Half a croissant, on a plate, with a sign in front of it saying '50c'
h a l f b a k e r y
Please listen carefully, as our opinions have changed.

idea: add, search, annotate, link, view, overview, recent, by name, random

meta: news, help, about, links, report a problem

account: browse anonymously, or get an account and write.

user:
pass:
register,


                                                                                                                                       

pre-compressed-air supercharger

A tank of compressed air which may be fed to engine for rapid accelleration
  (+17, -7)(+17, -7)
(+17, -7)
  [vote for,
against]

The power generated by an internal combustion engine is a function of engine displacement, rotation speed, and intake pressure. In a vehicle without a turbocharger or supercharger, this intake pressure is controlled by the throttle. When the throttle is wide open, intake pressure is nearly equal to ambient atmospheric; when it's closed down, intake pressure is far below atmospheric. A supercharger or turbocharger enhances engine power by increasing the intake pressure above atmospheric. Since an engine will operate more efficiently when intake pressure is near atmospheric than when it is substantially below, a smaller supercharged or turbocharged engine will often be more efficient than a larger non-charged one.

Unfortunately, superchargers and turbochargers take some time to increase the intake pressure on an engine. Turbochargers are worse in that regard since they need to use engine power to provide the extra pressure; until the engine has sped up there may not be much power to drive the turbocharger.

My proposal would be to have a tank of air pressurized by an intermittent-duty compressor. Most of the time, the tank would just sit pressurized and the compressor would be idle. When rapid accelleration was required, however, a valve would open allowing the pressurized air into the vehicle's air intake. The pump would then run until the tank had returned to its normal pressure level.

While the 'charger' itself wouldn't be terribly efficient, it would allow for a smaller-displacement engine to better mimic the performance of a larger one. Since cars generally spend relatively little time at maximum accelleration, the fuel economy win of the smaller engine (which can be run closer to atmospheric pressure when at cruise speed) should more than make up for the waste of energy during moments of peak accelleration.

supercat, Mar 13 2002

Air-powered cars http://www.howstuff...om/news-item106.htm
Related; cars powered 100% by compressed air [Jeremi, Mar 14 2002, last modified Oct 21 2004]

(???) Electric supercharging http://www.turbogen...lications.htm#turbo
Not pre-compressed, but is not dependent on engine revs [Gordon Comstock, Mar 14 2002, last modified Oct 21 2004]

(???) ford f-350 tonka www.visteon.com/new.../2002/012302a.shtml
similar results, using hydraulics [mihali, Oct 04 2004, last modified Oct 21 2004]

[link]






       It's worth a try. Have a roll.
lumpy, Mar 13 2002
  

       Hmmm . . . How about a turbocharger that is driven by a small (auxilliary) gas-turbine engine, rather than exhaust gases, to maintain constant pressure? The waste gate could bleed off the over-boost when it wasn't in use.   

       Or not.
bristolz, Mar 14 2002
  

       bristolz: The problem there is that if the compressor is always running it's always wasting power and thus energy. By contrast, keeping a can of air compressed takes almost no power or energy unless the air is being released. Since the air would only be released when there was a need for sudden accelleration, the compressor would not waste energy the rest of the time.
supercat, Mar 14 2002
  

       Oh. I thought you were after power without spool-up lag, not energy savings. My mistake. Sorry.
bristolz, Mar 14 2002
  

       Some dragsters use nitrous-oxide for this purpose as it's more efficient than compressed air.
angel, Mar 14 2002
  

       I think bristolz is on to something there, the idea of a supercharger powered by a dedicated engine, say a 250cc motorcycle unit, is truly inspiring. The argument about waste does not apply because there is aways a need for rapid acceleration.
IvanIdea, Mar 14 2002
  

       This could be combined with the regen-braking air compressor, mentioned elsewhere on HB. The tank could be refilled if required during braking, automatically topping up the pressure reserve. The only problem I forsee in this kind of power boost system, is what happens when you demand the power, and get nothing in return but the sinking feeling of impending doom, when the tank is empty, and your vision is filled by a huge truck....
drew, Mar 14 2002
  

       Vacuum\ | /Boost
thumbwax, Mar 14 2002
  

       How much energy are you actually saving if you have to haul around a tank of compressed air all the time?
phoenix, Mar 14 2002
  

       I don't suppose there are any energy savings to be had by this method, but it would provide a system for attaining instant boost pressures, regardless of engine speed - something neither turbo nor superchargers can provide. You would also lose the lubrication problems such devices bring with them. The tank needn't be very large, as it's only required in relatively short bursts, but I guess it would still weigh in at around 50-60 lbs.
drew, Mar 14 2002
  

       The idea was to have a system which would allow an engine to provide greater performance when needed without adversely affecting fuel economy when such performance is not being used.   

