underdrive pulley worth it?

[Pro Stock John]

Thanks MrGW, I'll give it a go and report back when it's on. My buddy will be installing it he has a shop.

[MRGOODWRENCH3]

There are several modes that the alternator can run at. It all depends on what loads are on and the state of the battery.

Battery Sulfation Mode

The BCM will enter this mode when the interpreted generator output voltage is less than 13.2 V for 45 minutes. When this condition exists the BCM will enter Charge Mode for 2–3 minutes. The BCM will then determine which mode to enter depending on voltage requirements.
Charge Mode

The BCM will enter Charge Mode when ever one of the following conditions are met.

• The wipers are ON for than 3 seconds.
• GMLAN (Climate Control Voltage Boost Mode Request) is true, as sensed by the HVAC control head. High speed cooling fan, rear defogger and HVAC high speed blower operation can cause the BCM to enter the Charge Mode.
• The estimated battery temperature is less than 0°C (32°F).
• Battery State of Charge is less than 80 percent.
• Vehicle speed is greater than 145 km/h (90 mph)
• Current sensor fault exists.
• System voltage was determined to be below 12.56 V

When any one of these conditions is met, the system will set targeted generator output voltage to a charging voltage between 13.9–15.5 V, depending on the battery state of charge and estimated battery temperature.
Fuel Economy Mode

The BCM will enter Fuel Economy Mode when the estimated battery temperature is at least 0°C (32°F) but less than or equal to 80°C (176°F), the calculated battery current is less than 15 amperes and greater than -8 amperes, and the battery state-of-charge is greater than or equal to 80 percent. Its targeted generator output voltage is the open circuit voltage of the battery and can be between 12.5–13.1 V. The BCM will exit this mode and enter Charge Mode when any of the conditions described above are present.
Headlamp Mode

The BCM will enter Headlamp Mode when ever the headlamps are ON (high or low beams). Voltage will be regulated between 13.9–14.5 V.
Start Up Mode

When the engine is started the BCM sets a targeted generator output voltage of 14.5 V for 30 seconds.
Voltage Reduction Mode

The BCM will enter Voltage Reduction Mode when the calculated ambient air temperature is above 0°C (32°F). The calculated battery current is less than 1 ampere and greater than -7 amperes, and the generator field duty cycle is less than 99 percent. Its targeted generator output voltage is 12.9 V. The BCM will exit this mode once the criteria are met for Charge Mode.

[SSDan]

Originally Posted by Pro Stock John

Just to be clear... Pic I found

Do you have the console 4 Guage package? If not I think that is the difference. I do not have that screen in my DIC. I do know about cycling through the menu to see all the screens (tire pressure, coolant temp - etc.) I'll stop now and let this thread get back on topic.

[Pro Stock John]

I have the 4 gauge package.

[Camarowguy]

Originally Posted by Bo White

I dont recommend a pulley on a stock engine or a very mild cam that idles low like stock. Once you get to an idle past 800rpm then the negatives about a pulley almost go away.

Mine is all stock. Had it for almost a year now. No issues

[sschevybear11]

It was the last volley of mods I did, I really felt it on my 00 Z/28 but sadly didn't feel anything on the '11.

[John Deere Racer]

Good mod 2 do

Help me make 430rwhp. With bolt ons

[jeffny09]

again...can i use this with a turbo set up?

[2012REDSS]

for a turbo it will be fine but for a procharger or maggie, KB etc. it wouldnt be any help. Ive had mine on for a little over 4 months with 20 or so passes down the track and its fine. No charging issues or idle issues and I put out 407 rwhp and 401 tq with just the ud pulley, solo cats, muffler delete with x pipe, rotofab cai and ported TB.

[Pro Stock John]

407rwhp with 6 speed, stout numbers!

My belts and crank bolt finally showed up, planning install early next week. Weather has been cooling off by me again, I hope this continues because I'll hit the TRACK!

[jeffny09]

thank you!

[hcoll003]

Which pulley is expected to give better hp results, or do they all give the same hp numbers? I see there is the ASP pulley and SLP, which one should I choose?

[LS3 SS]

Originally Posted by hcoll003

Which pulley is expected to give better hp results, or do they all give the same hp numbers? I see there is the ASP pulley and SLP, which one should I choose?

Haven't heard too many people running ASP. I did see that they had reported "failures" back in the day on Lsx motors. I would go with a Powerbond or SLP UDP. If you have the money? ATI.

[SSDan]

Originally Posted by hcoll003

Which pulley is expected to give better hp results, or do they all give the same hp numbers? I see there is the ASP pulley and SLP, which one should I choose?

It's not the brand as much as it is picking the % of under drive you want. Commonly UD pullies come as either 25% or 10%. The higher number spins the accesories slower by that % thus creating less parasitic loss (frees up more HP).
In other words go 25% if you want the most power benefit. I put on a 25% pulley and have had zero issues for 9000 miles now. I have the Powerbond brand (a common brand used by many).