Barry it will be interesting when you get it going, maybe Carl's bracket will work for you? I bought one bracket that also might work but I will deal with that when I get there. I took off the S4 pulley but it would need a sleeve and something to fill in the keyway. I would be concerned about balance given it can spin to 18,000 rpm.

Here's link to the Bosch racing alternators, don't worry Carl you won't lose any sales, starting at 2050 euros. It is the McLaren equivalent but 200 grams heavier.

http://www.bosch-motorsport.com/cont.../html/2615.htm

If you really want to get blown away, how about $9,000 for some inconel headers. Another way of losing weight from the front end, Oh yes your wallet will be lighter too.

 

Let's make it turbo and put a smaller Inconel pipe inside a slightly larger inconel pipe, thermal block coat all four surfaces, and make some equal length tubular turbo headers. The cost, by the way, is not 2*$9000... ;-)

 

Greg, that was no problem :

1) i made the bracket from 1/2 the OEM one and 1/2 the OEM A/C bracket. Just 1 weld and you have as Carl makes but with the tensioning bolt on the back.

2) McLaren is dia 15 , OEM 17... now "SKF" sales the perfect little bushing with a edge for this. ( you have to put the OEM pully in a lathe to turn away some of the thickness, simple, but no diameters to work on )
You need the bushing with edge as to compress everything with the alternators bolt , there's no keyway.

3) little scary work is on the pivot bolt : you must cut away the rear extension on the alternator and make a new one in front to have it aligned with the engine belt. In fact no big deal either.

So yes, there's some DIY involved... Carls set will be easyer to put on !

 

what does the club/GT alternator weigh. I did one of those, and it was a little lighter, but this Carl product is very cool. thats big weight! I think the club sport alternator /GT is about 3 lbs less weight, and it has only 80amps charging capacity.

 

Hi I have one fitted to my race car, but it stops charging when it gets very hot. It seems to get heatsoked in traffic and when at max rpm on the track. When it cools down on the freeway or after a long stop, it charges again. At the track again yesterday when I came back in after a session, the battery volts were right down again so I was charging the battery between sessions. My thoughts at the moment are to either take steps to cool it down or the swap it out for a different unit.

Maybe I could put a heat shield between the alternator and the engine and maybe run a cooling duct that blows on to the alternator.

The previous aftermaket Bosch one worked OK, but the belt would rub the top bolt and break occasionaly. This one sits lower and the belt issue is solved, but has been replaced with the overheating issue.

Any thoughts on the modify or replace question?

 

Paul how many fans does your alternator have? The Mclaren units have two, now what they did tell me was make sure you run them fast enough. Just like Porsche with the GT and Clubsport alternators their peak rpm is 18,000 at the GT redline of 6.800 rpm. So the fans drawing air into the alternator being crucial. Ducting I doubt will help in traffic. Maybe not suitable for Australian conditions? Have a look at your pulley ratio.

Greg

 

These lightweight racing alternators are wonderful, but really designed just for bare bones track cars.

No electric windows or electric seats. Rear window Defroster, stereo, etc. They can be easily over-drawn in those conditions and the alternator will have a very short life.

Lets add it up in a race car: 1 Bosch 044 electric fuel pump, 20 amps. 1 Ignition coil and EZK box, 18 amps. 8 injectors and LH computer, 16 amps. Out of a 65 amp alternator, you are at 54 amps right now. Done. A big electric radiator fan will put you over the top, there is just enough to run a small electric fan if you want to.

Balance the weight savings with the battery.... if you switch to an Optima Red Top, you can run a smaller battery and save weight compared to stock. Or go even further... to a larger alternator and run a single Odessey PC680 gel cell battery. I run two PC680's in my racer and they are still less than half the weight of an Optima.

PS: If racing a K-Jet CIS car like I did, then drop the 8 injectors and LH computer at 16 amps from your calculations, and you have plenty of "room" for a big radiator fan if you want one.

 

Thanks Carl and Greg. From Carl's response I think that maybe the load is too high. The car is stripped out but I am running the fuel pump, Motec ignition, the interior fan (for me) and there is a modern twin fan setup on the radiator. When the first radiator fan comes in is probably about the same time as the volts start to drop and the battery starts to discharge. It probably charges on the freeway as the fan has cut out leaving some headroom for the battery to charge.

 

Paul you may want to adapt a used McLaren Electronics unit or a Bosch Nascar unit, they wont have this trouble, the Mclaren unit I was keeping for spares is a 140 amp unit. The lower amp units such as 100 amp unit have more of a street charging cycle. Read up on what Belgium Barry said to get an idea of what I am saying. They do come up from time to time, just watch the milage, they normally stamp it onto the alternator when the teams sell them.

Greg

 

You want a little headspace on your alternator load. A 65 amp alternator can run at full load for a little bit, (like when the 2nd fan starts up, no problem) but if you run an alternator at max load constantly, the diode tree will overheat and short out.

Ideas: put an ammeter at the battery and turn everything on to see what you max load is. Design the charging system accordingly. A garden variety ammeter like those we used to mount in the dash of hot rods isnt very expensive, attach two wires to the posts on it and now you have a diagnostic tool.

Try to design your system for about a 10% headspace. More is better. Either lower your current draw, or increase the size of the alternator to suit.

Paul: one wonders why you have so many fans on your race car. At speeds over about 35 MPH they actually slow the air down going thru your radiator. I carry one fan only on a fairly high temp switch. Its usually not on. Mark Anderson (last time I checked) did not have one at all. Just keep moving!