Guest gtmattz Posted December 17, 2003 Share Posted December 17, 2003 was looking through the pictures of your awesome Z car and saw the section on the alternator, very interesting setup there! I was wondering why? weight distribution? Quote Link to comment Share on other sites More sharing options...
TomoHawk Posted December 17, 2003 Share Posted December 17, 2003 If you put magnets ON the driveshaft, you could put a stator around that and use the driveshaft as the armature of the alternator/generator. What would be the RPM of the driveshat ast 60 MP? 100MPH? gotta take that into account probably. Quote Link to comment Share on other sites More sharing options...
jonzer12 Posted December 17, 2003 Share Posted December 17, 2003 I agree that his setup in ingenious but I can't see any advantages. You could always gear it up to get rpm but now you have no juice at idle. I too am curious as to what forced this decision. Quote Link to comment Share on other sites More sharing options...
Guest gtmattz Posted December 17, 2003 Share Posted December 17, 2003 well, since his car started out as a true race car, the only reason i can see is to move more weight to the rear to obtain a better f/r weight distribution. Looks like a neat idea, but I wouldnt do it to my car, as I am building it to be a dialy driver, and in the winter that nice hole in the back there would be a nut-freezer Quote Link to comment Share on other sites More sharing options...
JMortensen Posted December 17, 2003 Share Posted December 17, 2003 I don't want to put words into Terry's mouth, but my understanding is that if you run the alternator off the driveshaft you have less parasitic drag, because the driveshaft turns slower unless you're in overdrive since it is already past the gear reduction in the transmission. So assuming you have a 1:1 drive ratio on the driveshaft and the alternator pulley, if you are in first gear the engine makes about 3 rpms before the alternator spins once. It also would move the weight in between the axles, meaning lower polar moment of inertia. It's a race car thing. Since Terry originally built his car to be a race car and not a street car, he probably didn't have to power any stereo or headlights. Not sure how much juice you would need to run the car on the street, but I'd imagine you'd need a pretty good battery if you were driving at night in stop and go traffic for a few hours. Lot's of serious race cars don't have an alternator at all. They just run off the battery. IIRC that's called a total loss system or a dump system something to that effect. Less drag, more hp. Some also run electric water pumps to get the rotating mass off the front of the engine. Jon Quote Link to comment Share on other sites More sharing options...
blueovalz Posted December 17, 2003 Share Posted December 17, 2003 Serveral reasons brought me to this unusual solution. When I raced the car I had no alternator at all, so I knew that none was needed "full time". On top of this, I have invested a great deal of blood, sweat, and tears in a design of a hood that lies within 1/2" of many parts of the front of the engine. To add another device, and its subsequent blister to cover it, was not something I did not look forward to. So by pushing the alternator back, I eliminated the hood problem, put the weight close to the rear axle, and provided more elbow room in front of the engine. Some of these issues can be trivialized, but in the end, "it was there", and I wanted to conquer it. It has a 2:1 ratio, which with the 4:11 rear end, is too high. At 70mph, it turns about 7k (driveshaft is turning 3300 rpm). My rational for the sizing of the pulleys was the many examples on motors that I saw that were of 3:1 ratios or higher, off the crank, so I felt this was safe. The alternator "turns on" at about 15mph to 14vdc and has happily charged my battery (electric fans, fuel pump, etc) for a couple of years now. It makes a nice whine when it "turns on" or off, so I am always reminded whenever I slow down or speed up enough to charge the battery. Quote Link to comment Share on other sites More sharing options...
Guest gtmattz Posted December 17, 2003 Share Posted December 17, 2003 AH! i didnt even think about the design of your hood, it all makes sense now Quote Link to comment Share on other sites More sharing options...
Tim240z Posted December 17, 2003 Share Posted December 17, 2003 If you just want to save space, you could use this one: http://www.portcityracing.com/cgi-bin/portcityracing/shop/pcr_displayitem.cgi (hmm...the link no worky. Go to Port City Racing and choose catalogue, then electrical, then Racemate alternators). Barrett Engineering introduces an innovative new concept for the electrical demands of Racing Professionals. An alternator that is totally housed under the water pump pulley, drawing less than 1/3 HP to produce 16 volts at 15 amps, and will not interfere with other electrical equipment. The heart of the alternator is the custom manufactured ring magnets which rotate about a set of custom stator pick-up coils. These are housed under the pulley used to drive the water pump. Thus, by driving the water pump, the RACE MATE´S magnets are also rotated. This eliminates the need for an alternator bracket and drive belt, as well as their associated problems (breakage, slippage, etc.). The entire alternator is practically unseen with only a single wire, which feeds the output voltage to the battery, being visible as it exits the RACE MATE. Experienced race car owners agree the alternator has long been the weak link in the alternator-battery-coil system. The RACE MATE appears to be the first new solution introduced - engineered to specifically end this problem once and for all. With so many race tracks now requiring restarts under your own power, the 16 volt output of the RACE MATE will insure that your battery will always be charged and ready when needed. In addition, modern high output ignition systems ("MSD" or GM´s HEI) will operate ideally with the RACE MATE. A little pricey at $550, but you are getting a quality water pump and a quality alternator, so maybe not too bad. Tim Quote Link to comment Share on other sites More sharing options...
