bgd73 Posted May 22, 2006 Share Posted May 22, 2006 Anyone experimented with superchargers on subes? I found a sube manufactured with it (looked like a new brat 2.5rs), and a site claiming the wrx was going to get one. I remember an old pump for recycling purposes on a 70's v8 I had,that really cranked some air out, small enough to fit where the A/C pump is on the old sube. On the v8 it did nothing, but the tiny EA82 may get something out of it.Anyone try something like it? Link to comment Share on other sites More sharing options...
cubastreet Posted May 23, 2006 Share Posted May 23, 2006 I wanna stick a twin-screw on my brat, but the cheapness of a little rootes from a toyota engine may mean i'll end up with that instead. Link to comment Share on other sites More sharing options...
bgd73 Posted May 23, 2006 Author Share Posted May 23, 2006 I was reading how those superchargers worked. http://auto.howstuffworks.com/question122.htm Above site is where I started. Why did mainstream production go with a turbo anyway? Turbos are hot, they lag, inconsistent, need a "special" rpm to function and die at another "special" rpm. they are hard on an engine even after killing a realistic physical compression, to mimic that physical compression with inconsistent air.I have only seen one supercharger run (the roots lookin one) and thier was no thought of intercooler, it didnt need it. I saw the centrifugal supercharger and thought "that really makes sense" (truly). Why challenge the 87 quick burn octane? A big 'ol sloppy burnin diesel seems to be a great place for a turbo, like a tractor trailer rig. Am I retarded or what? I cringe at the thought of an exhaust driven turbo! Someone enlighten me? :-\ And even if to go with a charge of air, why pressure it? I would think to buffer the 180 "full stroke fire" needed for a 4-banger to run good would do well with a little boost to help and nothing more, while keeping high physical compression.A balance of n/a durability and natural precision, And helping it a little....not much... seems like an engine I'd like to see:burnout: Link to comment Share on other sites More sharing options...
mikeshoup Posted May 23, 2006 Share Posted May 23, 2006 I can give a few reasons why you may want to use a turbo over a supercharger: Cheaper Lighter than most superchargers (except centrifugal) Centrifugal superchargers can have as much lag, if not more than a turbo. Cent Superchargers can make lotsa boost, but only in high rpms. For a safe amount of boost, you wouldn't see it come on until much later than a turbo. (This is due to the exponential growth of boost with a cent supercharger. Turbos have an exponential growth too, but you have a wastegate to divert the power driving it) Oh, and superchargers can still make use of intercoolers. Same principle, compressing air increases the air temp. Some supercharged engines do use intercoolers. All types of superchargers (turbos included, hey, they are superchargers), have their own uses. Sometimes it even boils down to personal preference. Link to comment Share on other sites More sharing options...
bgd73 Posted May 23, 2006 Author Share Posted May 23, 2006 True, it must be the cost. Linear type flow to parallel instantaneously to throttle is as close to zero lag as a charger (turbo or super) can get. Also , I read about the fantasy of EGR and Subaru enjoying cannibilizing thier own engines with it. The turbo is good for thier pursuit.As far as higher rpms being better charge... of course. Just like a turbo. I searched around to see successes of it, I really like the thought of it. Subaru has several models out with them now with realistic numbers. I bet the 'ol EA82 will still be runnin until Subaru makes something I really want if it takes half a century... Link to comment Share on other sites More sharing options...
Uberoo Posted May 23, 2006 Share Posted May 23, 2006 how does a turbo stress an engine built for forced induction more than a supercharger?Granted if you add forced induction to any engine (turbo, charger, nitrous) it will put stress on that engine.The turbos you speak of that have a lot of lag is exemplifed by 70's and 80's porsche's. Modern turbo technology can have a turbo that starts spolling(making boost) at 1200 rpm, and make 20 PSI by 3500.A belt driven blower can never generate that much airflow,due to design impossiblies. A belt driven blower at max spins 7000 rpm(redline of car) where as a turbo spins at 100,000's of RPMs. Granted it is true that a blower makes the most power at low rpms.Becuase of the design of the screws boost is heated far to much,then you can't use that boost or you will melt a piston or blow a head or something.For my driving offroad I would be making a little below base boost offroad so about a 20HP gain if done right.The only reason turbos get hot is because they are driven by hot exhaust gasses.Not to mention that a supercharger on a small engine can use as much as 75% of the engine's power to turn the thing.turbos are "free" power becuase it uses energy that would otherwise be wasted-exhaust heat.not to mention the turbo itself works as a great muffler.A turbo kills about 1/3 of the sound of an engine so straight pipes are not super loud like on a non turbo. whew, long... Link to comment Share on other sites More sharing options...
bgd73 Posted May 23, 2006 Author Share Posted May 23, 2006 The superchargers I found spun at 56-65000 rpms,thats (sixty five thousand -not hundred) not as high as a turbo, but it still does the purpose(I was finding 8psi- just add that to physical compression higher than a lower 20lb turbo engine...)and centrifugal pump with gear reduction, must equal the exhaust pressure driving same turbo turbine, if customed to the engine to get same output. Turbos get away with more thier cheaply to be more universal with blowoff valves, etc.A supercharger would absolutely have to be precise from the get go as it functions instantly, exactly to the engine it is bolted up to. I saw this on a 5.0 mustang (not my fav car, but very common for mods) A bolted on SC drove oem to 600hp and the guy threw a stock conrod thru the block laying on the ground. Only for the reason, that it was exactly built for the 5.0 and its oem intake, compression, etc.maximizing it. It can be done, but it is no doubt the cost. I like to see the suby's do have some now. The Brat looking car has 230 hp and high torque with it. Nice. What can i do with an ea82 to have belt driven air charge (just a little one- not thinkin dragster.... ) the old smog pumps seem like a candidate from 70's american v8's. Link to comment Share on other sites More sharing options...
