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Davemk1

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Davemk1 last won the day on February 6 2018

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About Davemk1

  • Rank
    Average Joe Driver

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  • Car Details
    Westfield Mega S2000
  • My Location
    Bozeman, MT USA

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  1. It sounds like one 'knock' per wheel revolution....is that right? Does the timing of the knock follow road speed? Does it change with load?.....in other words if you let off and coast is the noise the same? Is it the same if you apply throttle? How about if you get up to the speed you were going in the video and then put the trans in neutral and coast? dave
  2. Davemk1

    Aero on a Westy?

    I made one out of lightweight ripstop nylon and it ended up weighing 3 oz in total. Interestingly when at speed it gets pushed down by the passing air and not pulled up. That surprised me. dave
  3. Very cool. What brand exhaust is this? And do I have it right that the perforated tube is 2 1/4" ID? dave
  4. Do you have a Ford differential? If so check the two bolts that bolt the diff to the strap at the very rear of the diff. It's a short strap that joins the chassis to the rear cover of the diff. If those two bolts are loose it will make a noise like you describe. dave
  5. I did this on the tunnel top panel......drilled and tapped to an M5 and small dome head bolts and it comes right off. dave
  6. I like the blue. dave
  7. Have you tried giving it a new fuel filter? dave
  8. Merry Christmas from snowy and cold Montana, USA. Be well all - dave
  9. You're right - it seems like it should work. I've seen others use them with success so was trying to be open minded. One thing Supertreapp says is that this size is good for 250 hp and that some cars with very high flow (like turbo cars) might be better off going with the larger size. The one I used has 4" discs and the larger size has 5" discs. Doing the rough math tells me that it would flow MUCH better. I suspect that the Honda engine at 8000 rpms flows too much for the system to handle despite the fact that it's within the 250 hp limit and that the 5" system might work well. However - the 5" system weighs much more and the chief thing I was looking for was weight savings and going with the big one wouldn't help me there. Live and learn. dave
  10. So.....I've had some time to get the Supertrapp set up and tested and I thought it would be worth a report. The muffler can be set up a few ways - first you can use the diffuser discs and an open end cap....or second you can use lots of discs and a closed end cap. It seems obvious that the open cap would flow better but also be louder. I set it up first with the open end cap and all 12 of the diffuser discs and then checked the sound level. My race rules say it can make a max of 100 dB at 50 feet so I set up a dB meter 50' of the road and went by in 2nd gear with WOT at 8000+ rpms. It made 105 dB. Far too loud to meet the rules. It was also annoying and just felt way too loud. Next I put the closed end cap on with all 12 discs. This forces all the gases and sound out at 90° and Supertrapp says 12 discs is the same as "full open" (I was more than a bit skeptical that this could be true given the size of the slots between the discs). I drove by my meter the same way as before and the car felt sluggish and I couldn't tell if the tires where spinning (very cold out and limited grip) or if the power was down. I checked the meter and it said a nice low 96 dB but it felt funny so I reset the meter and tried again this time focusing more on how it felt as the rpms climbed. It felt normal until about 5000ish when it suddenly bogged (it wasn't wheel spin) and then suddenly there was a very loud BANG and the revs shot up very suddenly until it hit the limiter and then I dropped the throttle and could hear the sound of metal grinding on the pavement. I pulled over and found that collector Y pipe had blown right off the headers and only the wire going to the O2 sensor kept it from spinning around and being run over by the rear wheel! I think one can safely say that the claim by Supertrapp that 12 discs is the same as being "full open" is complete and utter BS. There was so much back pressure that it blew the system right off the car. Not so good. The muffler weighed less than the claimed weight and the savings would have been nice but it was way too loud or way too restrictive so I came home and removed it and put on the old system and there was much rejoicing. Anyone want to buy a used Supertrapp? I'll make you a good deal on it! dave
  11. When I built my car I tried each hole and the upper hole gave me poor throttle modulation and the lower hole felt as it should. I suspect that the messing with that throttle stop screw (not actually an idle screw) is the core issue. If the throttle is closed further than Honda intended then the TPS only sees it as "out of range". The Omex ECU will mess with timing to maintain idle regardless of the TPS reading but when you move the pedal it will not know what to do.....but once it opens enough to come "in range" it will suddenly be happy and rpms will suddenly rise. This will make modulation near impossible when coming off closed throttle. I'm guessing that once you get the throttle stop screw set properly that the car will run as it should. I wonder if you Google how to set that screw if you might find a way to get to the stock Honda setting that the Omex tuning depends upon? dave
  12. Well the Supertrapp arrived and I made a bracket for it and bolts it on and all went very well. It sounds great sitting in the driveway but I'm not taking it for a drive today because the temperature is currently 15° F (-9°C) and that's just too cold for it to be any fun. I weighed the old silencer and brackets and of course did the same with the Supertrapp and the total weight loss ended up being 5.2 lbs (2.4kg). Once I've driven it and put it on the dyno and tested it I'll report back. That could be awhile as it's full on winter here but if I can pull it off soon I will. dave
  13. Good stuff - thanks for taking the time to do that. Very cool. I've ordered a SuperTrapp and it's going to arrive today. I hope to get a bracket made for it very soon so that I can test it. The claimed weight is 3.4 kg without whatever bracket I make for it so it's pretty light. My concern is that it will be louder than I want and only time will tell. It cost $210 shipped so it's not too spendy. I'll be sure to report back with the actual weights and how loud it is....or isn't. dave
  14. As obvious as this may sound I think that the weight comes from everything. The stock part is a stainless perforated tube, surrounded by a dense insulation, wrapped by stainless sheet (to form the outer surface we see) and capped on the ends with thick stainless caps. Add to that the stainless 90° bend exit and the stainless entrance tube and braces and there's a lot of stainless in the mix....in fact I'd guess that a good 80% of the package weight is from the stainless as the only other thing is the insulation. Replacing the outer surface with ti or aluminum would of course save some weight on that part but it leaves all the other heavy stuff in place. I think the real cost-is-no-object way of going about it is to use Ti in place of ALL the stainless used. Ti is just as strong so the wall thickness of the Ti would not need to be thicker than the stainless and the simple fact that the item weights less means it can have less bracing to keep it from coming apart with vibration....making it light means it can be made lighter is you will.....a positive feedback loop. The link to the TiCon mufflers shows just what I'm talking about. I think the downside to the TiCon is that it's too small and will likely be too loud for me to pass my competition noise tests. And of course all that Ti is spendy. dave
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