       I don't think a very large air reservoir would be needed if the compressor were large enough to charge it real-time or if there were a turbocharger or supercharger in addition to the reservoir. Basically the goal would simply be to have a rapidly-deployable power source which would provide a power boost until the turbocharger or supercharger could kick in.
supercat, Mar 14 2002
  

       I don't see much purpose. But anyway, the engine shall be able to power its own electrical air compressor/tank system for the occasional acceleration through the existing car electrical system. I failed to see the reason to add another engine and big compress air tank just to improve acceleration.
bing, Mar 14 2002
  

       I dont think you're familiar with modern rally car derrived engines from mitsubishi and subaru. In the UK you can buy four door saloon with 2 litre turbo charged engines capable of over 300 bhp and 300 ft/lb, 0-60 times just over 4 seconds. The turbo's are scarily fast at speeding up!
edski, Mar 14 2002
  

       Why even bother running a small electric motor or another engine to produce your stored compressed air? You could install this system on an already turbocharged engine, and use the blowoff gas from the wastegate in the turbo to fill the storage tank. Just trying to simplify things.
lumpy gravy, Mar 14 2002
  

       I was thinking about this much before... I wished for an easy way to supercharge any car, and I do quite a bit of scuba diving....   

       The average scuba tank holds 80 cubic feet of air at 3000 psi... (about as much volume as a phone booth) and each tank weighs about 30 lbs, 35 when filled...   

       My car is a 1.6L, so @4500 rpm it uses less than 7200L/min of air, or 254.3 cubic feet per minute, the same as 4.2 cubic feet as second. ("less than" because of volumemetric efficency losses)   

       That means it would take a little more than 3 tanks for 1 mintue worth of boost.... (thats flow rate at 1 atm, I have no idea how much higher the flow would have to be to actually raise the manifold pressure).... One tank would last a bit less than 20 seconds... I don't belive that scuba cylinders are capable of delivering that type of gas flow anyhow... which pretty much sucks, because i really wanted to try it...   

       but on a go-ped, motorcycle, and other small displacement motors.... the fun could be endless....
Mad Scientist, Mar 24 2002
  

       Bear in mind this would be something which kicks in very briefly - instant gratification, if you will - prior to the actual boost from turbocharger - then the extraneous air supply cuts off, as it has been supplanted by turbocharger doing what it does best. There would need to be several connections made - to various sensors already in place, cutoff switch, etc.. To improve a cars performance and/or emissions in 5 minutes or less - remove, check and clean your Oxygen Sensor. It's on the Exhaust Manifold.
thumbwax, Mar 24 2002
  

       The compressed Air idea has nothing over NO...   

       A turbocharger, intercooler, NO tank, and injection system would probably weigh 30-60 lbs and make 50-80% extra peak HP, and a nominal 30-50% HP, It could probably be used up to 10 times....   

       A Pressure Tank/Turbo type setup probably would provide anywhere from 1-150% hp gains instantly, and the turbo would be doing the rest - The downside is that it could only be used a few times before refilling, and all the equipment would weigh at least 50 lbs...
Mad Scientist, Mar 24 2002
  

       I also had to mention something I heard in my VIP class. (visual inspection certificate - to inspect scuba cylinders for work)   

       A steel high pressure tank (3500 psi) has the same potental energy as a Cadalac going 50 MPH.   

       Not something you want blowing up if you get in an accident.
Mad Scientist, Mar 24 2002
  

       Hey, what a cool site....glad to input. I've been looking for the Popular Mechanics, or possibly Popular Science issue circa 1978 to 1980 timeframe in which they took a Ford Granada of 17mpg and put a compressed air tank in the trunk. The car was modified to run the engine at an efficient RPM to pump up the air in the tank. The car ran off an air pump/motor...can't remember design. Braking also provided air pressure into the air tank. Bottom line...the car got 30mpg. If you think this is BS....it's for real. The Honda Insight is a wonderful implementation of energy storage. The other thing to realize is that the "electric supercharge" can be scaled up (why the hell hasn't aftermarket companys seized this idea????) to easily 50 to 100 hp. Now that's a real jolt of supercharged power (compared to tranditional superchargers which take mucho energy at high RPM). Yes, the idea of energy storage with air is for real. Can you use compressed air to "accelerate" a car. OF COURSE you can. You simply don't want to have to PRE-STORE the compressed air. You make a design which compresses the air using the cars own braking.....or stores the energy slowly during normal running like the Honda. The one comment is right about Nitrous being more efficient...but your idea...coupled with the energy storage system....is by far a great idea for the future. Bob
BobWade, May 07 2002
  

