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TunersGroup TunersGroup is offline
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Join Date: Feb 2009
Location: Sydney, Australia
Posts: 125
Originally Posted by Craig 930 RS View Post
I want OEM fitment w/o screwing up the intercooler positioning - a freaking nightmare of BS I don't want to deal with.
I works closely with a very talented fabricator in Sydney. He has made inlet manifolds for me before for various project cars. He is the best TIG welder I've ever seen and was chief fabricator for one of the Australian touring car teams for many years.

I was looking at a stock 930 manifold the other day here on the workbench and though the same thing - equal runner lengths would be a very slick setup.

A custom 930 inlet manifold is definitely do-able, but it depends on whether you do a custom casting or use mandrel tubing to do it.

A cast manifold requires making a sand casting mold etc and potentially a lot of hand finishing, whereas a mandrel tubing manifold would simply involve cutting and welding, with an appropriately sized plenum chamber.

If it is made from mandrel tubing, then you need to take into account the radius of the mandrel bends from the ports on the head. The fabricator I know has made stainless steel inlet manifolds for me in the past, and stainless steel mandrel bends are readily available - they are used to make stainless exhaust headers.

The stock 930 manifold is super low profile - I doubt that using mandrel bends you'd be able to get it as low in profile as the stock 930 manifold.

Assuming that 90 degree mandrel bends would end up too high ...

With mandrel tubing you could end up with the throttle body at the same height as a factory 930 manifold, but in order to do that with mandrel bends, you'd either need a tighter radius on the mandrel bend (not good for flow), or have the mandrel bend continue through more than 90 degrees then bend up again (again not good for flow).

How much clearance do you have from the throttle body to the fuel distributor and from the fuel distributor to the intercooler ? Is there room to raise the throttle body and / or fuel distributor ?

The reason I ask is that if you have some clearance there then the throttle body could potentially be positioned higher (which would eliminate the need for super tight radius mandrel bends at the heads), and you simply use a custom tube from the intercooler to the throttle body. Clearance will dictate if the FD can sit at the factory height relative to the heads or if it would require raising the FD and making new fuel lines.

If the 90 degree mandrel bends would NOT end up too high in profile, and give you a simple 90 degree bend and no crazy curves in the intake runners, then that would simplify it a lot. I have a 930 manifold here - I'll measure it up.

I'll be talking to my fabricator friend in Sydney tomorrow - I'll ask him his thoughts about this 930 manifold project and check on the radius of the mandrel bends needed from the heads.

- Adam
Sydney Australia
Managing Director, Tuners Group, A division of Waenick Pty Ltd

Last edited by TunersGroup; 02-08-2009 at 05:30 AM..
Old 02-08-2009, 05:09 AM
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