What is Turbo Surge?????
08-02-2004, 04:40 PM
#81
Well......not read this post as my input from this is thru experience on my lo comp T4 engine,...the turbo was producing more air at a specific rpm (around 5k to 6k on mine in 4th gear onwards) than my engine could consume which meant what it couldnt take it was spitting it back which results in the tubo trying to stall.
Hope that answers all your questions..ROFL.
Hope that answers all your questions..ROFL.
08-02-2004, 04:49 PM
#83
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lol - i know that would happen pmsl
yes - having got the flu, i got mixed up that i had posted it to view the picture and then edited it
you reply quicker than i can type !!!!!
IMA have you got the dyno for it with rpm and boost - i will see if i can find the surge line on the t4
yes - having got the flu, i got mixed up that i had posted it to view the picture and then edited it
you reply quicker than i can type !!!!!
IMA have you got the dyno for it with rpm and boost - i will see if i can find the surge line on the t4
08-02-2004, 06:28 PM
#84
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Originally Posted by Stu @ M Developments
I hope its not another 2 day wait for an answer Mike 
Come on Mike - surely you can read those books faster than this!
08-02-2004, 07:24 PM
#85
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As Mike asked me to post on this I've read through the topic and done some extra research on what I "thought" I knew already. On my travels I found a useful site on turbo surge/stall and this is just a cut and paste of what it says, save me rewritting it. There is also an example of his experience with surge and how he fixed it (think his is diesel but application is relevant):
So all the chatter is is basically the blades rapidly changing acceleration direction, ie accelerating up to accelerating down (decelerating) and vice versa.
Surge is basically the fact that the turbo isn't dampened so when it gets to the required airflow for that rpm it "over shoots" and feeds too much, this causes it to try and slow down to the correct level, and again "under shoots". If the rpm was raised to a level and held you would hear chatter and as time went by it would disappear. as in diagram below.
As you can see it tries to get to the correct level and as time goes by the "over" and "under" shoots get smaller.
As stu said tho, its understanding it thats one thing and explaining it in a way for people to understand thats the problem!
Originally Posted by turbo website
The condition known as turbo surge or stall occurs under heavy load conditions where boost pressures are elevated. The root cause is generally an imbalance of pressures between the turbine side and the compressor side of the turbo. When the forces on the turbine are no longer strong enough to drive the compressor side of the turbo adequately, stall occurs. Often on Powerstrokes the stall will manifest itself as a surging and the boost pressure in the manifold will fluctuate as the vehicle surges and you can hear an audible cyclic sound which corresponds with the surge.
EXAMPLE
The truck used for this article is my own 2001, F250 Powerstroke, crew cab, long box 4x4. The truck has a 4" exhaust, aFe intake, gauges and Banks Big Hoss 120hp chip. I would experience turbo stall/surge when towing a 30' travel trailer weighing about 10,000# over the passes at highway speeds of 65-75mph. When the boost would reach 17-22psi the stall/surge would be very strong and the boost would oscillate 2-4psi while making a wooh-wooh sound. If the throttle were pressed further so the boost would climb to 23-28psi boost the surge would go away, but its hard to explain to the state patrol why you are pulling a trailer at 90mph up hill.
The following is some information about our experience with this problem, its causes and how to fix it. The fix itself was quite simple, we installed a Banks quick turbo and compressor wheel and a Big Head actuator. This resolved the problem completely. The following are some photos and things which were observed and changed while the truck was apart.
Performance with Banks Turbo
When the truck was driven with the Banks turbo housing, compressor wheel and Big Head actuator no apparent performance gain was recognized. In fact the turbo comes on slower in the low end than the stock unit and we experienced considerably more turbo whistle than the stock unit as well. Mid range and high end performance seems about the same as stock with the same top boost pressures experienced at about 28psi. Under load towing where severe surge was experienced, absolutely no surge with Banks.
