's some serious pulsation happening above 5k or so.
  17. I reckon the steering wheel is bent because people will put all their weight on it to get out of the car... Might be worth adding a grab handle somewhere to make it easier for oldies to get in and out. Also, gizz a hoon on your rusty penthouse .
  18. It's so cool seeing this car on the ground with a front bumper and bonnet. Looks staunch as fuck.
  19. Hey y'all. Hypothetically, is there any way to reverse a lapsed registration? I'm pretty sure the car in question fell off hold in May 2017 and the owner didn't realise until it went for a WOF the other day. I've heard there's a form you can fill out to reverse the cancelation process, is this true? Asking for a friend.
  20. A few snaps from Thursday night. There were more cars earlier on that I missed.
  21. @~Slideways~ - either top hat bearings or a mismatch with the spacers that slot into the top bearing. The spacers have shanks that slot into the top bearing, if they’re a bit long or machined a bit too small you’ll get the same play as a worn bearing. If you replace the bearings, make sure to get good quality PTFE lined sphericals. Anything else will wear out in no time.
  22. Far out, that is some bad pitting man! Condolences. On the plus side, if you think it went awesome before, it'll blow your mind once you get a decent bottom end into it. It's getting pretty hard to find 18R blocks now, so might be best to go oversized. Are there any friendly engine reconditioners in CCH who might be able to help? Also, what to the valves and seats look like? Hopefully not as corroded as the bores.
  23. Well done re: attendance. Shame about security. Im happy to chat to plaza management if it’ll help at all.
  24. Those have “49cc” cast into the cylinder and no one will ever know it’s 60cc anyway. It still won’t be fast, but at least it won’t be so slow .
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