....Ever notice how some of the weirdest thoughts come to you while your wrenching? I don't know if it's been done but I was thinking... hypothetically... and ignoring issues like heat, lubrication, etc. Could you not modify a turbocharger (delete the compressor) and run either a pulley or a mini drive shaft of some kind to an alternator or power steering pump? The benefit being, one less belt to worry about breaking in the middle of no where and possibly freeing a few HP in the process. The only flaw in the idea I can see immediately is heat being transfer from the manifold to the Alt. or pump and cooking them, but I'm sure something could done about that. I'm basing my theory off of a 350, where room in the engine compartment is plentiful. Anyway feel free to blast or encorage me on this one.
I suppose anything is 'possible'.......whether it's practical might be another issue. I think if I was trying to free up space in the engine compartment and/or trying to eliminate one more engine driven item - I'd go with a rearend driven alternator ala NASCAR. Only catch there is, you are only charging when it's in gear........wouldn't want to try that for long in the stop & go traffic of a large city. ou:
I think what you would gain in getting rid of one belt would be more then made up for by the loss of power from the backpressure, and less reliability from the heat and more oil and cooling lines, but it never hurts to dream. Personally I would use the shaft from the turbine and run it through a fluid coupling to the crankshaft like the turbo-compounders the huge radial aircraft engines had.
I wasn't trying to free up room or anything, if your refering to my comment about the 350 engine compartment, I was just pointing out that there is room to do such a mod. I like the Nascar concept but yea I diffently see a problem in stop-n-go traffic. This whole idea kinda came together after I noticed an ad or something in Car Craft about a turbo that was located by the diff. or something around those lines. Anyway I'm just trying to think of something productive the burned exhaust gases could do, other than spinning a turbo. If they can spin another engine accessory and not eat fuel or a couple of ponies why not? Thx for info Cheers.
Steven, You've made a good point about the backpressure, I'll diffently have to think about after I get some sleep. Off the top of my head If I increased the bore of the exhaust pipe or maybe cutt a few teeth out of the exhaust gear, that could decrease the back pressure?! Either way I'm sleeping on this one tonite. Thx bud Oh one more thing... what is a turbo compunder?!
If you made the turbo larger then you would have less back pressure, but also less power would be extraceted for the alternator. I suppose if you tuned it just right you would notice barely any difference. Here's the best description of turbocompounding I found from a NASA site after doing a short search. btw,I think they've recently been applied to large diesel engines too. "The Wright 3350 turbocompound engine employed a two-speed gear-driven supercharger and, in addition, was equipped with three exhaust-driven turbines. The three turbines were geared to a single shaft that in turn was hydraulically coupled to the engine crankshaft. Each turbine was driven by the exhaust of six cylinders. About 15 percent of the total power of the engine was obtained from reclamation of exhaust gas energy. The specific fuel consumption was probably the lowest ever achieved in a reciprocating aircraft engine."
I really do not believe that a lowly alternator can handle being spun at the RPMs that Turbos run. It would fry it.
That would be correct Andrew, the exhaust wheel turns at something around 143,000 RPM or around those lines anyway. However the solution there would be a simple gear reduction unit. And thanks steve, I did some browsing around last night and the closest I got to finding info, was a quick blurp on a site in Arabic. The Turbo compounder is an interesting concept and yes from the few englsih words I found on that sight, there was some mention of it being used in diesel engine applications. Well keep the flaws with me idea coming guys, I'm more then thankful for them! Always better to sort out things on paper before you toast an engine eh?! Cheers.
i think the biggest problem would be the geometric rate that the turbo spools up in relation to engine rpm. remember, that at low rpms the turbo is barely spinning over (relatively speaking) but that as the engine rpms come up the rpms on the turbo will increase much more quickly. this is the source of the dreaded 'turbo lag' that turbo manufacturers spend so much time talking about how they've minimized it. the reason why turbo's are so much more prevalent in prop driven aircraft and diesel applications is that these engines operate over a much more narrow rpm range (~1000 to 3000 rpm) than automotive engines do so it's orders of magnitude easier to control the turbo speed and maintain boost levels. i agree that there should be more than enough power in the exhaust gases to drive your entire accessory set. if you can find some way to normalize or even fix your turbo driveshaft speed to a certain rpm you can probably make your belt driven accessories both more efficient and more durable by keeping each accessory at the rpm at which it functions best. i do like the idea of the turbo compounder though. applying the turbine output directly to the drive shaft ... neat.
