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Greetings, I am an avid sports car enthusiast and enjoy the benefits a turbocharger can give you. However, as most of you are aware, the bigger the turbo the more lag you experience before it kicks in. Pro rally cars combat this with a anti-lag system that dumps a good amount of gas into the engine when
the throttle is closed, so that a massive explosion occurs when the throttle is opened again. This in turn produces a massive surge of exhaust gas as well as a big bang (this is also called the bang-bang system). The problem with this type of anti lag system is that on a normal street car, it would destroy the exhaust system within 50-100 km. Quite frankly, this is unacceptable. What I propose, is a system that uses steam rather then gas to quick-spool a turbo.
By cladding the exhaust pipe with a water jacket you have sufficient heat to create steam. This steam could be held in a boiler located in the trunk or rear regions of the car. A separate computer would monitor RPM and the input from the TPS. When you went WOT and (detected by the TPS) and your RPMs were below a certain user-defined number, the computer would open a valve at the boiler, thus shooting a high velocity jet of steam into an independent secondary turbine that would power your primary, laggey turbo. When the RPM has reached a high enough level for the engine to push the primary turbine (also a user-defined number), the valve on the boiler would close and build up more steam for re-use. The steam would reach the secondary turbine via stainless steel pipe, and once it has gone through the turbine, would return via same route but different pipe and back into the boiler. The one part of this system that I can't decide is wether to have the secondary turbine power a compressor which would then spool the main turbo (which would make it a asymmetric turbo arrangement), or have the turbine turn a shaft somehow connected to the main turbo's compressor, which would almost certainly mean designing a new turbocharger. Anyhoo, any comments or well-thought criticism would be appreciated.
(?) Something Similar
http://www.automoti...ressrel/020107.html
Ford uses Hydraulics to achieve something similar [senatorjam, Aug 26 2002, last modified Oct 17 2004]
(?) Electric Turbocharger
http://www.autonews...stories/tech128.htm
3rd section [half, Aug 27 2002, last modified Oct 17 2004]
[link]
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Turbos run hot as it is, why not cool air instead? |
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Fishbone for 'Anyhoo', but I'll change it to a criossant if you tell me the boiler and the window-washer draw from the same reservoir. |
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I think that running the impeller at a _constant speed_ through the use of an ancillary power source is an idea that would work and provide immediate boost without lag. The waste-gate just dumps while the boost is not in use. I'm not at all sure that steam is the best source of that power but maybe a small gas turbine burning gasoline. |
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When this topic came up here before, someone suggested running the turbocharger at constant speed with a motorcycle engine (also running at a constant speed). |
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Maybe an electrically powered turbo charger? (link) |
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As far as the steam power goes, I was thinking of an idea for just that the other day, however, it would'nt be to run secondary turbine, but rather spool the primary turbine quickly, the system would install an injector into the exhaust manifold upstream of the exhaust turbine, a switch in the throttle linkage would activate a solenoid that would release a certain amount of semi heated water into the exhaust, the heat of the exhaust would instantly turn the water into steam being forced thruogh the exhaust turbine producing instant boost. the problem is finding the proper amount of water to release, as too much could have dire effects, like: overcooling the cast iron manifold causing it to crack, or overpressure from the steam either blowing the turbo to bits, or overpressuring the exhaust gas coming from engine, and entering the motor through the exhaust valves, instantly killing the motor.
so, it can be done, but much care would be required to get the function correct without blowing a hole in your car where your engine used to reside. |
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If you think about it, this is how aircraft carriers overcome turbine lag. |
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Good idea, but be certain to get it checkout by a boiler maker, hot steam is invisible. You only see the the condensing water in the air, so you if get in its way you are in for some horrible pain.
I have study a similar idea to this for years,
have you seen thermotec tape? its like the stuff on the shuttle, it will hold in the heat and increase the speed of your turbo by itself, the hotter the gases the faster it moves. The temp of the exhaust manifold is 600c and around 1000c for a turbo motor running hard.
Just a coil around the exhaust, pre heated from the
a coil in the water cooling system for the engine. (the higher the latent heat in the water the less energy needed to turn it into steam. Maybe a button on your gearshift to prime the steam coil, so the water is only put into the system on upshifts and direct the system at the turbine. |
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From Ron
mitchell@byrononline.net |
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Hello every one, I designed a turbo steam anti-lag system about 16 years ago. System # 1 gave me a blown head gasket, system # 2 worked good but the boiler was not the right size had to make bigger one. With a bigger boiler it was able to hold pressure longer, the turbo spooled up was quicker but not instant boost. I ran 50PSI to 500PSI the turbo still spoolup was about the same, it only took longer to build up pressure. It took about 10 min. to build up 200PSI that I ran on my car. Its takes a lot more heat than you think to make steam. I tryed Spraying water into the exhaust manifold also, before I went to the boiler didn't work as good the boiler. Watch out for boilers blowing up, had that happen very dangerous!!! If you guys want the best bang for the buck, try spraying high pressure gas like CO2 into the turbine, that will give you instant boost. I've done it on cars with stock turbos, and cars with way to large of turbos. The CO2 will spoolup your turbos to full boost faster and easyer than the steam system .
