I was in a local Marine store picking up parts to do the deckplate mod, and noticed a small 4" electric fan, supposedly high output.

Assuming that the flow of the fan was greater than the draw of the intake of air into the engine, would it be silly to try mounting a small fan to pump air into the airbox through the deckplate? I suppose any significant pressure would just be diverted through the elbow, but I'm wondering what would happen.

It sounds a bit ludicrous, and am opening myself up for ridicule, so bring it on!

 

someone beat you to that idea. if you search on ebay there is someone always selling the 'electric supercharger'. in my opinion it is jsut a fan and can't build any real preasure.

 

I agree- unless you block off other outlets like the elbow, extra air pressure will just follow the path of least resistance out of the air box, not through the air filter. I may give it a shot anyways if the fan isn't too expensive (I don't remember the price).

 

It might be capable of building up pressure in a confined area, but it won't move anywere near enough volume.

Remember that your engine gulps something like the same cubic footage of air that is contained by a three bedroom house every minute or something insane like that... There's a chart on the web somewhere that shows just how much air by volume that particular engines take in and every time I see it I am amazed...

The things you see on eBay go inline after the airbox and from everyone I have heard from, the only effect they have is making your wallet faster by lightening it.

 

He he he- just wanted to bump the first thread I ever started on Yotatech, when I was still researching the deck plate mod. Pretty funny stuff...

 

NICE!!!

wade

 

a buddy of mine used a SMALL electric leaf blower. Somehow rigged it up and said it gave him a little bit of power. I guess a leafblower has enough to power to pull air.

 

oh man... nice... was it secured with duct tape, because that would make gold

 

i saw someone do the math - it is basically impossible to make an electric supercharger or turbo because the electrical draw would always be more than the increase in air volume.

 

I have not seen the site, but having done the math I'm calling BS. Check it out...

A third gen has a 3.4L V6, aka 3400 cubic centimeters of displacement. Since we run 4-stroke engines, and only ONE of those strokes is tasked with the lovely job of intake, let's assume this example:

- Vehicle cruising down the highway at 3,000 RPM. (Just a nice round number here...)
- 3,000 divided by 4 (remember, only one stroke is intake) gets us 750 times per minute that the engine takes in an air/fuel charge.
- At 14:1 air to fuel ratio (just an average, this varies greatly depending on engine state-of-tune and how rich or lean the ECU thinks you should be), that means about 93% of what we take in for each intake stroke is air, the other 7% is fuel. Since fuel is denser than air, this makes perfect sense.
- 93% of 3,400cc's is 3,162cc's of actual air volume taken in, per intake stroke.
- 3,162 multiplied by our 750 intake strokes per minute, nets us 2,371,500cc's of air used by our motors, every minute.
- That sounds like a big number. Until you convert it to Cubic Feet per Minute. We use ~83.75CFM of air per minute, in a 3.4L motor, cruising at 3,000 RPM at an efficient 14:1 ratio. Stomp on the gas and it'll give more fuel vs air, let off and it leans way out (though we don't care about air intake when decellerating, since a lot of it just gets pushed back out the exhaust anyway).

For reference, a 12x14 bedroom with typical 10 foot celings, has 1,680 cubic feet of air. It would take a little over 20 minutes for your 3.4L motor to consume that volume of air, which is a far cry from using a three bedroom house EACH MINUTE.

Not busting your chops, just throwing some truth at whatever website you saw. To even use one bedroom in a minute you'd need a 68.2L motor.

By the way if you used a 3 bedroom house's worth of air each minute, it'd be like standing next to the dangerous end of an airliner's turbine. It would suck you up against the truck.

 

you have a slight problem with your math. it's true that only 1 of the 4 strokes is the intake stroke, but a "stroke" is only 180 degrees. so really, the intake stroke happens once every 720 degrees or once every two revolutions

3,000 rpm / 2 =
1500 intake strokes * 3.4 L =
5100 Lpm =
180.1 cfm * .93 (for 14:1 air:fuel) =
167.5 cfm of air for a 3.4L at 3000 rpm

of course all of this is assuming that there's no vacuum. i don't have a vacuum gauge on my truck, but i image that cruising at 3000 rpm, the engine is pulling about 10 inches (wild ass guess) of vacuum, so that lowers the air (at atmospheric pressure) requirement to about 2/3.

 

Ahh, thanks. Well, it's still a far cry from a three bedroom house... haha

 

Did that with a golf cart once long ago when I was young and foolish. (Not like now when I'm old a foolish...) First we disconnected the governor - that helped. Then we (yes Duct tape) taped a gas leaf blower to the intake. It went like a top fuel dragster for about 30 seconds, then rolled smoke and slowed down. It didn't run right after that...

 

You guys get hung up on the strangest things, especially for a thread that has been dead almost two years.

I can't speak to the math, it's not really my area, but I am looking for the site that has the table with displacements and air use now.

Regardless, it doesn't change the fact that putting a hairdryer inline with your airbox is not going to give you an increase in horsepower.

 

You keep notes on this stuff? Man, I forgot my wedding anniversary 2 years in a ROW with my first wife! Whoops! Did I say that? I mean my current wife.

 

I know what my next mod is....

A 62.8L motor! Mopar's 8.0L can kiss my ***!

 

I'm not finding the chart that I saw two years ago before I posted that and I am running out of time to look. I will post back this thread if I can find it again later.

I did run across this quote;

"Running engines demands a lot of air. According to Mr. Branch, his 1200cc big twin head flowed some 145cfm. With two heads running at wide-open throttle, 290 cubic feet of fresh clean air are needed for engine breathing per minute."

http://www.replikamaschinen.com/arti...ne_bigger.html

 

The math is actually quite simple.

CFM = engine displacement (in³) × rpm × Volumetric efficiency ÷ 3456

CFM = D × R × VE ÷ 3456

For rpm, use either redline or at least the highest rpm you're likely to ever see.
Volumetric efficiency for a normally aspirated engine will be .80 or .85, for a boosted engine use at least 1.00 or 1.10 (that is the whole point of a turbo/supercharger after all), it could be as high as 1.30 or 1.40 for a street driven engine, even higher for race engines.

For an electric supercharger to be of any use on a 3.4 engine you'd need a mere 300cfm @ 5000rpm and 100% VE. While this is more than possible with an electric fan, electric fans don't like to develope any pressure. The problem is that they have no sealing ability. Most of the air pumped by an electric fan will leak back past the fan blades rather than develope any pressure downstream of it. With virtually zero pressure in the manifold, you're not going to increase VE above maybe .90 (90%) which although better than stock, is nothing like a true supercharger can achieve.

 

My thoughts EXACTLY!!



they say great minds think alike!

 

Well said, although this concept seems quite difficult for most to grasp.
Just because it moves air does not mean it builds any significant pressure in the intake (like a S/C will).