Guest gtmattz Posted December 17, 2003 Share Posted December 17, 2003 that is awesome.. a little pricey for my wallet, but still awesome nonetheless Quote Link to comment Share on other sites More sharing options...
Guest 240hybrid Posted December 19, 2003 Share Posted December 19, 2003 My grandfather has a old MG motor he's rebuilding and if I remember correctly the generator/alternator ran off the front of camshaft. It was a neat idea, but don't know if its very pratical as I haven't see it in any other cars. Leave it to the brits. to come up with a crazy alternator drive method. That post that Tim put up of the alternator built onto the front of the waterpump is neat and a good space saver. Chase Quote Link to comment Share on other sites More sharing options...
blueovalz Posted December 19, 2003 Share Posted December 19, 2003 I've seen these, but couldn't justify the expense, number 1, and 2, If something went wrong a year or two down the road, replacement would be a cast iron bitch, so I chose the combination of easily accessible parts and the joy of successful hybridization. Quote Link to comment Share on other sites More sharing options...
preith Posted December 19, 2003 Share Posted December 19, 2003 I beleive Trans Am cars have been using the same basic design as Terry's for quite a while as well. Quote Link to comment Share on other sites More sharing options...
Tim240z Posted December 19, 2003 Share Posted December 19, 2003 Many, many race cars use it. I've used it myself on a race car, but a street car is a different story altogether. Be a real bummer if your battery went dead while sitting in bumper to bumper slow moving traffic In Los Angeles you'd likely get shot! Tim Quote Link to comment Share on other sites More sharing options...
preith Posted December 20, 2003 Share Posted December 20, 2003 Terry, perhaps you can shed some light on how it is in heavy traffic...if you have in fact experienced this? On a side note, I have to say I loved the Zcar Magazine article on your car. This probably has been covered already, but why did you decide to make it into a street car? Have you had any desire to build a tube frame car? Phil Quote Link to comment Share on other sites More sharing options...
blueovalz Posted December 20, 2003 Share Posted December 20, 2003 I used to run the car for about 30 minutes without an alternator at all, but now the fans really add load to the battery. Do date I've had no problems with the way my alternator charges, but I rarely get stuck in really slow traffic, so I really can't answer your question. After racing it for a few years I ran out of discretionary funds, sold the trailer and truck, and set the car in the garage for 5 years. Then my wife asked me one day, "why I don't do something with the car! You should sell it, or drive it, one or the other, it's not a hard decision, one or the other, either drive it or sell it." The car seemed to be pretty popular, so after playing with selling it a few times (nobody wanted to give me what I thought was fair), I decided to drive it, and thus the "street legal" phase came about, and hopefully the "car show" phase will follow some time soon. The only "tube frame" car I nearly completed was my "formula Subaru" project. I took the boxter 4 cylinder and tranny from an '80s Subaru, and mounted it behind a single drivers seat (was a mid engine now), fabbed up the uprights, arms, pushrods, brakes.....really just about everything but the body, and then just quit. It weighed about 900 lbs, so with even the weak Subaru motor it would give impressive performance. I'll get it going again some day, but this time use the newer motors and an autobox tranny. I learned a lot with that project and look forward to starting it up again. Quote Link to comment Share on other sites More sharing options...
Roggaman Posted December 22, 2003 Share Posted December 22, 2003 The water pump /alternator solution seems like a good Got me started on thinking about a "homebuilt" solution to save some bucks Quote Link to comment Share on other sites More sharing options...
JMortensen Posted December 22, 2003 Share Posted December 22, 2003 Am I the only one that noticed that the alternator water pump combo only puts out 15 amps? Great for a racecar, not good for a street car. Just trying to save you guys several $100s. Jon Quote Link to comment Share on other sites More sharing options...
blueovalz Posted December 23, 2003 Share Posted December 23, 2003 Well, well. We appreciate that significant detail that I had missed. Quote Link to comment Share on other sites More sharing options...
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