Radix pulley, how much boost is safe?
#1
![Question](https://www.performancetrucks.net/forums/images/icons/icon5.gif)
I have 2 pulleys that I got with my radix. I was told they are 2.75 & 3.25 but I have no way to tell because they are not marked. They are the lightweight aluminum ones and the 2.75? has the built in nut for mounting/removing and the other does not. My questions is how do I know for sure the size and what boost level can I safely run on a stock 5.3? I see sigs that show people running 10 #'s and I don't see any engine upgrades other than bolt ons such as headers, exhaust, etc...What can I get away with and not blow it up? I'm running the standard 3.4" magnuson pulley and seeing about 6-7 #'s on top.
#2
TECH Veteran
![Default](https://www.performancetrucks.net/forums/images/icons/icon1.gif)
You should be able to run the 3.25, but I wouldn't want to try the 2.75. Did you buy the blower used? Sounds like your blower may have come from a 6.0L motor. The LQ4 guys can run the 2.75 no problem, the LQ9 guys usually run into diminishing returns at 2.8 or so, but you'd definitely be pushing it at 3.0. Perhaps you could run a 2.9. Once you get up there in boost (lower in pulley size) you will need serious tuning. I don't think I'd be trying a really small pulley without an in-person tune, that is no time for mail order....
#5
![Default](https://www.performancetrucks.net/forums/images/icons/icon1.gif)
Originally Posted by moregrip
you should probably run the 3.25 and get a good tune on it, then bag that 2.75 pulley up and send it to me for testing![Winky](https://www.performancetrucks.net/forums/images/smilies/LS1Tech/gr_wink.gif)
![Winky](https://www.performancetrucks.net/forums/images/smilies/LS1Tech/gr_wink.gif)
#6
what a rush!
iTrader: (8)
![Default](https://www.performancetrucks.net/forums/images/icons/icon1.gif)
Originally Posted by Baumgardner2051
You think the 3.25 would be safe with a stock 5.3? What is the boost limit without a built motor about 10 #'s? P.S PM sent on the pulley.
I'm at 7 lbs now with no problems. No gaurantees, of course, but I think you'll be just fine. A tune for that pulley will be in order as well.
#7
![Default](https://www.performancetrucks.net/forums/images/icons/icon1.gif)
Originally Posted by moregrip
yes, I think the 3.25 would be safe. probably see around 8lbs of boost.
I'm at 7 lbs now with no problems. No gaurantees, of course, but I think you'll be just fine. A tune for that pulley will be in order as well.
I'm at 7 lbs now with no problems. No gaurantees, of course, but I think you'll be just fine. A tune for that pulley will be in order as well.
![The Jester](https://www.performancetrucks.net/forums/images/smilies/LS1Tech/gr_jest.gif)
Trending Topics
#8
TECH Veteran
![Default](https://www.performancetrucks.net/forums/images/icons/icon1.gif)
Originally Posted by Baumgardner2051
You think the 3.25 would be safe with a stock 5.3? What is the boost limit without a built motor about 10 #'s? P.S PM sent on the pulley.
Do you have logging software?
#9
![Default](https://www.performancetrucks.net/forums/images/icons/icon1.gif)
Originally Posted by Naked AV
The 3.25" should be safe - if tuned correctly. If your 3.4" pulley tune is aggressive (tuned right on the margin of detonation), you will likely run into KR, and perhaps even detonation with the 3.25". If you think you want to run the 3.25" all the time (which you should be able to do safely), I would schedule an in-person tune on the same day the pulley is installed, but that's just me.
Do you have logging software?
Do you have logging software?
#10
12 Second Truck Club
Join Date: Jan 2004
Location: CA
Posts: 780
Likes: 0
Received 0 Likes
on
0 Posts
![Default](https://www.performancetrucks.net/forums/images/icons/icon1.gif)
Originally Posted by Baumgardner2051
You think the 3.25 would be safe with a stock 5.3? What is the boost limit without a built motor about 10 #'s? P.S PM sent on the pulley.