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Everything posted by ablesnead

  1. The fluid damper site said rubber limited the tuning range to 50 hertz ..I don't know how that applies..the problem for me, with driving thru the resonance frequency in a highly modified motor ( hybrid if you will ) is that I don't have the ability to know where it is . As a side note , the BJH white paper says that a heavy fluid damper can cause snout problems because it introduces vibration that the damper cant see nor correct.
  2. With the help of the posts from 10 years ago on this site and a lot of reading on google , I think I have a handle on my questions , unfortunately I don't know if I have a solution...Smokey Yunick once told me that a 350 inch chevy needed 167 hp to spin the engine before putting power to the ground....I can't really quite grasp those numbers, but the concept of freeing up horsepower when the basic engine , as an air pump , had limits on its ability to make it , has always intrigued me . Contrary to the little difference one responder to my original post noted , I experienced a completely different feel in the IMSA porsche that I drove at the 24 , So now years latter my hobby car is limited by its factory efi intake in a normally aspirated form . Knife edging, lite fly wheels, lite clutch pak , are all tools I plan to use to put more of that limited power on the ground....so now we face the harmonic problem...no one addressed it specifically . Tony , in what I find , is a rude and overbearing way , uses an example of a hot rod vw engine that doesnt need a damper at the OE designed operating range , but a builder that is widely respected does address the problem with his modified engines......I found many likewise respected builders that did not subscribe to Bergs theory , I know on our 50,000 dollar GTU engines we never adressed it either...I now think that was a significant mistake . I think with our L6 we are still making that mistake...Note: one poster claiming intensive research quotes a harmonic between 72 and 75 k , Tony , in other threads makes lite of the " so called harmonic at 73 k , he has real world experience spinning a crank with stock rods to 9k...well thats the whole point....If a stock damper is designed for 6.5 K of therebouts , you essentially don't have a functioning one at 9 k.....Since any modification of the reciprocating mass needs a damper designed for that particular mass , to be effective , anything except a possible fluid damper alternative is just a sort of voodo bolt on....in the same vein as bigger throttle bodies....I wish sharper minds than me could apply thought to dampers that really are designed to be modified for our individual builds.... because if we say ifs not important then , the choice to run no damper at all , by default, is also not important . John lightened his crank from 51 to 32 lbs I believe...lite rods, lite pistons...you get my drift. no off the shelf damper would fit all cases..Apparently any damper that doesn't fit a prescribed resonance range offers no benefit and a wandering timing mark...note boxer engines by their design have a much lesser concern than we should . I really enjoyed this THANKS
  3. The posted previous thread on dampers was just what I was looking for ....sorry if my lack of information has offended , I did try the search function, but obviously not thoroughly enough .... the point on solid aluminum pulleys is that they lack damping material...thanks all for the insight..Tony you are a ******* arrogant ******* !
  4. No ,absolutely not saying it....just wishing we had an in depth dialogue as to why or why not...seems like just getting easy answers...similar things as in other threads that ended up teaching us the difference between science ( art ?) , and old wives tales .
  5. I'm wondering if this is similar to the belief that you need some back pressure... I dont have the background to quote any science on the subject , but even on this forum members that pooh pooh harmonics , touting that the factory internals were so well balanced from the factory , only reply with the stock answer ..get a so and so damper, seems to the uninitiated ( me ) like a little hypocracy . I am assuming that an out of balance reciprocating mass induces the harmonics that a damper is designed to damp....I am belaboring this point because it is a big red flag in the knife edge question of my original post....in Porsche boxer six'es we ran without dampers......hot rod VW's use aluminum pulleys across the board.... jut say'in
  6. Nope , bolt on aluminum crank pulley 199.00 Top End Performance..been using them for years yada yada yada They say )
  7. This is a continuation question that arise from the responses about dampners , I am fairly weak in the theory here , but I have read that the counter weights on a crank are weighted to balance the offset rod ( and all attached parts ) , to eliminate a harmonic vibration,,,the so called bob weight....so if properly balanced , why would a harmonic balancer be needed ? This question arose because some long established Z performance shop sells a light weight ( aluminum front pulley ), in place of a balancer . any thoughts ?
