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+--- Thread: what pressure should I be boosting at? (/showthread.php?tid=3361)
what pressure should I be boosting at? - TheCrimson - 09-05-2012
I fit a boost guage to my old turbro diesel this afternoon, mainly for faster moving needles
When you floor it it seems to hold boost at about 17.5/18psi. Its an old '97 plate with 155k on the clock, is this about what I should be expecting?
Re: what pressure should I be boosting at? - cwspellowe - 09-05-2012
Sounds like it's been fiddled, 18psi is about right for a mild tune by upping the fuel. IIRC they shold peak about 14psi when standard and in good nick.
Re: what pressure should I be boosting at? - Toby - 09-05-2012
Sounds like it's been turned up, stock boost is ~14-15psi.
If its holding it well though it is a good sign. With mileage like that the wastegate can start to creep more so than usual.
Re: what pressure should I be boosting at? - TheCrimson - 09-05-2012
I did think it boosted fairly well. One thing that makes sense now is when you first start it up in the morning from cold its pretty groggy and a big cloud of white smoke until you rev it up, then its fine. I did think maybe it was a glow plug but to look at they look pretty new, so could be excess fuel where its been "upped"?
The only thing that makes me sad is no low down power, but then I did come from my remapped 406 hdi so maybe I'm just used to that.
Edit: what do you mean re: the wastegate? something I should check?
Re: what pressure should I be boosting at? - Toby - 09-05-2012
White smoke is typically partially burnt fuel.. If the boost has been upped I would imagine the fuel has been turned up a bit too.
Could also be condensation if it's cold and gloomy.
The wastegate, depending on the turbo, uses potential energy stored in a spring to keep itself closed. Over time this spring can start to get old and weary, the main symptom of this is peak boost diminishing as rev's rise. Although this can also be caused by *normal* wastegate creep which is another matter.
Re: what pressure should I be boosting at? - TheCrimson - 09-05-2012
ok thanks for the info. if the boost is diminishing I should see it drop on the boost guage?
Re: what pressure should I be boosting at? - Toby - 09-05-2012
You will do.
In lower gears boost will drop anyway at high rpms due to the turbo leaving it's efficiency range.
To test it properly, you need to be in 4/5th gear, at highway speeds, bury the throttle down and make sure boost holds steady.
Re: what pressure should I be boosting at? - 4WayDiablo - 09-05-2012
Yeah mine gives a good puff on startup lol. Go for a good drive and get it up to good temp turn it off then back on again and see if it turns a lot darker
If it is a lot darker it will just be the fuel if there isn't any then it could be stem seals but not much to worry about really
Re: what pressure should I be boosting at? - Dum-Dum - 10-05-2012
What boost gauge is it, cheap ones can be pretty inaccurate.
Re: what pressure should I be boosting at? - Ruan - 10-05-2012
Up until about 24psi peak, you won't see it easing off up the RPMs... If it's losing boost up high, that's because the fuel is dying off up high.
Re: what pressure should I be boosting at? - TheCrimson - 10-05-2012
Its holding boost OK, the higher up the RPMs the further it boosts until it maxes out at 18 then holds all the way to the redline.
so next question... how do you (safely?) get more boost out of the standard turbo?
Re: what pressure should I be boosting at? - strictly_perv - 10-05-2012
When I put the 1.9 engine in my car which had a standard Bosch pump with anti-tamper ring still in place, she boosted 19psi due to the wastegate unplugged so it could just be that?
Do a search about upping the boost...