BlueZ31 Posted August 1, 2009 Share Posted August 1, 2009 Okay so some time ago i posted a thread concerning a project involving a (hold on give it a chance) electricaly operated turbocharger. im stationed at 29palms ca for the USMC electronicscomm school and in my downtime ive played with this idea. most "turbos" you see on ebay are just bilge pumps and the only mild "sucess" was thomas knights ridiculously complicated and expensive unit, but i was suprised to see no ones tried driving the turbo by the means it was intended, ie through the exhaust side, all the ones ive seen are electric motors directly geared (in vain) to the compressor in hopes of producing some boost, but heres my idea. I looked into STS's kit for my 94 z28 awhile ago and recently looked more into it on a theoretic basis mostly, i figure that if a single, small sized turbo can operate at the rear of a car where the pulse of the exhaust stroke is mostly disrupted by the cat converter and the exhaust bends and the vast majority of the heat has been dissipated AND still manage to charge the long length of intake piping running from the rear to the engine bay then surely i could drive the exhaust side via a blower and make a decent amount of boost considering it could be mounted up front without the need for a intercooler or long lengths of intake tract. i calculated (and correct me if im wrong) the airflow of the vg30e at .80 VoluEff to be around 250cfm at 5500rpms. ive located two electric blowers and heres the ratings. 1. 425 cfm @ 195mph or 2. 255 cfm @ 235mph Which would be best? more cfm or a higher velocity? ive been working on this for some time and am ready to work on a experimental version (of which ill include pics ect) i just need expert advice on what would be the best path to take on the blowers and what size turbo would be best also. Thanks for your time and advice hope to hear something soon so i can start on it. -Rob- Quote Link to comment Share on other sites More sharing options...
sweetleaf Posted August 1, 2009 Share Posted August 1, 2009 Why would you use the blower to spool a turbo ? , when you can just use the blower directly. You are trying to over complicate things. Either, 1 just use the turbo as it was meant to be or , 2 Just use the blower directly. And if you do decide to use the blower. #1 is a much better choice Quote Link to comment Share on other sites More sharing options...
theghosttanker Posted August 2, 2009 Share Posted August 2, 2009 The whole idea is totally impractical. Your electric blower ratings are for unrestricted airflow; as soon as you resist the airflow the CFM's will drop to useless levels. A real turbocharger consumes a huge amount of power to make boost...in the neighborhood of 30 hp. They are flowing hundreds of cfm's AGAINST 15 or 20 lbs of pressure. (or whatever your boost is set at) A 30 hp electric motor is huge, and because it takes power from the alternator, you would need a similarly sized alternator to drive it. In addition, the process of converting mechanical energy at the crank to electrical energy at the alternator and then back to mechanical energy with a blower motor is extrmely inefficient...alternators are about 60% efficient and motors are only a little better. That means a total efficiency of about 50%, as opposed to the relatively high efficiency of a turbo. Stick with a turbo. Quote Link to comment Share on other sites More sharing options...
JSM Posted August 2, 2009 Share Posted August 2, 2009 I hate saying this, but it has been discussed on hybrid before. Search there is a lot of info on this site. Quote Link to comment Share on other sites More sharing options...
BlueZ31 Posted August 2, 2009 Author Share Posted August 2, 2009 what i meant by "blower" is a fan, not a blower in the sense of a supercharger like sweetleaf assumes, and i wouldnt couple it directlyto the alternator thatd be just straight retarded since (like it was stated) the engine and alternator would have to work harder to produce the electricity needed to run the blower, and yes i know its an unrestricted rating but im not going for the wild 15-20 psi more like 5-6 ( as i stated this is an experiment) and the 30 hp your saying the turbo consumes is mostly the heat energy being expelled by the exhaust i dont think anyone takes into consideration the force of the exhaust gases itself in a hp rating, and i know that the restriction of the turbo creates backpressure the engine has to work against but if the restriction was that great i dont think turbo motors would even run at all. and the 30hp electric motor idea has been debunked by thomas knight using a 8hp motor (although for a measly 15 seconds per run) to produce in excess of 5psi. again most of that wasted power in the exhaust is heat and while the expansion created by heated gases has an effect on the turbo heat energy itself does not drive the turbo, if such was the case id just dump some gas on the exhaust side and light it up. i also know that the pulse from the exhaust stroke exhibits force on the turbine blades so should i also use a sort of tubular sub enclosurein connection with the blower and use the speaker to produce pulses similar to that from the exhaust along with the blower? id like to think that doing so would pressurize the enclosure and put more force on the exhaust side. i appreciate the constructive critiscism posted previously, i really do because it helps me look at this idea from all angles, however im not giving up i just need to put more thought into it. i also understand that this is really a Z forum (which i do own it just happens to be 2400miles away from me at the moment) and not a "random idea" forum so i also appreciate everyone taking the time to just read the post and not delete it . thanks all Quote Link to comment Share on other sites More sharing options...