       I am sorry to say , but the idea of having pure oxygen injection into the engine will not work. Pure oxygen is to unstable, volatile, and uncontrollable. The engine would be to lean when you "hit" the bottle, and you would have to jet the engine so rich you couldn't drive it. Even newer fuel injected cars couldn't adjust. That is why on a nitrous kit you have a solenoid for nitrous and the fuel; so you won't melt the engine. The main reason nitrous is more effecient is that nitrogen acts as a buffer in the cylinders, and also cools the compression down. But I do have a theory that would probably work, but would not be as effecient as nitrous.
jgreen, Jun 10 2002
  

       Battery-based hybrids don't seem too great to me. Lead acid cells are very efficient at storing ENERGY, but what's usually needed for performance is POWER. A 1000kg car travelling at 30m/s (~60mph) has 450,000 joules of kinetic energy. Accellerating such a car to 60mph in three seconds, ignoring air friction, would take 125KW of power; keeping the car at 60mph would take much less.   

       A power reserve which can dump 500kJ of energy in three seconds, combined with a power supply capable of producing enough power to overcome air friction at 60mph while recharging the battery, would result in zippier performance than one that can hold 100,000KJ but only output it at a rate of 50Kw. Unfortunately, most batteries tend more toward the latter than the former.
supercat, Jun 11 2002
  

       Humm.. this all sounds really cool..   

       i have recently started a new project, conserning the building of a robot on tank tracks, the tank would be powered by a chainsaw engine. and i would really appresiate this ekstra powerboost..   

       but i dont know a lot on 2 stroke engines.. is it posible to turbocharge a chainsaw, using the same system with compressed air, or nitrox?   

       The shainsaw in mind, is 50ccm 8Hp engined.   

       Really Backing cool to have a turbocharged chainsaw :)   

       /Rune Kyndal
kyndal, Jun 22 2002
  

       This all make ineresting reading, But what i think most you have forgotten is fuel. If you increase the air to an ICE then the fuel dilivery has to increase as well. Most standard injector can not diliver any more fuel than equates to 11psi of boost. Above this the ECU with shut the injector down to stop the ICE from running lean and causing damage. so if more horses are required then more air is needed and a new set of high dilivery injectors not to mention a higher pressure fuel pump. which bring us to the exhaust, if it is not big enough the back pressure will be too great to allow all the exhaust gases out of the ICE and performance will suffer. It's a complete package
DJW2, Sep 13 2002
  

       The problem I think you'll find with this idea is getting a valve big enough to flow the air needed to provide the boost. The outlet from a scuba tank is small, and I don't know of an available valve that can be electrically triggered and flow that much. On the comment about fuel for the added air, if the engine is carburated you have to seal the floats and jet a bit rich, but there's a group called 21st century turbo that has been successfully adding turbos to just about everything for years. Carbs work based on volume of air flow, and will work with the additional pressure. I've been considering using compressed air to power a turbine from a small turbo charger. Basically using a nozzle and a compressed stream to spin up the turbine, boost the engine on my motorcycle, and all while hiding under the seat. A kind of sleeper that doesn't require modifying the exhaust or finding some way to tap power off the engine to drive it. By spinning up a turbo you can tap the power of the compressed air, extend it's usefulness, and avoid the valve problems.
frogman27, Sep 19 2002
  

       Does anyone know what happens when 1.5 cu.ft. of gas pressurized at 3000 psi. returns to atmospheric pressure in .003 seconds? Everybody would probably die!   

       In my mind, this is the main problem: What if there is an accident? The cylinder is most likely in the rear of the car, right?   

       As intreaguing as it may be, there are definite safety issues.   

       I have heard that they tried this in the '60s along with straight oxygen injection, and had disasterous results. Mostly engines exploding.   

       Not to mention, I don't think any NHRA or even IHRA tracks would sanction this, I'm not sure though.   

       It would definitely be cool for the street though if it proved to be reliable.   

       I'f you try this, please be careful. And I'd suggest trying it on a $250. junkyard motor first.   

       In response to frogman's valving question: Have you ever opened a 90 degree ball valve on a 1" air line pressurized @ only 125 psi.? It'll scare the hell out of you how much air comes out of that thing. I think if you looked through a couple of industrial supply catalogs like McMaster-Carr you could find plenty of goodies if you know what you're looking for.   

