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f1karting

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Everything posted by f1karting

  1. Before unfortunately.. so no back to back testing.. I am not sure what process you would like pix of?? If you dont have to kill me if you tell me.. how did you get over 400 lbs out of you car? Go lite or go home, I say! ... CABC would love us.
  2. This is what Richard Jenvey at Jenvey Dynamics writes: "The air horn serves three main purposes; 1) To convert the pressure difference between bore and entrance into air velocity with the minimum of energy loss. 2) To act as the interface between the induction system and the atmosphere, i.e. the point at which pressure waves change sign and direction. 3) To complete the system to the required overall length. For ease of description the air horn may be considered in two parts; the 'flare' and the 'tube'; The main job of the flare is to spread the low pressure zone over the largest possible area - to reduce local pressure reduction - whilst guiding incoming air into the tube with minimum disruption or induced vortices. The flare should be shaped to encourage air to enter from the sides, but not from the rear, of the mouth. This is achieved by either finishing the mouth with a sharp edge when the arc is a little beyond 90 degrees from the air horn axis or by folding material back, parallel to the axis, when the arc is at, or just below, 90 degrees to the axis. The main job of the tube is to accelerate the airflow smoothly and progressively. This is best achieved by an exponential shape - i.e. one where the radius of curvature is increasing constantly until the angle of the sides matches the next part of the system, usually the throttle body. At the intake end this should blend smoothly with the flare. " Maybe in our situation a full radius would help... but remember our trumpets are in a small box and the masking extends around the trumpet curtain area as well! Does anyone have any supporting evidence for what constitutes "sufficient distance"? As far as my current testing shows, there isn't in our application. It would be interesting to see what a full radius would do.. but to be honest, who cares.. the short trumpets work! BTW.. The 16mm trumpets I used were selected because that was all that were available to me without fabricating ones from scratch. If anyone wants to provide me alternative trumpets, in whatever shape and size, I will arrange to test them at my expense. I also believe that the emulsion tubes need to be factored into this equation. The richness could well be changes in the mixture strength discharged through the emulsion tube as it reaches its upper limits.
  3. An update from a previous discussion... I replaced these as well with normal 45mm diameter cosworth isolators.. no dyno comparison tho... the cosworth ones need to be quite snug and do seep a little fuel on boost. Better solution may be to machine the original 'restrictor' out or make new spacers and use the nice fat o-rings lotus have. Sandwich plate not required BTW
  4. The rule of thumb I have always believed is that the distance from a trumpet to any airbox face or other should be at least the diameter of the trumpet.. therefore 45mm not 16mm in this case. Perhaps the curtain area does set the minimum, however if you look at the relationship of the OE trumpets to each other and to the sides of the plenum, there is very little clearance all around. I never thought the OE lotus S3T setup was well thought out... it seems to bear out. As to reflections and harmonics in the intake system, I think OE intake length is too short to make good use of anything within the rpm range of the engine. Shortening the trumpets 30mm may move any harmonic up perhaps 500 rpm. Such harmonic, as far as I can figure, would be up around 6K rpm and pretty weak.
  5. Air fuel mixture, your running lean somewhere...
  6. Sorry folks.. Ive been away... quite the commentary... I am at 19 total degrees advance for one main reason and that was before we got to 12.5AFR (we were at about 13-13.5AFR) and getting detonation at spots along the peak torque range.. I have done some research and found 16-20 degrees of advance at peak boost/torque safe (without WI).. given factors like IAT and fuel. Once we get past the peak torque more can be added, but with the analog distributor it just isnt possible (as far as I can see) so I live with 19 (which is 3 degrees more than the book values for the fed spec distributor. Without an intercooler and the stock 40trim compressor..the IAT gets up there. We measured close to 160F on the surface of the intake tube.. 160F is the limit before bad things can happen. The OE trumpets sit less than 16mm from the plenum face which I thought was a bad design but figured that the blow-thru turbo setup needed to have some form of restriction to get a signal across the jets (a method I have read about for BT turbo VW and A-series mini engines) I decided to do a back to back test and honestly figured it would be unsuccessful because of that theory.. not so!! I now believe that lotus added the boost feed pipes to the carb tops to get a slightly higher pressure over the jets vs using restriction methods. Good on them if that is true! I am still playing with jetting trying to get 12.5AFR across the board, but the top end is still too rich at about 10.5 to 11.5AFR I have ordered some 250 and 260 air correctors to see if we can flatten it out. The 40hp drop off the end of the curve is the dump valve opening prematurely. We got one run where it held, and we got to 6500 before it popped. I will be changing the OE DV to something like the Hyperboost CORE DV I am as surprised as you all are.. the car drives just fine and pulls like a freight train. Albeit I am still working on the idle circuit. Using 55/#1 I have had good results but will be trying 55/#7 to see if I can knock the last little bit of progression hesitation out of her. The dyno runs were on an eddy current dyno at 10m/s load all numbers are uncorrected.. add 15-18% to get FW numbers. This shows the plenum clearance: This shows the trumpet change: As an added bonus the turbo spools up faster and delivers slightly more average psi up up to WG opening...
