# Turbo question



## 2014Oilburner (Feb 1, 2015)

I'm curious about how the turbo works...how much boost does the turbo put out and does it make boast all the time or only at a certain rpms ?


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## plasticplant (Mar 26, 2013)

According to my Ultragauge the CTD turbo peaks at just a little under 24 PSI (during over-boost). Also according to my Ultragauge, the CTD is making boost almost all the time. Even at idle it shows .5 or higher PSI. I have seen "negative boost" and 0 PSI a few times, but the reality is that boost is being created almost all the time. The trick is to try and keep the PSI below 10-12 and you really should not see too much effect on MPG. The turbo is variable geometry(variable nozzle) and the following link should give you all the info you need on how it works. http://www.enginebuildermag.com/2014/05/turbochargers-small-engine-performance-future/


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## akorte (Dec 1, 2013)

then you sir have a vacuum leak......it should NOT read boost on idle


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## obermd (Mar 3, 2012)

akorte said:


> then you sir have a vacuum leak......it should NOT read boost on idle


Or a gauge calibration error.


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## plasticplant (Mar 26, 2013)

akorte said:


> then you sir have a vacuum leak......it should NOT read boost on idle


NO vacuum leak (dealership verified). Nature of the gauge I suppose. For $80 and the ability to clear codes, I'm not complaining. It's been a nice addition.


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## Cruzator (Dec 31, 2014)

plasticplant said:


> According to my Ultragauge the CTD turbo peaks at just a little under 24 PSI (during over-boost). Also according to my Ultragauge, the CTD is making boost almost all the time. Even at idle it shows .5 or higher PSI. I have seen "negative boost" and 0 PSI a few times, but the reality is that boost is being created almost all the time. The trick is to try and keep the PSI below 10-12 and you really should not see too much effect on MPG. The turbo is variable geometry(variable nozzle) and the following lnk shold give you all the info you need on how it works. Turbochargers: Small Engine Performance - Turbo Technology, MPG


I haven't seen the Ultragauge before. That's a great price. What mount did you get with it? Have you had any problems with it?


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## plasticplant (Mar 26, 2013)

Cruzator said:


> I haven't seen the Ultragauge before. That's a great price. What mount did you get with it? Have you had any problems with it?


It's a very nice gauge (IMO). On the website they have different mounts you can choose from. I went with the suction cup one that has a bendable rod attached so you can pretty much mount it where ever you want.


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## Colorado_Cruze'N (Feb 11, 2015)

2014Oilburner said:


> I'm curious about how the turbo works...how much boost does the turbo put out and does it make boast all the time or only at a certain rpms ?


turbo diesel or 1.4 turbo? btw, i have access to service information being a gm employee... ill give you the info straight from the sight. i doubt posting a link would work because on your end you wont have a login.


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## plasticplant (Mar 26, 2013)

Colorado_Cruze'N said:


> turbo diesel or 1.4 turbo? btw, i have access to service information being a gm employee... ill give you the info straight from the sight. i doubt posting a link would work because on your end you wont have a login.


Seeing that this is only your second post and you might not have noticed, but his username is oilburner and his question is posted in the Diesel section, I think it's safe to assume the request is for the diesel turbo. There is a link posted above to all the information he might need about how it works. Just out of curiosity, what service info can you provide for the CTD? And welcome to the forum.


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## KpaxFAQ (Sep 1, 2013)

I know there was a GM employee here who hooked their diagnostic stuff to it when he took a CTD for a spin at his dealership and he said it showed slight boost even at idle as well.


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## revjpeterson (Oct 2, 2013)

I think I remember my torque app showing similar results - a small amount of boost (<1 lb.) at all times, and maxing out at around 23. I could never see the difference between regular boost and "overboost," because I could never stay in overboost for the full 10 sec. without hitting too high of speeds to be safely looking at a gauge. Torque did the same thing with the supercharger on my Grand Prix - never quite letting the boost reading fall to zero - not sure if it was a gauge error or it was an accurate reading.


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## Danny5 (Dec 22, 2011)

Diesel engines, by nature, do not draw vacuum. You need a throttle plate to create levels below 0, so you'll never see below 0 on our cars.

If you do see below 0 at idle, the culprit is probably a dirty air filter.


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