Intake Runner Length

[Bruce Plecan]

-----Original Message-----
From: Ord Millar <ord at aei.ca>
To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
Date: Tuesday, February 02, 1999 11:20 PM
Subject: Re: Intake Runner Length

Cylinder Bore x .85= some dimension.  The sum of both valves head diameters
should about equal that.
4" borex .85= 3.4   1.9" intake, and a 1.5" exhaust would work very well.
None hemi type head.
Not an absolute, but a good guide.  Yates, and them NASCAR guys are now
getting around that.  But, they spend a ton of money to do it.  Angle
cutting
the heads to get the stems more parrael to the cyl bore works to.
Bruce


>Bruce,
>
>can you explain the 85% diameter thing?  It's not fitting into my brain too
>well...
>
>Ord
>
>-----Original Message-----
>From: Bruce Plecan <nacelp at bright.net>
>To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
>Date: Tuesday, February 02, 1999 10:52 PM
>Subject: Re: Intake Runner Length
>
>
>>
>>-----Original Message-----
>>From: Van Setten, Tim (AZ75) <Tim.Van.Setten at CAS.honeywell.com>
>>To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
>>Date: Tuesday, February 02, 1999 4:47 PM
>>Subject: RE: Intake Runner Length
>>
>>I worked at an R+D shop, and for a while Ollie Morris (one of the great of
>>manifold designers), and find Smokey Yunick's quote of "square ain't as
bad
>>as
>>it seems" (or words to that effect) meaningful.  While many ports look
like
>>beautiful
>>sculptures, sometimes it's just better to take you licks, and be done with
>>it.
>>Specially with a dry manifold.  Considering at 6,000 rpm from butterfly to
>>intake valve the "air" is only in the intake for like .008 (and possibly
>>much lesss) of a sec. it ain't there long enough to estabish boundry
>>layers/laminar flow enough to matter (for other than all out race
>>applications).  Worry about the bowl, and valve,
>>the most.   Specialy if were still talking about a turbo VW.  Then we can
>>get to keeping the total valve diameters not to exceed 85% of the bore, or
>>shrouding
>>gets to be an issue (non-hemi heads)..  Sir Harry Ricardo, just realised I
>>hadn't mentioned him in two weeks.
>>Cheers
>>Bruce          Well, if the smoke alarm batteries fail, the Fire Dept is a
>>distant
>>                  second for a Food Timer.  Gotta teach Doc to use the
>>microwave.
>>                  Least we got new windows in the Kitchen outta the deal.
>>
>>
>>> I can understand air speed
>>>in the runner, etc., but where it goes out the window for me is when you
>>see
>>>the runner, where it attaches to the plenum, is a square corner!  A lot
of
>>>plenum / runner combinations are shaped like a "T".  Believe me, I'm not
>>>trying to make an issue out of this, just trying to understand and make
>the
>>>best setup feasible.
>>> Thanks.....Tim.
>>
>>
>>
>