Manifold/throttle bodys-ED:-)

Edward C. Hernandez ehernan3 at ford.com
Wed Sep 4 16:42:33 GMT 1996


talltom wrote:
> 
> Hey Ed, if you're the manifold guru for Ford, how come the
> manufacturers haven't gone to throttle bodies for each cylinder like
> on some of the vettes? 

Guru?! Your words, not mine, but thanks. I was unaware of any Corvettes
with actual port throttles, though I believe the LT-5 had what we call
runner controls. Those can deactivate one runner of a dual runner
design, they don't actual control engine speed like a true throttle.

>...it can't cost very much when they're already using port inj. Heck 
> it might even be cheaper, being as the current
> massive aluminum castings could be eliminated in place of plastic
> plumbing.

It does cost very much. True throttles have to seat accurately in their
bores, and the shaft CANNOT bind under any conditions. Thus, special
care must be taken when manufacturing the bores, whether they be plastic
or aluminum. Most Al throttle bodies are die cast(cheap) and then their
bores are machined. Without going into a lot of manufacturing detail, a
cost effective plastic throttle body must be made a certain way to avoid
this machining operation, and thus far, that way is incompatible with
how most plastic intakes are made today. Even if you hurdle that one,
you still need, for a V8, 8 separate plates, 16 screws(or welds),
anywhere from 2 or 4 or even 8 shafts, accompnied by 4 or 8 or 16 sealed
bearings, cables(or motors)....It will never be as cheap as one throttle
body. BUT, I like port throttles(ala Euro spec BMW M3) from a
performance standpoint since they make for excellent throttle response
while letting the designer get as wild as he wants with the intake
tracting.

-- 
Ed Hernandez
Ford Motor Company
ehernan3 at ed8719.pto.ford.com



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