rotary barrel throttle bodies

[beef_bourito]

so i was looking at a motorcycle website given by one of the other threads and it said they wanted to use "rotary barrel throttle bodies".

what are they, what do they look like, and what are their advantages over regular ones?

[TheSilentChamber]

I'v never heard of one, but it sounds to me like it would be a deisng that didnt use a plate, but some sort of rotory system to restrict flow without disturbing it like a throttle plate does. I could be completely wrong though.

[beef_bourito]

wow, thesilent chamber stumped, that's quite rare.

anyone else?

[GreyGoose006]

barrel throttles are a way to throttle the engine without using a butterfly valve.
it reduces resistance in the intake and all that stuff.
basically, it turns the gas pedal into an on/off switch. you have less control over the precision of teh throttle.
barrel throttles are commonly used on rally engines where the gas pedal is used either on or off anyway.

if this didnt make sense, there is stuff out there on them.
try a search or something

[psychopathicdude]

ummm.....try this mental picture....quarter turn ball valves! like in plumbing....when the valve is open, there's nothing to obstruct anything! just an open hole. and though it may be less progressive than a flutterby plate, it can be varied.

[UncleBob]

I assume this is in reference to the drysdale site I posted.

I used to have a link to some absolutely gorgeous one-off billet machined rotary valves someone was making for turbo'd busa's. I think they were worth more than most bikes! Can't find them unfortunately....

but they are as discribed above, like a ball valve in plumbing, when fully open, they are 100% flush with no ridge, steps or restrictions. A perfect pipe.

I always thought about taking a set of flat slide carbs from bikes and adding injectors. Same thing really. Only problem is, the larger flat slide carbs are pretty spendy too. Don't find those lieing around for cheap. But definitely flows well, used as a carb or a throttle body

[534BC]

http://www2.towerhobbies.com/cgi-bin...CH=ROTARY+CARB++

Here's some tiny ones, same concept.

[GreyGoose006]

the only ones i have seen in cars are in the ford cosworth rally engine put in the Focus.
i think it was a 2.4L V-6
they are common in racing bikes i think

[Moppie]

Originally Posted by GreyGoose006

barrel throttles are commonly used on rally engines where the gas pedal is used either on or off anyway.

Care to substantiate that?
Because it smells like really, really bad information.

[Moppie]

Originally Posted by GreyGoose006

the only ones i have seen in cars are in the ford cosworth rally engine put in the Focus.
i think it was a 2.4L V-6

If your talking about the WRC Focus, then its a 2L 4 cyl.
Theres that bad information again.

[UncleBob]

I don't see how the rotary valve would be "on/off"....it would actually be more linear than a butterfly. A butterfly leaks at both axis as the shaft turns, where as the rotary only leaks on the leading edge.

High performance applications always use huge throttle bodies, no matter what style they are. Many motorcycles use 40+, even 50+mm ITB's (individual throttle bodies) for example...and they have very good drivability....and thats with butterflies

[Moppie]

Originally Posted by UncleBob

I don't see how the rotary valve would be "on/off"....it would actually be more linear than a butterfly.

Their used in Pneumatics for this very reason.

Iv seen 50mm Webbers on a 1600 Lotus Twincam, but never on a motorbike, thats a lot of air to be ingesting

[UncleBob]

as far as 4 cylinders, the new ZX14 uses 44mm TB's....but keep in mind, thats a dead stock bike. Not heavily modified as your example. Thats also a ~190rwhp (calculated ram air)

the busa (1300cc, I4) uses 46mm TB's stock.

An RC51, 1000cc V twin, for example, uses 56mm TB's stock

[GreyGoose006]

Care to substantiate that?
Because it smells like really, really bad information.

If your talking about the WRC Focus, then its a 2L 4 cyl.
Theres that bad information again.

i got both out of the same car and driver magazine article a while ago.
their reasoning was that it is harder to modulate a rotary barrel throttle.
there was some technical reason i missed because there was a picture of the WRC engine that used these rotary barrel throttles on the next page, and it was making me horny...
i swear that was the prettiest engine i have ever seen.
the throttles were too.
nine of them...
one for the boost controller. apparenty they were limited to like 6 psi of boost with 8 psi for like 30 seconds total per event. the idea was that if boost spiked at all above 6 psi or 8 psi while the button was pushed, they were disqualified. barrel trhottles were used to release the pressure as fast as possible between shifts.
that was a gorgeous engine tho.

[UncleBob]

I would like someone to attempt an explanation on why a rotary valve TB would be more abrupt than a butterfly of the same size. I'm not seeing it.

I think this is an assumption based off of very large TB's.