Next we tried the Banks Turbo housing with Big Head actuator and the stock compressor wheel. This reduced the whistle and helped bring back some of the low end. However under heavy load conditions an audible surging sound is present, but the boost gauge does not fluctuate. We suspected that the sound was being caused by the waste gate trying to open so a ball was placed in the tube leading tot he actuator to plug it. With the ball in place a noticeable reduction of the sound previously heard under heavy load conditions was present. The plugging of the Big Head actuator did not completely stop the sound but reduced it by more than half.
From this experience it would appear that the majority of the turbo surge or stall experienced with modified trucks especially those using large horse power chips which produce high boost pressures is associated with the waste gate. It would seem that the exhaust pressure against the waste gate is at least a contributing factor in unseating the waste gate allowing it to flutter effecting the pressures in the turbo charger.
The combination of the Banks turbo housing, compressor wheel and big head actuator work together to resolve the surge because the turbo housing is larger and flows more reducing the back pressure behind the turbine. The compressor wheel reduces the amount of drag on the wheel reducing the load on the turbine. The Big Head actuator with its larger, stronger spring helps to keep the waste gate shut. Since this was initially done we have found most cases of turbo strall can be resloved by replacing the stock compressor wheel with the Banks wheel and either plugging the actuator line to the waste gate or replacing it with a Banks Big head actuator. It is probably best to use the Banks Big Head so that control for opening the waste gate is not dependant soley on exhaust back pressure.
EXAMPLE
The truck used for this article is my own 2001, F250 Powerstroke, crew cab, long box 4x4. The truck has a 4" exhaust, aFe intake, gauges and Banks Big Hoss 120hp chip. I would experience turbo stall/surge when towing a 30' travel trailer weighing about 10,000# over the passes at highway speeds of 65-75mph. When the boost would reach 17-22psi the stall/surge would be very strong and the boost would oscillate 2-4psi while making a wooh-wooh sound. If the throttle were pressed further so the boost would climb to 23-28psi boost the surge would go away, but its hard to explain to the state patrol why you are pulling a trailer at 90mph up hill.
The following is some information about our experience with this problem, its causes and how to fix it. The fix itself was quite simple, we installed a Banks quick turbo and compressor wheel and a Big Head actuator. This resolved the problem completely. The following are some photos and things which were observed and changed while the truck was apart.
Performance with Banks Turbo
When the truck was driven with the Banks turbo housing, compressor wheel and Big Head actuator no apparent performance gain was recognized. In fact the turbo comes on slower in the low end than the stock unit and we experienced considerably more turbo whistle than the stock unit as well. Mid range and high end performance seems about the same as stock with the same top boost pressures experienced at about 28psi. Under load towing where severe surge was experienced, absolutely no surge with Banks.
Next we tried the Banks Turbo housing with Big Head actuator and the stock compressor wheel. This reduced the whistle and helped bring back some of the low end. However under heavy load conditions an audible surging sound is present, but the boost gauge does not fluctuate. We suspected that the sound was being caused by the waste gate trying to open so a ball was placed in the tube leading tot he actuator to plug it. With the ball in place a noticeable reduction of the sound previously heard under heavy load conditions was present. The plugging of the Big Head actuator did not completely stop the sound but reduced it by more than half.
From this experience it would appear that the majority of the turbo surge or stall experienced with modified trucks especially those using large horse power chips which produce high boost pressures is associated with the waste gate. It would seem that the exhaust pressure against the waste gate is at least a contributing factor in unseating the waste gate allowing it to flutter effecting the pressures in the turbo charger.
The combination of the Banks turbo housing, compressor wheel and big head actuator work together to resolve the surge because the turbo housing is larger and flows more reducing the back pressure behind the turbine. The compressor wheel reduces the amount of drag on the wheel reducing the load on the turbine. The Big Head actuator with its larger, stronger spring helps to keep the waste gate shut. Since this was initially done we have found most cases of turbo strall can be resloved by replacing the stock compressor wheel with the Banks wheel and either plugging the actuator line to the waste gate or replacing it with a Banks Big head actuator. It is probably best to use the Banks Big Head so that control for opening the waste gate is not dependant soley on exhaust back pressure.