turbocv Oct 29 2002 |
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True, but I was trying to stay within the context of the original idea, which is to reduce turbo lag. Really a twin system is normally only needed if you want to run big turbo's for high hp. A small turbo i.e. a Garret T3 properly tuned will generate full boost by 2500-3000 rpm on your standard 4 cyl. I agree, twins aren't necessary. Quite frankly on street cars bang-bang systems are useless as well. Do you really want your turbo at full boost when turning a corner in a residential area? Watch out kiddies. |
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Back in the 40's the merlin 12 cylinder aircraft engines ran some superchargers with 2 and 3 speed gearsets, the idea being that the higher gearings (higher boosts) would be used at higher altitudes, allowing a very similar amount of power at say 6,000 feet and 36,000 feet. |
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You could take a small supercharger, and basically reverse the principal, that is runing the s/c at higher gearings at lower boost rates. Then when the turbocharger comes into it's powerband, reduce the gearing on the s/c so as not to drag the engine unnescesarily. |
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Another idea, continuing more along the original thread; why run a boiler? all that you would need to superheat the water to steam instantly is a high voltage coil placed immediately before the entry point into the exhaust manifold. Instant steam would solve the problems inherent to the boilers. (You know, like, death, if instaled improperly.) |
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I don't like the idea of injecting high pressure gas, as one of the things that high pressure gas does as it expands... it COOLS. (Basic physics here.) This is exactly the opposite of what is most effective for this application. Thats part of the effectiveness of nitrous oxide. It leans the mixture, but it also super cools it, thus allowing "dry" nitrous kits of up to 100 horsepower without additional fuel enrichment. |
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I'm sure we all know that the effect of a turbo isn't just the exhaust gas velocity turning the turbine, but rather a combination of the velocity, and the thermal reaction of the immediate depresurization of the exhaust gas in the turbine housing, this is why the temperatures directly before and directly after the turbine housing will have a differential of several hundred degrees. The turbo converts the thermal energy of the exhaust into dynamic energy spinning the turbine and comressor wheels. |
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My original idea was to introduce a high density low volume substance into the exhaust that would almost instantly turn into a high volume low density vapor causing as much as a 200% increase in pressure, while only effecting roughly a 20% decrease in the thermal energy contained in the system. |
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My first idea would still probably be the most efficient of what I have suggested (I'll make no claims about anyone else's ideas) but it is also one of the most dangerous to implement. |
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the problem i see here is that you would have the added weight of the water, the waterjacket, the steam tank, and a compressor. use a small light weight compressor coupled with a compressed air tank and use it to spin the turbo during acceleration. 30psi of compressed air released at around 7.5psi would surely give you enough energy across your turbo to get it spinning and do so for the 4 seconds or so you experience lag. this should increase acceleration by as much as half a second therefore making you the guy they all whisper about being the man to beat at your local drag strip. of course the larger your turbo the more pressure you need in the tank and the higher output pressure you would need. and as discussed on another post you could run the compressor only during braking to prevent hp drain due to compressor ops. see the pre-compressed air super-charger post where I discuss how to wire this system to operate. i think you will find this is likely the best way to reduce lag without spending loads of cash on NOS. and if you still want to put NOS on the engine at least you don't have to worry about using it during acceleration which seems a waste of money to me. unless you are able to bottle your own NOS of course. the added weight of this system could be from ten to 30lbs. or totally eliminate the electric clutch mechanicl compressor driven by the engine to a brake light switch wired electric 12v air compressor mounted under the passengers seat or the drivers if your can handle the mild vibrations caused while driving. put the entire system on an electric toggle on your dash to prevent excess boost during normal driving and you could easily eliminate lag without an loss of HP. |
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hundreths of a second can make the difference between winners and losers |
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Nice idea, but instead of using the steam to reduce turbo lag instead I am very sure u can produce a complete steamturbo system using the engine cooling water and extra heat by extracting the heat from the exhaust in the exhaust pipe as well. Either just cooling the walls or using a grid like a cooler inside an increased diameter part of the exhaust.
This since an otto engine has an efficiency of about 30%, so 70 percent of the energy turns into heat and in a powerfull car like 500 hp u have approx 1000 hp of power in heat. Looking at the efficiency of the old steam engines of the past century that was using about 80% of the energy from the heat created.
Using a good insulation in the system would create more then enough power to drive the turbo constantly.
