I haven't been driving my car very hard so i haven't been paying attention to the boost guage, but today i noticed that when i floored it i only hit a max of 4 maybe 4.5 psi on a 3.125 pulley. I checked my belt a few weeks back and noticed that i could turn it 90 degrees sort of easy(which i thought is how it is supposed to be). Could a loose belt cause such a dramatic drop in boost? I know loose belts have been the culprit of boost loss on alot of people but i didn't think it would hurt this much. Also it is in the mid 70's right now with high humidity if that factors in much

 

no, temperature should nto play that much of an affect if anything on the amount of boost u push. Loose belt can definitely show a decline in boost. I forget how it goes. I believe its something like you probably see high boost and it just drops heavily before redline....i know it does something funny cause i seen a few stories on here before....

 

Your belt is probably slipping. Tighten the belt up 1/2 turn of the tensioner adjuster until you get back to the boost level you are used to seeing. If tightening doesn't do anything you must have a boost leak.

Is 70 cooler or warmer than usual? Rubber gets harder and loses its grip as it gets colder.

 

It is a little above average for this time of year.

Mecca now that you mention it. It does seem that i remember seeing the needle kinda jump around. I don't pay attention to my boost guage much because i rarely get on it(maybe like 3 times a week). I cant afford to keep replacing axles

 

You will usually see boost hit 6-8PSI on a slipping belt, then it will suddenly drop (VERY suddenly) to 3-4PSI...it may bounce aorund a little at that point also, depending if the grip on the pulley is intermittent or not.

 

I noticed that my belt last year looked great, but with only 10-15000 miles it definitely wasn't as good as it was new. And I could I was losing about 1-2 psi of boost. My suggestion is to change your belt about every 15-20000 miles depending on driving habits and weather.

And i disagree on the weather comment I notice that when the weather is cold I build boost much quicker, and maybe a 1 lb more.

 

Don't the belts usually strectch over time?

 

Sure, if your belt doesn't slip, then cold air will give you more boost, being denser. That doesn't change the fact that cold rubber doesn't grip as well as warmer rubber.

 

I agree with the FACT that (unless the rubber was specifically designed for cold temps) cold belts definitely wouldn't have as much grip as a warm one.

 

Ok so i just checked my belt and it is fine(could barely turn it to 90 degrees) and all of my pressure pipe couplings and BOV is tight. So what the hell is happening to all my boost. Either my guage is f***ed up or my little oil leak i have got some oil on the belt causing it to slip. Are there any specifics when hooking up a boost guage. I have it hooked up to a vaccum source. At idle when in gear it reads 20 vaccum.

Also on the 5th gen piping the is a hole that comes in the charge piping that i putt vaccum fitting in to hook up my boost guage. I put it there along time ago before i found out that you use a vaccum source to read boost. The hole in this fitting is about as big as a sharpie tip. Could that leak off a significant amount of boost? I just haven't messed with it since i am doing a custom 3" charge pipe in a couple of weeks

Any Thoughts?

 

Also the car still feels like it pulls very hard, but i just dont know what to compare it to since i hardly ever look at my boost guage.

 

i usually try feeling for leaks at the couplers. i found the easiest ways was just to idle the car and i would wipe my hands on a damn cloth to get them a little moist. then i would feel around all the couplings if there was air coming out you will feel it. if there is a air leak you can feel it cause you hand will get cold.

sounds stipid but it worked. i was able to find leaks in my ic piping that way.

 

Sounds like the gauge is hooked up correctly. Oil on the belt is definitely a bad thing. I've got the same problem. I fixed the oil leak, but I didn't clean the crankshaft pulley and now I can't seem to make more than 11.5 psi with my newly installed 2.87" pulley.