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Davemk1 last won the day on February 6 2018

Davemk1 had the most liked content!

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About Davemk1

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    Average Joe Driver

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

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  1. Davemk1

    Merry Christmas everyone!!

    Merry Christmas from snowy and cold Montana, USA. Be well all - dave
  2. Davemk1

    Lightweight silencer/exhaust options.

    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
  3. Davemk1

    Lightweight silencer/exhaust options.

    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
  4. Davemk1

    S2000 Throttle

    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
  5. Davemk1

    Lightweight silencer/exhaust options.

    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
  6. Davemk1

    Lightweight silencer/exhaust options.

    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
  7. Davemk1

    Lightweight silencer/exhaust options.

    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
  8. Davemk1

    Lightweight silencer/exhaust options.

    I find it interesting that Raceco lists the Ti silencer being 5.6 kg.....as a guy who has worked with titanium making bike frames for way too many years I can't figure out how they could make a Ti can weigh so much. The real cost difference in working with Ti is the material itself.....it cost a lot per kg so in a way it makes sense that the part would cost so much because they used so much of the very spendy material. The Raceco silencer would seem to be the right way to go....one would think that making a standard straight-through muffler and substituting Ti for stainless would make a great system and would result in a silencer that is roughly 1/2 the weight of the stainless version (Ti weights about 1/2 that of SS).....why the Raceco is so heavy I don't get. Either the weight quoted is for their stainless version (seems likely) or it's packed full of stainless wool packing that really adds up. Hmm? In my searching around I've found a few things. First is the Supertrapp system. They are adjustable for noise level/back pressure. I used one on a different car many years ago and it worked very well. They make a stainless version that would fit out cars well and I was told yesterday that it weighs 3.4kg. this would save me a few kg and that would be pretty good. https://supertrapp.com/shop-products/auto/auto-s-c-elite/4-universal-24-2-5-id-brushed-ss-443-2524 I also found a Ti system made here in the USA that looks promising but one needs to buy the separate parts and piece it together. The weight is what I would expect it to be given that Ti is about 1/2 the weight of stainless. They list the silencer itself as being 1.4kg. One needs to add other pipe and clamps but that should add only another 2kg at the most. Given it's length and size I suspect it would be louder than I'd want it to be. https://www.ticonindustries.com/collections/ultra-lightweight-race-muffler/products/copy-of-2-5-titanium-ultra-lightweight-race-muffler-12-oal Thoughts? dave
  9. I have the stock stainless muffler (or silencer on your side of the pond) on my S2000 and it's a bit of a tank at over 12 lbs (about 5.5 kg). I'd like to replace it with something lighter. I've been searching around online and finding a few titanium and aluminum options but none seem quite right to me. I'm interested in hearing what others have gone with to replace the heavy stock stainless silencer. Thanks in advance. dave
  10. Davemk1

    Mega s2000 Omex throttle bodies

    Good deal. I give mine a quick spritz whenever I'm giving things a check. I've not had mine rev hang is a long time. Is this ideal? Nope. Should Omex make it right? Yep. Are the ITB's addictive? Oh yes. dave
  11. Davemk1

    Mega s2000 Omex throttle bodies

    Yes - I've focused the lube on the edges of the butterflies and not on the shafts. The sides of the butterflies sit right against the inner bore regardless of the throttle position. The top and bottom are held off the inner surface of the bore at all times but the sides are in constant contact.....and the reduction of the main shaft end play when hot points out that the center-to-center distance of the aluminum bores changes more than the center-to-center distance of the butterflies and this causes one side of each butterfly to rub on the surface of the inner bore. I'm convinced that this causes friction (that is lessened by the WD40) that holds the throttles open the very small amount needed for the revs to hang. Does that make sense? Dave
  12. Davemk1

