Rut Roh!

[Technology]

http://www.mitsustyle.com/photopost/data/529/medium/DSC03099.JPG

http://www.mitsustyle.com/photopost/data/529/medium/DSC03101.JPG

http://www.mitsustyle.com/photopost/data/529/medium/DSC03100.JPG

http://i132.photobucket.com/albums/q27/galakadon/GiggityGiggity.jpg

[joey_crandall]

i bet that is worth more than my car.

[Technology]

i bet that is worth more than my car.

You would win that bet, I bet.

[Maxzillian]

OH! </Quagmire>

[smallblock12]

oooooo aaahhhhhhh shiney!

[Kougar]

Looks like win.

 

Frumrolls for all of the twin cities area people!

[Komeuppance]

Put BOTH on...

 

-Robert

[dmyers151]

Yeah, I'll go with 'rut roh'. Edited April 3, 2010 by dmyers151

[UlrichWolf]

Can you give us some specs on the beast?

 

Tim

[D_Venable]

it's a billet 6262SP Precision Turbo with a 3" v-band dp flange

[NotStock88]

it's a billet 6262SP Precision Turbo with a 3" v-band dp flange

 

 

giggity!!! i want updates of how it pulls when you get it installed.. i have my pt-5857 w/billet wheels installed and haven't had a chance to run it yet...

Edited April 3, 2010 by NotStock88

[pure_insanity]

ok, i know thats the anti surge compressor cover, but who can explain the details about it and how it works and all that stuff. in detail.

[NotStock88]

ok, i know thats the anti surge compressor cover, but who can explain the details about it and how it works and all that stuff. in detail.

found this on a supra forum...good reading, video and picture;

 

In order to understand how an 'anti-surge' compressor housing works (which is technically a 'ported shroud'), you need understand what surge is, in the first place.

 

Surge: The 'Surge Line' is the leftmost boundary of a compressor map. This is where flow instability occurs - This is where the compressor wheel is spinning at a high enough speed to force more air than the engine can injest. On initial thought, one might think this would just give you more pressure in the intake - and this is true, as long as you are on the compressor map. Basically, the surge line is the MINIMUM airflow needed to keep the pressure from backing up, and causing reverse flow pressure waves - these are INCREDIBLY damaging to the turbocharger!

 

Follow that thought a little further - when are you constantly seeing high flow of air, but little entering the intake? That's right, when you get off the throttle from boosting. This surging is what a BOV protects the turbo from. You also see this, if you have attempt to spin a compressor wheel such that it is forcing more air into the intake than the engine can take - or attempting to get more boost per rpm of the compressor wheel, than it is designed for.

 

That said, the ported shroud allows the surge line to be moved further left - this is because the compressor housing allows some of the air that starts to get backed up in the intake, to flow back out the housing.

 

Here's a pic from Garrett:

http://www.supramania.com/images/doward/Turboinfo/shroud.gif

 

 

WATCH THIS VIDEO - that's what real compressor surge is - when you are attempting to flow LESS air than the compressor is capable of delivering.

 

The ported shroud allows that airflow to circle back into the tract, preventing surge.

 

In this pic of my billet turbo you can just barely see the port line. It is just above the smaller set of fins, but below the larger ones;

http://www.echowavepro.com/supraphotos/hta/HTA%20061.jpg

Edited April 4, 2010 by NotStock88

[patra_is_here]

http://www.supramania.com/images/doward/Turboinfo/shroud.gif

 

wouldn't it just ALWAYS being flowing air through those holes, effectively increasing lag slightly?

[NotStock88]

http://www.supramania.com/images/doward/Turboinfo/shroud.gif

 

wouldn't it just ALWAYS being flowing air through those holes, effectively increasing lag slightly?

Yes, introducing a leak in the system will affect lag time BUT I would say less then 5%, more in the 2-3 range. I say the lag time is acceptable for the shear fact it is actually protecting the turbo/engine from blowing up.