Surge is basically the fact that the turbo isn't dampened so when it gets to the required airflow for that rpm it "over shoots" and feeds too much, this causes it to try and slow down to the correct level, and again "under shoots". If the rpm was raised to a level and held you would hear chatter and as time went by it would disappear. as in diagram below.
As you can see it tries to get to the correct level and as time goes by the "over" and "under" shoots get smaller.
As stu said tho, its understanding it thats one thing and explaining it in a way for people to understand thats the problem!
08-02-2004, 08:06 PM
#86
turbo man,
Surge is basically the fact that the turbo isn't dampened so when it gets to the required airflow for that rpm it "over shoots" and feeds too much, this causes it to try and slow down to the correct level, and again "under shoots". If the rpm was raised to a level and held you would hear chatter and as time went by it would disappear. as in diagram below.
Surge is basically the fact that the turbo isn't dampened so when it gets to the required airflow for that rpm it "over shoots" and feeds too much, this causes it to try and slow down to the correct level, and again "under shoots". If the rpm was raised to a level and held you would hear chatter and as time went by it would disappear. as in diagram below.
08-02-2004, 08:21 PM
#87
Professional Waffler
Originally Posted by Stu @ M Developments
turbo man,
Surge is basically the fact that the turbo isn't dampened so when it gets to the required airflow for that rpm it "over shoots" and feeds too much, this causes it to try and slow down to the correct level, and again "under shoots". If the rpm was raised to a level and held you would hear chatter and as time went by it would disappear. as in diagram below.
Surge is basically the fact that the turbo isn't dampened so when it gets to the required airflow for that rpm it "over shoots" and feeds too much, this causes it to try and slow down to the correct level, and again "under shoots". If the rpm was raised to a level and held you would hear chatter and as time went by it would disappear. as in diagram below.
08-02-2004, 09:35 PM
#89
15K+ Super Poster!!
i think that surge is a word which is used to describe quite a broad chain of events. I think in simple terms, the "too much air for the engine" analogy is best.
08-02-2004, 09:45 PM
#90
So,is "chatter" a bad thing? (even tho it sounds nice and all the rally cars do it).Regarding surge,is this what is happening when my car comes on boost and kind of...erm...stutters sort of,its running 15psi,or is it fooked?? 
08-02-2004, 09:53 PM
#93
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i know u made it fisher price. i dont need to be told what turbo surge is,and im not asking it to be made simpler. I said that imo, the best way to describe it when keeping things simple is "too much air for the engine". And i know that uve already posted that, im just confirming this is my opinion too. I could go into fundamental fluid dynamics, but who really cares?!
08-02-2004, 10:07 PM
#95
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I have heard "turbo surge" on Lee's (porkie) 3dr round bedford. He was accelerating hard and the turbo was chattering/fluttering a good'un when i asked him whats the chattering noise he said "fuck knows, i'll ask Martin"
But it was confirmed as turbo surge, and i noticed it disappeared once you got over 4K+ rpm as the engine was consuming all the air the turbo was producing.
But it was confirmed as turbo surge, and i noticed it disappeared once you got over 4K+ rpm as the engine was consuming all the air the turbo was producing.
08-02-2004, 10:23 PM
#97
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the interesting this is,
If a turbo is producing more boost than the engine can consume - the boost pressure would rise
There is more air available at the inlet manifold than can be consumed - so the boost gauge would read more pressure - thats it.
I wonder here if the actual term "Surge" with relation to a compressor map is the problem - surge could perhaps means something else as well - its the surge line on the compressor map i'm intereted in
If a turbo is producing more boost than the engine can consume - the boost pressure would rise
There is more air available at the inlet manifold than can be consumed - so the boost gauge would read more pressure - thats it.
