RB25 DTH throttles anyone?

[Goddard]

Hey all,

I'm thinking about getting a side feed inlet and was looking at the possibilities (Greddy, Plazaman, japspeed,..). They all seem to have issues, good points/bad points etc. And there isn't alot in terms of GTT options.

There is a company I am currently doing some consultancy work for who manufacture custom direct to head throttle bodies. Anyone who isn't familiar with these can do a google search to find out their advantages (this is what RB26DETT engines have). I have asked about them making an RB25 option and they said they would consider it.

I need to know if people would be genuinely interested in this. What sort of option would you want?

1. Direct to head throttle bodies with trumpets (velocity stacks) and plenum chamber to ~80mm spout.
2. Complete inlet manifold to standard throttle body.
3. Complete inlet manifold and larger CNC throttle body.
4. Top half inlet manifold to standard throttle body.
5. Top half inlet manifold to standard CNC throttle body.

I know there are other options available already on the market, but this would be a chance to get a manifold that fits the standard fuel rail and injectors, has all the connectors in the right place, and fits the standard throttle body etc. I am also thinking of looking into the possibility of having a custom CNC throttle housing made that can be rebuilt with the standard GTT sensor/butterfly etc and the traction control motor. A set of DTH throttles would also be a benefit to NA peeps.

If no one is interested fair enough, but I need a genuine commitment, not a flimsy jump on the bandwagon. Anyone?

[Ahapartridge]

I think the gains you would get would be fairly hard to justify against fitting a RB26 head.

In an NA application I think they would be a great idea and I would love to see what sort of power a RB25 could produce in NA form if set up correctly.............oh, and the associated induction noise

[Goddard]

I have never seen an RB26 head for sale for reasonable money though. and I have NEVER seen a set of RB26 throttles for sale. I would put those on my car if I found a set. BUT as they never get changed because there are no better options (or need to upgrage) they are never for sale.

I know that people want to change from the standard (and rather shite) RB25 inlet manifold, and there are options available, but nothing that makes me want to part with £700 - for all the hassle they are worth. I wasn't expecting people to neccearily want DTH throttle bodies, but was just putting it out there as an option. I would have them if they were reasonable money and available.

I agree too, I would love to see an RB25DE with ported head, forged pistons etc to take 9000rpm with some DTH throttles. Imagine a specc'd up RB30 running NA - the noise would be pure sex alone.

[ivor]

i was thinking about this a couple of years back but of a different variation.

With the equipment and manufacturing processes a lot cheaper than they where why not a set of throttle body's with trumpets that then take a feed from a carbon plenum as carbon would be a lot easier and lighter to work with plus it could work in kit form i.e just buy the body's if you have an NA or the full kit if you have a turbo.

But as usual i think it will all come down to one thing How Cheap can they be produced for.

[Goddard]

I wouldn't reccomend carbon for a turbo plenum. I have made carbon plenums before and even under vaccum they look like they want to split open, and a backfire will explode them. Carbon "plenums" are generally just airboxes for NA cars where they see no pressure at all.

Well this company currently sell kits from £600 to £900 for various engines. They're not just any throttle either. They are billet aluminium which is CNC machined (very light weight and small). Use a patented shaftless design for improved airflow. I might see how much an inlet and single throttle would be as it seems that is what people want.

[ivor]

the price sounds good as the greddy plenum seems to doubled in price . With the carbon wouldn't it be possible to put in some kind of reinforcing

[Goddard]

Trust me I tried carbon and it didn't work at all. To make it strong enough it just ends up weighing more than aluminium does. You would need a proper double layer honeycomb pre-preg inlet that costs mega dollar for it.

I'll let other people see if they want to add their interest before I abandon this though. Can't afford to pay for all the design/development costs myself to get a first off working.