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Need help understanding Turbo surge from lack of preasure? (airflow maps understandign)


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curtains
User

May 1, 2010, 4:43 AM

Post #1 of 5 (2577 views)
Need help understanding Turbo surge from lack of preasure? (airflow maps understandign) Sign In

OK so i've been learning about turbos and turbo air flow maps (to help me understand about turbo) and i understand turbos can get compression surge from getting to much back pressure say without a wastegate or what ever, and thats pretty easy to understand as the pressure build up can slow down the turbine.

And now I learnt that turbos can get surge from lack of pressure from what i think i've learnt, according to these air flow maps? or am i reading them wrong?



So according to the flow maps if you are trying to boost too much with little air flow, then you get surge? which i guess happens more on big turbos on small engines like lets use this one for example



^^^^this turbo on a small displacement engine.

I know that most times if its only a bit off to the left of the surge area you get lag, but I've told (or i've read) this is bad for the turbo if your too much into the surge area?

whys that? and how does it damage the turbo from lack of pressure?


(This post was edited by curtains on May 1, 2010, 4:50 AM)


re-tired
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May 1, 2010, 9:00 AM

Post #2 of 5 (2561 views)
Re: Need help understanding Turbo surge from lack of preasure? (airflow maps understandign) Sign In

Go back to basics. If you have a eng of X displacement and you where feeding it a set amount of fuel Y to produce a given hp Z . Now if you increase the volume of fuel , say going from 3/8 fuel line to 1/2, if X remains constant the eguation goes out of balance. X+(y)?= Z where increases of Y cannot produce an incease of Z .Which is equiviant to to much turbo flow. Now go the other way. Increase X without a corresponding increase of Y . Z= (X)?+Y , Z cannot inrease do to the imbalance of the formula. This time its the equiviant of too little turbo low for the demand . I hope this answers your question.


LIFE'S SHORT GO FISH


curtains
User

May 1, 2010, 9:35 AM

Post #3 of 5 (2558 views)
Re: Need help understanding Turbo surge from lack of preasure? (airflow maps understandign) Sign In

Still a bit lost... how does the turbo actually get damaged?


re-tired
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May 1, 2010, 10:28 AM

Post #4 of 5 (2557 views)
Re: Need help understanding Turbo surge from lack of preasure? (airflow maps understandign) Sign In

Only from over pressure , which the waste gate prevents.


LIFE'S SHORT GO FISH


Loren Champlain Sr
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May 4, 2010, 6:53 PM

Post #5 of 5 (2537 views)
Re: Need help understanding Turbo surge from lack of preasure? (airflow maps understandign) Sign In

RT; Couldn't have said it better, myself. Ouch. My head hurts.
Loren
SW Washington






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