       I definitely like the compressed air driven turbo idea though. Good luck with it
joe boo, Oct 15 2002
  

       after hearing about this I've decided to add a tank to my fiero(where I get it) I'll use a a/c compressure so I can switch it on and off.(so It won't kick on during take off) So I'll have a supercharger thats being fed by a turbo and have a air tank and a bottle of nos under the hood. the air tank to handle 0-2000rpm the supercharger to handle 2000-3000rpm the turbo to handle 3000 and up and a bottle of nos for the heck of it. I'll be getting a 3.8L supercharged motor I have a air tank, compressure and turbo already I just have to get the nos.
marcus18, Jan 31 2003
  

       Just a cotton-pickin' minute......   

       What problem do you want to solve here ? The requirement seems to be a brief, instantaneously-available power surge that won't blow the engine .....   

       Instead of trying to feed compressed air (O2, NO, Nitromethane, whatver) into the engine to make it kick out lots of extra torque, why not use a live-fast-die-young torque booster by coupling an air turbine directly to the gearbox outut shaft through a reduction gear and a magnetic clutch ? You'd only get a few seconds of boost but it would be enough for what's required ? A titanium storage bottle would be light but very strong; and air motors are very compact and lightweight.   

       The bottle could be slowly recharged when the car was back in normal cruise.
8th of 7, Jan 31 2003
  

       Well, The idea to use the compressed air to feed the engine is rather useless, because of the high Volume rate per second of an engine. What is much and more efficient is to use the compressed air to kick the turbo. This idea is already been studied in the huge naval Turbo. Basically it is really easy. A stream of compressed air is blow by a small inlet tangentially on the compressor wheel. With a small amount of compressed air you can accelerate the Turbo very quickly. Main problem is the high stress on the compressor blades. The extra excitement can easily bring the blade to resonance. And that is definitely not good . So far I know, nobody has tried this idea on a small car turbos. But the idea seems to be worth for an easy experiment. Drill two or three holes on the turbo compressor case and mount small air injector aiming the rotation direction. Make some experiment to guess the suitable air pressure. And that's all.   

       Sorry for the bad English.
Peace, Feb 10 2003
  

       This compressed air system would not work so well. The intake mainfold has to have a higher pressure upstream than downstream to flow into the cylinder.   

       The compressed air tank would probably blow air right out of the air filter unless it had some way to pressurise the entire intake mainfold like a super or turbo charger does by running all of the charge through a pump.   

       Also all the concerns about your volume consumption are correct. You couldn't release a substantial volume of air fast enough to add much performance to the engine.
shlepzig, Feb 10 2003
  

       ford has a regenerative braking system on their f-350 "tonka" truck, that essentially fills a high-pressure tank with hydraulic oil during braking, then releases it through a hydraulic motor in the drivetrain during the next acceleration. it supposedly saves 25% in fuel costs. see link.   

       not exactly the same as this idea, but gives similar results.
mihali, Feb 10 2003
  

       phoenix, an air tank does not have to be very big to get you a small initial burst of air to prevent turbo lag. In fact, look at something the size of say a 20oz soda bottle possibly even as small as a CO2 cartridge like for a pellet gun. You wouldn't need it to hold a huge volume or high pressure. a tank with a hydrostatic test pressure of around 60psi and a max operational pressure of 30psi would do just fine. a quick 7.5 psi burst would get your turbo moving and bring you up to speed faster therefore reducing your lag time of around 3 - 10 seconds to nothing. slightly modify drews awesome idea of compressor operation during braking to operation during clutch compression and you've got a clever little device which increases acceleration by as much as half a second and you're looking at one hell of a street machine. then you can save your NOS for near peak RPMs for that short burst that will send you rocketing even further ahead of the guys in the other lane behind you. all of this at an added weight of maybe 10lbs. that's 6lbs for a small compressor, 2.5lbs for the tank, and 1.5lbs for the tubing necessary to make it all work. as for how to make the compressor work during clutching, use an electric clutch on the compressor wired to a NC time delay switch on the clutch pedal that is opened when there is no pressure applied to the pedal. the pulley would be so small that it would cause very neglible energy drain even when the clutch was engaged which would only be when you were decelerating or stopping anyway. this same wiring method could be used in line with the brakes so that the compressor only kicks in when you aren't worried about losing HP anyway especially useful to those who insist on running an AT or an autostick. and finally mad scientist is so hung up on using NOS he fails to realize this is more economical than NOS and you're not likely to kill yourself using it. so you have a compressed air accelerated turbocharger   

       hundreths of a second can make the difference between winners and losers.
AirForceBilly, Mar 28 2003
  

       if a scuba tank cannot flow the air fast enough, maybe one of those air tanks that seat tire beads by letting out a huge blast of compressed air will work. I have a briggs and stratton 3.75 horse engine with a 12v electric bed inflator supercharger, and a blowtorch for propane injection, to eliminate the need for a feul pump. Im still testing it. I have been thinking about using a small air tank, and sealing the gas tank (to be pressurized) for fuel enrichment under boost, or using propane and gas if possible, with propane as a fuel enrichment while under boost
dpearce455, Apr 01 2003
  

       Woo. I can't wait to be the only kid on my block with a ridiculously sized spoiler on my car, and 30 stickers that all say "02".   