Hey finally some encouragement! Followed by yet another valid issue. Well.... suppose I were to install the turbo so that only 1 or 2 cylinders in the bank contributed to the turbos speed? The next question is; what speed do exhaust gases leave a cylinder/at what RPM....? If I had those numbers, I should be able to figure out what RPM the turbo would spin at (incomparison to engine rpm) and the rest is a cake walk. Of course using only 1 or 2 cylinders to drive the turbo would not be very helpful in stop-n-go traffic....... hmmm, you would almost need a way to utilize all 4 cylinders at idle but gradually phase out a couple of them as your rpm's rise. Just came back from walking the dog, cold air did me some good to. If I ran a pipe off the manifold that had a butterfly in it, all I need is a spring rated at the same psi as the exhaust pressure at say 2,500 rpm. This would allow all the exhaust to be routed thru the add-on pipe at idle, maintaining the proper rpm range for the given accessory. And as the rpms increase it would slowly close off the butterfly limited the flow of exhaust and keep the turbo at a reasonable rpm. How's that sound? Cheers and thx
i thought alot of turbos nowadays came with variable inlets to accomplish much the same thing you're talking about? smaller inlet at lower rpm to maintain the velocity of the exhaust gases and then it opens up as engine rpm increases to reduce backpressure. but they still have lag.... the decades old standard way of dealing with excess inlet pressure to the turbo is the wastegate ... basically a spring loaded blow off valve. i don't think i'd want to run only some cylinders on the turbo and not all of them. that would make the engine unbalanced by introducing backpressure to a select few cylinders, making them more inefficient in comparison to the rest of the engine. have you ever run/modded a standard turbo car before?
Can't say that I have, with the exception of bolting in a few nitrous systems, my power adder experience is pretty low. To my vague knowledge the turbo's available now-a-days do have a varying inlet diameters, but for the purpose of this particular application I was just going to go liberate one from a firefly or sunbird at the local bone yard.
if i were you i think i'd live with/play with mod a regular turbo for a while before i tried jumping off into the deep end. less of a learning curve that way. also, i don't think there is much point in moving only the alternator to 'turbo-drive'. i don't think it puts that much of a load on the engine most of the time anyways. if i was going to do this i would definitely be trying to move everything off of the fan belt that i could. maybe even go dry sump with turbo driven oil pump and water pump? :jd: oooooh, and you could leave the impeller connected, plumb it to the block and use it as a manifold vacuum pump. :TU: yeah, some of these comments are way out there smart assery but that['s mostly because i'm a way out there smart ass. hey, if you're gonna do it, you might as well go all the way, right? i really don't think this whole project is a very good idea unless you have access to a fairly decent fabrication/machine shop because i think there's going to be quite a bit fabrication involved in a project like this. although that manifold vacuum pump, that would be really unexpected.
Funny you should mention a machine shop, ironically a retired and fully equiped machinist happens to live 20ft from my door step. And I concour with what you say, everything should be moved to the "turbo-drive" system. As the car lacks A/C, that would just leave the fan and water pump which, obviousily, many aftermarket manufacturers produce electric versions of. So I believe that would leave me with zero belts? Now that should be good for a horse or two at the rear wheels! Well, I finally managed to located my xtra passenger side manifold, less the bolt eyelet for the last cylinder, so I've got something to wreck in attempting to pull this off! I guess I'll start blue printing this sucker tomorrow. Thx for the advice Bob. Especially for the Hp and torque ratings on buicks.net . Cheers, ~Snake~
Smokey Yunick spun an alternator using a model aircraft propeller. Stuck it in the airflow at the front of the car. 'Course, that was NASCAR, and about a thousand years ago.
I'd think with a belt system, if something goes wrong its easy to fix. A turbo adds one more spinning thing that would be expensive to replace, and the accessories would rely on it. It does sound like a cool idea, though.
True, belts are easier to fix when things go wrong... If you happen to have a spare belt and the tools. Not much to go wrong though when there is no belts! Put it this way, during my only trip I've ever taken to the U.S (to get a buick exhaust manifold no less) I lost my Alt belt in the middle of Omish country, nothing around for a good solid 30 miles. Thankfully an older Omish gentlemen stopped and offered me a ride to the nearest phone, which was 37 klicks away at a scrap yard (and I thought my lesabre had a harsh suspension!) Anyway you should've seen the scrap yard owner when I arrived in horse and buggy. Moral of the story, I hate belts and if I can do away with them, God help me I will! Thanks for the input, Cheers
Mid 50's Desoto PS pump / generator combination I looked at a mid 50's desoto several months ago and the PS pump and generator were lined up one behind the other and connected by a shaft on the factory HEMI. I thought what a great space saver---you still could climb in the whole engine compartment.
Was that just a one-off mod by the owner or did it come from the factory like that? Sorry I'm not up on my 50's car history. Thx
