Overdrive crank pulleys?


adulbrich

Lock up your daughters!
May 11, 2014
14,015
0
Ames, Iowa
My alternators already have slight "underdrive" pulleys compared to stock. I now have "320" amp and "370" amp hairpin Singer alternators on my truck. I idle around 500 rpm and my truck shifts around 2k.

Does anyone know where I can get an "overdrive" crank pulley for a 2007 Silverado Classic 1500 with the 5.3? I've seen overdrive crank pulleys on other vehicles with superchargers, and was wondering if I could get an overdrive pulley for my truck.

I saw one mentioned on a GM trucks forum that was 10% bigger, but all the links were dead :/

 

wew lad

wew lad inc
Mar 22, 2015
5,808
77
MA
Just tune your truck and raise your idle rpm, I bumped mine up about 200 rpm, takes some getting used to but I don't drop as much now

 
OP
adulbrich

adulbrich

Lock up your daughters!
May 11, 2014
14,015
0
Ames, Iowa
are you trying to speed up your alts?
Yes, that's the general idea

Just tune your truck and raise your idle rpm, I bumped mine up about 200 rpm, takes some getting used to but I don't drop as much now
Was planning to do that also, so there's an even bigger difference

 

Popwarhomie

Team Lethal Pressure
Jan 22, 2010
6,261
306
Florida
I wouldn't run an overdrive pulley. You risk overspinning your alts and destroying them as well as other belt driven acc.

 
OP
adulbrich

adulbrich

Lock up your daughters!
May 11, 2014
14,015
0
Ames, Iowa
I wouldn't run an overdrive pulley. You risk overspinning your alts and destroying them as well as other belt driven acc.
During normal driving, I don't go above 3k rpm and the overdrive pulley I'm looking for is only 10% larger than stock. After getting a slightly larger crank pulley, I plan to then adjust the idle up. The problem I'm having is the "320" amp alt is only putting out 60 amps even under load at idle on my truck. My car idled at 1500 rpm, so it wasn't a problem. At 500 rpm on my truck, it's not happy. I put a smaller pulley on it yesterday and it helped, but I'm just trying to do a few more little things that will hopefully make a difference overall.

Jim was going to call Mike for me on Monday and see if there's anything else I can do. The diodes in it are good, and the local electrical shop couldn't find anything "wrong" with it. I don't know if I'll have to send it in for warranty service or what the deal is

 

big scott

blazin low, and loud
Apr 4, 2014
3,612
0
edgewood, md
well i was not sure as you were talking crank and idle speed.

but i would not do it either, 105 would be a lot at highway speeds.

do what the pros do, put a electric ram on your tb . that why when your at idle and slamming you can bump up your idle speed to were you want it.

i have been considering doing this.

 
OP
adulbrich

adulbrich

Lock up your daughters!
May 11, 2014
14,015
0
Ames, Iowa
well i was not sure as you were talking crank and idle speed.
but i would not do it either, 105 would be a lot at highway speeds.

do what the pros do, put a electric ram on your tb . that why when your at idle and slamming you can bump up your idle speed to were you want it.

i have been considering doing this.
Changing the crank pulley wouldn't change the idle speed of the engine, but it would change the pulley ratio and change how fast the alternators were spinning.

I assume you mean 10% at highway speeds. The fastest I normally go is 70, which is around 2.5k rpm. 100mph is a little over 3k rpm iirc

An electric "ram air" supercharger? I don't feel like those really do anything if this is what you mean:



That's an underdrive crank pulley, if I was trying to get as much horsepower to the wheels as possible. That would make the alternators spin even slower

To open up your throttle body? I wouldn't want to use an electric cylinder for that

 

Massive spl

Banned
Jun 27, 2015
3,017
0
Michigan
So your alt only clamping 60 amps at ideal??? Sell it already! U had nothing but problems. Buy an excessive amperage plug it in and be happier then fvck... These hairpins I got are beast at my trucks 500-700rpm ideal. Way impressed.

 
OP
adulbrich

adulbrich

Lock up your daughters!
May 11, 2014
14,015
0
Ames, Iowa
So your alt only clamping 60 amps at ideal??? Sell it already! U had nothing but problems. Buy an excessive amperage plug it in and be happier then fvck... These hairpins I got are beast at my trucks 500-700rpm ideal. Way impressed.
I'm not just going to sell it to someone, because I know it doesn't perform correctly.

(In before Hispls rant about my Z's)

Jim was going to call Mike about it on Monday and see what the problem could be. Hopefully it can be fixed inexpensively.

You're right, should have just gone Excessive in the first place. Way cheaper

 

A_Contraptions

Senior VIP Member
Sep 1, 2015
170
0
NC
just making sure. I wouldn't change the crank myself. the alt company is supposed to use your engines stock crank diameter as a general reference to the pulley for the alt. atleast a lot do to avoid over spin and destroying bearings.

 

wew lad

wew lad inc
Mar 22, 2015
5,808
77
MA
when i went from the cs small case alts to a HO ad244 they used a pulley a little smaller to match up with the new belt with the higher center point of the ad244 case. the guy who owns https://alternatorparts.com/ i think randy, knows a hell of a lot about it and explained it to me when i first purchased it and was wondering why there was a different pulley

never had a problem with an overdrive pulley

 

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