    Mega s2000 Omex throttle bodies

    I'm one of the 10 or so folks that bought one of the very first sets of these. I had them "hang up" on the very first drive and I did a lot of fiddling but could never get it to be 100% correct. They replaced it with a new set that I was told was made to a tighter tolerance and these have been slightly quirky but if I set them up just right (not 100% to the specs set by Omex but my own way) I've been able to get the driveability to be pretty darn good. It's not like driving a Lexus but it's more than acceptable for me. It's not hard to drive smoothly that's for sure. I learned a lot during the process of trying to get the two sets to work and being on the far side of the pond makes it so I'm on my own just that much more. I have a strong hunch as to what the cause is and I sent my thoughts to the powers that be at Omex and I never heard back from them. It's a bit hard to put my thoughts into words succinctly but I'll give it a go in bulleted form - - Typically aluminum is used for the bodies of ITB's and brass is used for the butterflies. One of the reasons for this as I understand it is that the aluminum expands at a greater rate than the brass does so it doesn't lead to the brass binding in the aluminum bores when they get hot. - Typically stainless is used for the shafts that the butterflies are attached to. Stainless expands less than aluminum does when it gets hot. - when you have a new set of the Omex ITB's sitting on the bench you can feel that there is a slight amount of axial end-play in the shafts (i.e. they can move side to side a very small amount) and it looks to be limited by the sides of the butterflies touching the insides of the bores in the aluminum casting. - the butterflies are paired in the Omex design so you have the two butterflies on one shaft and the distance between the two butterflies on that shaft is fixed by design of the shaft (must be a better way to word that). - In the Honda application hot coolant flows right adjacent to the rearmost #4 bore. If you drive the car and get it hot and then take the temps of all four bores you'll see that #4 is the hottest by a good bit....makes sense. - so.......I think that when the rear pair of the ITB's gets hot that the aluminum expands and then starts to rub against the edges of the butterflies where they meet the shaft. In effect the hot alloy swells and pinches open the two butterflies that are on a stainless shaft (that expanded less than the alloy) which take out that shaft end play which makes the butterflies bind against the inner bores. - I've noticed that when mine are cold that one can use your fingers and feel the end play but when they are hot the end play is no longer there on the rear pair (#3 and #4) - so.....when it's cold they snap right back into closed position with gusto and a solid metal-to-metal 'clack' of the screw hitting its stop......but when they are hot the butterflies are being pushed against and they rub slightly and you lose the gusto and the 'clack.' I think the Honda application is a double whammy here...first is that the heads run hotter than other brands do and secondly that coolant running adjacent to #4 heats it more (and asymmetrically) and this causes the body casting to get bigger to the point where it swells and tries to spread the butterflies apart on the stainless shaft.....but of course they can't move on the shaft so they rub on the inner bore. This is one of the reasons that putting some light lube like WD40 on the butterflies is helpful....it reduces the friction of the butterflies rubbing the hot alloy. I did a test once....I had a consistent rev hanging issue and I knew that WD40 would temporarily fix it. So I sprayed just the front pair of intakes and the rev hang didn't change at all....but when I sprayed the rear pair it went away. This told me the hang up way in the rear pair. On the off-chance that I'm right where does that leave this? I suspect with a complete redesign starting with the casting and working from there. I think the tolerance issue was a red herring and that it may have contributed to some sets working OK while others sucked. So I don't think holding the current tolerances will fix it - I think it needs a new design and new tolerances to account for the different thermal expansion rates and the uneven heating of the Honda head. When and if Omex comes to the above conclusion I hope they send me a new set - I feel I've earned it for the amount of time I've fussed with the things. Sorry for making this so long. I would have written something shorter but I didn't have the time Thanks for reading. dave
  13. Davemk1

    Fuel tank sumps / swirl pots

    FWIW - I had bad fuel starve issues with my S2000 and I really didn't want that I perceived as a complicated set up of a second pump and "all the plumbing" that comes with a swirl pot. After trying a few other options without much success I took the plunge and installed a swirl pot and secondary low pressure fuel pump. It took longer to grasp how it needed to be plumbed than it did to actually plumb it (I found making a diagram and labeling the ports on the swirl pot to be a huge help) and it works flawlessly. I've raced with less than 2 gallons in the fuel tank without any issues. It worked perfectly right out of the box. One of my main aims was to reduce the weight of the car by being able to run less fuel and I wrongly assumed that the weight saved in fuel would be offset by the weight of the swirl pot and associated stuff. But in the end I added 3 lbs of swirl pot stuff while saving 30 lbs of fuel. So it was a huge weight savings with no down side for me. It sounds so much more complicated to have a custom tank made compared to running a swirl pot so I wanted to share my experience. all the best, dave
  14. Davemk1

    EBC brake pads

    I'm also using EBC Yellows in the rear and 1144's up front. I tried yellows all round and they lacked the bite I was looking for and required too much pedal effort. I then tried 1144's all round and I had way too much rear lock up even with the bias adjusted to the extreme. On a whim I tried the 1144's in front and the Yellows in the rear and they are ideal for my use. Very good cold bite, zero fade and the balance was easy to adjust so for even braking front and rear. The bias is adjusted to give a bit of front lock up just before any lock in the rear. The set up seems ideal for my mixed street and competition use. dave
  15. Davemk1

    17 year wait over...

    Welcome.....what model will you be building? dave

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