Shaftless throttles for RB26DETT

[Cris]

Originally Posted by goddard

Slide throttles are notoriously difficult to get to seal and to move when under pressure, and can stick alot. Roller barrel throttles are great at full throttle, but rubbish at everything else (similar for sliders). There is a reason why everyone uses butterflies. These are just butterflies, but a little better

This is a question I've been asking myself for a while. Whilst wondering through the Ferrari Galleria I was having a look at some of the old F1 engines they had on stands. Several from the early 90s had flatslides and the later engines went back to butterflys. My assumption was that the butterflys gave better response.

None the less this idea looks good. Seems like a far better idea than a big single TB.

[Nocturnal]

That sounds interesting, keep us updated.

[andy@amt]

All i can say with out giving away secrets is that on the flow bench the standard
butterflies are very restrictive. We have taken out the shaft and just had the butterfly in and gained a very small percentage of flow, we have also bored the throttle body out to 50mm and also gained a very small percentage. The most flow was gained taking out the butterfly and the spindle altogether, the conclusion I came to was that the transition of the port shape to the round butterfly was limiting the flow. Most flow was gained with a single throttle body plenum but we also found this was critical to gain equal flow to cylinders 1 & 6 when off boost. However by angling the throttle body you could also balance out the flow on 1 & 6 but obviously you are governed by space in the engine bay to carry this out.

thanks
andy@amt

[goddard]

Andy, you have PM

[makenski]

Originally Posted by andy@amt

All i can say with out giving away secrets is that on the flow bench the standard
butterflies are very restrictive. We have taken out the shaft and just had the butterfly in and gained a very small percentage of flow, we have also bored the throttle body out to 50mm and also gained a very small percentage. The most flow was gained taking out the butterfly and the spindle altogether, the conclusion I came to was that the transition of the port shape to the round butterfly was limiting the flow. Most flow was gained with a single throttle body plenum but we also found this was critical to gain equal flow to cylinders 1 & 6 when off boost. However by angling the throttle body you could also balance out the flow on 1 & 6 but obviously you are governed by space in the engine bay to carry this out.

thanks
andy@amt

Just curious what are you measuring the flow of?

[Chris Wilson]

Why not roller barrel bodies? The downside of shaftless butterflies is if a back fire occurs, they are easily bent. That aside, does your company offer a plenum for twin DCOE style throttle bodies capable of taking positive pressure, and with trumpets within to stabilise air flow? Thanks.

[goddard]

These butterfly's are stainless steel. You could try bending it, but I don't think you'd get very far!

Roller barrels very big and heavy for the size of throttle you get, plus the only work on full throttle. These designs can be within 0.5% of having nothing there at all. Not much of a benefit going to a roller/slider throttle when you start to list the faults with those systems.

At the moment I have only seen filters, the body, runner and trumpet itself are all machined a to good fit so should take some positive pressure without any seals or gaskets. The guy at Active did want to know if people would be interested in a carbon plenum to go with the throttles. I'm gonna start some work on this tomorrow I think, it may turn into a series of options you could buy from direct replacement, to new direct to head throttles with profiled butterflies to match the ports and a much improved blend into runner/trumpet along with a new plenum. Obviously it depends on requests from people and subsequent testing of prototypes.

I'll be in touch when I have some initial concepts and prices for you.

[Stachi]

Tell'em to manufacture them! Would be a very nice feature, they look cool. I don't care about power increase What Control are they using? My bet's on Fanuc.

Marc

[goddard]

AT don't have any CNC machines themselves, but the company where I am based (TML Precision Engineering) make some of their stuff. Depends on what machine. Alot are Fanuc yeah Latest machine is a Mazak Integrex 200 Mk2 SY (sub spindle, Y axis driven tooling etc) with Mazatrol though - can make turbines, which is cool.

[Stachi]

Offtopic but.. I like the Mazatrol alot! I have been working on Super QuickTurns, Super Quadrex, Variaxis..

Looking forward for those items Look really nice!

Marc

[tarmac terror]

Original TB's have that wierd rubber type seal around the inner part of the tract that sees so many folks have idle problems after they remove it. Any info on how that will be addressed??

TT

[Chris Wilson]

Originally Posted by tarmac terror

Original TB's have that wierd rubber type seal around the inner part of the tract that sees so many folks have idle problems after they remove it. Any info on how that will be addressed??

TT

What seal is this? Not sure what you mean there, can you tell me more please?

[tarmac terror]

Originally Posted by Chris Wilson

What seal is this? Not sure what you mean there, can you tell me more please?

Inside the barrel of the TB's there is a rubber type seal that the butterflies rest on when closed. I have read stories on here of folks who have 'cleaned' there TB's and removed this only to find that their idle is crap.

TT

[Chris Wilson]

I have just looked at 2 sets of stock TB's and can see nothing like that, the idle ("closed") position seems solely controlled by the adjustable external stop screws and lock nuts. Anyone got a pic of these things please?

[goddard]

Originally Posted by Chris Wilson

Anyone got a pic of these things please?

Will have a look tomorrow at the GTR unit. I can't remember there being a seal there, just a slight build up of "crap". I guess if the throttles have been set to idle with a build up there, and you remove it, you may have problems. Care needs to be taken when setting up multi throttles to ensure even flow at part throttle and that they are closed at idle.

AT Power throttles are machined to 0.05mm tolerance and as such the butterfly is a perfect fit inside the bore. Each one is hand built, tested for vacuum, and set to idle condition (which isn't actually required with an IACV).