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Hi Kevin,
I am building a new manifold (see photos I just posted to the list) that
uses a 95mm (3.7") LS1
throttle body on my 13B powered RV-6A. I previously used the stock 13B,
three port throttle body and got excellent results. My best guess is that
any throttle body with a cross section area that is larger than the total of
your primary and seconary runner crossection area does not add much - if
anything. Up to that point, you can make an argument( don't know how valid
it is) that if your throttle body area is less than the net cross section
area of your runners then it may be causing some restriction/loss.
I personally "respring" all my aircraft throttle bodies such that should
the cable break or come lose, the throttle body goes to full open. I agree
the cable (as long as its attached) will do the job without any spring, but
on that one in XXXXX chance the unthinkable happens, the effort to
"respring" the throttle body would have been well worth it ( to me).
I don't know about the 20B, but I can tell you it does not take much air
at all to keep a 13B at an idle of 2000 rpm. In fact, while I have not
plugged the hole in the throttle plate you refer to (yet), I suspect that I
will need to. I will probably stick a rivet in the hole and mash it flat.
Well, thats my 0.02$ worth, hope it helps. What are you planning on putting
your 20B in??
Best Regards
Ed Anderson
RV-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com
----- Original Message -----
From: "kevin lane" <n3773@attbi.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Sunday, June 29, 2003 12:55 PM
Subject: [FlyRotary] ho-made throttle body questions
> I am building my throttle body for my N/A 20b, a 3 1/2" monster! for
> aviation use, what is really needed? Are springs really necessary to keep
> it closed or open? it seems to me that the throttle cable takes care of
> that. perhaps a small spring to hold it open in the case of a broken
cable?
> I realize I will need an adjustable stop to control how much the valve
> closes. some have holes drilled in the butterfly so it never totally
shuts
> off the air flow. is this needed?
> because I am attempting to reuse some 20b carb parts it is possible I
> may have some minor air leakage thru the butterfly axle. it is sliced in
> the middle to accept the butterfly but a bit too long and the sliced
portion
> may extend past the bearings. I can plug that up or have it welded, but
> then I wonder what difference this makes if the valve needs to be kept
> partially open at idle anyways?
> Kevin Lane Portland, OR
> e-mail-> n3773@attbi.com
> web-> http://home.attbi.com/~n3773
> (browse w/ internet explorer)
>
>
>
> >> Homepage: http://www.flyrotary.com/
> >> Archive: http://lancaironline.net/lists/flyrotary/List.html
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