Use of ribbed hoses and its adverse effects on the intake air flow

[Chillidoggy]

See photo - black arrow shows where the purge line should go (ignore the brass fitting and large pipe in my photo!)

There should be a grey plastic screw-in barbed fitting into the inlet manifold, probably M12 x 1mm, a little non-return valve in the direction of the manifold, and an inline reducer to take the pipe size down from the larger diameter on the canister purge outlet. This is all shown in the parts manual. Hope that helps.

[89esprit]

I got a picture of my vacuum diagram from the engine compartment. It's the yellow hose marked "Air In". It's just there... it doesn't really show what is supposed to be hooked to. As I said earlier, the PO had punched a hole in the elephant trunk, but that can't be right, after the re route of mine I don't wamt to do that again.

[Escape]

The 'air in' connection to the charcoal canister is just that, an air intake to equalize pressure. It is not connected to anything, it just hangs somewhere it can get ambient(ish) air.

[RobinB5]

Interesting thread. I assume the ribbed 'elephant trunk' hose is used just to provide structural rigidity (for the very low pressure interior) due to the use of cheap materials that would otherwise collapse if smooth and the smooth hose alternatives are made from much stronger materials?

Viscous-sublayer and laminar/turbulent boundary layer profile stuff described is a bit of a red herring as, with the ribbed hose, there won't be a continuously developing boundary layer, the flow will be highly turbulent throughout (with associated much greater press loss coefficient). The Moody diagrams are for smooth walled pipes, with some extensions to ones with so-called 'sand grain' roughness (order < 100s of microns).

The key though is one of relative contributions to the overall pressure loss. I'm assuming the air filter loss will dominate so if there's one bottleneck area to address first, it's that. Then one could hunt down the other next dominant contributors such as hose wall shapes, surface areas, cross sectional areas, number of bends etc.

Fluid, be it liquid or gas, doesn't like being made to turn, twist, contract or expand. Being made to do so takes energy, which is a drain on the provider of energy, i.e. the internal combustion cylinders. Any energy saved by easing the flow of the fluid (in or out) will result in more energy being made available for traction. The reason why an Alunox manifold contributes to increase in available power, as does de-catting.

[MrDangerUS]

Sweetest smooth bore "RAM AIR" for 89 and onward cars:

Here is my Ram Air solution:
one 3.5" dia silicone 135 deg elbow, trim one end by ~1"
one 3.5" dia silicone 90 deg elbow, trim one end by ~1
50mm long section of the aluminum 3.5" tube
4 Norma clamps

Tube has to be slightly squeezed to form an ellipse to clear the tank inlet tube.
Clamps on the tank pipes have to be re-clocked to avoid interference.

All positives: Short, smooth bore duct, easy to make, under $50 from eBay. Car is running like a scalded cat!

Note: to facilitate "friendly" installation of the shelf trim piece  add couple wraps of smooth plastic packing tape over the 90 deg elbow

[Chillidoggy]

I see the original mesh is still in place at the inlet. I was wondering whether you had considered replacing it with something less restrictive?

[CHANGES]

Good point.  In a study it was shown that the original mesh in the picture created a 35-40% reduction in flow capability in comparison to no mesh..   When doing mine  I used a fine wire 10mm mesh which produce less than 5% flow intrusion.  It was also shown that the induction area under the panel next to the fuel cap also caused flow disturbancies. By fitting a simple smooth curved guide to that area, which also blanks out flow leaks through the fuel cap,  increase flow capacity to the air filter was achieved.  This in turn reduced the suction work needed from the turbo compressor to provide boost, reducing the cavitaion heat generation and work load on the compressor  thus improving overall VE capabilities..     Who would have thought such an insignificant part could have such an influence on flow performance..    The level to which this makes a difference is all tied in with many other factors, but as part of a complete package is essential..      

[MrDangerUS]

On 14/01/2020 at 03:36, Chillidoggy said:

I see the original mesh is still in place at the inlet. I was wondering whether you had considered replacing it with something less restrictive?

How about something more radical, without any mesh?

[Chillidoggy]

You could have at least painted it red.

[pete]

Always the perfectionist 😄

[Jacques]

On 23/01/2020 at 15:55, MrDangerUS said:

How about something more radical, without any mesh?

Yes, and soon it'll look like the new Scalectrix version of a certain car.

In my country, this should be legal, despite it's protrusion, as no part is pointy or having a sharp edge (to injure a bewildered pedestrian, which in turn could upset a variety of violent action-lusting vegans, who might be upset by the squished plants rights, used as a means for propulsion in said vechicle). So by all means, go ahead!

How about symmetry? One for the other side? More cool air to the turbo? There's more evidence than one may see in the spot, as there are already a series of heavy cales being installed in the rear of the car.

Soon, it'll be so fast, that it can drive back to the future, and this way Lotus might be saved preemptively and remain on british hands and loose that silly all too late suv. That must count for something.

Kind regards,

Jacques

[Bibs]

[red vtec]

That's a nice under the radar setup

I've seen similar on MR2 Turbos. and didn't the GT1 have a Naca duct on the roof?

[CHANGES]

Yes the GT1 Naca duct was for the transmition cooler which was mounted up top around the back window..  . 

 

[MrDangerUS]

Here is an idea...

[Jacques]

On 28/01/2020 at 01:15, Bibs said:

While this may provide more air with all the effects that may bring, it may also loose in going freely under the blocades for say bridges, pay roads, parking lots etc.

Merry Christmas.

Kind regards,

Jacques

[MrDangerUS]

Another clever ideas...

[Barrykearley]

🤢🤮

[MrDangerUS]

Taking advantage from trunk floor removal I have replaced  the "dryer" hose with 3" smooth bore alloy tubing. See below.

This mod combined with Alunox header and modified turbo turned the car into a rocket ship!