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Why superchargers fail

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  • #31
    Dan, I'm not sure I understand the 70% efficiency part. Is the loss in efficiency from the impeller clearance or something else? Trying to understand.

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    • #32
      Nels, no belt driven supercharger, centrifugal ball drive or gear drive or otherwise, is 100% efficient. I'm not sure what Paxton had rated the SN60, but I believe it was significantly less than 70%.

      Turbos are the most efficient way to boost an engine. On real high end turbo setups the magic word is "crossover" - which is when the power created is in excess of theoretical. The simple theory is based on atmospheres of boost (every 14.7 psi is one atmosphere, or 1 bar). So an engine at 1 bar of boost could in theory have double the non boosted horsepower (14.7 psi atmospheric, plus 14.7 psi boost equals the engine breathing as though it were twice the displacement).

      Thomas

      Long time hot rodder
      Packrat junk collector
      '63 Avanti R2 4 speed

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      • #33
        You really need a direct oiling system that was installed in many cars in the 50's with superchargers where engine oil was pumped into the unit. A drain hole was made half way up on the side of the case and when the oil reached that hole drained back to the oil pan or oil adding tube. I have this setup on my 57 Packard Clipper and it has worked great. On my 58 Packard Hawk I will not do it because it is not "correct". So when not showing the car I remove the belt and put it the belt on for shows. The superchargers are getting harder and harder to find and more and more expensive. I have a 7 of them and paid hardly anything for them because years ago they were worthless.Cubic inches put the last nail in superchargers coffin besides its failure rate. Getting back to direct oiling. At my shop every late model Camaro,Firbird and Mustang I have seen with an aftermarket supercharger set up absolutely used a direct oiler system.No ands,buts or maybes about it. If Paxton Superchargers were so great more manufacturers would have installed them.

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        • #34
          quote:Originally posted by jlmccuan

          John, I'll be testing out one of the dipstick coolers in the next week. I should be able to get temps of both the SC case as well as the air charge temps with and without the cooler. Although this information will not give direct evidence of extending SC life, one would think that if the dipstick cooler does in fact reduce the operating temp of both the SC and the air the SC delivers, it would be a good thing.
          Jim,

          I found a picture of a dipstick cooler for Paxton SC by a company called JC Performance in Grover Beach, CA. Is this the one you are trying out or something similar to it. If so I definitely would like to hear about your results.


          <div align="left">John</div id="left">

          <div align="left">'63 Avanti, R1, Auto, AC, PW (unrestored)</div id="left">
          sigpic
          John
          63R-2386
          Resto-Mod by Michael Myer

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          • #35
            That's the dipstick and pump exactly, but my heat exchanger is different. The dipstick is the hard part, the pump is FLAPS available and a variety of heat exchangers can be used. As I said earlier, I bought one of the dipsticks, but I think one can be built for less if you're handy. I've been logging temps coming from the air charge and the SC oil temps and it looks as though the bulk of the heat is from the compression. Possibly, more heat is going into the oil from the heat of the air being compressed than from the mechanical operation of the SC. Probably why most SC manufacturers concerned with heat going into the engine use intercooling or aftercooling rather than trying to directly cool the SC. But it's still too early for any conclusions.

            Jim

            ____1966 Avanti II RQA 0088_______________1963 Avanti R2 63R3152____________Rabid Snail Racing
            Jim
            Often in error, never in doubt
            http://rabidsnailracing.blogspot.com/

            ____1966 Avanti II RQA 0088_______________1963 Avanti R2 63R3152____________http://rabidsnailracing.blogspot.com/

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            • #36
              I don't have any direct experience, but have been told and read that engine oil and regular ATF do not have the correct friction modifiers needed at higher RPM's and boost pressures to efficiently operate the ball drive SC's, hence the specification of the type "F" ATF by Paxton. I'm not sure, but weren't Paxton and McCullough the only ones using the ball drive? I also have a Procharger with an intercooler (more correctly, an aftercooler). It is a gear drive unit and recircs engine oil for lube and cooling, similar to other currently made brands.

              Jim

              ____1966 Avanti II RQA 0088_______________1963 Avanti R2 63R3152____________Rabid Snail Racing
              Jim
              Often in error, never in doubt
              http://rabidsnailracing.blogspot.com/

              ____1966 Avanti II RQA 0088_______________1963 Avanti R2 63R3152____________http://rabidsnailracing.blogspot.com/

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