If you want to use a 3" mandrel bent crosspipe from throttle body to airbox, without using flextube, how about using thin wall aluminium?

It would be very light, and it would be a bit flexible which would reduce loading on the airbox mounts.

Last edited by relaxed_diplomacy on Mon Dec 22, 2008 9:20 pm, edited 1 time in total.

Doubt it would be flexible enough, and if it were I would think the vacuum of the engine running might cause it to compress...

Okay. I'm not sure myself. Some here use stainless steel without a flextube, but i'm not keen on that.

I'm pretty sure the vacuum won't be enough to cause the tube to collapse. I'm guessing around 1.5mm wall thickness, but you'd have to go with what's available. I once saw a bullbar made of large diameter thin-wall aluminium tube and you could easily bend it with your hands, no sweat. It was fitted to a Rav4 so they wanted to keep it light, it would only really take a medium hit with a shopping trolley. Maybe that kind of stuff would make a good crosspipe?

The point I was making is that if the aluminium was flexible enough for it to replace the flex tube it would be pretty thin, and probably unable to handle the vacuum of the engine running and probably not the heat either without deforming in some way...

on the flip side, if it were strong enough for neither of those things to happen I doubt it would flex much if at all...

Maybe if a cut and rubber joiner was added around the halfway mark, maybe just outside of the bbm, that would bring enough flex?

You need it to be better than a BA flextube for it to be worth it, i reckon. I wonder how much of a bummer the BA flextube is to airflow?

Maybe if you just got rid of the airbox and put a pod on the end of the pipe you wouldn't need flexibility at all as pod could move with engine.?.?.?....

Maybe put that pod in an unmounted airbox, then run 4" flextube from it to a 4" bellmouth in the front bumper?

Yeah mate - Now you're talking.
I reckon we could prove that is a good idea with science to back it up too


Have we met before someplace around these parts?







EDIT - PS - The BA Flexitube is pretty good (for a flexitube). It doesn't use spirals and at it's narrowest is still fatter than the pipe at each end. If you buy a length of flexi from s**t Autos or similar, you'll find it connects to the same, but is actually thinner and has a more vibration effect on the air. I checked this by bending flexi into different positions and listening to the different tones and notes produced by the air creating harmonics and the like. Anyways, from my relatively inaccurate testing, the BA flexi was not that bad... Which is part of the reason why it is still there in my engine bay. I would have thought replacing it with a straight pipe would have helped quite a bit, but the curve into the throttle body seems to effect air more according to some bloody aero scientist and engineer guys who checkout out my intake quickly the other week. They did say to get rid of the flexi entirely, but not at the expense of replacing the smooth BA intake pipe to throttle with something with a greater curve. I imagine a mandrel bent 3" would be "more bent", or "tighter curve"

On a side note --- I could not find a machine or engineering shop that would bend a 3" stainless pipe for this purpose. You'd have to buy a donut or some pre made angles, and they are getting a little on the "tight" side of bent.

I only really thought about this alloy 3" thingy because i cut my BA flextube to fit my LPG mixer and if i ever (!) get to fit my (or another) e-gas TB i will have to go and buy another BA flextube. But yes that would be much less expensive than getting a 3" bent-up setup.

Then again, maybe some 3" PVC might be the go? The 2" is pretty flexy but the 3" might not be flexy enough.

Hmmmpppph... I'd say it'd end up rupturing (the PVC). You've noticed how fast the motor moves when you use it? All that backwards and forwards combined with vibrations sent through suspension etc etc etc.

I say leave your airbox loose!

I had 2.5'' pvc piping on my raptor and it didnt actually melt it but it was soft enough that where it had hoses clamped onto it it deformed into an oval/egg shape from the heat and it also sat over passenger side extractor.
Id recomend pipes from an intercooler kit if you could.

Ahhhhah... I've seen the plastic piping on Subaru turbos die - not melt, but get real hot and crack before it's real time is due... Your Raptor would move with the engine, but intercooler possibly wouldn't?

I didnt have an intercooler on my raptor setup, pvc was just bunnings cheap s**t with a 90* bend that had a screw in plug wich i used for the bypass valve.
I ran that car fairly hard and without the pvc breaking only warping.
I wouldn't use it again.

Ahah - My theory of it breaking over time comes from the movements of the motor compared to the movements of the other things the pipe is attached to. The constant push, pull and twist along with engine bay heat would see a failure sooner or later. Between your charger and motor there should be virtually no movement at all.

It seems the BA intake rules, maybe apart from the snorkel, which could be better, and maybe apart from some other creative options.

And if you don't care about cold air, i.e. you are the kind that removes the airbox and puts a pod, then you might be better to just put in the BA intake without the snorkel. Slammed my back into the seat at 3800rpm.