So long story short I had a jrsc street always boosted 5psi no problem. Today I decided to put in my 3.8 pulley and belt
First run went up to 7psi then ran agains my bro fa5 and when the boost gauge would start to pass 5psi, it would slowly go back down to 3 or 4 psi?
Anyone know why it what can cause this?
I am running kpro 480 cc inj I/h/e
It does feel faster but not sure why my boost gauge wouldn't show the correct psi
Also the guy that sold me the pulley said it was a 3.8 when I measured it I got 4inch is that correct?
Ur belt is slipping . And a 3.8 should be close to 9 psi. And if your not running an after cooler or Meth that pulley is pointless. If ur not tuned ur doing nothing but damaging your motor with that pulley. And tuning the 3.8 with out a cooling system will make the same power as the 4.0.
Wow didn't know that about the 3.8 pulley I do think it is also belt slipping since the belt isn't really tight due to my manual tensioner bolt not being longer
Think I might swap back the 4.4 pulley
Good idea !
So is it safer to go with the 4.0 pulley?
As long as u have kpro and 440cc injectors , fire up the base map in kpro and get it tuned
cool now i have to find a 4.0 pulley one thing i did notice is that the belt seemed to big i thing i grabbed the 62.2 seems big for the 3.8 pulley
doesnt bigger pulley = more boost?
It's hit or miss on the 3.8, for me it was also to big and it actually flew off the dyno. Switched to a smaller dayco belt and never had an issue, ur tensioner will almost not be tightened at all, don't ask me the part # Caus I won't remember. I might have a post or a YouTube video with the part # but I don't remember.Originally Posted by gtecd20
Last edited by superchargedk20; 02-02-2013 at 03:39 PM.
No. Smaller pulley = more boost, and on a supercharger more boost doesnt always mean more power
yea i can approve that im running smaller pulley and have less power than with my corrected 4.4 pulley im sure its due to my bolt being all the way down and still cant tighten the belt all the way
actually the only thing that comes to my mine is to rethread the manual tensioner with an 8mmbolt instead of the 7mm i have and i can find a longer one to apply more tentions on the belt
Give it a try. And i remember the dayco belt is actually in the jrsc sticky, the 4.0 pulley and ur 62.2 belt shouldnt slip. If ur tensioner is all the way down there's a problem
Woops sorry. Just saw my YouTube review for the belt. It was a napa belt, for the 3.8 pulley
oh thanks ill look for it monday i got the gatorback belt and yea its to big
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