To make the system u can pretty much use a regular turbocharger of any make or kind even a cheap one since it will not have to take much heat and therefore bearings and material is not very important. U use a computer controled injector to inject the hot water in to a wide tube before the turbo preferably as wide as the turbos internal diameter. And since water naturally pass trough the exhaust part last it will hold a temp of approx 120+ degrees, to be able to cool the engine efficiently indepentent of the system u have a bypass hose to the cooler before the injection to the turbo that is controled by the thermostat.
Also re-using the water in the system is possible by passing the steam through a pre-cooler simular to an intercooler turning the steam into water again before running it through the main cooler and then back in to the engine.
The pre-cooler will be able to cool a massive amount of steam into water since the difference in temperature only have to be a few degrees, the bigger difference in heat, the more power extracted so the size of the pre-cooler is determined by the poweroutput wanted.
In using this engine u will allways have enough heat to drive the system since the more power u need from it the more power the engine will produce in heat and it will allways be ready for more action instantly due to the pre-stored energy in the water.
So now u have an integrated engine cooling system and turbo system that dont take any energy from the engine like a supercharger nor stopping or hindering the exhaust leaving the engine and the problems with lag created by a turbo system.
With computer controlled valves and re-circulation valves u have complete control of the preload in the intake.
Last but not least u might think u have no extra power from the charger before u get the heat up in the engine and my response to that is do not expect your car to last very long if u have racing car performance and using it before u get the engine up to temperature!! |
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Problem. It's the heat of the exhaust gas that gives it most of it's energy and pressure. So taking some of that would have a negative effect on making boost. However, you could take just a little heat over a long period of time and store it in a pressure vessel. At 250 C steam can reach hundreds of atmospheres, and even a small shot of this steam into the exhaust manifold would be highly explosive and would spin the turbo back up to full speed AMAZINGLY FAST.
This would not only reduce lag to zero but be enough to drive the turbo on its own at low rpms. |
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*ponders the technical details for a momment* |
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It's actually stupidly simple and possibly even crazy enough to work. Dare I say bloody brilliant. |
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On a tangent, I often wondered about running a engine hot, say at 125 C and having the water jacket at about 5 atmospheres. The superheated water would expand through a turbine generating more than enough power for a supercharger for example, the water would then go on to a convetional radiator and then to a high pressure pump. |
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That's slightly baked though. But it has lots of potential. A 30% efficient 100Kw car motor generates 220Kw of waste heat, a steam turbine could regain a good fraction of that under ideal load conditions. |
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However, if you want a simpler DIY method that doesn't involve dealing with high pressure water vapor, you could just do directly injecting some liquid into the manifold. See the manifold has a certain heat capacity. If you inject cold water through a short coil then through a nozzle it'd take up some of that heat and make it available to the turbine. Enough to get a noticeble decrease in lag i'm sure. |
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You cold even take a smidgen of the car's existing pre-warmed pressurised coolant water and use a standard solenoid type injector to squirt it through a few turns of tube and into the manifold. *ponders again* I bet you I could rig that up in a few hours.... |
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It'd be better to inject something with a lower vapor point like methanol or gasoline, it'd have the same effect as water and if there is a small ammount of free oxygen in your exhaust gas you'd get a bit of combustion too (but not overly high temps or any explosive effect). Plus very cool ten foot flames out the back of your car. |
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The latter was actually banned a long time ago in drag racing although. It's a forgotten trick really, nobody really uses it so most current drag racing rules don't exclude it. |
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This idea gets a steaming hot crossiant from me. |
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I just started thinking of this myself. Heres my plan: A water injector on the exhaust manifold, linked to the turbo's wastegate. So, when the wastergate is closed, water is injected, increasing exchaust manifold pressure, spooling up the turbo, opening the wastegate, which stops the water injection. this should keep the turbo spooled up at max boost AT ALL TIMES. |
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found an old turbo book with a yank military diesel truck with a turbine engine in the exhaust that was also said to be a redundancy system(???) but anyhows it was like a antilag from what the book said they were in use at the time (old book but) |
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If you have a hot street car then perhaps you have airbag suspension. If you have airbag suspension then you have an air compressor (or maybe you can just add one anyway if you don't) Consider a very small stainless steel nozzle in the exhaust system pointed directly at the edge of the turbo's "hot side" fan blades. Configure the system with a valve from your compressor connected with the clucth pedal. When you depress the clutch have compressed air let into the nozzle to spin up the turbo. Since the nozzle would be pointing at the edge it would be able to spin it up fairly rapidly while at the same time not overly increaing back pressure in the exhaust manifold. While the clutch is down during a shift it would maintain the turbo speed and as a result the boost. When the clutch goes back up the valve closes and the cars exhaust powers the turbo like normal. The only downside i can see to this method is the possible need for a large holding tank and a fairly high pressure in the holding tank. Another idea is to cicumvent the turbo's lag by temporarily creating your own intake pressure. Hook same said compression system up to the intake (with an even larger tank yet) and add a valve to the intake manifold. In the event that you release the clutch the pressure would come from the reserve tank instead of the turbo until the intake system repressurised. Possibly one could hook the cut-off for the reserv pressure tank to the Blow off valve so that when the blow off valve was open it didn't release additional pressure. Just a couple ideas. |