theghosttanker Posted August 2, 2009 Share Posted August 2, 2009 You seem to be looking for no advice, but rather an argument. How can you possibly think that you can use a fan to move air which in turn is used to turn a turbine and that this could somehow be more efficient than just directly turning the turbine with the fan motor? And your arguments about heat vs exhaust pressure being what drives a turbo are silly, too. Exhaust gasses expand because they are under less pressure after they leave the exhaust port, and their temperature drops because the temperature of ANY gas changes in direct proportion with the pressure. Remember PV=nRT from high school chemistry? P=pressure V=volume n=Avagaddro's constant R=number of moles of gas T=temperature on the Kelvin (absolute) scale. The exhaust gas temperature is higher on the engine side of the turbine because it is at higher pressure; on the other side it is under less pressure and therefore has a higher volume and lower temperature. Thus, the amount of energy absorbed by the turbine is proportional to drops in pressure AND temperature; nevertheless this energy was produced by the motor and is quite large, in the area of 30 hp at "decent" boost levels. By "decent" boost levels I don't mean a lame boost level like 5 or 6 psi, either. The fact remains: if you want to force air into a motor under pressure, you need a lot more power than you think. Turbos rule because they are the most efficient, simple, cost effective way to do it. By the way, the whole point of forced air induction is to raise the VE above 100%, so your CFM requirement calculations aren't much use, either. The thing you need to look for is the horsepower (wattage)of the motor, and the efficiency of the fan. The higher the horsepower, the more air it will move. If the blower you are using only matches the requirements of the motor at 80% VE, then it won't raise your horsepower output at all, except for freeing up the horsepower lost through pumping loss. CFM's are DIRECTLY proportional to HP; they are both work/time units of measure. Quote Link to comment Share on other sites More sharing options...
Six_Shooter Posted August 3, 2009 Share Posted August 3, 2009 I don't think I understand what is being attempted here, but maybe getting a foggy picture...... Are you wanting to take an average ordinary conventional turbocharger, and instead of connecting the Turbine inlet to the exhaust manifold of an engine, you want to attach an electrically driven "fan" to the turbine inlet to drive the turbo? If that really is the case, you need to do a bit more research on how turbochargers really work. The average input pressure to a turbine will be approximatly twice what the boost pressure is. There is some veriation to this, but it is a commonly accepted principal of what drives a turbocharger. On top of that, why would you want to take mechanical power (crank) that drives an alternator that then creates electrical power, that charges batteries and runs this electric fan that changes the electrical power back to mechanical, that then is being converted to pressuring a gas (the air we breath), to then again be converted to mechanical power (through the turbine wheel and compressor wheels) to pressure the same gas that was being pressurized by the fan, to feed the engine? I'm sure there are more conversions of energy in there too, especially if you want to the BTUs of the gas being used, to turn the crank, that could also be used to drive the turbine more directly, through the use of the now "burned" gas and the by products of which do run turbines conventionally. The most effciant way to get to where you want to be is a straight line. I don't understand why so many people want to connect electrical power to things that don't need it. The best advice is: Don't try to re-invent the wheel. Quote Link to comment Share on other sites More sharing options...
BlueZ31 Posted August 6, 2009 Author Share Posted August 6, 2009 thanks sixshooter i had no idea the amount of force exerted by the exhaust on the turbine, i do need to research more but this was just a sort of random thought that breezed through one day. And to be a little more specific i never planned on connecting it directly to the alternator, ever, because itd just add unnescessary drag and power loss,like the bilge pumps seen on ebay and youtube. the fan runs on a pack of LiIon batteries. Quote Link to comment Share on other sites More sharing options...
Challenger Posted August 6, 2009 Share Posted August 6, 2009 As mentioned what about a low end electrical assist for the turbo. Have some sort of capacitor that will charge up as you drive and then when you step on it it discharges to a really powerful motor that assists the turbo in spooling up............. just an idea, Id just stick with a good old, normal, run of the mill turbo set up. But I always like seeing people doing new stuff, regardless of outcome. Quote Link to comment Share on other sites More sharing options...
Six_Shooter Posted August 7, 2009 Share Posted August 7, 2009 As mentioned what about a low end electrical assist for the turbo. Have some sort of capacitor that will charge up as you drive and then when you step on it it discharges to a really powerful motor that assists the turbo in spooling up............. just an idea, Id just stick with a good old, normal, run of the mill turbo set up. But I always like seeing people doing new stuff, regardless of outcome. Something like that would be better suited for a hybrid (like a Prius hybrid), where there is recumbant braking used, to charge a capacitor, and is then used on the accleration to save batteries/fuel, through an electric motor, connected directly to the drivetrain. I want to play with this idea once I build an electric vehicle, I have a 1972 Honda CB500, that needs too much to get back to original running form, that I want to convert to straight electric, recumbant braking is definatly on the board of plans for that project. Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted August 7, 2009 Share Posted August 7, 2009 It's all up to motor technology. It was touched upon in this thread but was taken to an extreme. http://forums.hybridz.org/showthread.php?t=147040 Quote Link to comment Share on other sites More sharing options...
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