Advanced tech: Vizard's Polyquad


10 replies to this topic
  • HeadTrauma

Posted December 27, 2009 - 11:22 AM

#1

I found this article from David Vizard on gofastnews.com while pulling a red-eye reading marathon several days ago. It is a variation on the familar pentroof head design. I thought you all might be interested.

http://www.gofastnew...er-concept.html

All that effort and the method to get rid of tumble and replace it with swirl reminded me why the '83-87 twin carb engines work so well. The twin carb setup essentially does the same thing(on the intake side, anyway) in varying degrees at anything below WOT. I think the mild cam timing events these engines have means that less is lost by having a more conventional exhaust valve and port arrangement. Lots of swirl also lends itself to knock resistance and these engines definitely need all they can get. A good example is my father's XL600 compared to my XR600. His has the same compression and stock cam specs as mine and is much less picky about fuel.

It would be fun trying the PQ design on an RFVC head and seeing how it responds. Captain Midnight is working on adding quench pads to the chamber....maybe this could be another project. :cheers:

I would have posted in the "Advanced" Technical Discussion forum too, but this topic would just get buried among newbies asking how to clean chains or drain oil. :moon:

  • pwrpapa

Posted December 27, 2009 - 04:57 PM

#2

So if I run one larger int. valve and one larger ext. valve on my XRR I would get better swirl?
I'm going to read that again thanks for posting, great info.

  • ThumpNRed

Posted December 27, 2009 - 05:21 PM

#3

So if I run one larger int. valve and one larger ext. valve on my XRR I would get better swirl?
I'm going to read that again thanks for posting, great info.


I suspect one would have to reshape the chambers as well. Possibly tinker with the cam profile also. Interesting read. :moon:

  • HeadTrauma

Posted December 27, 2009 - 07:24 PM

#4

So if I run one larger int. valve and one larger ext. valve on my XRR I would get better swirl?
I'm going to read that again thanks for posting, great info.


Maybe, but the article is about using one larger and one smaller valve on each side, the idea being to keep valve area the same as before.

Something else that came to mind as probably being beneficial with single cylinder bikes is the fact that the carb(and often the port as well) is already angled and biasing flow to one side. Doing a PQ conversion might show higher gains than it would with a straight-flow multi-cylinder head.

  • cleonard

Posted December 28, 2009 - 11:31 AM

#5

Good stuff. Thanks for posting that. It was a very interesting read.

The whole problem with Advanced tech forum is what "advanced" means to people. For a guy that doesn't know which way to turn a bolt cleaning a chain is advanced. That forum needs a mod to send 4 out of five threads to the General forum.

  • ThumpNRed

Posted December 28, 2009 - 12:33 PM

#6

Good stuff. Thanks for posting that. It was a very interesting read.

The whole problem with Advanced tech forum is what "advanced" means to people. For a guy that doesn't know which way to turn a bolt cleaning a chain is advanced. That forum needs a mod to send 4 out of five threads to the General forum.


This is the old farts thread... makes sense that you'd have a more "mature" conversation here considering many here have been turning wrenches and twisting throttles for 20+years. :moon:

  • bork

Posted December 28, 2009 - 04:27 PM

#7

Sounds good but how do they really know the swirl or tumble pattern?

  • HeadTrauma

Posted December 28, 2009 - 05:41 PM

#8

Wet flowing with a clear cylinder allows you to see how the fuel is moving around.

  • Ryanthegreat1

Posted December 28, 2009 - 09:15 PM

#9

There are also devices that give a numerical value for swirl in a test chamber.

http://performancetrends.com/swirl.htm

  • phuzz

Posted December 29, 2009 - 07:06 AM

#10

Wet flowing with a clear cylinder allows you to see how the fuel is moving around.


HT, isn't dry air, with dye/colorant, also used? Like in a wind tunnel "tracers"?

  • HeadTrauma

Posted December 29, 2009 - 09:20 AM

#11

I don't really know. The wet flowing I have read about involved either water with a dye, water with a UV dye, or naptha/stoddard solvent with no dye. Wet flowing still doesn't seem to be popular outside of ultra high level motorsports.





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