h a l f b a k e r yThe leaning tower of Piezo
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Guys I am a "nub" and am not an engineer> I just want to go faster. My car has the exhaust pointed straight back and burns a little over 3.25 gallons of race gas in a little over 1& 1/2 min... I visualize building a second collector over my exising collector that is a little bit shorter than the inner
one then pumping water into the space onto the 1400 deg f inner collector---I welcome ideas on all aspects but especially on where and how to do the math to figure out the THRUST to figure out if it is worth the effort. Or how to make a afterburner out of a similar configuration
Ps to get an Idea of what I am trying to do go to youtube
car 2211
thanks Sparky
[link]
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1) The exhaust heat cannot be separated from the exhaust pulse without substantial restriction, on an open pipes car this is going to involve the introduction of substantial back pressure. |
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2) The pipes may be hot now but the moment you pour any water on them they will be dead cold. You could increase thermal mass but then you get the weight. |
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3) There isn't enough energy to produce a steam jet of adequate volume and velocity. |
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4) Water is heavy, even under efficient circumstances the weight of the water would not offset the resultant loss in acceleration in a conventional piston engine. |
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The collector is 4" x 18' long, the secondary colllector would be over the front 17.5" of the insided collector. I am already carrying the water to cool the eng.. I am aware that we would dramatically cool the out going exhaust whic ould make it more dense and slow it down is there what are the fluid laws that i need to consider? |
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I guess it would help if we knew the setup a little better. Sounds to me like you are running an 8+8 sbc setup (could be one very hot 8 the sound isn't so good) in a rear engine slingshot setup (help me out here). Is your current cooling system ice, total loss, or radiated? How much does your current setup weigh? Are you competing in a record class? |
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Anyway here's the skinny IMHO. You have a large output of hot gas but your EGT is likely pretty modest. If you could spray water straight on the back of the exhaust valve you could capture quite a lot of that heat and convert it into pressure, pressure that could provide a slight boost in speed but that pressure would be back pressure on the flow through the head: more pressure (jet action) more restriction), so you move the jet to the exterior of the pipe but then the heat of the exhaust has to pass through the pipe to heat the water, which it will not do. |
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If you had a turbocharged car then you could dump some water in between the exhaust valves and the turbocharger and use the back pressure produced to increase boost (and cool the whole shebang) but even then the increase in exhaust volume is pretty small. |
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I guess what I am saying is that the amount of steam you are going to produce isn't going to be adequate. |
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What's the all-up weight of the vehicle on the start line ? From that you can back-calculate the energy requirement for any given delta-vee. |
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PS welcome to the HB, you may find that your idea is a little too sane and sensible for this foum ... |
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I dunno [8/7] its a little fantastic. I have avoided doing any figures thus far but I'm guessing that even a rocket filled with water pre-heated to his EGT isn't going to reach 300mph under it's own thrust. Unless he is already running a total loss cooling system its a pretty wild idea. Steam gasoline hybrid jet piston dragster is pure HB. |
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NACA duct to stream air over the exhaust, it heats up, expands... |
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"separated from the exhaust pulse without substantial restriction, on an open pipes car this is going to involve the introduction of substantial back pressure." |
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Erm, I'm probably completely wrong on this, but motorboats use water-cooled exhausts, and they seem to do ok. |
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I am thinking of going to a total loss system and was just trying to use the water and the heat!!!!!! I presently have a radiator in a box with external water for cooling---- this is the water I am thinking about for steam generation. |
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Thanks again for you help guys!!!!!!!! |
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motorboats do suffer a slight back pressure penalty (at low speed) but this is compensated by not requiring a muffler. They also make no attempt to cool the exhaust before it escapes thus it can still be hot and fast. |
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How much water do you currently carry, at what initial temperature? Is your block filled or part filled? How many cylinders? |
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UPDATE:
My start procedure is I empty the coolant surrounding the raditor in the heat excanger box, warm the eng coolant that is in the radiator and eng to 190 f when we get read to run we pump 11 gallons into the HE box which leaves 14 in the reseve tank I han pump most of that through the tank during the 1min and 40 seconds that I am under power---the water coming out I assume is around 190f
Thanks Sparky |
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