Shaftless throttles for RB26DETT

[TriniGT]

Interested as well, ER34, RB25DET. these can work with the RB25DET from the GT-T right?

[nozza1]

also interested.

[iVeR]

Nils
R32 GT-R
HP ?
Usage Street, drag

[Monster GT-R]

I'm very interested !

R32 GTR
520 HP and going UP
Street only

[RB26zcar]

Interested, pleeez put me down for a set!!

R33 GT-R motor in a s30
Twin GT2876r's
Street use

[curtisgoodman]

Name: Curt
Car: BNR32 GTR
Power: 550whp
Turbo: GT2860-5's
Street use

Keep us updated i'd love a set of those!

[makenski]

Originally Posted by goddard

The idea is that the AT throttles use their own linkage, but is then linked to the GTR linkage via one of the tie rods. The other two tie rods would be reduntant, and would be removed.

Just wondering would the single pull shaft have flex offsetting the opening the throttle bodies. Where having at least 2 would minimize that elastic deformation the puller shaft experiences.

[goddard]

Guys thanks for the interest. I will try to get some updates for next week on the progress.

To answer a couple of questions - No these won't fit a GTT (or GTsT). They would need an adaptor plate, and a std RB26 manifold, plenum and gubbins to work.

To answer the question on flex - each pair of throttles has its own support with a bearing for the AT Power linkage shaft. The AT power linkages are from the centre of each twin body - which means that between the bodies there is much reduced flex across the throttle shaft that you would get in a throttle with the linkage on the side (ala std RB26). Obviously AT bodies don't actually have a throttle shaft, but the idea is the same to keep each blade consistent. The linkage shaft itself isn't exposed to a great deal of load, is supported along it's length with bearings, and is made of stainless steel - so is nice and stiff.

The question on turbulance - The injector itself should be more than capable of atomizing the fuel in a modern fuel injection system. Having turbulance is something akin to carburetta era to pick the fuel up and atomize it. I would expect more of a problem from running larger injectors at low engine speeds, which everyone does anyway

[makenski]

Originally Posted by goddard

To answer the question on flex - each pair of throttles has its own support with a bearing for the AT Power linkage shaft. The AT power linkages are from the centre of each twin body - which means that between the bodies there is much reduced flex across the throttle shaft that you would get in a throttle with the linkage on the side (ala std RB26). Obviously AT bodies don't actually have a throttle shaft, but the idea is the same to keep each blade consistent. The linkage shaft itself isn't exposed to a great deal of load, is supported along it's length with bearings, and is made of stainless steel - so is nice and stiff.

Material selection does play vital role in flex. But the loads you describe are linear.. like if I were to step on it...linear. And to my error I was referring to torsional flex, like a drive shaft experiences under a large load. The furthest throttle linkage will have a greatest force on the throttle shaft, then adding the middle with a third of the first, assuming each throttle linkage exerts the same force.

[goddard]

Originally Posted by makenski

And to my error I was referring to torsional flex, like a drive shaft experiences under a large load.

I was talking about torsional and bending. Both should be negligable

[fabianGTR34]

The most critical load on the shaft / butterfly would be the force of the air bouncing against the valve when closing. This force should not be underestimated. And this force is much bigger on turbocharged engines.
There can be a pressure difference of 3 bar or more between the plenum side and the head side of the valve. (on 2 bar boost and full vacuum)

3 bar equals 30 kg /cm^2 so that equals a force of 15.9 cm^2 *30 kg/cm^2 = 477 kg's of force on those little valves..

And this does not include the extra momentum that the fast moving air generates.. So be sure you do some calculations and choose the right materials. As alloy may be too weak for a highly boosted engine like the rb26.

For the rest, I like the design I am experimenting with new rb26 designs as well

[goddard]

Originally Posted by fabianGTR34

So be sure you do some calculations and choose the right materials. As alloy may be too weak for a highly boosted engine like the rb26.

The butterflies are stainless steel, and I would take a pepsi challenge they are stronger than the standard butterflies any day of the week :-)

I've seen a similar design to yours before. I would think it's quite an expensive way of doing things, but we are all different - if you're in need of some good throttles for your project, AT Power do larger bore single throttles too (with the same patented technolgoy)

[fabianGTR34]

Dont get me wrong, I am not mugging your design. And I have seen your design before too :P For now I just have 3D concepts as I am still in school. When I finish I plan to do some fun projects And I have flattend some throttle shafts before and think it do helps. They can add a few % more VE (usualy only @ WOT) wich can give that little bit extra that makes an engine one of a kind. And I am not saying that it isn't strong enough, just saying that it's wise to look what forces work on the part and make sure it is strong enough.
And if you are going to use stainless, then I have no worry's

Also dit a quick stress analysis of a butterfly in that style:






This butterfly is 2mm thick and also from stainless material, and has a diameter of 45mm.

As you know stress will gather around (sharp) edges wich can be seen in the picture, the first has the edges finished with a 1mm radius, the second with a 0,1mm radius. You can see that stress is building up near the edges.

[goddard]

I don't suppose you are at Delft university are you?

Thanks for the analysis. Some things you will learn with experience is that a good engineer can judge a design without needing to do analysis of every part. But it is good that you understand the problems and ways to solve the issues. I don't think it would be possible to achieve 0.1mm rad with laser cutting, more like 0.2mm - but of course a design will hardly ever have radii that small for the reason you have demonstrated.

[Monster GT-R]

I curious , , , any news ?