i bought my car with the s/c now to check how much psi

zeusmoto

New Member
Feb 15, 2004
390
0
0
utah
just as the title implies i bought my car quite a while ago and i was running about how many pounds i was running, it is an s-trim and i have athe boost gauge, but i have never understood it. it reads like 35 20 25 20 15 10 0 10 15 20 25 etc i dont know quite how to explain it but i was just wondering how much psi i was running. and how can i up the psi. i heard you could do it with a new belt
 
An s-trim with the stock pulley is 8-10 lbs of boost. Obviously you can change the pulley easily enough if you wanted to. Regarding the boost gauge issue, the numbers to the left of the gauge indicate vacuum. No boost will show while the car is sitting still, you'll need to drive it to register boost. Then pay attention to what the boost guage reads as you get into it and the rpm is above 3,000. Then watch what the gauge does and you'll know what you've got.
 
so the needle almost always reads in the vacuum. it moves when i give it some gas but it has never gone above the zero yet, is there somethign wrong. like it will move from 25 to 20 or 15 but it hasnt reached zero or passed it is somethign wrong? i guess this is kind of hard unless you can actually see what i mean.
 
If you go WOT (wide open throttle) the gauge will go to 0. Once you get around 2800-3000 RPMs DURING WOT, then you will make boost, and the gauge will read boost. Anything above 0, is boost. I don't make any boost until I really get on the car, which is kinda good because it saves gas.
 
thanks fellas. if what you are telling me is the case then my car is damn fast and i havent hardly ever used the s/c damn i need to break that thing out, where can i find some long abondoned public roads.....haha j/k. its still hard to believe that all the cars i have beaten so far were without the aid of the s/c damn, that makes a man feel good.:)
 
RydeOn said:
yea you need to lay into that thing until just short of redline to see that boost. dont be scared. :p
what the others were saying is true, you wont see boost ulesss your on the throttle pretty hard and hitting around the 2,500 rpm range, with a 8-9 lb pulley it may be around 2lbs or so then continue going up till redline 5,500 you should see 8-9 lbs if your S/C is working properly. The easiest way to find out how much your getting is go for a dyno, thats what i did, a good shop can tap into the boost and see how much your getting and at the same time measure your air fuel ratio to make sure your not going too lean at redline which will protect your engine. Then you ll have peace of mind if you ever go racing like i do once in a while. oh yeah and of course you will also know for sure how much power your actually getting to the rear wheels.
 
no i get on it, but i am up to speed and way over the speed limit way before red line, i am pretty daring most the time but i have to be careful cause one more ticket and they get my license. of course i "lay" into it just i have beaten everyone so far by not even getting near redline... hmmmm also i have an oil leak somewhere in my car...:( i need to find it, it makes me mad

thanks again
zeus
 
OK, wait, so until you get some high rpms there is minimal to no boost? I always thought SCs were better than turbos because there was no boost lag. What am I not understanding. Oh supercharger gurus please enlighten me. (sorry to jack your thread zeus)
 
I'm having the same issues. At the dyno the car read boost across the board, but my autometer gauge always reads vacuum. Ive got a Procharger D-1 and the gauge NEVER says boost. Not even at 5000 rpms. Yet if I go to the dyno, it reads boost. If I hook the gauge up before the carb I get the correct boost reading, but after the carb, I ust get vacuum.