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View Full Version : Do I have my boost gauge/controller piping right?



Confused
31-12-2009, 12:51 PM
A few weeks ago I removed my boost gauge, which whilst looked good, was very, very slow at updating, so I couldn't really see exactly what it was doing.

At the same time, I fitted a Blitz Dual SBC Type S electronic boost controller.

The vacuum pipework, however, I'm not too sure about whether I've done it the best way.

I've taken a T piece from the feed to the fuel pressure solenoid, which runs through into the cabin.

This then goes through another T piece, and goes to both the gauge and the controller unit.

Both now seem to react fairly quickly, but the two don't seem to tally, and even when set to the point of fuel cut, don't seem to register much beyond ~0.7 bar (with the old gauge, it would be closer to 1.0 bar indicated)

By splitting this pipework so many times, would this have had an effect? Would it be a sealed system, or would having two items on it therefore have the effect of "leaking" out through one/both, thus causing the other to not see the proper values?


Is there a better place to take pressure feeds from? Should I keep the two completely separate from the engine to the cabin?


Cheers!

Garry

miller
31-12-2009, 01:29 PM
Not sure on the amount of junctions but both my gauge and controller read from the single pipe into the cabin. If this helps.


Mike

Confused
31-12-2009, 01:59 PM
Cheers, Mike :)

Nick Mann
31-12-2009, 02:38 PM
I'd bring the piping from the back of the manifold. Having said that, the fuel pressure solenoid should be the same, as the feed for that is after the throttle body, IIRC.

The less hose the better, but that should change reaction time/spikes, not overall pressure readings.

Dom B
31-12-2009, 02:56 PM
In an ideal world, you really want to have the pick up right next to the factory map sensor as the actual measured pressure will be different for the same mass flow at different points of the system depending on the volume or area of that piece of pipe where the tap is taken from. A blind tube from that point will then read the same pressure even at a meter or so away within reason. Ideally you would have an electronic sensor feeding an electronic (fast acting, boost gauge). Even better tapping into the original sensor signal. Has anyone done this?


I think a lot of the difference of where people find fuel cut depends on what their gauge is showing depending on where and how it is mounted. the manifold pressure may well be exactly the same but the tap point may be seeing a different pressure.

Also cheap mechanical gauges are never very well calibrated. You could buy 2 and neither would read exactly the same as the other.

Confused
31-12-2009, 04:32 PM
The gauge I took out was an electronic one, but it was so slow!

The "new" one is a mechanical one, so has a feed right into the back of it. It certainly reacts much quicker! But I'm insure of its accuracy.

The boost controller has a vacuum feed into the back of it too, so that's on a fairly long run of pipe, too.

I'd trust the reading from the EBC more than the mechanical gauge, but of course is the fact that they're both there skewing each other?