  8. I need a smooth (no vents ) early Z hood , located in central to south Florida
  9. I really suck at the search function on this site...I remember a long thread with pictures discussing diesel water pumps ...now I can't find it..can someone clue me in , I've got one to sell if it really is a diesel pump..Thanks
  10. I like the response and feel already , just wondering about how the reliability would suffer...its effect on the 7300 rpm harmonics that I heard about , a damper should work similar to stock weight I assume
  11. Talk to me about knife edging a crank on a 2.8 ,,,,, I've driven a porsche in the past with a knife edged crank , and almost 6 lbs lighter ,, it was a hoot , very motorcycle like response. Dave of Rebello is not in favor of it , but I cant really find a downside in internet discussions of knife edging ..( this is for a track car only ) any datsun experiences out there ?
  12. Because this site was developed to cater to those that enjoy modifications to the Z
  13. I apologize for the confusion my previous caused you...in person I would talk slower in an effort to make my point. But I think that its interesting that we approach the question of moving back an engine to approach 50/50 weight distribution ..and have different opinions , as to the good or bad , its effect on handling would be . Both of us with years of racing , yet different approaches ...I think it makes for interesting racing ..destabilizing is an interesting word...being that the stable state is a straight line , and road courses have occasional turns
  14. I only disagree on a quickly reacting car being destabilizing , I belive , balanced , the quicker the better ,remember how 20 laps in , the car had a different feel than the setup you started with. Any movement desired or not is transmitted thru your contact patch , that you try an optimize with your setup . This compromise is evolving to a small degree every lap...a car without a weighted end hanging out , allows this to happen in a more uniform manor....so I found the result of a 50/50 setup both initially quicker and consistently so...I have experienced the quick and relatively violent polar movement off track or in the marbles, but with a normal racing surface and a good tire setup , lateral movement planned or otherwise is mediated by grip or lack of it.
  15. I am enjoying this thread , and would like to add from my experience as a race driver in 50/50 cars and others..( I have no engineering expertise )...when a car breaks loose with a 50/50 weight distribution , ( with a reasonable race setup) , both ends react in a balanced manner...easy to control, and use , for a quick time. With oversteer or understeer , one end reacts quicker , and can be more tuner intensive to set up, I belive the well balanced car easier to drive as tire wear occurs .. the reaction speed of the driver is equally vital to both setups and I belive moot to the discussion .
  16. I'm new to Charlotte, NC where is our local track ? the tight one ?
  17. I have many years racing ITS datsun 240s....our brakes suck , if you need to use them , ( particular tracks ) , then you are at a distinct disadvantage..ducting carbo tech rear lining , latest porter field ....they still suck , I have finished 1 hour enduros with the calipher piston all the way thru the pad metal...no brakes , but we expect that, still won !
  18. I'm way to old to get roped into this kind of posturing....but hell , I just have to throw in my 2 cents. I raced 240z's in ITS for a bunch of years , then took a 911 pro in the old IMSA GTU wars...6th at Sebring in 93 , nothing of note after. My 911...3.6 , in its final edition was the best handling car I , or my 3 very experienced co-drivers , had yet to drive, in all respects , balance ..inducing oversteer , and with awesome turn in . we ran the first non whale tail wing..off a s2000 . The 240 was an incredible car at the club level...but required big bucks to run a season at the 300 plus HP level...Porches niche was that while they were expensive initially... they were still able to reach pro competive levels , with the basic factory platform.
  19. Looking for an early model three piece front valance / no turn indicators needed ..... also some p90a hydralic lifters
  20. Got my hood scoop from Les.....prompt, great packing...excellent fit and finish !
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