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Posted: Sat Jan 06, 2007 2:46 pm
by Micke
You're right. It doesn't make a big difference.
However, as a new wheel probably has to be made anyway, it makes sense to make it bigger for the sake of the inertia you mentioned. I also think it must have at least some resistance. This should be decreased by running it at lower rpm.
Posted: Fri Jan 12, 2007 1:52 pm
by kterkkila
It may also last longer with lower rpms..
Posted: Fri Jan 12, 2007 2:20 pm
by Mats
kterkkila wrote:It may also last longer with lower rpms..
Yes, 250 Years instead of 200...
Posted: Fri Jan 12, 2007 11:04 pm
by Jim K
HAHAH! That was funny!!
Jim K.
Posted: Sat Jan 13, 2007 2:11 am
by kterkkila
Mats wrote:Yes, 250 Years instead of 200...
Hey, this is race car, not sunday cruising topic. Race cars use to live on high rervs and it's good idea to lower alternator speed in many respect..
Posted: Sat Jan 13, 2007 2:09 pm
by Mats
kterkkila wrote:
Hey, this is race car, not sunday cruising topic.
Yes, and it gets silly amounts of use compared to a daily driver...
Posted: Sat Jan 13, 2007 4:04 pm
by MD
At the risk of getting some flack out of it, I feel a need to chime in.
The issue here regarding the longevity of the alternator based on its rotational speed is not about the DURATION of its use but has everything to do with its rotation speed and amperage load.
Classically rally alternators shit themselves by excessive revs and high amperage loads when using a zillion lights.
Air conditioner compressors can suffer the same fate if revved above their mechanical stable rate. to offset this, the electric clutches can be disengaged by a rev limit setting to make sure that doesn't happen.
A larger diameter pulley will reduce engine load and improve reliabilty. For a race car, the amperage so produced will still be more than enough to provide for any current drain. Isn't that what we are all trying to do here?
Posted: Sun Jan 14, 2007 1:33 am
by kterkkila
MD wrote:Isn't that what we are all trying to do here?
Exactly.
Here's my setup. Small Suzuki alternator with bigger pulley. Saves 1500g on dead weight and some on inertia. Our typical race is 6 hours, so reliability is also very important. If the alternator get broken, the race is ruined.
http://uk.pg.photos.yahoo.com/ph/kterkk ... pg&.src=ph
Posted: Sun Jan 14, 2007 2:25 am
by Mats
Ok, I can see your point. Rally alternators surely die because of constant use outside their electrical envelope though. I have yet to see even one alternator fail in a race car because of bearing failure.
As an exercise in making eveything
taut, I have no objections.
Posted: Fri Oct 26, 2007 11:11 pm
by ar4me
Long overdue update... Find below some pics of the 30 amp, 6 lbs Denso mini alternator and install I ended up using. Bought 2 brand new off Ebay for $50 each, off a Yamaha 3 cyl tractor application. I have run this setup at 2 events without issues, sufficient juice to run dual fuel pumps.
It came with a vee-belt pulley, but digging through the trash bin at an alternator shop and a visit to the local autoparts store for a proper length serpentine belt provided pulley and belt. Bracket is modified from a stock Milano mount.
Jes
Posted: Sat Oct 27, 2007 12:32 am
by MD
yep, using a 40 amp version myself on my race car.
Posted: Sat Oct 27, 2007 3:39 am
by x-rad
Nice conversion...Honda also makes some small light alternators
.
Posted: Tue Nov 20, 2007 1:11 pm
by OzMidnight
There is an extra 50grams of weight to be saved if you chop the excess off the ends of the mounting bracket! Also, cannot the pulley be made from aluminium? How about the bracket itself?
The Geo/Suzuki alternators can beb had for as little as $50AuD in working order.
www.redlinegti.com - there are one or two there right now.