       Oh jeahhhh.
rapid transit, May 20 2003
  

       i think what you are suggesting is already fullybaked,In the uk it's called a dump valve, it sends compressed air through a turbo when engine revs drop say when you change gear. It also makes a cool pssshhhhhh noise
itchynads, Jul 14 2003
  

       I like the idea. people are nieve to the fact that you only use your turbos boost about once a year if you live in a conjested city. why not store air for boost on demand, if 0-60 takes under 7 seconds the tank wouldn;t have to be big at all.this idea is not for f1 cars its for punks like me who want to haul ass for short periods of time. like through that playground zone.
mini1, Oct 13 2003
  

       [itchynads], it sounds like you are describing a blow-off valve. The purpose of a BOV is to dump air from the intake system when the engine RPMs drop so that the boost doesn't rise too high. But the air is just released to the atmosphere, it isn't stored in a tank.
GenYus, Dec 15 2003
  

       I think there are a few fundamental concepts you are overlooking here. First would be the obvious weight problem; a steel tank and compressor adequate to perform the duties you describe would add at least 50 lbs to the weight of the car, and the compressor would have to either be run on the engine itself (countering the benefits of the system) or another engine (which would require even more weight), not the mention the size of such a setup. Also, condensation would form in the tank, especially on a humid day - you don't want that in your combustion chamber. You do not need full boost at low RPM's as most engines simply cannot handle that much pressure at low engine speeds. That is why 4-cylinder engines usually use turbos instead of superchargers, because superchargers will produce more boost than the engine can handle at the those speeds, causing unnecessary friction and dramatically shortening engine life. Another thing to look at is the turbo is essentially "free" energy; it runs of the engine's exhaust, so there is no auxillary mechanism to power it and it is of minimum weight. Superchargers (and your compressor) run on a belt on the engine itself. Garrett has designed a turbo that has variable nozzles that allow it to begin boost at engine speeds just over idle, making it act like a lighter-weight supercharger, that doesn't tax the engine. Turbocharged engines are also more effecient - my car has a Chrysler 2.2L engine with a turbo in it and it gets about 35MPG on the highway. Most non-turbo versions of that engine got in the mid-to high 20's. New turbo'd engines use a smaller turbo that spool up faster, providing maximum boost at around 2500 RPM. I think your idea, while nice, is unpractical. I'm sure engineers have already experimented with such setups, and found them to be less than adequate.
40fordsedan, Jan 06 2004
  

       I think the compressed air thing has merit for getting a trbo onto boost quickly - but you can't just blow compressed air on the turbine wheel to spin it up to speed and eliminate "turbo lag" but remember a cold jet of air on the very hot turbine wheel is likely to cause some major cracking and fatigue. And if you just blow straight into the motor (induction side) you are going to need some serious volume - a car engine at high revs needs a LOT of air. But with a small tank fed by a little electric air compressor, you could use it like a 5-seconds-only turbo if you were keen.   

       As far as the use of nitrous (and oxygen) is concerned, nitrous is commonly used to bring cars into the rev range that can create boost in drag cars - but engines have to be built to cope with the intense heat and pressure that are created - and nitrous is illegal for street use (in Australia) anyway.
klaw81, Jan 08 2004
  

       How about having a second set of injectors, like fuel injectors, to squirt a bit of water into each cylinder during the exhaust cycle(in a four cycle engine) This water would flash to steam to produce extra power. I've read that the typical internal engine temperature is around 700ºf so you would get instant steam.
John_T, Jan 08 2004
  

       Folks, Check the patent literature. US patents 2,965,083 and 2,983,267 (circa 1961, and issued to General Motors!) describe an "accumulator supercharger" which uses a venturi effect device for forced induction and a storage tank of compressed air to feed it. The tank is recharged between bursts. The rig for my car is half-fitted and will be commissioned in the next couple of weeks.....
DoctorNemo, Mar 09 2004
  

