I am particularly interested in hearing from people with the Defi HUD Boost Gauge, but would like to hear from anyone with a boost gauge.

My boost readings fluctuate a good bit. The fluctuating readings have a pattern to them, so I would guess that it is the digital equivalent to a vibrating boost gauge needle.

I tapped in the factory selected location (had to buy a 1/4" x 1/4" x1/4" T-fitting, then a 1/4" to 1/8" reducer to a 1/8" vacuum line that is about 4' long so it can reach around the intercooler and run along the firewall to the passenger side wheel well, where I installed the pressure sensor).

I am wondering

1. whether there is a better place to tap for the vacuum line,
2. whether the vacuum line I used is too long or the wrong ID size and
3. whether I should use a "damper" (which other boost gauges seem to use).

 

the only thing i can suggest is using the smallest line you can for faster responce and shorter line.

 

oh yes, where did you tap it from.

 

I certainly see the logic to that suggestion. My specific concern is not responsiveness, however. In fact, my sense is that in some way, my set up may be too responsive. I get a fluctuating readout on the gauge, i.e. if plotted, it would not be a smooth curve. The graph would average out to a rise in boost, then a taper off as the rpms get closer to redline. The actual readings would deviate from that average significantly, i.e. the graph would show a line that deviates significantly from the mean through its path.

 

where did you tap for the vacuum.

 

I used this picture to guide my installation

 

darn, perfect location. how much fluctuation are we talking about 1 psi or like 5?

 

It measures in bar, to one hundredths. I would estimate that the fluctuation is .20 plus or minus a smooth curve, so around 3 psi.

 

wow, thats odd. how often does it fluctuate. does it got from 5-8-10-7-16-12-18-15 psi. is it irratic.

 

I anticipated this question while I was out and about today. Not as simple to answer as I would like, but here it goes. I'll refer to a curve in describing the readings. This curve exists only in my head and is my impression of the readings I am getting.

In the low gears and at partial throttle, the boost gauge shows pretty smooth curve.

In third and above, if I'm at WOT from low rpms (below 3,000), the readings climb slowly, then as the rpms hit over 3,000, the readings quickly spike at 1.07 - 1.10 bar, then back down to mid to high .9s and fluctuate rapidly around that range. During the time that the boost is at the high end (before the high rpm taper off of boost), I'll see a series of rapidly changing numbers flash by. The range is generally .8s to just over a bar. I'll occassionally see a .7-something in there, but the majority of the readings are in the range described.

The impression I get is that the boost stays in the .9s during the period of time that the turbo is making maximum boost, but the fluctuations are of some concern with regard to future plans for modifications. The boost gauge is not nearly as useful in monitoring increaased boost if it is fluctuating all over the place.

 

Definitely get a turbo timer harness. I talked to the guys that sold me the thing and they suggested a shorter vacuum hose (as short as possible) and securing all connections.

The kit, as I recall, came with a 1/8 x 1/8 x 1/8 t-fitting. If you tap into the factory selected spot, you'll need a 1/4 x 1/8 x 1/4 t-fitting (which I couldn't find) or a 1/4 x 1/4 x 1/4 t-fitting with a 1/4 to 1/8 reducer.

I'm going to try putting the sensor closer to the fitting, so as to reduce hose length (1/8 " ID, by the way) and zip tie or clamp all connections. I'll post the results Monday at the latest.

I have not been able to figure out how to rewire so as to allow me to arm the alarm with the timer counting down. I downloaded some additional instructions and will retry that also. I must confess that I am not incredibly motivated to figure this one out, since I am way too neurotic to leave my car running and out of gear on any surface that is not absolutely flat.

 

Shortening the hose and clamping it didn't fix the fluctuations, although I do think they might be slightly reduced. I'm looking for a restrictor for a 1/8" line. Will post when I find and install it.

Also, timer is fully functional with alarm now. Don, if you need help, pm me.

 

Could it be that the boost-level actually IS fluctuating, and that your meter displays the correct values?