? about stock boost gauge

[larryc7777]

Will the stock boost gauge continue past "10"? Do some of you guys have an aftermarket gauge & the stock gauge both working at the same time? Does the stock gauge seem to mirror the action of the aftermarket gauge in regards to indicating additional boost? Here's why I'm asking these questions. If the stock gauge will continue it's swing past ten AND seems to continue to indicate the proper boost, why not simply add a "15" mark to the stock gauge face? I have been investigating the different boost gauges available & the mounting types, but I haven't found anything that looks as good as the factory setup. So, why not make use of the stock gauge if possible. I have a 2.93 DUB on the way so I figure if the gauge will reach a position equivalent to 13 or 14 psi AND do it repeatedly, I will just VERY CAREFULLY paint a line with the number "15" next to it in the proper position on the gauge face.
One more question. Does the needle travel appear to be linear as boost builds? For instance, is 5 psi on the aftermarket gauge halfway between 0 & 10 on the stock gauge? If your car will pull14 or 15 on the aftermarket gauge, is that reading about the same distance over 10 on the stock gauge as the distance between 5 & 10 on the stock gauge? Sorry for all the questions but if this works out right, I will be able to keep my interior free of pods & still monitor the additional boost. Thanks, Larry

 

[Dana]

Larry,
You have a bunch of good questions, but I don't have any answers for you right now. After I installed the new boost gauge, I haven't looked at the old (stock) one. They are both still connected and working, you just tee into the stock line. If you want to wait until the streets dry up, I'll try to watch both boost gauges, the tach and the shift light and where I'm going too and if I survive, I'll let you know what I found out.
Too bad you didn't ask yesterday, I was out practicing hole shots and my passenger could have watched the gauges and let me know.
I haven't installed my 3 inch pulley yet, so someone else will have to tell you what happens after 10 lbs. The highest mine has gone is 9 lbs on the boost gauge so far.
The aftermarket gauges are probably going to be more accurate than the stock gauge, just a guess though.
And, I don't know about painting the stock guage...

Dana

 

[larryc7777]

thanks for the reply Dana

 

[larryc7777]

???anyone else have any input???:shrug:

 

[coleman]

stock gauge maxs at 10 psi. aftermarket goes to 15 and also indicates vaccuum so you know just when the S/C will kick in.

 

[larryc7777]

Great looking gauge cluster, coleman. Is the stock gauge still working? With your mods you should be pulling about 15 psi. Does the stock gauge swing past 10 far enough to be at the equivalent boost that the ATM reads? Thanks, Larry

 

[coleman]

yes, i do see 15psi for short periods of time, but my belt is slipping -- too small of a pulley.
my stock gauge is working -- i used a tee just as i saw other people do.
but no, the stock gauge hard stops at 10 -- is there a peg that stops it?

 

[larryc7777]

I don't know. I couldn't see one on the face. It must be either internal or the needle swing runs out of travel room. Bummer, I sure wanted to keep the dash area just the way it is. Oh well, I guess I'll move on to Plan B. Thanks for the reply. Larry

 

[matt lankford]

my stock one points towards the a/c knobs under full boost:burnout: :burnout: :burnout:

 

[rsom1]

Coleman, oyu have the exact guage combo I was thinking about, although I haven't been able to decide if i want a fuel pressure instead of the a/f. how much did you pay, and who did you get them thru, if you don't mind me asking.

thx

 

[coleman]

everything through summit racing and nick-nacks from autozone/o'rileys...

i have yet to connect the A/F gauge and from what i hear it's pretty useless, but looks good

 

[Mowgli]

Wait we have a couple folks who say the gauge hard stops at the 10psi indicator, and another that says it goes past to point at his A/C knobs.

Whats the scoop?

Others want to know.

 

[coleman]

any-quality is job one...

 

[JKD COBRA]

My pulley/chip will be in this week so I don't have any first hand experiences but, people have posted pictures of the stock boost gauge going way past the max 10psi mark. Why would you want to paint a line on the stock gauge??? If you want to keep watch on boost levels just get an aftermarket gauge.

 

[larryc7777]

Why do you want to add an aftermarket gauge if the stock one will do the job?

I am going to test the stock boost gauge tomorrow by hooking it to a regulated air supply that I can adjust to whatever pressure setting that I want. I will post the results in the next couple of days.

I will also be able to test the accuracy of the stock gauge with a very accurate gauge.

