Supercharger...

**bogan** · 18th August 2010, 09:55

Originally Posted by avgas

I thought the intake valves close in a 4 stroke engine.......

pretty sure idle means the throttle ain't WFO either

**bogan** · 18th August 2010, 10:00

Originally Posted by thehollowmen

If I just put bad mechanical judgment into this, a litre bike at 1100 rpm (idle for a GSXR) will be sucking 1100 cubic litres of air per minute.

A VANTEC TD8038H 80mm Case Fan (I'm being generous picking a high end one) puts through 84.1 cubic feet per minute at 5700RPM. This translates to 2.4 cubic meters. Scaling to keep up with the engine, the fan will have to scream away at er... 2612500 RPM

So I look at these calculations, and use what little mechanical knowledge I have and it makes me wonder if it might give an unusual increase in low end torque due to being choked a little and therefore running rich. That or the placebo effect.

What does worry me is the engine will start sucking these fan blades up to speed, and I'm not sure how much stress they can handle (I'll probably work the forces out tomorrow when I'm bored at work), which makes them likely to break off into nice sharp bits of plastic, perfect for cutting through or getting stuck in the filters / carb / injector bits and pieces. Whadaya mean the warranty doesn't cover this?

Feel free to put me out of my misery if I'm in error.

ok, apart from the intake valves and throttle position, 1100 cubic litres is 1.1 cubic meters. At 10000rpm and wfo, it'll be around 5 cubic meters per minute.

**avgas** · 18th August 2010, 12:09

Originally Posted by imdying

positive effect on your engines output, right?

Just to clear something up......never mentioned that it was going to revolutionize the industry. And I have time and time again mentioned it is not worth the coin.

However is amusing to do on the input of the engine. And its only a matter of time until more commercial versions are available (Friend is currently working on a 1kw bushless DC puppy on his 'tang). I hold it in the same region as Air rams.......can't be dismissed until its tried.

As for the Vaux - she is long time dead, and before she died the hairdrier was removed along with air box, filters.......and all was replaced with a big of pipe connected the carb to an crappy air ram.
Which sucked in grass seed real good.

But previous to that, down low, with a constant forced feed of air into the airbox......the "blower" was doing a good job - I doubt it was worth HP or NM........but definitely let the girl pick up her skirts before she tried to run. Kinda similar difference between gravity feed and fuel pump on small cc bikes. Not shit loads of increase, prob not even measurable.......but you know its there.

**imdying** · 18th August 2010, 13:09

Originally Posted by avgas

However is amusing to do on the input of the engine. And its only a matter of time until more commercial versions are available

Ebay China, plenty of versions already available.

Originally Posted by avgas

(Friend is currently working on a 1kw bushless DC puppy on his 'tang). I hold it in the same region as Air rams.......can't be dismissed until its tried.

Of course it can, that's why we have physics 101. Of course, your mate might be immune to the first law of thermodynamics I guess... if he can package that and sell it, good on him

**stig** · 18th August 2010, 13:20

There are plenty of people who have done the math to prove that these things are snake oil. Heres one more: http://autospeed.com/cms/title_The-T...7/article.html

I noticed someone read through all the Q&A on the auction and still bought it in spite of the warnings. Some people can't be saved from themselves unfortunately.

**bogan** · 18th August 2010, 13:31

Originally Posted by stig

There are plenty of people who have done the math to prove that these things are snake oil. Heres one more: http://autospeed.com/cms/title_The-T...7/article.html

I noticed someone read through all the Q&A on the auction and still bought it in spite of the warnings. Some people can't be saved from themselves unfortunately.

haha love it

Reaction of all technical experts who examined the Twin Turbo Zet:

Extreme mirth

**imdying** · 18th August 2010, 13:32

Yeah but but but his mates gonna use a 1kW brushless motor on his taaaaang

**bogan** · 18th August 2010, 13:50

think of it like a ducted fan, if the power isn't enough to create significant boost, it'll still develop a low pressure zone in front of the vehicle, otherwise where would the 1kw of work you put in go? So he'll have and extra kw of forward power, if you draw from the battery only for short periods rather than the alternator obviously. I reckon at a kw there will be some boost developed anyway, that article reckoned 14kw for 10psi didn't it?

**imdying** · 18th August 2010, 14:00

An extra kW? Even if it could work the way you describe (it can't), it's also a magic lossless system now too

Shit, gotta get me one of these

**bogan** · 18th August 2010, 14:45

so why can't it work as I described, as far as I'm away ducted fans create lift by generating a pressure differential on the blades, if theres no boost on the downwind side, theres gotta be some vac on the upwind right. Would you prefer me to say an extra kw (before fan losses) then?

**imdying** · 18th August 2010, 14:59

Originally Posted by bogan

so why can't it work as I described, as far as I'm away ducted fans create lift by generating a pressure differential on the blades, if theres no boost on the downwind side, theres gotta be some vac on the upwind right. Would you prefer me to say an extra kw (before fan losses) then?

It's already been covered.

But yes, before fan losses would be a good start

It is impossible to take 1kW from a battery, and turn it into 1kW at the output shaft on the engine. It's also impossible to use a tiny little fan like this to produce boost. It's all been covered in this thread. Start with jonbouy's post.

**stig** · 18th August 2010, 15:49

Originally Posted by bogan

so why can't it work as I described, as far as I'm away ducted fans create lift by generating a pressure differential on the blades, if theres no boost on the downwind side, theres gotta be some vac on the upwind right. Would you prefer me to say an extra kw (before fan losses) then?

A good axial fan in a duct would at best make 250pa which is about 0.04psi.
after that they will just hold that pressure and cavitate, the extra energy gets turned into noise and heat.
They are designed to move lots of air at low pressure

**bogan** · 18th August 2010, 17:05

Originally Posted by imdying

It's already been covered.

But yes, before fan losses would be a good start

It is impossible to take 1kW from a battery, and turn it into 1kW at the output shaft on the engine. It's also impossible to use a tiny little fan like this to produce boost. It's all been covered in this thread. Start with jonbouy's post.

don't hink he specified whether the 1kw was shaft or electrical, motors are generally good for about 80% though, so you're splitting hairs.

Also I disagreed with his post and I'm yet to hear a convincing counterargument

Originally Posted by stig

A good axial fan in a duct would at best make 250pa which is about 0.04psi.
after that they will just hold that pressure and cavitate, the extra energy gets turned into noise and heat.
They are designed to move lots of air at low pressure

from here we have a 2.5kw ducted fan producing 40N of force, given a fan area of 0.012m2 I make that 3.3kpa right? which is half a pound of pressure differential. Doesn't give airflow but shows the theory works, it ain't practical as there are better options out there, but it can be done.