really need some help here please if anyone could share some ideas

[benno440]

hey gents, I got a mate over here that has a VG Valiant with a slant 6 motor, he is turbo and efi it.
He wants me to build him a turbo efi plenum chamber.

I am a skilled boilermaker and handy with aluminium tig welding.

Only problem is I do not know where to begin or to be honest I do not know what a turbo efi plenum chamber is.

my guess is that it is the intake manifold but it will have the thread sockets welded into for the efi injectors and a bracket for the throttle body.
I don't want to be told I cant do this as I believe I can do pretty much anything if I put my mind to it, I just need to learn and am struggling to find the required info on the net.

 

[Meep-Meep]

Is it port EFI? If so then you don't have much in the way of fuel distribution issues to deal with. Many Jap and Euro cars use a long runner intake with the runners going into a tube. I have seen turbo setups with similar design so if you follow some factory examples you should be fine. It may be wise to make sure the output from the turbo doesn't look directly into one or two cylinders but rather is 90 deg to the intake runners. The intake will be under pressure of course (boost) so the air will find it's way in each cylinder. Just make sure all the runners draw equally from the plenum. You may also look to see if there is an ideal plenum volume vs. intake runner volume ratio. The air coming out of the turbo is probably very turbulent and maybe the properly sized plenum volume will tend to damp all that turbulence. I have not read up on this but these would be my concerns if I were to make an intake for a turbo. Good luck!

 

[Photon440]

There are a few custom /6 intakes in this bunch...
http://www.bing.com/images/search?q=slant+six+turbo+intake&qpvt=slant+six+turbo+intake&FORM=IGRE#a

This one in particular should be what your friend needs: (scroll down half a dozen posts for the example, but read all the pages)
http://www.slantsix.org/forum/viewtopic.php?t=53276&start=30&sid=14e42f95e9138f7775d8ad60e9b7af9d

 

[benno440]

thanks gents,
I figured I would fabricate a log with the throttle body at 90* to the engine, and yes it is port efi. just trying to figure out how the injectors will mount and stay in place

 

[Meep-Meep]

What can be important is the location of the injector. If I were to do it I would mock up a piece of clear plastic tubing to simulate an intake runner but with an injector bung that allows various angles for testing the spray pattern. Then spray some light oil (not too flammable) while sucking on the cylinder head side with a vacuum cleaner. Ideally you would adjust the airflow to something that resembles what the engine does but that requires some sort of flow meter.

 

[benno440]

I will be welding in 2 bungs per runner, i have been researching that near stock - mild requires the injector to be pointed at near a 45* angle as close to the valve as you can get it, and the more power you put into the engine the further away the injector is to be placed. Iam trying to work out but not sure how is to work out the volume of the plenum i intend to build as it has a few varying angles and shapes etc.
I will make the runners 11" long from flange to end of velocity stack which will sit 1.5" into the plenum and not fluch with the floor of the plenum.
the plenum will taper down from throttle body and at the end will be 50% of the width the plenum will be at the throttle body to distribute the air evenly