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Why not use a big air tank linked to the engine air intake (between turbocharger and engine). The tank would be filled with air when the engine is running at high power, but a valve would close to keep the air inside whe you reduce power. When you open throttle again, air from the tank is released into the engine until the turbo is a full speed again, at which point the tank would refill. |
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Not a terrible idea raoulduke, However, one of the principal reasons that turbos spool down between shifts and at idle is because the intake manifold pressure would get really high as soon as you dropped the throttle. The throttle body closes and causes a sort of shock wave in the intake. Thats why you have a BOV (Blow-off Valve) When the pressure in the intake gets too high it activates the BOV and allows the pressure to escape to prevent damage to the turbo. (Intake backpressure shocks are akin to shoving a stick into the compressor vanes. Not a good thing) Adding a tank the way you described could cause a serious failure of the BOV's ability to do its duty. You might get increased boost but your are more likely to end up with a damaged turbo, a worn out BOV, and an engine that runs way to lean at idle or shift. |
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The most brilliant solution of all was posted and largely ignored. Instead of using the exhaust gas pressure to power the turbo, use superheated steam from the cooling system. By using a much higher pressure in the cooling system you would allow the water to reach a higher temperature. This means you could run the water through jacketted exhaust manifolds like the offshore race boats use. The water would pick up additional heat from the exhaust, which has two advantages. First, it puts more energy into the water which can be harnessed by the turbine. Second, taking heat out of the exhaust gasses causes them to contract which reduces the pressure in the manifold. A lower pressure in the exhaust manifold helps scavenge the waste from the combustion chamber. This superheated water is then sent through a nozzle where it flashes to steam and spins the turbine. There would have to be a condensor to allow the steam to convert back to water before entering the radiator. This is quite possibly the perfect induction system. There is no belt drive causing power loss and no backpressure in the exhaust from a turbine, all the energy used to power the system is energy currently wasted. andreasn99, pure genius. |
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WikdWaze, You are missing a serious issue with this. Where are you going to get all the water? If you leave a 3 gallon pot to boil on the stove the water will be gone in about an hour or two. What do you do after that? Also this is going to be dumping steam into the turbo. The turbo is part of the exhaust manifold or directly below it. This means that you will be adding pressure to the exhaust manifold. Not only that there is the accute possibility of water getting sucked back into the exhaust valves and into the cylinders. Sure its not likely but it is possible. Then we have water in the oil... Just a few thoughts. |
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You're right, hondahunter, this topic has digressed. You're also right about my interpretation of andreasn99's idea. I have seen where you started a new thread on this subject, so I'll continue the dicsussion there. |
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Great stuff, this a pet project of mine.
Isn't the whole idea, really get the most of the waste,
in this case heat, by converting to steam and holding boost pressure, creating no lag?
Just a couple of quick throughts, recycling the released air into the air intake, from the bov, it should be cooler. Make the pressured volume bigger to store more air or go really wild and put a butterfly valve before the throttle body, so when the clutch is engaged the butterfly is shut and a secoundary non-pressised air intake could be opened "with a oneway valve" and as the clutch is released back comes the bottled up air.
More throughts have dropped in.
Put a flywheel of sorts on the turbo shaft, the bov
would help to control the speed of the turbine but
a brake may help. Now here comes the steam part.
Have an oil filled coil around the exhaust, feeding into the flywheel, have a steel turbine stuck on the hub of the flywheel, with a housing casing around it. Then spray preheated water "by eithere the oil from the sump or waterjacket, using a heat exchanger"
on to the blades of the turbine. This could be controlled simple by wiring the thermostats (oil temp and water) and a switch on the bov to control the times when the water is sent. Spraying water into the outlet for the second turbo, will creates a vacuum and water to reuse. Completely closed water systems needs water conditioning, its expensive and takes testing, I'm told. So regular changing of the water would be good.
So in closing to my thesis, you would have no lag, expect at startup. Constant boost pressure. You would avoid the problem of moving steam, (steampipe is expenses and heavy) a simple water coil around an exhaust would be so dangerous. At what point would the flashpoint be for the steam in the coil? and imagine the pressure, each 30c increase in temp doubles the pressure, so how much pressure out of the
the 1000c exhaust and lots of 100c water. Turbo type oil pumped from a small sump would be far easier to control and move
.
This subject is great, just typing about it brings out more ideas. |
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