Re: Vespa intake timing: let's talk numbers

Marc Friedman /
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I've been thinking about these numbers for quite some time and trying to compare this rotory valve design to the supplanting technology ie reeds. Take for instance the open time between tdc and The 60-72 degrees after tdc. Isn't the piston descending but the crankcase side unpressurized due to the intake being open? Why isn't the flow at the carb reversed until valve closure. What's the point of it? What's the point of fifty degrees or so of valve closure at bdc until it reopens. Does this somehow increase the rate and volume of charge flowing up the open transfer interval. Wouldn't a reed valve close much closer to tdc and reopen much closer to bdc? Why does increasing the intake duration further past tdc as in an anticipato grind do any good. Wouldn't increasing the intake open to almost tdc and closing it earlier after tdc increase the molar volume of gas and air to flow via the transfers when they open and increase horsepower?? Wouldn't the engine want to start better because the vacuum at the carb is more efficient?

This not entirely abstract. I am still trying to figure out why my polini kit with anticipato is such a dog.

This single post is part of a larger thread. Start from the top or view this post in context.
Subject Written By Posted
  Vespa intake timing: let's talk numbersTopic by: Simon Nyi Simon Nyi 10/01/13 03:23PM
  Re: Vespa intake timing: let's talk numbersRe: Maciek Dub Maciek Dub 10/01/13 04:27PM
  Re: Vespa intake timing: let's talk numbersRe: Adam Blickhahn Adam Blickhahn 05/14/14 11:50PM
  Re: Vespa intake timing: let's talk numbersRe: #CrazyWayne™ rocks. #CrazyWayne #CrazyWayne™ rocks. #CrazyWayne 06/22/14 02:34AM
  Re: Vespa intake timing: let's talk numbersRe: Josh G Josh G 10/01/13 05:47PM
  Re: Vespa intake timing: let's talk numbersRe: Josh G Josh G 10/01/13 05:52PM
  Re: Vespa intake timing: let's talk numbersRe: Josh G Josh G 10/01/13 06:19PM
  Re: Vespa intake timing: let's talk numbersRe: Maciek Dub Maciek Dub 10/01/13 06:37PM
  Re: Vespa intake timing: let's talk numbersRe: Simon Nyi Simon Nyi 10/01/13 06:50PM
  Re: Vespa intake timing: let's talk numbersRe: Graham Motzing Graham Motzing 10/01/13 08:23PM
  Re: Vespa intake timing: let's talk numbersRe: Simon Nyi Simon Nyi 10/01/13 10:55PM
  Re: Vespa intake timing: let's talk numbersRe: Allen Halk Allen Halk 10/01/13 11:25PM
  Re: Vespa intake timing: let's talk numbersRe: Deadped Ryan Deadped Ryan 10/01/13 11:42PM
  Re: Vespa intake timing: let's talk numbersRe: Simon Nyi Simon Nyi 10/18/13 12:58PM
  Re: Vespa intake timing: let's talk numbersRe: Jason ( ͡° ͜ʖ ͡°) Jason ( ͡° ͜ʖ ͡°) 12/28/20 03:51AM
  Re: Vespa intake timing: let's talk numbersRe: «tyler » «tyler » 10/18/13 01:42PM
  Re: Vespa intake timing: let's talk numbersRe: Simon Nyi Simon Nyi 10/18/13 02:44PM
  Re: Vespa intake timing: let's talk numbersRe: Maciek Dub Maciek Dub 05/15/14 04:07AM
  Re: Vespa intake timing: let's talk numbersRe: Maciek Dub Maciek Dub 06/20/14 01:16PM
  Re: Vespa intake timing: let's talk numbersRe: Pete Puczasaurus Pete Puczasaurus 06/20/14 02:30PM
  Re: Vespa intake timing: let's talk numbersRe: Maciek Dub Maciek Dub 06/20/14 06:43PM
  Re: Vespa intake timing: let's talk numbersRe: Graham Motzing Graham Motzing 06/24/14 03:26PM
  Re: Vespa intake timing: let's talk numbersRe: Maciek Dub Maciek Dub 07/13/14 02:38AM