Uberoo Posted May 23, 2006 Share Posted May 23, 2006 airpumps would work on a lawnmower for extra power but not on an engine,it wouldnt flow very much air at all.might as well strap a leafbower to your cars intake tract. Link to comment Share on other sites More sharing options...
NorthWet Posted May 23, 2006 Share Posted May 23, 2006 Turbos were chosen mostly for their use of "free" energy... not exactly true, but truer than mechanically driven compressors. A mechanically driven compressor is consuming power all of the time, whereas a turbo-supercharger uses virtually no power until it starts producing enough flow to produce boost. I was reading a Mercedes Benz webpage a year ago, and they were talking about their Mechanically supercharged model (the C230???... memory too flaky :-\ ), and they stated that their supercharger required some 54 HP to run at the engine's HP peak. Can you imagine taking 54, or even 30-something horsepower, off of an EA-series engine to run the compressor? You would have to run 7-8 PSI of boost just to break even. Now, in reality a turbo-supercharger does not use "free" energy, but takes its toll in backpressure that the engine has to pump against on its exhaust stroke. But the amount of energy is far less than a mechanically driven device would require. The turbine-compressor is also more efficient at compressing air than current positive displacement compressors. Mechanically driven centrifugal compressors suffer from being tied to the engines speed, and thus willl have a narrow range that they are useful. A turbo-supercharger's speed (and thus its output) are divorced from the engine speed, and is capable at producing useful flow over a wider range of conditions. Turbo-superchargers are not ideal, but they tend to be more practical than mechanically-driven superchargers. Myself, I am interested in 2 different methods: Fluid-ring compressors and thermo-compressors. Link to comment Share on other sites More sharing options...
bgd73 Posted May 23, 2006 Author Share Posted May 23, 2006 from about how stuff works dot com There are tradeoffs in both systems. In theory, a turbocharger is more efficient because it is using the "wasted" energy in the exhaust stream for its power source. On the other hand, a turbocharger causes some amount of back pressure in the exhaust system and tends to provide less boost until the engine is running at higher RPMs. Superchargers are easier to install but tend to be more expensive. They have my thought exactly about engines being forced to wait for a beneficial return on a turbo. A flawless full stroke is needed (4 banger) to achieve higher rpms. At bottom of stroke another cylinder is finally compressed to fire (the biggest self strain on any engine besides friction), the just fired stroke is at its weakest point of its own fire to get the other one ready. A supercharger responds at slow rpm which would be especially beneficial to a four cylinder. I hope a genious company with thier supercharger simplified proves it out loud.(I bet it is going to be a subaru) http://www.automotive-technology.com/projects/subaru%5FSTX/ Now back to a turbo creating backpressure at slow rpms on a four cylinder that really needs every bit it can get to wind up... I don't like it. It is unrealistic, and is a factor in thier lag. Just two more cylinders and a turbo is phenomanol becuse there is still fire left in one bang while another cylinder starts thiers. Four cylinders need something special. A turbo just doesn't make sense for the full range of rpms and every day stop and go driving, while a supercharger could, even in the cold (even better i would guess- less oxygen needs more air for the engine to make up for it, especially torquing take offs etc) Link to comment Share on other sites More sharing options...
mikeshoup Posted May 23, 2006 Share Posted May 23, 2006 Well, perhaps you should have picked a different title for this thread... A centrifugal supercharger does not respond to low rpms. Link to comment Share on other sites More sharing options...
bgd73 Posted May 23, 2006 Author Share Posted May 23, 2006 better than a turbo however. I found something.... http://www.magnusonproducts.com/mp45.htm The roots seem to be main stream. This charger even looks like it would fit... What a day dream I could be having. 135+hp quietly , no lag, internal bypass direct link for a broad range of rpms-- up to the normal. I wonder if 200ft lbs of torque is out of the question being the response is so tight.. I'm satisfied, I may take a crazy dive into something like it on an old EA82 sometime.I still may try a smog pump, where there was no air, now there is some....If opening an air box and cooling top end down etc gives noticable improvement, any pump would work.... Link to comment Share on other sites More sharing options...
reddevil Posted May 24, 2006 Share Posted May 24, 2006 My eaton m62 installation. I currently have TWO installed. http://forums.nasioc.com/forums/showthread.php?t=605625&page=1 Link to comment Share on other sites More sharing options...
bgd73 Posted May 24, 2006 Author Share Posted May 24, 2006 What it comes down to is keeping just one belt running the whole shebang, the proper pulley ratio, and belt coverage of the pulleys. That was my deepest thought about the whole idea.the rest is managable dynamically. I have read up to the dyno pic, if they could only get the proper weight of the car in the algorithm... is a legacy 3250 lbs? I had a wagon claiming similar weight, I dont believe it. I have always assumed the numbers for hp to be off because of it. Excellent work.Alot of custom fine tuning without the deep math to work with by engineers. The dyno pic for torque, is well rounded.I could analogize the engine glowi ng at its peak. I would guess at this point cramming anymore in isn't likel? forgive the typos, new iexplore is killing my keyboard at ng's only. Link to comment Share on other sites More sharing options...
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