you need 2/3 the port area in every directon from the port opening seens
hard to thionk in will fit with those dimensions but might. Surface finish
through empirical testing for 35 years..
----- Original Message -----
From: "Larry Mayfield" <drmayf@mayfco.com>
To: "Dave Dahlgren" <dahlgren536@comcast.net>
Cc: <land-speed@autox.team.net>
Sent: Sunday, June 05, 2011 12:55 PM
Subject: Re: [Land-speed] Intake Manifold Question(s)
> Plenum is to be made from 4 in sq tube, 1/8 wall for a 3.75 sq inside dim.
> and about 14 inches long. That covers all the runners and provides about
> 196 cubic inches. Plus the TB mount on the side will hang out a couple of
> inches for a few more cubic inches. And the motor will have a new smaller
> displacement. Will come pretty close to 2/3 displacement size. Important?
> I don't know. Wont be the first thing I have tried that didn't pan out,
> lol.
>
> Curious as to the technical aspect of why some roughness or smoothness is
> needed. Seems to me that the smoother the walls the smoother the flow
> because of boundary layer thniness, ie velocity profile is improved.
> Again, I have no real insight to this though.
>
> ______________________________
> drmayf
> Worlds Fastest Sunbeam, period.
> 204.913 mph flying mile
> 210.779 mph exit speed
>
>
> On 6/5/2011 9:24 AM, Dave Dahlgren wrote:
>> 36 to no finer than 60 grit is just fine.
>> You will be hard pressed to build a 200 cu in plenum...
>> 10 X 5 X 4 =200 and will not reach the end runners very well.
>> ----- Original Message ----- From: "Larry Mayfield" <drmayf@mayfco.com>
>> To: <land-speed@autox.team.net>
>> Sent: Sunday, June 05, 2011 11:48 AM
>> Subject: [Land-speed] Intake Manifold Question(s)
>>
>>
>>> Ok, those of you who consider me a crank can hit delete now, lol....
>>>
>>> I am making or revising an old manifold for use on the Sunbeam. I notice
>>> that the runners are pretty dog gone rough and I want to do port
>>> matching and polishing. My questions have to do with the smoothness of
>>> the air flow in the runners. This is an EFI manifold so it is what I
>>> would call dry. No fuel in the manifold. So do I want a really smooth
>>> runner wall or rough? If smooth just how smooth? Should I have it
>>> extrude honed for smoothness and removal of any small turbulence
>>> generators? If really smooth would coating the runner walls with glyptol
>>> be a good thing? That stuff drys to a hard finish and is pretty slippery
>>> and dang near impervious to oils and anything else.
>>>
>>> The manifold will be a short runner box with a plenum about 2/3 size of
>>> the engine displacement (an old rule of thumb I once heard and maybe be
>>> invalid) for use with my HP72 turbo(s).
>>>
>>> Thoughts, comments, ideas? I'll listen to them all....
>>>
>>> Just going to try and increase the Sunbeams speed over the old first
>>> Sunbeam top speed. Class record speeds are way beyond my capabilities
>>> and pockets, lol...
>>>
>>> --
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