  Re: Vespa intake timing: let's talk numbersRe: Maciek Dub Maciek Dub 07/13/14 03:33AM
  Re: Vespa intake timing: let's talk numbersRe: #CrazyWayne™ rocks. #CrazyWayne #CrazyWayne™ rocks. #CrazyWayne 07/13/14 03:49AM
  Re: Vespa intake timing: let's talk numbersRe: Pete Puczasaurus Pete Puczasaurus 07/13/14 02:09PM
  Re: Vespa intake timing: let's talk numbersRe: Maciek Dub Maciek Dub 07/13/14 07:10AM
  Re: Vespa intake timing: let's talk numbersRe: Maciek Dub Maciek Dub 07/17/14 12:17PM
  Re: Vespa intake timing: let's talk numbersRe: Marc Friedman Marc Friedman 07/17/14 12:46PM
  Re: Vespa intake timing: let's talk numbersRe: Maciek Dub Maciek Dub 07/17/14 12:59PM
  Re: Vespa intake timing: let's talk numbersRe: Maciek Dub Maciek Dub 07/17/14 01:31PM
  Re: Vespa intake timing: let's talk numbersRe: Marc Friedman Marc Friedman 07/17/14 01:42PM
  Re: Vespa intake timing: let's talk numbersRe: Maciek Dub Maciek Dub 07/17/14 02:11PM
  Re: Vespa intake timing: let's talk numbersRe: Marc Friedman Marc Friedman 07/17/14 02:57PM
  Re: Vespa intake timing: let's talk numbersRe: Maciek Dub Maciek Dub 07/17/14 04:24PM
  Re: Vespa intake timing: let's talk numbersRe: peter heid peter heid 07/20/14 10:35AM
  Re: Vespa intake timing: let's talk numbersRe: Maciek Dub Maciek Dub 08/19/14 02:51AM
  Re: Vespa intake timing: let's talk numbersRe: Marc Friedman Marc Friedman 12/14/14 02:59PM
  Re: Vespa intake timing: let's talk numbersRe: Maciek Dub Maciek Dub 07/22/14 03:30AM
  Re: Vespa intake timing: let's talk numbersRe: Marc Friedman Marc Friedman 12/14/14 03:50PM
  Re: Vespa intake timing: let's talk numbersRe: Marc Friedman Marc Friedman 12/14/14 04:06PM
  Re: Vespa intake timing: let's talk numbersRe: Marc Friedman Marc Friedman 12/14/14 04:20PM
  Re: Vespa intake timing: let's talk numbersRe: Marc Friedman Marc Friedman 12/14/14 04:26PM
  Re: Vespa intake timing: let's talk numbersRe: Marc Friedman Marc Friedman 12/15/14 09:44AM
  Re: Vespa intake timing: let's talk numbersRe: «tyler » «tyler » 12/15/14 12:24PM
  Re: Vespa intake timing: let's talk numbersRe: Marc Friedman Marc Friedman 12/15/14 12:28PM
  Re: Vespa intake timing: let's talk numbersRe: Maciek Dub Maciek Dub 12/16/14 05:34PM
  Re: Vespa intake timing: let's talk numbersRe: alex . alex . 12/19/14 04:35AM
  Re: Vespa intake timing: let's talk numbersRe: alex . alex . 12/19/14 05:00AM
  Re: Vespa intake timing: let's talk numbersRe: Walt W Walt W 12/22/14 08:35PM
  Re: Vespa intake timing: let's talk numbersRe: Marc Friedman Marc Friedman 12/22/14 08:48PM
  Re: Vespa intake timing: let's talk numbersRe: alex . alex . 12/23/14 04:15AM
  Re: Vespa intake timing: let's talk numbersRe: Marc Friedman Marc Friedman 12/23/14 01:12PM
  Re: Vespa intake timing: let's talk numbersRe: Maciek Dub Maciek Dub 12/24/14 11:48AM
  Re: Vespa intake timing: let's talk numbersRe: «tyler » «tyler » 10/02/13 08:46AM
  Re: Vespa intake timing: let's talk numbersRe: Simon Nyi Simon Nyi 10/18/13 01:52AM
  Re: Vespa intake timing: let's talk numbersRe: «tyler » «tyler » 10/18/13 09:31AM
  Re: Vespa intake timing: let's talk numbersRe: Pete Puczasaurus Pete Puczasaurus 06/11/14 07:38PM
  Re: Vespa intake timing: let's talk numbersRe: Pete Puczasaurus Pete Puczasaurus 06/20/14 01:09PM
  Re: Vespa intake timing: let's talk numbersRe: «tyler » «tyler » 12/15/14 07:52AM
  Re: Vespa intake timing: let's talk numbersRe: Marc Friedman Marc Friedman 12/15/14 09:19AM

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