  7. hope those that were interested in trhis upgrade found this information helpful.. J
  8. Some of you may find this worth considering in your tuning plans.. Just finished a dyno session with the 45mm long OE intake trumpets replaced with some 16mm stub stacks... Test was run on '85 S3T with the HC engine using 45DHLA; 9.5psi and 19 degrees total advance. Jetting 185M/240A Results came back with a 15% improvement in HP and 20% increase in torque over the entire rev range, plus, gained 500-1000 useful rpm!!! Discovered the OE BOV is pretty much crap at consistency and vents randomly at peak boost/rpm, dumping 40-50hp in the process. A hyperboost CORE DV with an adapter to mount the FPR, looks like a good option. A cam timing change from OE would aslo help improve the power more. Jan
  9. As to ride height..ensure springs are the same rate and static length as the originals. Higher rate (if original length)=higher ride height. And it wont take much more rate to add 30mm ride height. Take the springs to a chassis shop and get them compared to the originals. Have them modified or replaced as required. I believe the OE rate for the S3 fronts are 125lbs.. or put the originals back in. As to level: I would trust that all the checking has been done on an absolutely flat level surface? Ensure that there is no binding in the suspension, and all the springs are seated, then do yourself a favour and take the car to a chassis shop and scale the corner weights, and balance them. No other real way to get it 100% IMO. Jan.
  10. heres the diagram.. finally J window-lift-upgrade
  11. I dont have any pix but Mike R has pix of his conversion..he is on this forum at times. The driveshafts sit about 25mm further back and the tail of the GB reguires mods to the rear parcel shelf and muffler config... also linkage assy was improved on Mikes project.
  12. True.. maybe 0.2A on the headlight circuit, but 5-7A runs thru the switch's park light/dash light circuit!! I added a relay to my park light circuit after my switch melted itself together. J
  13. Check the power relays behind the glove box... Also check (although not likely unless PO had been in there) but..perhaps the 12v power post connection behind the RHS A-pillar is loose or bad?? J
  14. I have no choice on my project but to consider the UN1 unless I want to spend a fortune on an RBT ZF transaxle. With tuning to about 320hp.. the SM box would not last... hence my project conversion to UN1 The SM box output flanges are about 75mm wider than the UN1.. I decided that the OE IB brakes were not going to work well, so on my conversion to a UN1 I have conceptualized an inboard brake system to match the UN1 using aftermarket components. That way I can retain the wheel assy and links. The drive shafts need to be longer for the UN1. Mid 80's BMW 5 series shafts are the ones to use, unless you get custom ones made. I have all the conversion parts in hand, and have Mike Rodriques on this forum to thank for all his valuable input.
  15. Did Lotus happen to recommend any particular tire brand and model as a 'best' alternative from this exhaustive testing? --------- As of 2007, I honestly believe we have little choice in size, but much in brands and compounds in a 225 size. I am in need of new tires now, to replace the 245/50 and 225/50 set I have. I feel that 245/50 are great for rears but 225 a bit wide for fronts. A 205 or maybe a 215 would be better IMO.. (225 fronts seem a bit road surface sensitive). Is there any possibility of one of the manufacturers, like Dunlop or Goodyear, being convinced to do a run for a group buy?
  16. Ok figure this one out ..I just got my 85 back on the road and the speedo needle doesnt move. If I twist the cable at the gbox end by hand the needle works.. turn the wheels, the drive works.. cable seems long enough to seat in the drive end and isnt broken anywhere.. hook it all up, but no worka speedo? Anyone ever had that problem? J
  17. I had a set of damaged alloys that I simply ran over to a machine shop and had them turned on the lathe to remove a few thou off the surface to remove the damage, and then run some emery over them to make them ready for polishing.. cost me
  18. I think if you rebuild them with the nitrile type turbo gaskets, the turbo needle and seat, and add the pressure port style jet covers.. and make sure you have sealed t-shaft bearings, cant see why not.
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