[Main General Bulletin Board | BBFAQ | Prev by Date | Next by Date | Post Followup ] Member Login / Signup - Members see fewer ads. - Latest Member Gallery Photos Yep... Like This Post: - Subscribe to Daily Digest for this Bulletin Board Posted by Justin VanAbrahams [Email] (#32) [Profile/Gallery] (more from Justin VanAbrahams) on Sun, 8 Sep 2002 15:37:53 In Reply to: Apparently the current SVC needs supercharging, AdamB [Profile/Gallery] , Sun, 8 Sep 2002 15:14:37 Alert me when someone posts in this thread: Members do not see ads below this line. - Help Keep This Site Online - Signup

My understanding of the technology is that it would not be easy to manage with anything other than a supercharger. With a turbo, boost is unpredictable - there is not a 1:1 ratio of engine speed vs. boost. A mechanically driven supercharger skirts this issue, and would allow Saab to map engine speed to boost to compression ratio extremely accurately. I think this would be important to this design, where effective compression ratio is dynamically adjusted... use of a turbo would probably result in drivability issues. Additionally, within the design, a clutch-operated supercharger (like the early MR2 and Thunderbird SC) would allow the engine management to disengage the supercharger altogether when cruising with a high-compression ratio, thus improving fuel economy dramatically. You would be unable to do this with a turbocharger without some serious engineering.

All this said, it would be pretty neat if the SVC was also a Miller Cycle engine... talk about some serious power and serious fuel economy...

As for durability, I can't imagine this design is any less durable than a conventional motor. The adjustment is only a few mm, and the mechanicals necessary to do it aren't very complex. The problem is the cost - an integral head and block cannot be cheap to produce. The reason we have discrete parts currently is because the cost of producing this type of design is *expensive*. I expect maintenance on the engine - things like valve seals - could be quite pricey as well. Who knows, though? Saab made turbocharging affordable years before anyone else - maybe they can do the same with this design.

-Justin

posted by 64.166.4...

• Variable Compression Ratio Engine ..., J, Sat, 7 Sep 2002 19:32:28
  • wouldn't that apply to all turbo-charged engines?, Aero'ed, Sat, 7 Sep 2002 19:56:18
    • CR is purely a function of cylinder geometry..., Mr. Science, Sun, 8 Sep 2002 01:27:01
      • Actually..., Justin VanAbrahams , Sun, 8 Sep 2002 15:44:20
        • My mistake Justin..., Mr. Science, Mon, 9 Sep 2002 08:47:22
          • Re: My mistake Justin..., Nathan Work, Mon, 9 Sep 2002 14:39:28
      • Re: CR is purely a function of cylinder geometry..., Aero'ed, Sun, 8 Sep 2002 08:56:13
        • Saab is not just experimenting -, saabaru, Tue, 10 Sep 2002 14:16:56
        • SVC Link, Mr. Science, Sun, 8 Sep 2002 13:08:47
          • Yea, high compression at low load for max effeciency..., Mike Lynch , Sun, 8 Sep 2002 18:48:54
          • Help me Mr. Science ... I'm confused, J, Sun, 8 Sep 2002 15:08:06
            • Apparently the current SVC needs supercharging, AdamB , Sun, 8 Sep 2002 15:14:37
              • Yep..., Justin VanAbrahams , Sun, 8 Sep 2002 15:37:53 <-- Viewing This Message
                • What ever happened to the electric supercharger?, Mr. Science, Mon, 9 Sep 2002 08:52:35
                  • Re: What ever happened to the electric supercharger?, Justin VanAbrahams , Mon, 9 Sep 2002 18:05:24
                    • Isn't it the other way round?, AdamB , Tue, 10 Sep 2002 04:35:33
                      • Nope...., Justin VanAbrahams , Tue, 10 Sep 2002 19:38:55
                  • Word was that they're going to use it on the new, RS , Mon, 9 Sep 2002 08:57:48
        • Aero'ed, I have a link that will help, ERP, Sun, 8 Sep 2002 10:59:42

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