Miata Turbo Forum - Boost cars, acquire cats.

Miata Turbo Forum - Boost cars, acquire cats. (https://www.miataturbo.net/)
-   Insert BS here (https://www.miataturbo.net/insert-bs-here-4/)
-   -   This is either the greatest or worst idea ever. (https://www.miataturbo.net/insert-bs-here-4/either-greatest-worst-idea-ever-20036/)

wes65 04-23-2008 11:38 PM

This is either the greatest or worst idea ever.
 
http://www.geekologie.com/2008/04/ex...he_work_ou.php

I just dont know.....

compy 04-23-2008 11:42 PM

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.

levnubhin 04-23-2008 11:44 PM

Could that restriction damage the engine?
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miatamania 04-23-2008 11:57 PM

hmmmz

Trent 04-24-2008 01:03 AM


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.
:rofl:

patsmx5 04-24-2008 01:08 AM


Originally Posted by levnubhin (Post 246864)
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.

wes65 04-24-2008 01:18 AM

I hope youre not using the gasket maker between your exhaust parts when you use this. It would probably mean no more gaskets.

elesjuan 04-24-2008 02:20 AM


Originally Posted by patsmx5 (Post 246903)
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.

samnavy 04-24-2008 08:25 AM

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

Braineack 04-24-2008 08:57 AM


Originally Posted by levnubhin (Post 246864)
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...

Rafa 04-24-2008 09:28 AM


Originally Posted by samnavy (Post 246958)
You can't hurt the motor by plugging the exhaust.


Sorry to disagree but; yes you can. I did it.

levnubhin 04-24-2008 09:41 AM

Wouldnt it also cause egt's to go up?
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wes65 04-24-2008 11:36 AM

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.

SamS 04-24-2008 11:46 AM

From the link at the bottom of the paragraph:

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

Joe Perez 04-24-2008 12:02 PM

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

Rafa 04-24-2008 12:09 PM


Originally Posted by Joe Perez (Post 247039)
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.

icantthink4155 04-24-2008 02:42 PM


Saml01 04-24-2008 02:52 PM

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.

TeamPLUR 04-24-2008 03:50 PM

that thing lifts high as FUCK, 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 ;)

Braineack 04-24-2008 03:55 PM

certainly doesn't sound good on this motor:



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