I wonder here if the actual term "Surge" with relation to a compressor map is the problem - surge could perhaps means something else as well - its the surge line on the compressor map i'm intereted in
08-02-2004, 10:58 PM
#99
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well the wastegate controls the boost
however the boost at the compressor wheel and at the inlet manifold can be quite different
consider these two senario's
1. a turbo supplying say 10 psi at the compressor may supply say 14psi at the inlet manifold if the engine can't consume the air - it will spike and drop back as the pressure at the compressor raises to suit and the actuator opens
2. and like wise a turbo supplying 10 psi may make 7 psi at the inlet manifold if the engine consumes more than it can supply (a bit like the mod to the crossover pipe on the rst)
I appreciate it looks like i'm being awkward here, but i'm genuinely interested to find out why surge can mean such different things to people in this industry
however the boost at the compressor wheel and at the inlet manifold can be quite different
consider these two senario's
1. a turbo supplying say 10 psi at the compressor may supply say 14psi at the inlet manifold if the engine can't consume the air - it will spike and drop back as the pressure at the compressor raises to suit and the actuator opens
2. and like wise a turbo supplying 10 psi may make 7 psi at the inlet manifold if the engine consumes more than it can supply (a bit like the mod to the crossover pipe on the rst)
I appreciate it looks like i'm being awkward here, but i'm genuinely interested to find out why surge can mean such different things to people in this industry
08-02-2004, 11:23 PM
#100
Mike.
I dont mean to be rude, but why ignore my two points for you and then blatently ask me ato give presedence to two of your own mate? Play the game fair
I honestly believe that if you give my two questions some thought, you will answer your own worries as i know your an intelligent man from previous convo's we have had
Why didnt you just ask that in the first place then?
A: Its because some of them are wrong
I dont mean to be rude, but why ignore my two points for you and then blatently ask me ato give presedence to two of your own mate? Play the game fair
I honestly believe that if you give my two questions some thought, you will answer your own worries as i know your an intelligent man from previous convo's we have had
Mike Gurney,
but i'm genuinely interested to find out why surge can mean such different things to people in this industry
but i'm genuinely interested to find out why surge can mean such different things to people in this industry
Why didnt you just ask that in the first place then?
A: Its because some of them are wrong
08-02-2004, 11:28 PM
#101
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well i was with it until them two questions so mike when youve sorted it post the answer up here so I can get back with the program!! lol
from the maps... surge occurs when the pressure is high and the flow is low??
and how did you get 100bhp from 10lbs/min? there must be a conversion loosley based on a AFR for air to power??
oh and its sunday stu.... get chillin
from the maps... surge occurs when the pressure is high and the flow is low??
and how did you get 100bhp from 10lbs/min? there must be a conversion loosley based on a AFR for air to power??
oh and its sunday stu.... get chillin
09-02-2004, 06:58 AM
#103
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Originally Posted by AndyRST
I have heard "turbo surge" on Lee's (porkie) 3dr round bedford. He was accelerating hard and the turbo was chattering/fluttering a good'un when i asked him whats the chattering noise he said "fuck knows, i'll ask Martin"
But it was confirmed as turbo surge, and i noticed it disappeared once you got over 4K+ rpm as the engine was consuming all the air the turbo was producing.
But it was confirmed as turbo surge, and i noticed it disappeared once you got over 4K+ rpm as the engine was consuming all the air the turbo was producing.
However Martin and Sean were right all along
430bhp is sooooo gay... So the MD240 is now sitting on Dans BMW and I have a nice bill coming from Martin coming very soon.
09-02-2004, 08:06 AM
#105
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Originally Posted by AndyRST
Cool, so stu mapped it so your turbo didn't surge
So more power from you this year then Lee?
So more power from you this year then Lee?
and LOADS more power coming this year.... starting again from stratch and even Martoon said 'the Sierra is gonna be really spunky'
09-02-2004, 08:11 AM
#108
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Me neither, the parts have all been ordered and when they all arrive it won't take very long at all. I'm hoping for 5-6 weeks...
Thats 5-6 Martin weeks though...
Thats 5-6 Martin weeks though...
