Vacuum at 30.. is that normal?

[buugiewuugie]

I have an aftermarket boost gauge installed. When i am at idle it sits all the way down at 30 vacuum. A friend of mine who has a turbo probe says thats not normal. That it should sit at 20. Is that right?

 

[dsmchiz]

My car when i am at idle sits at 15 on the vaccum side real solid. I dont think that 30 would be normal. One of these other gentleman will be able to give you more info on all that.

 

[zippyshoe]

30 inches of vacuum at idle is definitely not normal. You may have a defective boost gauge. If you rev the engine, does the needle move up and down?

 

[SexperT]

i get 20 at idle 20-15 depending on how warm up the car is..

 

[buugiewuugie]

Yeah it goes up with I rev it.

 

[weith1111]

Does it sit at zero with the car off? It should NOT be at -30 idleing.

 

[daren_p]

Yea the gauge shouldn't read 30, should be somewhere around 18-20 (with stock cams). The the gauge read zero when the car is turned off? I would suspect a problem with the gauge, not the car.

 

[SprayinGS-T]

30 is not correct at all, you should be sitting around -19 or -18 it idle, and zero when the car is turned off.

 

[buugiewuugie]

it sits at 0 when the car is turned off. That kinda worries me then. That may mean that im boosting way more then 12 psi.. right?? Also the gauge only goes to -30 and it sits all the way down. So it may be farther I dont know?

 

[weith1111]

Defective. Call the manufacturer and get a new one.

 

[buugiewuugie]

I was going to get a new anyways. are the sunpro ones accurate? I dont care about looks. I just want accurate.. Because I dont have a hell of a lot of money.

 

[weith1111]

I had a POS brand I never heard of in my car, it was $20 or something from some auto store. It worked perfectly. I upgraded to Autometer since I was trying to match gauges, otherwise I would have left it.

Whatever you buy, just make sure it has a warranty, they aren't complicated machines, so anything that's calibrated correctly should do the trick.

 

[leakyfaucet]

Having 30in vacuum would probably be a good thing, although its pretty much impossible. See if you can borrow a different guage to test the one you have.

 

[buugiewuugie]

why would it be a good thing??

 

[jhines]

Yea, 30 is not really possible just idling. You should be looking at about -17 to -19 "Hg when just sitting there warmed up. You definitely have a bad gauge. But get a new gauge and it all should be cleared up. If not, find someone who has a hand-operated vacuum pump and hook it up to the nipple on the intake and take a reading there. It should be around -17"Hg.....if not, then you have a problem. But yea, if it's off on the vacuum side, then it's gonna be off as bad if not worse when you are under boost.
-Hines

 

[dsm-onster]

19-22" is stock. Whoever posted that he had 15" w/ stock cams and intake mani either has a wornout engine or a significant boost leak.

Have you checked your airfilter? When you raise it to the sun, can you see plenty of light shining through?

 

[buugiewuugie]

Who? me or the guy at 15?

 

[GSntncT]

I typically read between12-16, but then again, I have 264/272 cams. Even when I was stock, I never read 30. Autometer is the best way to go for gauges IMO. cheap, and very effective. What gets better than that?

 

[dsm-onster]

Who? me or the guy at 15?

No, I looked back up and dsmchiz has a vacuum reading of 15". That is not normal.

Neither is yours. Have you checked/replaced your airfilter recently?

 

[psychlow]

15" can be perfectly normal, depending on cams and altitude.

 

[weith1111]

No, I looked back up and dsmchiz has a vacuum reading of 15". That is not normal.

dsmchiz has cams. He might be losing a pound or two, but 15 is probably pretty good.

 

[dsm-onster]

A couple of posts up you'll notice that I was referring to his reading in reference to stock cams. I looed as his profile. Obviously, I missed that he had 264s. . .

sorry

 

[Spoolio]

i wouldnt buy any sunpro guages. unless your low on cash.

 

[buugiewuugie]

No, it's a k&N. I cleaned it recently but its still dont look red..

 

[zhjiln]

time to get a better gauge asap.... i get about 18 inHG in idle....and 23 inHG in decel ....