DamirGTI 327 Posted June 7, 2007 Hi ! Anyone try this magical stuff : http://www.bestservis.com/digerurunler/alt...erpower_eng.htm Me thinks that this is one more stupid "plug and play" product like all other strange things on e-bay - magic chips filters etc. When the battery voltage drops engine menagement EFI will be affected (in injection equipped car) like injector spraying control , or not ? I don't understand if this is a good thing why don't they use this in race-rally competition cars ?! Thanks Damir Share this post Link to post Share on other sites
Rob_the_Sparky 9 Posted June 7, 2007 This will release some power otherwise used to run the alternator. 1hp = ~750W so I'd be surprised if it releases anything like what it claims to though. 6hp = 4.5kW, or ~320Amps - I've never seen an alternator put out anything close to this much power so you are very unlikely to save that much even in the "best case". ECU should compensate for the lower voltage but not sure the alternator life time will be improved with this thing switching in and out... Not something I'd use... Rob Share this post Link to post Share on other sites
Gentrix 2 1 Cars Posted June 8, 2007 I recently heard from a guy, who made bigger pulleys for alternators, so that they run slower and need less crankforce. He argued, that this will give some miles per gallon and the recharge of the Batterie won´t be affected if you are not driving in traffic all the time. Nice idea, but he asked for silly money - like 300 Share this post Link to post Share on other sites
Dj_mini 7 Posted June 8, 2007 Gmc sell a simlar thing dont they? Share this post Link to post Share on other sites
jonnie205 1 Posted June 8, 2007 they do work well these, alternators are a lot of drag whee they are loaded up Share this post Link to post Share on other sites
pugrallye 0 Posted June 9, 2007 OOOOh these have made a reoccurrance, yes the theory works as back emf is quite large at high rpm and consumer load. So dumping alternator at high rpm can only be a good thing Could be amusing at night though, as soon as you floor it your headlamps momentarily dim! Share this post Link to post Share on other sites
Pugnut 9 1 Cars Posted June 9, 2007 70a(standard 1.9gti alternator at 14v = 980w . for arguments sake call it 1kw = 1.34HP Share this post Link to post Share on other sites
Rob Thomson 6 Posted June 9, 2007 Yep, but the alternator's probably only 50% efficient at best, so you're really looking at ~3HP. Which is worth saving. Share this post Link to post Share on other sites
DamirGTI 327 Posted June 9, 2007 You are joking right ?! so it's not a crap after all But 6hp for switching of the alternator - strange .. Damir Share this post Link to post Share on other sites
niklas 1 Posted June 9, 2007 It's easy to test really, just remove the alternator belt and take a run. If you can feel the difference in performance then... Share this post Link to post Share on other sites
DamirGTI 327 Posted June 9, 2007 But what about battery charging ? for how much driving can battery hold voltage without alternator charging ? i don't want to stop i the middle of the road because of this test Share this post Link to post Share on other sites
niklas 1 Posted June 9, 2007 But what about battery charging ? for how much driving can battery hold voltage without alternator charging ? i don't want to stop i the middle of the road because of this test I'm sure you can get at least half an hour of driving on a fresh battery! Share this post Link to post Share on other sites
Pugnut 9 1 Cars Posted June 9, 2007 But what about battery charging ? for how much driving can battery hold voltage without alternator charging ? i don't want to stop i the middle of the road because of this test fit a voltmeter across the battery and don't let it go past 12.5v ish. but to be honest your 3hp saving will only be when the alternator is outputting full load which means you'll need to have lights,heater,demister,wipers running. this throws up a couple of questions, 1, the road conditions are too treacherous to reap the benefits of another 3bhp 2, you're battery isn't going to last long throwing out 70 amps. on a dry bright day with a battery in good condition i cant see the alternator outputting more than 20a (guessing - fuel pump,injectors,coil etc) so x2 = 40a (efficiency) x14v = 560w which is 0.75 hp anyone agree? Share this post Link to post Share on other sites
pugrallye 0 Posted June 9, 2007 (edited) The doofangly black box only works on full throttle, therefore you have to have your demisters on etc whilst burying your pedal, which really isnt going to happen, as i remember of them last time they were about, they used to make a loud clunk as they switched in and out..in case you where one of those people who hate noises. and for those people using P=IV formula then converting it to horsepower, its not that straightforward if i remember (a long time ago doing calculations regarding back electromotive force (the more current generated the harder something is to turn) , it has its own unique equations) Edited June 9, 2007 by pugrallye Share this post Link to post Share on other sites
Rob_the_Sparky 9 Posted June 11, 2007 fit a voltmeter across the battery and don't let it go past 12.5v ish. but to be honest your 3hp saving will only be when the alternator is outputting full load which means you'll need to have lights,heater,demister,wipers running. this throws up a couple of questions, 1, the road conditions are too treacherous to reap the benefits of another 3bhp 2, you're battery isn't going to last long throwing out 70 amps. on a dry bright day with a battery in good condition i cant see the alternator outputting more than 20a (guessing - fuel pump,injectors,coil etc) so x2 = 40a (efficiency) x14v = 560w which is 0.75 hp anyone agree? Sounds reasonable. Share this post Link to post Share on other sites
calvinhorse 870 Posted June 11, 2007 that box sure looks heavy to me Share this post Link to post Share on other sites
Rob Thomson 6 Posted June 11, 2007 But what about battery charging ? for how much driving can battery hold voltage without alternator charging ? i don't want to stop i the middle of the road because of this test I've currently got a wiring problem that means the 205's standard alternator activation and warning circuit is buggered. So until I can be arsed to fix it I've got a bypass wire that goes from the battery to the alternator by way of a light-bulb as a current regulator. Anyway, I have to connect/disconnect this wire when I start/stop the engine. But often I can't be arsed, and the battery is more than capable of getting me home from work (50 miles) without any noticeable effect to starting the engine the next time or anything else. The EFi doesn't use a huge amount of power, perhaps 10A including the fuel pump (which is the big draw). So unless you're using the fan, heated window or headlights you've probably got a good couple of hours without an alternator, leaving 50% capacity in your 40A/hr battery. Anyway, if you want to test the difference, just disconnect the spade connector from the side of the alternator, since that's what the black box thing essentially does. You probably won't notice anything, but if you're on track I suppose you might gain a tenth or two a lap. Share this post Link to post Share on other sites
Dream Weaver 2 Posted June 12, 2007 I'm sure you can get at least half an hour of driving on a fresh battery! More than that even When I bought mine, the alt had gone so I had to drive from London to home on a charged up battery - approx 300 miles and 4 hours driving. Share this post Link to post Share on other sites
niklas 1 Posted June 13, 2007 More than that even When I bought mine, the alt had gone so I had to drive from London to home on a charged up battery - approx 300 miles and 4 hours driving. I didn't want to say something that I, without actually testing, don't think is 100% safe. Imagine if someone tries what I say and the engine cuts out in the middle of nowhere... Share this post Link to post Share on other sites