       *waves to [marcus18] as a fellow Fiero owner*
GenYus, Mar 09 2004
  

       First of all turbos are almost 100% eficialt, but as a famous scientist once said nothing is created nor destroyed. The power comes from somewhere to turn that turbo! now...the problem is turbo lag? Simply put a nozzle in the cast exaust housing that on demand will spool the heck out of the turbo giving you instant boost. you can get vacume sensing switches that would do this all electronically, and automaticaly. Im and so glad I came across this web site, because I have a turboed buick v6 in a ford ranger 4x4, and also an onboard air system! im taking my housing out, and having a 14mm bung pressed into the housing at work tomorrow! ill use a ceramic tip from a tig welder as the air nozzle, and I already have the switches! Dang guys..your gonna see this one in summit with my name on it! Sean From Nebraska!
84maztang, Mar 14 2004
  

       I like this idea.   

       This concept would be especially useful, if you use it in combination with a Diesel engine (higher compression ratio and no throttle). The engine could be used as an air compressor when you brake. (The engine would pump compressed air directly into the airtank, replacing the compression retarder.)   

       All what's needed is a tank and a few valves. Excellent concept for a diesel powered vehicle driving in a city.
Globi, Jun 08 2004
  

       John T. suggested water injection.   

       That has been done on RVs for ping control under heavy loads. I tried a water-methanol injector on my '73 Dodge pick up years ago. The same idea was used in some WWII fighters for emergency speed, and an old pilot helped me design the rig.   

       I got over 115MPH in that 5500lb aerodynamic brick with only 318CID engine and was still accelerating when I saw the red lights...   

       The other down side was the transmission was shredded 2 weeks later. I bet it was never designed for the RPMs it hit.
TD3, Oct 25 2004
  

       Were the red lights on the dashboard?
bristolz, Oct 25 2004
  

       Problem with this would be city driving. Either the compressor would have to be huge) killing engine efficiency), or it would run out of air after 2 or 3 blocks in city traffic.
bobad, Oct 26 2004
  

       I think this idea would better be applied with turbochargers instead of superchargers, but it certainly has merit.   

       I think that the mechanical complexity and weight would be offset as really not much air (from a ~1000psi tank, regulated down to 15psi at the manifold) would be used per accleration cycle. I would expect only a few seconds of air injection would be required until the turbo catches up. Superchargers, being belt driven from the crankshaft, don't lag much.   

       Some means of preventing the air from escaping backward through the intake manifold would be required, meaning direct port injection of the air would be most practical.   

       A commecially made direct-port N2O injection system could be modified to readily and easily test this idea.
weezil, Nov 12 2004
  

       There are cars currently being tested in Mexico I believe which run off of compressed air from the stationary compressors at gas stations.   

       I beleive your idea would work well as an idea for regenerative braking or in concert with a super/turbocharger. You would not need much boost from the tank; only a few seconds untill the turbo spools up or you are done accelerating. Good luck!
discontinuuity, Aug 03 2005
  

       Pretty good idea really. Because of the limted supply of stored compressed air, really only practical for short burst to get a turbo spinning at low rpm. The Author seems to imply some benefit on a small capacity normally aspirated engine, which there may be, but most NA engines have compression ratios much higher than engines designed for turbo or superchared applications. Increasing manifold pressure above atmospheric on an engine not designed for boosted operation may result in detonation, poor performance and ultimately engine failure.   

       I don't see the SCUBA tank system working for all the reasons that have already been stated, but a reasonably compact 100-150psi tank could supply more than enough CFM at 6-10 psi and 1,500 to 2,500 rpm for 1-2 seconds to eliminate "turbo lag".   

       I'm currently upgrading my turbocharged 2.0L engine which makes 290HP to a larger turbo that will make 400+, trouble is, lag will go from the current 2,900rpm to 4,000 rpm which will make it a real dog around town. If I could boost manifold pressure to 6psi from 1,500 to say 3,000rpm that would not only generate more low end torque but also wind the big turbo up a lot quicker.   

       At 3,000rpm my engine will consume approx 250 CFM of air. With a 2 cubic foot air tank at 100psi that would give me about 4 seconds of boost which would be more than enough to get things moving nicely. The tank could then be recharged during normal highway cruising or regenerative braking (more complex).   

       This would not work for racing applications because the system would drain too quickly and the energy loss of trying to recharge the system in real-time would outway the benefits. However, for "laggy" turbo systems under "normal" street driving conditions, it would work great and is a lot cheaper and safer than using Nitrous or a hybrid supercharger/turbo or even twin turbo system.   