Edited April 4, 2010 by NotStock88

[patra_is_here]

the thing is, to me that just seems like it's just increasing the A/R

 

like, they had a bunch of .70 A/R turbos that people were pushing too hard, so they machined in the anti-surge holes and now the same cartridge and compressor housing is a .75 A/R

Edited April 4, 2010 by patra_is_here

[NotStock88]

the thing is, to me that just seems like it's just increasing the A/R

 

like, they had a bunch of .70 A/R turbos that people were pushing too hard, so they machined in the anti-surge holes and now the same cartridge and compressor housing is a .75 A/R

 

Yes and no, if you increased the A/R to .70 the lag would be significantly larger than using a .63 A/R w/anti-surge cover. The lag created by anti-surge covers is so minimal that it will barely be noticed, where as the HP gain is highly noticed.

[NotStock88]

Here it is, straight from Garrett:

 

A Ported Shroud compressor is a feature that is incorporated into the compressor housing. It functions to move the surge line further to the left by allowing some airflow to exit the wheel through the port to keep surge from occurring. This provides additional useable range and allows a larger compressor to be used for higher flow requirements without risking running the compressor into a dangerous surge condition. The presence of the ported shroud usually has a minor negative impact on compressor efficiency.

[Maxzillian]

Keep in mind that those ports aren't in the area where the majority of compression occurs. As with any centrifugal compressor, the main amount of compression occurs in the section where the compressor wheel transitions from the inducer to te exducer.

[Technology]

Surging, like was stated above, is the turbo trying to force more air into the engine than the engine can take, basically the compressor wants a bigger engine. The anti surge doesn't really detract much at all, in fact, I just installed the turbo today and drove around and it did not do the chicka chicka chicka that it did when the blow off valve closed (about 5-7psi and below). It sounds way better, and it is spooling sooner than the 61. My stupid self put the wideband sensor in a bad spot and it hit the frame rail when the engine vibrated and stopped working. Luckily, a kind soul is letting me use his and I'll just buy him a new one. I have to take the downpipe off to reposition the bung so it doesn't hit anything.

 

Dyno is wednesday, so I'll see if I can get an overlay of the new graph on the old one.

 

Tim, the specs for the turbo are a 62mm inlet compressor, billet aluminum, ported S cover, I believe it's still a .70a/r housing. Journal bearing and the exhaust is a T3, .82a/r housing with a 3" v-band outlet. The exhaust wheel is different too, it's about the same size as the 61mm, but the blades are swept and "tilt" back toward the center of the turbo as they radiate from the shaft. You can see it in the third picture pretty well.

[mikec]

Many jet engines - on commercial airliners or fighter jets - have similar technology. A jet engine looks a lot like a turbocharger really: a whole bunch of compressor disks/stages (instead of just one compressor wheel on a turbo) feeding a combustion stage feeding several turbine disks (again, like multiple turbo exhaust wheels). Each compressor stage builds up the air pressure... and can "surge" just like the turbo. On a jet engine when this happens you get a really cool looking fireball blasting out the front of the engine. And often a whole lot of really expensive engine bits going everywhere. Even if the engine doesn't suffer any damage, it often quits working properly and doesn't make thrust for the aircraft - the compressor has "stalled" - and it takes some pilot action to recover the engine... meanwhile the airplane is flying sub-par because an engine isn't doing its job. Jet engine compressor stall/surge is very bad when it happens. So jet engine makers have incorporated some sort of "bleed" system to bleed high pressure air (compressed air) back to the engine inlet or at least to the first compressor stages. This widens the "safe" operating envelope of the engine. Just like this little air passage in the turbo.

 

Since efficiency is so important to jet engines, this bleed air is controlled by some sort of valve... the valve is open, allowing the bleed, only when operating conditions are getting near the "bad" area. The turbo doesn't have such a valve.

 

Turbos (and jet engine compressors) don't like to make air pressure against a dead-end pipe... they want airflow to FLOW through consistently. A closed throttle on a car looks like a dead-end pipe, stopping the airflow (actually reducing it to nearly zero... but from wide-open-throttle to closed throttle it's a massive reduction in airflow). The blades in the compressor and turbine wheels are really little airplane-style wings: spinning them in airflow imparts energy to the airflow. The RPM of the wheels, combined with the airflow velocity, determines the "angle of attack" at the leading edges of the vanes. More airflow = lower angle of attack, more RPMs = higher angle of attack. That's why snapping the throttle shut after a hard boost run is hard on the turbo: airflow drops but turbo RPMs are way up there... when the airflow stops moving, or you get that rebound pressure wave from the throttle plate, the angle of attack skyrockets.