 

[CWCobra]

Larry, I think you may be on to something...why add a guage if we can make use of the stock gauge! Wonder if the stock gauge can be re-calibrated?
Later,
CW

 

[larryc7777]

I was thinking about that also. Usually this type of pressure gauge is a needle that is attached to a coiled spring wire. The tension of the coiled spring reflects the resistance of the needle to move. As boost pressure increases, the needle starts to swing across the face of the gauge. Changing the spring tension would cause the gauge to require more boost pressure to initiate its swing. This would be great but then the "10" mark wouldn't be "10" anymore. It might be 12 or 15 depending what was done with the dampning spring.
It would be so sweet if the gauge would just continue its swing past 10 AND retain accuracy. If it will do this, I will be able to add additional markings to indicate 11,12,13,14,15 if I so want.
After thinking about it, I decided that I will use something not as permanent as paint. Maybe fine line colored markers. I don't know about that yet, first I have to clear the needle movement hurdle.

 

[coleman]

my needle never goes above the 10 mark eventhough my aftermarket gauge goes to 15 on occasion :burnout:

so i don't know if some internal physical peg/limiter fell out of other people's internals, but that might explain it...

 

[larryc7777]

Well, I have good news & bad news. The bad news is that the stock gauge does indeed have a plastic tab attached to the needlle that stops the needle swing just past the 10 mark. The good news is that, if your are willing to pull the gauge cluster out of the dash; remove the clear plastic cluster cover; and saw the tab off of the needle; THEN your gauge will continue to swing 360 degrees if you so want. I felt that it was worth the extra work for me to do this modification.

Here are a couple of cluster removal tips. The gauge cluster bezel is held in place by 2 torx screws in the upper part & 2 side and 2 lower spring clips. Then, 4 torx screws hold the whole gauge cluster in place. These screws are identical to the first 2. I had a bitch of a time getting the gauge cluster to come towards me far enough to reach behind it to remove the 2 electrical connectors & 1 vacuum(boost) line attached at the back of the cluster. The vacuum line had NO extra length to allow it to come forward. The electrical connectors had additional wiring length. I ended up pulling the plastic vacuum tubing out of the rubber connector at the back of the gauge. Finally I had the gauge cluster in my hot little hands. After about 45 minutes of unneeded disassembly of the cluster, I noticed that the underside of the needle had a tab that protruded downward into a slot on the gauge face. The tab contacted the end of the slot at a little past 10. That tab is what needs to be removed. I used a serrated steak knife to "saw" my tab off. Once gone, nothing hindered gauge movement. I then proceeded to calibrate & mark the gauge face as described below.

I first hooked up a regulated air supply to the fitting on the boost gauge. I started at 0 and gradually increased the pressure signal until the boost gauge started to move. The beginning of movement was mirrored by the gauge attached to my regulated supply. At 2 psi on my AS(air supply) gauge the car gauge was reading 2 psi also. This was true for the entire swing of the stock gauge. 5 psi on the AS gauge was exactly halfway between 0 & 10(needle pointing straight up). 10 on the AS gauge was right on the leading edge of the thick black mark at 10 psi. 11 on the AS gauge was right on the trailing edge of the thick black line. I then adjusted the air supply to register 12,13,14 & finally 15. At each of these needle locations on the stock gauge face I put a small mark. After shutting off the air supply, I used a black ballpoint pen to fill out my hashmarks. I inserted the number "15" at the last mark, after making that mark longer & thicker(like the 10 mark). My markings look acceptably good but I wish that I had a means to make the marks & numbers "blacker". The accuracy of the stock gauge suprised me. It was calibrated to within 1/4 of a psi(as near as I could judge).

The gauge movement is VERY linear. The distance from 0 to 5(straight up) is the same distance as from 10 to 15. However, the most accurate way to calibrate the gauge is to have access to a regulated air supply & separate gauge.

More tips:
Once you have the gauge cluster in your hands, you only need to remove the clear plastic cover. Then you can access the underside of the needle where the tab lives. While cutting the tab, be sure to support the needle assembly so that you don't put unnecessary strain on the needle shaft.
During reassembly, I used a piece of vacuum tubing to extend the length of the factory plastic tubing so that I had more room to manuever the cluster. Otherwise, I don't think that I could have gotten the tubing hooked back onto the gauge nipple.

If I could have worked on the project without interruptions it would have taken about 3 hours total.

It wasn't easy, but it was inexpensive & I still have an uncluttered stock looking dash. Larry

ps. I'll post a couple of pics of the finished install later( my wife has to bring the camera to the Fire Station ).

 

[kom]

That sounds great. Maybe one of these gauge overlay companies can make up a small overlay for just the boost gauge.
Was there a stop going the other way that would let it show vacuum also?