turbo surge

ok, here is my experience with compressor surge.
same car, two different turbos.
car is a 92 eagle talon auto awd, with mitsu 4g63t

1st turbo is a "frank 5" big garret compressor wheel (58-60ish mm) with a tiny mitsu tdo5 turbine wheel in a 7cm mistu turbine housing

this turbo surged anytime i got it near 21-25 psi, light load or full load, did not matter. also did not have a surge ported cover. spooled up and hit "full " boost 25~ psi at 3900-4100 rpm (based on gear)

2nd turbo
PTE billet dbb 5857 in a .63a/r (roughly 8.5 cm) pte mitsu bolt on turbine housing and t04s surge ported compressor cover.

similiar sized compressor wheel, with a MUCH larger, higher flowing turbine wheel and moderately better turbine housing. and this turbo iis rated to flow 59lbs/min vs the roughly 53lbs/min of old turbo

this turbo reached full boost 27~psi at 3700 rpm based on gear and load. i could not MAKE this thing surge. was way up on driveability, and hp all around.

my conclusion:
even though compressor flows "x" amount, if the turbine wheel or housing cannot flow enough out of it, you reach the point of surge where air crammed into the engine cannot be used by the engine (think volumetric efficiency sucks due to tiny exhaust side), air stacks up, can stall turbine wheel (too small to impart work on shaft anymore), air has no where to go except out the compressor wheel.

no, turbine wheels do not surge, but as part of a total package, they can cause the compressor to surge.

i say upgrade to a 71mm turbine, or downgrade to a 62mm compressor. you can also have the 68mm turbine wheel clipped. you will lose a little spool, but it should be negligible due to weight cut off, and it will flow more while imparting less work on compressor. its an old school way to combat surge, and it works, is easy to get done in a short amount of time and cheap compared to a new turbine wheel.


oh, and Tormentor: suck it.
 
crackerman said:
ok, here is my experience with compressor surge.
same car, two different turbos.
car is a 92 eagle talon auto awd, with mitsu 4g63t

1st turbo is a "frank 5" big garret compressor wheel (58-60ish mm) with a tiny mitsu tdo5 turbine wheel in a 7cm mistu turbine housing

this turbo surged anytime i got it near 21-25 psi, light load or full load, did not matter. also did not have a surge ported cover. spooled up and hit "full " boost 25~ psi at 3900-4100 rpm (based on gear)

2nd turbo
PTE billet dbb 5857 in a .63a/r (roughly 8.5 cm) pte mitsu bolt on turbine housing and t04s surge ported compressor cover.

similiar sized compressor wheel, with a MUCH larger, higher flowing turbine wheel and moderately better turbine housing. and this turbo iis rated to flow 59lbs/min vs the roughly 53lbs/min of old turbo

this turbo reached full boost 27~psi at 3700 rpm based on gear and load. i could not MAKE this thing surge. was way up on driveability, and hp all around.

my conclusion:
even though compressor flows "x" amount, if the turbine wheel or housing cannot flow enough out of it, you reach the point of surge where air crammed into the engine cannot be used by the engine (think volumetric efficiency sucks due to tiny exhaust side), air stacks up, can stall turbine wheel (too small to impart work on shaft anymore), air has no where to go except out the compressor wheel.

no, turbine wheels do not surge, but as part of a total package, they can cause the compressor to surge.

i say upgrade to a 71mm turbine, or downgrade to a 62mm compressor. you can also have the 68mm turbine wheel clipped. you will lose a little spool, but it should be negligible due to weight cut off, and it will flow more while imparting less work on compressor. its an old school way to combat surge, and it works, is easy to get done in a short amount of time and cheap compared to a new turbine wheel.


oh, and Tormentor: suck it.
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Very nice. Once again pointing to the fact that in their quest for quick spooling some tend to shoot themselves in the foot. Slow it down a bit, your tranny will thank you.
 
And this is definitely on the right track. There is a power balance that must be met between the turbine and the compressor for the whole system to work right. Mass flow through the turbine is key.

Tormentor sucks it because he's totally ignoring that compressors do no work at all without a turbine driving them. They're on the same shaft, you'd think it'd be pretty obvious, but I guess that's hard to grasp if all your knowledge comes from surfing the web.
 
RonA said:
Not entirely true. I run a GT4094 as a secondary and it works extremely well. As a single, they suck.(actually, they surge)
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Well, surge is kinda suck and blow alternating at the same time LOL
 
crackerman said:
ok, here is my experience with compressor surge.
same car, two different turbos.
car is a 92 eagle talon auto awd, with mitsu 4g63t
Click to expand...
nwpadmax said:
This is COMPETITION DIESEL! Not subcompact.com!
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air stacks up, can stall turbine wheel (too small to impart work on shaft anymore), air has no where to go except out the compressor wheel.
Click to expand...
No, exhaust flow has nothing to do with compressor surge and there is no such thing as turbine stall. I bet next you'll tell us its "wastegate flutter"?
 
Tormentor said:
No, exhaust flow has nothing to do with compressor surge and there is no such thing as turbine stall. I bet next you'll tell us its "wastegate flutter"?
Click to expand...

Post actual facts or gtfo! I'm tired of your OEM hear say with nothing to back any of it up.
 
Nope it is not wategate flutter.
I did however just do one thing i have never once seen you do Tormentor.
I spoke from experience.

A turbine wheel needs torque (a.k.a. "energy")imparted upon it by exhaust gasses to compress air using the compressor wheel that it is attatched to via a shaft. (I am sure you know what a "shaft" is tormentor.) In a lot of surge cases the compressor wheel slows down and can sometimes turn backwards in extreme circumstances, such as when a throttle plate is shut and air has nowhere to go but backwards without a blowoff valve.
Yes. My experience was with an import car, but a mismatched turbo is a mismatched turbo regardless of the air pump (read: internal combustion engine) it is on. And yes, volumetric efficiency goes a long way in helping size a turbo.
 
Tormentor said:
No, exhaust flow has nothing to do with compressor surge and there is no such thing as turbine stall. I bet next you'll tell us its "wastegate flutter"?
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All your doing is disagreeing with what everyone says and making yourself look like a retard
 
Tormentor said:
Drive like a professional and don't let of the throttle suddenly. Problem solved.
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I think about this one from time to time. Usually when my truck is spinning the tires badly and heading toward the shoulder or into another lane. I usually roll out of it too quick and the secondary sounds like a fat guy who, after winning a chilie eating contest, spent 2 hours in church sitting between his mother and the pastors wife, then sneezed, farted, and burped at the same time when he stood up.
 
Mine really only surges bad if I lug it into a spool under high load. For example 1200rpm wot building boost in 4th or 5th untill it starts to surge real bad. But I don't drive like that because the people behind me would hate me. I also run a race cover on mine which may be a reason it doesn't surge bad under normal driving and towing conditions. Either way I received my 478 from taylor yesterday so no worries for long time.
 
Tormentor said:
No, exhaust flow has nothing to do with compressor surge and there is no such thing as turbine stall. I bet next you'll tell us its "wastegate flutter"?
Click to expand...

Explain how surge breaks shafts then...
 
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