Stupid idea time...

[matsondawson]

Has anyone thought if the intake plenum/runners were the other way round i.e. front to back (your throttle body would end at the front-left), and you ran your turbo pipes in a clockwise order instead of anti-clockwise that you'd save a heap of piping? Probably only work on manuals as we got a bit of space on the RHS...

[Kenneth]

Interesting Idea.

However the problem you face is that you still need to plumb in your intercooler. Eithier way you have to bring the turbo outlets to the intercooler and then from the intercooler to the throttle body.

you might save a foot of pipe, but may have issues closing the bonnet.

[Kenneth]

Thinking some more about it, you could be right (as you say, dunno about the auto though) if you can bring the pipes around lower on the right hand side, below the air box/intake.

I think you would need a custom intake for the engine though, as I don't think you will be able to just turn the existing one around.

You could probably also eliminate the sharp turn on the intake elbow that way

[matsondawson]

I think that a slightly customised manifold could fit under the bonnet easily as the turbo pipes on top of the engine already go over there and they would be moved. It would have to bend at a slightly higher angle. Maybe an opportunity to make a light weight mani out of Aluminium or something. It shouldn't cost heaps to make a manifold, assuming the vr4 one doesn't have anything funky going on inside it.

And I reckon you could save about about 80cm on the throttle body side, and about 50cm on the turbo intake side. Of course you'd no longer have pretty pipes showing on the top of your engine.

When the mani get's flipped you'd find some extra space, maybe you could move the intake over there and have a bonnet intake.

[Kenneth]

I wouldn't want the plenum at the front personally, as I don't like the way it would be in the path of the air comming from the radiator.
Personally I would like plenty of room for air to move from the radiator, especially in conjunction with a vented bonnet

EDIT: hehe, did i say personally enough? lol

[matsondawson]

I've just calculated that the reduction in space could be around 0.2 cubic feet. Which given the cumulative nature of how boost builds may be reasonably significant (but I'm guessing not really). Say at 150cfm(low revs) it would take 0.08s to fill. So not really much help. But if you were redoing all your pipework, if may be just as cheap to reroute it all and flip the plenum around the other way. I think it would only be particularly useful at low revs off the line, if you weren't riding your clutch ( :P which is to say practically not at all). But it would have the different factor.

Of course I have plucked random numbers out of my arse :)

Edit: I forgot also, you lose 3-4 bends. But once again how significant is that?

[matsondawson]

Do the turbine outputs have to have matched lengths where they join, as mitsi have done?

[ako]

The way I figure it, probably not a vital - air always fills the space up, so the overall length of each turbos piping won't really matter. If there is an imbalance, itll take about --><-- that long to sort itself out.

Here's an idea - how about using a 6A12TT inlet mani? Visually looks damn near identical, apart from the throttle body being on the other side. Oh, and its got that variable inlet runner thingy as well, but thats easy enough to remove / disable.

On the other hand... When is turbo lag EVER an issue with these engines??

[michaeli]

I wouldn't want the plenum at the front personally, as I don't like the way it would be in the path of the air comming from the radiator.
Personally I would like plenty of room for air to move from the radiator, especially in conjunction with a vented bonnet

EDIT: hehe, did i say personally enough? lol

Personally, I agree with my personally good freind Keneth.... Personally... :inquisiti