       Big question is where to inject the compressed air, the impellers of the exhaust side (possible cold shock) or the compressor side, or simply into the air intake before the compressor side of the turbo (need 1 way valve to stop blowing compressed air into the atmosphere through the air filter). If you pressurize the whole intake side, you would effectively force the turbocharger compressor to spin up which would also cause the exhaust side to spin up thus creating a lower exhaust back pressure or "sucking" exhaust out of the cylinders (which is good). The other benefit is when compressed air at 100psi is expanded to 6psi quickly, it cools significantly which is very good for the engine. Another side benefit is if once in a while you allow the pressurized intake to blow back through the air filter, it would help to clean it out a bit.   

       I like the idea! Has anyone tried to put this into practice?
MAX711, Apr 15 2006
  

       You are all too late. The idea has been used successfully three times i know of. In the early 60s Gm experimened with a ventur devive and a small air comressor and reciever on six cylinder cars (Chevy II) and it appeared in Mech\ Illust . Appaerently is worked well for passing but never made production. The late Mickey Thompson used it in a Mustang funny car with Danny Ongias driving. That was carried in many popular hot rod mags, (power was reportedly almost uncontrolable) and one that i have first hand knwledge of was a young fellow named Cecil Farrington who was a heating contaractor by trade and bult a system for a big GMC powered diesel pulling tractor from an air truck air brack compressor and large air tank hidden in the tractor chassis. It works absolutey wonderful and the lazy old diesel would scream like a banschi when he opened the throttle, tripping the boost switch and letting air in the intake which closed a flapper vale he had made for dling and pressurized the intake. It would last enough for the whole 300 feet . His biggest problem was the engine ran so fast and strong it would burn up transmission main shafts from the spinning slider gears sitting on it. I have watched this run on two occasions and I believe he still has it. He lives in Prince Edward County Ontario and can be easily found. Like many great inventors he doesnt realize what he has accomplished but just uses it. When I see it run i think of Thomas Edison's saying, "inventions are made by people too stupid to know they wont work" That is how he said it but not EXACTLY what he ment . Cecil is in no way stupid but cunning like a fox. He just need another way to boost the engine since only one supercharger is allowed by the assoc rules and on the GMC diesel one is actually needed for the intake cycle (They are a two stroke motor) He built this system to replace the turbo that also was stock on this motor . It is absolutey stunning to watch. With his background in heating he knew the formulas for airflow and how to figure it out. Unhampered by the dom sayers and engineering types (who always know why it wont work but have never built anything that does) he completed it successfully. I have been thinking of it often as for passing which takes only a few seconds in reality it would a wonderful and practical solution. Be fore anyone po- pos this look his number up in Canada 411 and talk to him. It is for real.
big-d, Aug 13 2006
  

       I will try and fill in some of the details I remember. The article title was close to (Supercharge by Jet). The jet was an air jet . The jet was placed in a venturi that blew into the small end of a long tapered tube shaped much like a baseball bat. The air came from a small scuba pump driven from the engine that stored air at say 2500 psi. This air was regulated down to 175 psi before entering the venturi. The entering air drew other air along with it to produce the 15 psi pressure and increased volume the engine used. This process is really based on Ejector Theory . This allowed a couple of 20 second bursts before the air was exhausted in the tank. You had to drive for a period of time before the tank was recharged and you were ready to hit the drag strip again. You could limit the time of your blasts to pass a car and have more bursts available. The carburator was pressurized to allow this to work (blow through). This was all before electronics were on the scene and is now ripe for development. A low tech example is the safety blow tip used by mechanics. More volume goes out of the tip than comes in from the compressor ( if the hole sizes are correct). Someone find the article.
eddif, Dec 15 2006
  

       Good info there, [big-d], but you've punched me square in the spelling gland.
discontinuuity, Dec 15 2006
  

       If you are not going to use this on the track, why not just get yourself a leaf blower/vac and hook it inline with your intake hose, when you want crazy 200 mph airflow, hit the button. You will need an inverter to put out the 1000 or so watts(at 8 amps and 120v) but the battery would regenerate at highway speeds with little pain in the tank. If you don’t want a hurricane I am not sure, but I think you can get a rheostat to cut the voltage without frying the motor. Or you could use a delay timer so when you kick it on it cuts off in the 1 or 2 seconds. But the air flow would be limited by how big your engine is, how much displacement is in each cylinder per revolution. It would increase the pressure though, quite substantially. The only problem is the air fuel mix. I think it would be very lean, and could cook your valves after a while. You could also get a rechargeable model at 18volts and a transformer from 12 to 18 volts and do some wiring. Cheers, Peace and Happy Trails!
WindsurfingPete, Feb 09 2007
  

