Boost Gauge ?

Thomas Mason · Dec 24, 2020

I have AEM boost gauge, I know it’s reading negative for vacuum when idling, but what ball park should it be in when idling? Or what is considered normal. Thanks

1990TSIAWDTALON · Dec 24, 2020

Depends on camshafts but a stock motor should be -15 to -18hg of vacuum. Lower when you add bigger cams with overlap.
My Blue 92 auto car has Kelford cams in it and she only has between -10 to -13hg.

Thomas Mason · Dec 24, 2020

Thanks brother well that’s some good news. I literally started my car after you said that and it read negative 18... went to Zero as I revved and I finally heard the tiny turbo spool

Maybe there is hope

1990TSIAWDTALON · Dec 24, 2020

I have a 13b turbo on my floor from my Auto 1g. They are a fun little turbo. We had some 1/8 mile "Street" races two years ago at an airport and I was outrunning 2010 SS Camaro's. If it had been any further, I would have got caught, but in the 1/8th, he never could catch up to the little car.

Now that car is a beast with a huge turbo, cams, injectors and a small shot of NOS. :cool:

Here is the video of her when she was all stock...........
Marty

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Thomas Mason · Dec 24, 2020

1990TSIAWDTALON said:
I have a 13b turbo on my floor from my Auto 1g. They are a fun little turbo. We had some 1/8 mile "Street" races two years ago at an airport and I was outrunning 2010 SS Camaro's. If it had been any further, I would have got caught, but in the 1/8th, he never could catch up to the little car.
Now that car is a beast with a huge turbo, cams, injectors and a small shot of NOS.
Here is the video of her when she was all stock...........
Marty

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That’s awesome brother. I have a 2G, gsx 98... I’m really thinking bout the evo 16, just gotta figure out the best supporting mods to go along with it. Merry Christmas brother and thanks for the advice

Wait... you beat the camaro stock in the video?

1990TSIAWDTALON · Dec 24, 2020

You can run that and don't HAVE to have bigger injectors/fuel pump etc. It will let you boost the car more than that 13b will. There is one for sale in the classifieds but it isn't set up to have our normal stock waste gate, it is set up for an external gate (which when we mod our cars, sometimes we go to an external waste gate that is on the manifold not on the turbo hot side)
Merry Christmas to you and yours too Thomas!

Thomas Mason said:
Wait... you beat the camaro stock in the video?

Yes, TWICE. He wanted a rerun so I said "Sure, you'll probably get me this time but spinnin ain't winnin so if you spin, you'll play hell trying to catch me". Then I found out he was a Preacher.....but after I heard him cussing at his car after loosing AGAIIN, I didn't feel so bad

Thomas Mason · Dec 24, 2020

1990TSIAWDTALON said:
Depends on camshafts but a stock motor should be -15 to -18hg of vacuum. Lower when you add bigger cams with overlap.
My Blue 92 auto car has Kelford cams in it and she only has between -10 to -13hg.

You just made me realize... I gotta try to figure out what cams is in it... I found stickers in the car, of stuff that was installed on the car...I wanna say a kelford cams sticker was one of em...

1990TSIAWDTALON said:
You can run that and don't HAVE to have bigger injectors/fuel pump etc. It will let you boost the car more than that 13b will. There is one for sale in the classifieds but it isn't set up to have our normal stock waste gate, it is set up for an external gate (which when we mod our cars, sometimes we go to an external waste gate that is on the manifold not on the turbo hot side)
Merry Christmas to you and yours too Thomas!

Your mad cool brother I appreciate you

1990TSIAWDTALON said:
Yes, TWICE. He wanted a rerun so I said "Sure, you'll probably get me this time but spinnin ain't winnin so if you spin, you'll play hell trying to catch me". Then I found out he was a Preacher.....but after I heard him cussing at his car after loosing AGAIIN, I didn't feel so bad

Ha ha can’t believe camaros are suppose to be so tough and cost some much but can’t beat a stock sports car from
The 90’s ha ha that’s gotta suck

Matter fact... question. What’s the main cause for running rich? I’m a little concerned... I was told the car was running rich before I bought it, but it doesn’t make the greatest sense. I have a recirculating bov... pushing the air back into the intake, after the maf... if anything shouldn’t this be running lean? As there would be air unmeasurable for maf ? I would think the computer isn’t sending enough fuel to compensate for the extra air

pauleyman · Dec 24, 2020

Thomas Mason said:
Thanks brother well that’s some good news. I literally started my car after you said that and it read negative 18... went to Zero as I revved and I finally heard the tiny turbo spool

Turbo is load dependent. You don't just build boost from revving.
I would very strongly suggest getting a factory manual for your year car. NOT a chiltons, haynes etc.
I would disagree with marty a little. I ran a consistent just under 20mmHg 19.xx on several different stock cars with different gauges. The actual number is in the factory manual.

1990TSIAWDTALON · Dec 24, 2020

Oh I agree Paul. I gave out a lower number to account for age and all motors have a bit different vacuum that they pull. My small block Chevys that are stock pull 20+hg, throw a cam in them and they drop pretty quick to 15.

Mech Addict · Dec 25, 2020

So vacuum and boost are both measured in the manifold, right? That’s why throttle effects it so noticeably. I’ve looked through the FSM and under the hood, and for some reason can’t figure out where the factory vac/boost sensor is located. Even in the electrical manual I don’t see it, but there must be one, since I can watch my gauge swing up and down while driving. I really like how that needle swinging up to 14 reinforces the sensation of torque under WOT.

1990TSIAWDTALON · Dec 25, 2020

Its just a calculation from the ECU. Thats why alot of us change it to a knock gauge, registering and showing on the needle.

pauleyman · Dec 25, 2020

Mech Addict said:
So vacuum and boost are both measured in the manifold, right? That’s why throttle effects it so noticeably. I’ve looked through the FSM and under the hood, and for some reason can’t figure out where the factory vac/boost sensor is located. Even in the electrical manual I don’t see it, but there must be one, since I can watch my gauge swing up and down while driving. I really like how that needle swinging up to 14 reinforces the sensation of torque under WOT.

There is no sensor. Thats not how it works.

Mech Addict · Dec 25, 2020

Well that explains half the answer: why I couldn’t find the sensor. Then how is the pseudo signal synthesized? Are there popular mods to make the factory gauge really read MAP? Or is the 14 psi max seen as too low to bother with for tuners, as they will usually need a much higher scale. 20 seems common, and some folks seem to be boosting 30+!!

pauleyman · Dec 25, 2020

The answer was already stated. Its a guess based on airflow. Its inaccurate. Most people just reassign the gauge to do something else and use a real pressure gauge.

1990TSIAWDTALON · Dec 26, 2020

Mech Addict said:
20 seems common, and some folks seem to be boosting 30+!!

Mine like 30-45..... :cool:

motomattx · Dec 26, 2020

1990TSIAWDTALON said:
Mine like 30-45.....

Mine like 70-80... :barf:

1990TSIAWDTALON · Dec 26, 2020

Isn't mine "cute"

???
They sure put a smile on a face. Went and put GASOLINE in mine today to get her thru winter. She did put a big grin on mine going to the station on 24 lbs and 53 lbs/min (no boost override today).
My car always returns the favor Matt

motomattx · Dec 26, 2020

1990TSIAWDTALON said:
Isn't mine "cute" ???
They sure put a smile on a face. Went and put GASOLINE in mine today to get her thru winter. She did put a big grin on mine going to the station on 24 lbs and 53 lbs/min (no boost override today).
My car always returns the favor Matt

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