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Old 04-24-2008, 12:38 AM   #1
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Default This is either the greatest or worst idea ever.

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Old 04-24-2008, 12:42 AM   #2
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I have never put a bag on an exhaust, but I can imagine unless you have a super free flowing 3" exhaust, it may take a little while to fill.
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Old 04-24-2008, 12:44 AM   #3
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Could that restriction damage the engine?
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Old 04-24-2008, 12:57 AM   #4
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hmmmz
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Old 04-24-2008, 02:03 AM   #5
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Quote:
Not sure if inhaling the bag afterward makes you talk funny like helium, but my guess is no, unless that's how dead people sound.
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Old 04-24-2008, 02:08 AM   #6
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Quote:
Originally Posted by levnubhin View Post
Could that restriction damage the engine?
hmm, and how does a turbo work? My guess is no, it's not gonna damage the engine. When your boosting there's a lot of pressure before the turbine, more than your boosting.
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Old 04-24-2008, 02:18 AM   #7
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I hope youre not using the gasket maker between your exhaust parts when you use this. It would probably mean no more gaskets.
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Old 04-24-2008, 03:20 AM   #8
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Originally Posted by patsmx5 View Post
hmm, and how does a turbo work? My guess is no, it's not gonna damage the engine. When your boosting there's a lot of pressure before the turbine, more than your boosting.
Thats different, man. We're talking about basically CAPPING off the exhaust. Turbos don't completely stop the flow of exhaust gases. Worst case I can think of is damage to exhaust valves.
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Old 04-24-2008, 09:25 AM   #9
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You can't hurt the motor by plugging the exhaust.

This product looks legit, they sell it at Northern Tool. Looks like a great idea.
http://www.northerntool.com/webapp/w...5091_200335091
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Old 04-24-2008, 09:57 AM   #10
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Quote:
Originally Posted by levnubhin View Post
Could that restriction damage the engine?

it could. in the least it will simply stall the car.

if the exhaust never exits the chamber, since it's backed up, then the new fresh mixture cant really enter and burn correctly...
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Old 04-24-2008, 10:28 AM   #11
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You can't hurt the motor by plugging the exhaust.

Sorry to disagree but; yes you can. I did it.
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Old 04-24-2008, 10:41 AM   #12
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Wouldnt it also cause egt's to go up?
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Old 04-24-2008, 12:36 PM   #13
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Well, i would think that it probably has some kind of bypass valve that allows it to maintain pressure in the bag and still keep the exhaust flowing. That way it would still have some flow at all times.
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Old 04-24-2008, 12:46 PM   #14
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From the link at the bottom of the paragraph:
Quote:
There is a hose coming out of it which you connect to the exhaust of your car. In about 30 seconds the bag will have inflated enough to raise your car up off the ground. There’s even a one-way valve to prevent air loss if you decide to turn off your vehicle
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Old 04-24-2008, 01:02 PM   #15
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Devices like this have been around for at least 15 years, probably much longer. Used to see 'em advertised in the JC Whitney catalog. I can't see how it's going to cause any damage to the engine, honestly. Let's do some math.

Let's say that we're lifting the BMW X3 station wagon that they show in the picture. That vehicle has a max gross of about 5 kilopounds. They're lifting half of it. I honestly don't know the exact formula for picking up half a vehicle at an odd angle, so let's err on the worst-case side and say that the bag is hefting 2/3 the weight of the car, or about 3,300 pounds. The bag measures 24" in diameter, giving a frontal area of 452.4 square inches. So, to lift 3.3 klb, it needs to be operating at about 7.4 PSI.

I'm pretty sure that a four-cycle engine can safely work against 7.4 PSI of backpressure. Heck, a turbo Miata with a stock exhaust system is probably close to that when at WOT. The efficiency will be reduced as you'll probably get some reversion towards the very end of the exhaust stroke, but it's not going to cause any actual harm.

By the way, here's the homepage for the company that produces the device: http://www.airjackusa.com/index.htm
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Old 04-24-2008, 01:09 PM   #16
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Quote:
Originally Posted by Joe Perez View Post
Devices like this have been around for at least 15 years, probably much longer. Used to see 'em advertised in the JC Whitney catalog. I can't see how it's going to cause any damage to the engine, honestly. Let's do some math.

Let's say that we're lifting the BMW X3 station wagon that they show in the picture. That vehicle has a max gross of about 5 kilopounds. They're lifting half of it. I honestly don't know the exact formula for picking up half a vehicle at an odd angle, so let's err on the worst-case side and say that the bag is hefting 2/3 the weight of the car, or about 3,300 pounds. The bag measures 24" in diameter, giving a frontal area of 452.4 square inches. So, to lift 3.3 klb, it needs to be operating at about 7.4 PSI.

I'm pretty sure that a four-cycle engine can safely work against 7.4 PSI of backpressure. Heck, a turbo Miata with a stock exhaust system is probably close to that when at WOT. The efficiency will be reduced as you'll probably get some reversion towards the very end of the exhaust stroke, but it's not going to cause any actual harm.

By the way, here's the homepage for the company that produces the device: http://www.airjackusa.com/index.htm
Joe, are you sure you're studying to be a lawyer?

You sound more like an engineer to me.
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Old 04-24-2008, 03:42 PM   #17
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Old 04-24-2008, 03:52 PM   #18
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Thats pretty hot.

If you are ever tired of living you can fill the bag, take it inside the cabin, punch a few holes in it and log off life.
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Old 04-24-2008, 04:50 PM   #19
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that thing lifts high as ****, ill just throw it under my car and come back 2 min later to see my rollbar doing its job.
and thats an X5, not an X3 station wagon in the pic
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Old 04-24-2008, 04:55 PM   #20
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certainly doesn't sound good on this motor:

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