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


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2 hours ago, Chillidoggy said:

Also, I don't think the charcoal canister should purge into the elephant's trunk, I think it should feed into the inlet manifold, probably at the front of the engine.

 

That's where the PO had it... I don't think it belonged there either seeing how it was held in by a wad of duct tape. LOL.  I'll figure out where to put it.

My car is a non SE, and I have freescan but I never could get it to work.

Thanks for your input, I appreciate your help. The car runs fine, it's just those little things ....

'89 Esprit, '77 Elite 503, '72 MGB, '95 XJ12, '10 Mini Cooper, '67 Imperial, '78 New Yorker, '76 Town & Country '73 Cessna 150

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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.

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Margate Exotics.

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  • 2 weeks later...

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.

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'89 Esprit, '77 Elite 503, '72 MGB, '95 XJ12, '10 Mini Cooper, '67 Imperial, '78 New Yorker, '76 Town & Country '73 Cessna 150

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  • Gold FFM

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.

I have made many mistakes in my life. Buying a multiple Lotus is not one of them.

 

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  • 1 year later...
  • Gold FFM

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.

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  • 5 months later...

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

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22 hours ago, 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?

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..      

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  • 2 weeks later...

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88 Esprit NA, 89 Esprit Turbo SE, Evora, Evora S, Evora IPS, Evora S IPS, Evora S IPS SR, Evora 400, Elise S1, Elise S1 111s, Evora GT410 Sport

Evora NA

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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?

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Professionals built the Titanic

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On 28/01/2020 at 08:34, red vtec said:

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?

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

 

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  • 7 months later...

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