Benefits of Slide Valve over other TB designs?

[euro911sc]

I'm interested in knowing what the benefits/penalties are for slide valve TBs vs. butterfly (or other).

Thanks,

Michael

[kenikh]

Simple: Slide valves at WOT leave the intake tract completely free of obstruction, unlike a butterfly. Better top end power. Downside (at least on older technology) is upkeep, since they get gummed up pretty quickly. That said, modern flat slide carbs like those by Mikuni seem to have solved this problem., so a similar fuel injection solution could be developed, although I don't know of any today.

[euro911sc]

Interesting... I suspect, though, that at any other setting less than wide open, the slide valves create much more of an obstruction to flow... I can't imagine the strange flow at half throttle behind the plate.

Are there any TB's that close on a diameter basis like... er... one of those metal vegetable steamers?

Best regards,

Michael

[euro911sc]

Interesting... I suspect, though, that at any other setting less than wide open, the slide valves create much more of an obstruction to flow... I can't imagine the strange flow at half throttle behind the plate.

Are there any TB's that close on a diameter basis like... er... one of those metal vegetable steamers?

Best regards,

Michael

[Eagledriver]

Obstructing flow is the whole point of having a throttle valve. If you didn't want to obstruct the flow you wouldn't want a throttle of any kind.

-Andy

[MBruns]

Also remember that slide valves never stick shut ! and the pedal is very heavy at part throttle due to the high vac. pulling down on the slides which makes them not very smooth in part throttle transitions(ie. very heavy return springs) and the maint. is high keeping them clean and free. I also remember that they were not allowed at Indy because of the sticking at WOT issue. But from a flow and power making standpoint hard to beat.

Mike Bruns JBRacing.com

[Steve@Rennsport]

A better solution is barrel valves,.......

[rs911t]

Originally Posted by Steve@Rennsport

A better solution is barrel valves,.......

Steve, that reply requires a picture

[safe]

This guy makes custom roller throttle bodies:

http://www.jpmotorsport.se/e/rullspjallhus.htm

Got a price around $6000 when I asked him

[TimT]

I think Lumenition makes barrel valve tbs. Their website is sucky as usual. Maybe it was Jenvey?






Images from Mad Scientist Racing/Jon Milledge

[HawgRyder]

If I remember correctly....Kendig used to make a barrel type carb.
It was like an off-set barrel (imagine a disc with the pivot pin off-set to one side) and it "rolled" into the bore.
It was a very smooth action and the venturi effect was always maintained through the complete cycle.
The only place I remember seeing them was at the drag races, so perhaps they also had problems with heavy action.
Bob

[HawgRyder]

Just another thought....If you were looking for an older, but very good carb....perhaps an SU might fit the bill.
No accel pump...variable venturi...few moving parts....and great gas mileage.
Bob

[euro911sc]

Actually, I was thinking about a valve that closes, but maintains the circular shape of the opening so flow maintains some resemblance of flow... Something that on wide open would look like a pipe and when closed would look like an hour glass.

Steve... ever seen that?

Best regards,

Michael

[Flieger]

Like an iris or the aperture in a camera, right?

I think I know what you are talkin' bout.

Isn't there one at the beginning of Goldfinger?

[Flieger]

[euro911sc]

BINGO Flieger! I'm wondering... anything ever done like that?

-michael

[cgarr]

What about a A variable venturi type carburetor? Opens and closes to keep the flow smooth?

[911 tweaks]

I smell a cool new design for induction... !
Please share all of your thoughts on how this materializes with the fellow pelicans.
Great ideas here!!
Bob

[kenikh]

I looked into building "iris" type throttle bodies last year. The petal rigidity (or lack thereof) and the technical considerations to make them work in this capacity made cost way beyond what I was willing to wrestle with. Getting an iris mechanism that is rigid and will seal accurately throughout the air flow/vacuum gamut is tough to make work. If you think that the sticking problems inherent with slide valves are bad, you should run your brain along similar lines in regard to irises.

[911 tweaks]

good point...