       The whole idea of the Magazine article was to use one horsepower over a period of time and store the results as compressed air. The high demand boost would only be needed rarely or just to get things moving. Any thing that would supply that much air might require 20 HP ( full size supercharger) or a turbocharger that might still have a lag time. It is just an idea that coupled to another system gives instant boost. I will concede they used it as a primary system for testing and it of course had its downsides. Anyone find that article yet?
eddif, Mar 19 2007
  

       Ok so you are saying have a huge tank in your trunk and the sound of a generator running at all times. if u are going by energy efficient then you would have to power your pump/generator therefore wasteing energy. so why not just have a engine powered turbo as bristolz had said earlier. and would your acceleration decrease stay the same or increase with the add of weight even though you are putting out more power. you need to think of the pros and cons of putting something in your car especially something as big as a tank or compressed air.
#1gknus, Jan 01 2008
  

       i was looking for the air nozzle compressed inlet into turbo shroud of peace describtion, and found it,..
sirau, Jun 10 2008
  

       If I'm getting the initial post right... There are a few things going on.. One this is for a light vehicle with a small engine. Generally the engine should be small enough to get awesome mileage, and have horrible acceleration.   

       However the airtank is so that the car can waste gas when needed to accelerate like a big car with a V8.. The tank is just needed until a supercharger can kick in, during the second or so of supercharger lag. Then the small car can waste gas for those spots where it needs to, and be as peppy as a car with a much larger engine..   

       So you can drive like a granny all day, get 70 mpg, and still leave rubber, when a truck is going to tbone you in an intersection.   

       I like the Idea, but you might improve the system by having 2 outputs on the tank 1 to the engine, and another to the supercharger so the supercharger gets a pneumatic boost, cutting the needed compressed air time.   

       Any keeping the tank small with a high outflow puts the tank at 10 kilos (titanium, and smaller than a scuba tank) with about 1 kilo of air, 2 kilos for hoses. With intermittent compressors on two tires add another 5 kilos.. so roughly 17kilo's of weight, or 40 pounds   

       This is going to be kinda wonky on a normally aspirated engine, as the compression will be less than optimal...   

       computerize it.. when the lady stomps the gas, from a dead stop, just send the boost the the wheels directly. That would be some monster pep to a car.
stormyk, Dec 04 2008
  

       // during the second or so of supercharger lag//
Never heard of that before - I've heard of turbo lag, but I thought superchargers were generally lagless.
AbsintheWithoutLeave, Dec 04 2008
  

       sorry it is automobile engines of today and tomorrow by irwin stambler 1972 grosset & DUNLAP, INC. PG 50-51
Birdlives, Dec 17 2008
  

       OOPS thought I had sent the first part already. Gm messed with this (RamAire yes with an e) for desel trucks. A engine mounted compressor sent air to a storage tank (2500psi) It then worked like the elephant blower for the sskl in that compressed air was released only at full throtle. where uppon a solenoid valve was opened and 150 psi air was sent to an injector sitting in a long venturi shaped intake runner slightly ahead of the narowest point - mid way (think like the shape of a v-1 rocket engine) This would 1. act a charge coolent like nos. 2. increase the velocity of any normal air in the induction system - create a low pressure and suck aditional air forward. 3. increase the pressure in the intake.
Birdlives, Dec 17 2008
  

       //(RamAire yes with an e) for desel trucks//
sp. "diesel" (yes, with an "i").
[birdlives] you seem to have spread your anno to a single idea over three separate ones. Welcome to the HB.
coprocephalous, Dec 18 2008
  

       //AbsintheWithoutLeave, Dec 04   

       In a normal car a supercharger is always parasitizing power off the engine.. part of the concept is to keep the engine as efficient as possible for normal driving. So the supercharger cant be ready at all times if it isnt pulling engine power.. so this is the proposed workaround.. But if a super could work instant on w/o pulling power all the time, then it would be awesome.
stormyk, Dec 22 2008
  

       <Jumps up and down excitedly, with raised hand> Ooo! Ooo! You could use the roll-bar tubing or the space-frame as a pressure vessel to store your compressed air! </juadewrh>
coprocephalous, Dec 23 2008
  

       oops I r bad speller - hey as far as the space frame goes if it worked as a storage device for NO2 for NASCAR in the 60s or 70s (Against the rules; but hey, anyone who would fill a "safty cage" full of nitro, and go nearly 200 mph almost should be allowed to.)
Birdlives, Jan 12 2009
  
      
[annotate]
  


 

back: main index

business  computer  culture  fashion  food  halfbakery  home  other  product  public  science  sport  vehicle