 

Any wing, and turbo vanes too, can tolerate angles of attack from some minimum value, through zero, to some maximum value. Once angle of attack passes that maximum value, the vane/wing "stalls" - lift is lost, drag goes waaaaay up. That's bad. The surge passage allows SOME airflow at all times - even when the engine throttle is closed - so angle of attack is lessened. Folks that have added "compressor bypass valves" to their cars (like a blow-off valve except instead of dumping the boost pressure to the atmosphere these valves route it back to the turbo inlet) basically have added aircraft style surge bleed valves to their cars. These new design turbos incorporate internal bypass valves that just never close.

 

mike c.

 

ps: I've known about the jet engine "surge bleed valves" for many years (I work in aircraft design) but never thought to apply that idea to a turbo. Seeing it though is a "duh, that's bloody obvious" idea.

[NotStock88]

Many jet engines - on commercial airliners or fighter jets - have similar technology. A jet engine looks a lot like a turbocharger really: a whole bunch of compressor disks/stages (instead of just one compressor wheel on a turbo) feeding a combustion stage feeding several turbine disks (again, like multiple turbo exhaust wheels). Each compressor stage builds up the air pressure... and can "surge" just like the turbo. On a jet engine when this happens you get a really cool looking fireball blasting out the front of the engine. And often a whole lot of really expensive engine bits going everywhere. Even if the engine doesn't suffer any damage, it often quits working properly and doesn't make thrust for the aircraft - the compressor has "stalled" - and it takes some pilot action to recover the engine... meanwhile the airplane is flying sub-par because an engine isn't doing its job. Jet engine compressor stall/surge is very bad when it happens. So jet engine makers have incorporated some sort of "bleed" system to bleed high pressure air (compressed air) back to the engine inlet or at least to the first compressor stages. This widens the "safe" operating envelope of the engine. Just like this little air passage in the turbo.

 

Since efficiency is so important to jet engines, this bleed air is controlled by some sort of valve... the valve is open, allowing the bleed, only when operating conditions are getting near the "bad" area. The turbo doesn't have such a valve.

 

Turbos (and jet engine compressors) don't like to make air pressure against a dead-end pipe... they want airflow to FLOW through consistently. A closed throttle on a car looks like a dead-end pipe, stopping the airflow (actually reducing it to nearly zero... but from wide-open-throttle to closed throttle it's a massive reduction in airflow). The blades in the compressor and turbine wheels are really little airplane-style wings: spinning them in airflow imparts energy to the airflow. The RPM of the wheels, combined with the airflow velocity, determines the "angle of attack" at the leading edges of the vanes. More airflow = lower angle of attack, more RPMs = higher angle of attack. That's why snapping the throttle shut after a hard boost run is hard on the turbo: airflow drops but turbo RPMs are way up there... when the airflow stops moving, or you get that rebound pressure wave from the throttle plate, the angle of attack skyrockets.

 

Any wing, and turbo vanes too, can tolerate angles of attack from some minimum value, through zero, to some maximum value. Once angle of attack passes that maximum value, the vane/wing "stalls" - lift is lost, drag goes waaaaay up. That's bad. The surge passage allows SOME airflow at all times - even when the engine throttle is closed - so angle of attack is lessened. Folks that have added "compressor bypass valves" to their cars (like a blow-off valve except instead of dumping the boost pressure to the atmosphere these valves route it back to the turbo inlet) basically have added aircraft style surge bleed valves to their cars. These new design turbos incorporate internal bypass valves that just never close.

 

mike c.

 

ps: I've known about the jet engine "surge bleed valves" for many years (I work in aircraft design) but never thought to apply that idea to a turbo. Seeing it though is a "duh, that's bloody obvious" idea.

 

VERY nice analogy!