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So the DB Electrical 200 amp alternator I installed last year in July went south on me the other day, so they warranteed it and sent me a new one. I got the new one installed yesterday and noticed that the idle voltage isn't looking as good as the last one was. On my Insight, which I know is about .3 or .4 lower than reading voltage right at the battery terminal, I'm seeing as low and 12.1 volts at idle which translated to about 12.5 at the batteries. Idle is averaging at 660 rpm.
When I raise idle to 1000 rpm, I get a nice solid 13.8 to 14.0 on the Insight, so about 14.2 to 14.4 at the batteries. I called BD about this and they say that on high output alternators sometimes they don't reliably put out those higher voltage numbers, especially at our idle speeds. When I asked why my last one did, they said it is a crapshoot and just varies from alternator to alternator and the last one may have just been an expectional performer. They asked me to measure the pulley diameter to see if maybe it hard a larger one on it, but I measured 2.5 inches across the front flange which they claim is the smallest pulley available for the 6G-cased alternators.
I did some searching online for overdrive pulleys, but can't find anything smaller than 2.3" (on EBay), which when I look at their schematic is measured at the belt surface and not the front flange like I measured mine so I imagine it's the same size as the one I have now. Anyone aware of a smaller pulley being available anywhere? My only other recourse is to call DB back today and see if they will do something else for me.
Alternator output goes up exponentially with speed on the low end of the scale, before it tapers off level. If you can get any pulley slightly smaller, even 10% smaller, you might see a huge increase.
Josh didn't you do a bit thread on the alternator subject that also
covered the smaller pulley? Not wanting to miss all the other good
info in there also.
I believe that this alternator has the 58mm on it now, and my Google searches have found nothing smaller. Is anyone aware of anything out there? I need to get more RPM out of this alternator at idle somehow.
Josh didn't you do a bit thread on the alternator subject that also
covered the smaller pulley? Not wanting to miss all the other good
info in there also.
Do you recall the name of the thread?
Sean
Might have been Mustang_309 that had the thread showing an improvement @ idle with the smaller pulley
Might have been Mustang_309 that had the thread showing an improvement @ idle with the smaller pulley
Josh
Hmm, Thought it was yours. Talked about the G6 Vs the other one with
a buck of info on RPM and what not. I'll search and see if I can come up
with the link.
I believe that this alternator has the 58mm on it now, and my Google searches have found nothing smaller. Is anyone aware of anything out there? I need to get more RPM out of this alternator at idle somehow.
58 mm = 2.28"
So yes, I believe you have the small one already.
After an exhaustive search on the internet turned up no pulleys made for 6G-style alternators that are any smaller than 58mm/2.30" I reached out to a local alternator shop for alternatives. They set me up with a 49mm/1.90" 8-groove pulley from a Bosch alternator for another appplication that shares the same 17mm bore size as the 6G pulleys. The difference is that this new pulley does not have a built in shoulder to ride against the front bearing and clear the lip that protrudes from the front of the alternator case. The backside of this new pulley is completely flat.
To overcome the case clearance issue that this alternative pulley presents, I've just removed the alternator from the truck and will be cutting the protruding lip from the front case of this alternator and then using a shim between the pulley and the front alternator bearing to get the proper belt alignment. Working on this as we speak, so stay tuned for the final results. This should get my at idle voltage where it needs to be.
Just thought I'd share this for anyone else who might find themselves needing a smaller pulley than the 58mm which at this time is the only purpose-built overdrive option for these trucks.
Using a Dremel with a cutoff wheel, we easily removed the lip from the front of the alternator case that surrounds the shaft that the pulley rides on. After doing some final smoothing of the cut with a straight file to ensure a nice flat surface and using the proper shim to get correct belt alignment, everything came together nicely and I'm seeing an average of 14.1V at idle versus the roughly 12.5 I was seeing before.
Hopefully some day this thread will come up in someone's search and it will help them to think outside the box to solve their alternator overdrive needs.
Because we are photo pigs. You have to post some photos
even if this means you have to disassemble the thing again to get them.
Just kidding but if you can post some we would really like that.
The WE being not WE the Queen Of England or WE the President.
But, We The People.
Because we are photo pigs. You have to post some photos
even if this means you have to disassemble the thing again to get them.
Just kidding but if you can post some we would really like that.
The WE being not WE the Queen Of England or WE the President.
But, We The People.
Sean
Ha! You know, I knocked this out so quickly today that I didn't even stop to think about taking pictures- sorry guys. These alternators come out so quickly that it made it easy to get this done. At any rate, this was a rather simpl emod and my lunch break test drive went perfectly.
04-09-2015, 08:15 AM
