Turbo-charger Compressor

[Turbo Tim 1]

Did the title get you attention? Ok here is some history, I was talking to a guy at wrok and he was talking about winterizing his pool and how he spent $250 on a blower to blow out the water lines, anyways I got to thinking and thought, why can't I do this with my sprinkler system at the house. Right now I use my old feable air compressor and between doing mine and the old boys across the street it takes the better part of an afternoon while we wait for pressure to build up.



So on to my plan, a briggs and stratton powered turbo turned into a supercharger, it would supply lots of volume and moderate pressure.



I have picked up a turbo off a 3208 CAT that is pretty big, I'll get some pictures but it's quite a bit bigger than my SPS66. I am thinking that I could take the exhaust wheel off and put a pulley on and turn it with a B&S.



Now for some questions:



1. How many horsepower do you think I would need?



2. How fast do I need to turn the turbo?



3. How fast can you spin pulleys and belts, figuring the engine will do 3600 rpm and the turbo would probably need at least 36,000 rpm, can I do that with puleys?



4. Any ideas you guys have would be appreciated, any thoughts you may have on my possibility of success or failure would be appreciated also.

 

[tgordon]

I do not have any ideas on what you are trying to do, but have you thought about just renting a engine driven compressor. Not one of the gas driven shop deals, but one of the jack hammer ones. Seems like dad is renting it for about $100 per day. If he could get one for a decent price he would buy it as he uses it a lot in the fall and spring if he had one, but hasn't found one yet. This is th esort of thing the commercial guys use, but you have no maintenance to do, just go get it, hook it up and take it back. Just an idea for you.



Troy



PS if you want, I have an old 1000 gal pressure tank you could barrow. Spent the days before building up pressure, but wouldn't take long to blow them out with the reserve

 

[rbattelle]

That's an interesting idea, but you've got some design work ahead of you.

First of all, you need to figure out just how much RPM that compressor is going to require.

Then you've got to figure out what pulleys you'll need to get to match WOT full-load engine RPM to the compressor RPM.

Given the speeds involved, you probably don't want to use v-belts. Then there's the question of how much power a flat belt can handle.

If it were me, I'd fabricate a test rig and try out different combinations of pulleys and belts and see what happens!

Ryan

 

[PToombs]

I think you oughta just pull your truck up to the hose, pull a line off the IC, and plug in there! Just winder up, and blow her out!

Or, hook a hose to the tailpipe. Just don't get caught in the spray! :-laf

 

[Forrest Nearing]

just use an air compressor... 36,000 is coasting... 100k+ is more like it

 

[rbattelle]

If you make a guess at efficiency at the pressure ratio you're trying to achieve, you could calculate an approximate power required to drive the compressor. But you'll also need to know the flow rate of the compressor and the inlet conditions (temperature and pressure).

Forrest is right - smaller turbos easily run upwards of 100k RPM.

But I still think it would be a really cool set of experiments.

Ryan

 

[Turbo Tim 1]

Come on guys, where's your scense of adventure?:-laf It's not a small turbo so I am thinking I can get something out of it at some slower speeds, like Ryan says, it's a cool experiment I'm gonna check with my buddy to see if he has a good horizontal shaft engine around and start experimenting.



here is a picture of the beast



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[PToombs]

I'll try to be a little more practical! Make a flange to pipe adapter, then put it on the tailpipe of your truck! You still need to figure out a lube system though. You are going to need a decent amount of pressure, along with flow, for what you are doing.

If the Briggs turns 3600 rpm, and the turbo needs to turn 36000, you need a 10 inch pulley driving a 1 inch pulley. (Roughly)

I can see the ambulance chasers lining up in your driveway when you start that puppy up! :-laf

 

[rbattelle]

Tim, don't forget to provide oil circulation to the bearings on that thing. 36k RPM (or more) will eat up dry bearings in no time flat.

Ryan

 

[nickleinonen]

still gotta get more speed than 36,000rpm for that little one



this tops out at about 22,000rpm [self destruct at above 25,000]

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this tops out at about 26,000 [self destruct at above 30,000]

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both the above chargers sit on 16 cylinder engines making +4000hp @ 1000rpm ±50rpm



the top one would work for you, as it already has gearing for turning the turbo as a supercharger until it over rides the clutch assembly

-



might need a little more hp than the lil briggs can put out to turn though :-laf

 

[Turbo Tim 1]

So can anyone say what a HX-35 turns when wastegated to 21 psi? I know there is a formula for figuring out when the tips of a wheel of X diameter reach the speed of sound, that is the self destruct speed basically, does anyone know how to figure that out?

 

[rbattelle]

I know there is a formula for figuring out when the tips of a wheel of X diameter reach the speed of sound, that is the self destruct speed basically, does anyone know how to figure that out?

Keeping away from sonic tip speeds is generally a good idea, although not necessarily because the wheel will "self destruct".

To calculate tip speed, just use:

V_tip = (Rotation in RPM)*(Wheel Radius)*(2 Pi)

The units of V_tip will depend on what units you use for wheel radius. Use inches, and V_tip will be in [in/s]. Use ft, and V_tip will be [ft/s].

Soundspeed is calculated from:

Soundspeed = sqrt(gamma*R*T*g0), where:
gamma is specific heat ratio for air (just use 1. 4 - close enough),
R is the gas constant for air (53. 35 [ft*lbf/lbm°R]),
T is the temperature at the blade tips in [°R], and
g0 is 32. 17 [ft*lbm/lbf*s^2].

Using the units I've given for the constants in the soundspeed equation, the value will be in ft/s.

So you've got to make a guess what the temperature at the compressor exit is. This will be a function of compressor efficiency (mostly). Assuming a 100% efficient adiabatic compressor, the ideal gas law predicts what the temperature will be based on the pressure at the compressor exit. But then you've still got to guess at (or design for) a pressure at the compressor exit.

[Note: there are some simplifying assumptions here. For example, the compressor is isentropic and you're dealing with dry air. ]

Ryan

 

[bmoeller]

Ryan, you're making my head hurt. I suck at formulas. :-laf

 

[rbattelle]

Ryan, you're making my head hurt. I suck at formulas. :-laf

Nah, it just looks nasty typed out in text format in a post.



Ryan

 

[PToombs]

Tim, maybe you are going the wrong way on this? Why not find a blower from a 2- or 3- 71 Detroit Diesel? Positive Large airflow, less lube problems, and you can put it on your truck when done!

 

[rbattelle]

Hey Tim, what's the status on this experiment?

Ryan

 

[PToombs]

I think this went on the back burner, he's got transmission issues he's trying to sort out this weekend!

 

[BGlidewell]

Centaur Forge-115 volt PB-50vs Blower, Variable Speed

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somebody beat you to it.

 

[DZink24]

I smell a project for our next upstate NY wrench day!!!:-laf

 

[bighammer]

I'm not an engineer, but I'm getting this gut feeling that a turbo is not going to push a large volume of air at low (compared to a real compressor) pressure thru a network of small dia hose and force the water up and out of sprinkler heads.