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Tech Spam thread - because 1/4" BSP gets 5 hand spans to the jiggawatt

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Re: intake system ram air scoop bucket whathaveyou

 

if you can get 10millibar more pressure in the airbox thats a 1% increase, which is not exactly, but still approximately in the order of 1% more air going in, which = 1% more power

 

so on a 200hp motor, thats 2hp. which is not heaps, but it is something

 

hence those drag guys make cool scoops 

 

because 1 or 2% on a 1000+hp N/A pro stock engine is 10 or 20 hp which is win or lose

 

drag5.jpg

DSCN0122.JPG

 

DEM_5014.jpg

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Yeah i guess regardless of motor size you get 2hp or so worth of air. So more beneficial to low power cars. Or things as above where youre going for 10/10ths

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What i mean is that a smaller engine only consumes a small mass of air per minure. So with a smallish cross sectional area of the scoop you can maintain positive pressure in the scoop at a lower speed. When you are huffing in 2000hp worth of air you need a huge cross section to keep positive pressure.

So a lower power engine gets a bigger % of gain from ram air.

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Yes but then you need to look at aerodynamic losses as you are trying to push that scoop through the air so for a low hp car you may actually loose power trying to move the thing

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So I have zero idea where this article was (I have a feeling it was autospeed) but lots of maths produced the conclusion that ram air scoops always caused more than enough drag to negate any HP gain.

/ling

Edit

And ram air on production vehicles was only really beneficial from a packaging/cold air/sales blurb perspective

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Autospeed has articles on this subject proving that its worthwhile.

If you have the scoop at an existing high pressure area within existing vehicle profile then theres zero difference to drag apart from removing several thousand litres of air per minute from an area where the high pressure is causing drag.

Example, front radiator panel area behind bumper or whatever.

Agree that a ling spec bonnet scoop or whatever is probably no good.

But in case of carina the bonnet is a low pressure area anyway with no flow.

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Has anyone seen/heard of a tramp metal detector that would work on a 2000 tonne per hour apron feeder with steel flights and a steel bin around it and boulders falling on it? And an operator's cabin in front of it with operators who don't want to die of radiation.

Are the bits of metal typically the same or similar dimensions? Eg always bits of rebar or something? Then maybe some kind of geometric/density sorting doowop might work to sift them out?

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Genuine question - why do people refer to Schedule 40/80 etc when you could just say I need 8 x 70mm lengths of 40mm ID and 6mm wall.

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Genuine question - why do people refer to Schedule 40/80 etc when you could just say I need 8 x 70mm lengths of 40mm ID and 6mm wall.

Because the wall thickness of a particular schedule increases as diameter increases.
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I would have assumed that but why not modify your description to suit?

 

Instead of saying 8 x 70mm lengths of 40mm ID and 6mm wall you say 8 x 70mm lengths of 38mm ID and 6.5mm wall

 

Sorry if this seems daft and asking a very simple question

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Because if you have a 150 diameter line with a 50 mm branch you can specify the whole thing as sch 40 instead of saying this bit has to be 2.4 mm and this bit has to be 4.6 mm, for example.

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^this

Pressure piping mechano set rules etc

The OD remains the same for all "weights and schedules" but thickness changes with diameter and weight/schedule

Weights and schedules relate approximately to pressure ratings but there are so many variables there can't be a fixed number that sch40 is rated to 20bar or whatever. Different temps, products, earthquake ratings, other static and dynamic loads etc etc etc

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Also, I only recently discovered Sch-40 and Sch-40s are not necessarily the same wall thickness, particularly in large diameter. I think. I could be wrong though.

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Because if you have a 150 diameter line with a 50 mm branch you can specify the whole thing as sch 40 instead of saying this bit has to be 2.4 mm and this bit has to be 4.6 mm, for example.

Ohhhhh I see. That makes sense sorta. Is the schedule akin to a pressure rating or flow rating of some sort?

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