Shaftless throttles for RB26DETT

[goddard]

Guys,

I have recently got hold of an RB26 set of throttles and inlet etc to fit onto my NEO engine in the GTT (thanks DaveW btw!). Project can be followed here, GTR inlet/throttles on RB25 NEO - Skyline Owners Club - The Nissan Skyline Enthusiast Community

Whilst dismantling the standard RB26 throttles I noticed that the shaft and butterfly were a ****in massive blockage. Far bigger than I have seen in Jenvey, Webcon, PTP, etc etc etc. Now it just so happens that at the moment I am working for a company called Active Technologies: The Mechanical Engineering Consultancy One of their products is a patented "shaftless" or "blade" design throttle body. These are precision CNC'd billet aluminium (trust me about the precision, I did the machining on the ones in the photos), anodised to various colours, stainless "blade" etc etc. Very smart and well designed/made piece of kit.

Before I go any further, take a look at a comparison photo between a 45mm GTR throttle and a 45mm Active throttle,


The increase in airflow for a 45mm is equivalent to running a 48mm throttle - but as the GTR one is a 10mm shaft, rather than a more usual 8mm shaft, it could be more of a gain. at 48mm you're talking a 15% increase in cross sectional area. But, because the throttle diameter is the same, you're not loosing out on torque - Plus everything else would fit as normal.

Normally development costs are quiet expensive for things like this. But because the GTR throttle is so simple, and I have let Active measure my set, they have all the information they need to get something designed and made. The only thing that is missing is people who would like to see a set on their skyline.

Anyone interested???







Video of them running on a Westfield that iirc made 27bhp more than when on twin 45mm carbs, with 38mm AT Power throttles,


(*note to admin. Although I don't work officially for this company I know and respect the rules on traders. If people are interested and would buy these I would gladly get Active to become trader status )

[DarkChild]

This is very interesting. I wouldn't mind hopping aboard.

[tarmac terror]

Looks good IMHO.
I think if they were a direct replacement with little or no fuss then I think more folks would go for them. I'd maybe be interested once I'd seen a spec and price.

TT

[goddard]

Yeah they should be a direct fit with no bother. The idea is they drop right in place of the existing ones, same bolt holes, the manifold and plenum aligns perfectly with them.

The price for three DCOE bodies is roughly £450. These should be cheaper as the machining is much simpler (no injector hole, or idle screws etc).

No picures at the moment, might get some CAD images before any are made. Essentially they would look like GTR ones but machined from billet aluminium with the "blade" system, and anodised to a colour.

[kismetcapitan]

looks so simple it makes me wonder why that hadn't been done in the first place!

I'll be very interested in a set - I'm hoping it'll take a few months to get a group order sorted, and that in that time the currency markets sort themselves out. Right now, ordering anything in a different currency is kicking my ass.

[tarmac terror]

IIRC Dave Walker did an article in CCC years back on the differences between thick and thin spindles on throttle bodies. Again, IIRC the flow differences were quite marked.

I' be very interested to see proper flowbench figures for these on an RB26 head. I'd imagine they would be a good bit more efficient....

TT

[goddard]

I think Dave is also doing an article on the westfield to go into Practical Performance Mag (or whatever, CCC turned into).

You're right the improvements in flow are not just from the increased area for the air, but the removal of the turbulance caused from the spindle/thick blade. The AT ones are also profiled to increase flow over them.

I'm sure AT Power would be interested in someone local to Norwich that is willing to give a set a try and see what improvements they find. I would do, but I don't have the inlet on my car yet :-( or a load of other things I need to get hold of first too.

[tarmac terror]

Maybe someone could loan a spare head for research purposes and have the whole AT Power assy flow benched alongside the std TB's.
I would loan one myself if I had one but alas, I do not

TT

[GT-R Glenn]

They do look pretty cool.
Not wanting to state the obvious but, theres a huge difference between the ability to suck through 45mm holes with 10mm shafts and blow 2 bar pressure through them ....
I would think you would get the same result just by boring the factory ones out to 48 as you would get by replacing them with spindle less ones.
The only difference I can see would be a change in speed as they hit the spindle.
Why not just make a slide setup ? easier and 0 restriction.

[makenski]

a group buy perhaps?

[goddard]

Well, I haven't done any analysis on this as yet so I can't say for sure what difference it would make. But whether you're sucking, or pushing it's pretty much the same thing. Normally you would have a 1Bar differential, with a turbo you might have 2-3Bar differential. And we all know that more static pressure does not equal more flow.

As for boring out the standard ones to 48mm - Well you would then need to find a spindle that was slightly longer, a 48mm butterfly, someone who could bore it out reliably so the spindle bore was still in the right place. Oh and then your inlet manifold and plenum wouldn't line up because they are still 45mm... but apart from that it would probably be easier But seriously, you just can't bore out throttles to bigger sizes.

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

[goddard]

Originally Posted by makenski

a group buy perhaps?

Yeah I think that would be best if there are numbers

[Piggaz]

Any chance of a very rough idea on the price?

Just the thought of taking off the plenum again is almost enough to not worry about it!!

[makenski]

Originally Posted by Piggaz

Any chance of a very rough idea on the price?

Just the thought of taking off the plenum again is almost enough to not worry about it!!

I was wondering to.. and like kismet I have to watch the exchange rates and wonder who will be responsible for shipping.

[GT-R Glenn]

The price for three DCOE bodies is roughly £450. These should be cheaper as the machining is much simpler (no injector hole, or idle screws etc).

!!!!!