Shaftless TBs

[emss]

Hello,

As I'm planning mods on my K-Series powered Elise, I'd like to know whether anyone here ever compared shaftless & classic TBs on the same engine ? (ATPower vs Jenvey DTH)

If yes, does one have clear advantages over the other or not, please ?

Regards

Éric Masson

[DVandrews]

I have done comparisons between roller barrels where there is no butterfly and regular TBs and there is no measurable difference that is worth spit.

A friend who makes throttle body butterflies for a number of manufacturer teams told me that the difference between properly developed shafted throttle plates and shaftless throttle plates was minimal,I.E. immeasurably small, but the surface machining given to the shaftless ones he makes promotes flow over the butterfly and can only be made to work on a flat countoured plate, any shaft would get in the way.

I have one of them here and it is a beautiful piece of engine jewellery.

Dave

[emss]

Hello Dave,

Thanks for your answer.

Éric Masson

[virgil]

DVandrews said:

I have done comparisons between roller barrels where there is no butterfly and regular TBs and there is no measurable difference that is worth spit.

A friend who makes throttle body butterflies for a number of manufacturer teams told me that the difference between properly developed shafted throttle plates and shaftless throttle plates was minimal,I.E. immeasurably small, but the surface machining given to the shaftless ones he makes promotes flow over the butterfly and can only be made to work on a flat countoured plate, any shaft would get in the way.

I have one of them here and it is a beautiful piece of engine jewellery.

Dave

Hi Dave - any chance of a pic of the butterfly?

[DVandrews]

I'll try to get some pics, but the surface machining is patented technology and also current...












Dave

Edited by DVandrews on Wednesday 11th April 19:07

[virgil]

Thanks Dave and very nice. My father was a tool maker so now I have this weird fascination with beautifully machined 'stuff'. It certainly looks beautifully made. Stainless? So the throttle bodies have to be split to drop the butterfly/shaft in? Does he say what the increase in flow over a shaft and plate style butterfly?

[DVandrews]

Machined from heat treated aluminium billet (goodness knows whay as they run quite cool). No flow figures are available as this is current technology, I assume the TBs are split, but there are other ways of fitting if the bearings are large enough and fitted from the outside.

Dave

[virgil]

The heat treating will add toughness to the alloy rather than reflect its heat bearing capabilities I would have thought?...stop the shaft from twisting off under heavy load?

You've got me scratching my head now though as to how you'd get that in a throttle body without it being split...no matter how the bearings go in or how big they are....interesting one...

Must get on with mine........

[virgil]

The heat treating will add toughness to the alloy rather than reflect its heat bearing capabilities I would have thought?...stop the shaft from twisting off under heavy load?

You've got me scratching my head now though as to how you'd get that in a throttle body without it being split...no matter how the bearings go in or how big they are....interesting one...

Must get on with mine........

[DVandrews]

There is no great load on the shaft nor any need for the grade of alloy used, it's just the customer being anal, the billets are imported from the 'states at very high cost, a lower grade of alloy could be used which would reduce material costs by 90% (and these costs are considerable). ?The lower grade alloy is used successfully on many other TB butterflies.

Dave