So how do you accurately do this? I am not this stupid, honest. I just keep getting the run around from dealer, and my stock pulley is not stamped. I did order the towing kit, so it should have a larger pulley I would assume. I NEED more boost, and would like to know what I have before I order.

If I measure pulley with the belt on I get 3.4". With belt off pulley I get 3.2" on top of 5 ribbs in the middle of pulley. Did not measure the 2 outside ribbs as they should not be the pulley OD. Which one is right.

With this setup I am currently getting 4.5 PSI at best with an easily achieved 3.5 PSI. I know I can get more, but Magnacharger says I should be at 5-6 PSI with a 3.2". Yes it is a stock engine. Only mods are to exhausts muffler and tail pipe.

Tuner guru also says the SD tune should compensate for the extra boost and be safe. Of course I am talking 1 or 2 PSI gain, maybe 3.

Also thinking of GT2-3 cam, but not if I don't gain torque on botom RPM's without losing on top RPM's

Please give me your thoughts.

 

i may be wrong but you will gain power with a cam but loose boost psi

 

you should have ZERO problems running a 3.1" pulley @ 7lbs of boost all day everyday(stock cam). Send your Superchips tuner back to Magnuson for the appropriate tune, done deal.

 

Thanks nightrunner. I have heard opposite but I don't know. lol.

I am most interested in quickly figuring out what pulley I have on there. Any ideas?

 

you dont sound like you could do with out the pulley for a couple of days( someone who uses their truck every day) BUT if you could do without it you could probably send it to magnuson and they could tell you what you sent them and what size you need to achieve x psi of boost

 

According to them I have a 3.2 " and should be at 7 PSI. But when I ordered it I was told they would set it up for 5 PSI for towing.

I have SD tuning so superchips is not in use. I am also waiting for my tuner to let me know what PSI I was at when he did the tuning. My guage has never really dropped much since then, but maybe it was never accurate at 4 PSI and it is making 7 PSI?

 

not sure I'm following you. As I understand it the towing setup for the LQ4 uses a 3.3 pulley. 3.2 is standard pulley now(non towing), but used to be 3.1. Maybe with a 3.2 it will peak at 7 lbs of boost. In any case, a 3.1 or 3.2 will do you fine.

 

What size pulley do you think I have according to the measurements in the first post? I think I have the 3.2", so where is all my boost?

Magna says stock setups use 3.2 or 3.3" at 7 psi. He guessed towing would be 3.3 to 3.4" at 5 PSI. I need to get the pulley size I have now, to verify what boost I should be seeing, and then if some is missing, find it or add more.

Oh yeah, good luck with your voyage in the next few months or years (which is it), and thanks for all the help you've been in the past. Cheers!

 

I've got some pulleys sitting here. What was your OD measurement of the pulley ribs?(i.e. not in the grooves)

and thanks

Back to Sea Duty for me, 4yrs

 

Are you running any underdrive pullies or smaller crank pulley for some reason? A 3.2" pulley should see more than 3.5psi on a LQ4.
Take a piece of paper. Cut it as thin as your truck belt. Wrap it around the pulley. If you get:
9 1/8" you have a 3.2
10 3/4" you have a 3.4

I have both sitting in front of me....