Opinions on Ported Shrouds

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karolko

Well-Known Member
Joined
Sep 18, 2007
I posted a similar question in one of the sticky's but i feel that it deserves its own thread,


after finding out what ported shrouds do, i am getting all excited about ordering my new turbo. but this just seems like a gift from god, which is always to good to be true.

so here is my question, how many of you guys are running ported shrouds AND NO blow off valve? the theroy is great, help eliminate compressor surge afte you slap the throttle shut without needing those crappy sounding blow off valves.

More importantly, does having a ported shroud effect the turbo efficency alot. or is it hardly noticeable??


thanks

Adrian
 
Patrick raises his hand.

I run a ported shroud on my PT6776RHP turbo.

The ported shroud does help cut down the compressor surge under light loads and decel, it's not the end all, be all answer tho. It will help the longevity of the rotating assembly, but at a slight cost.

The PS slightly takes away the compressors' peak power potential. We saw this with Supra turbo and Evo applications. In a Buick application, using my turbo as an example, it might cost me 15 flywheel hp, (790 down to 775) but I'd much rather have the extra surge protection and loose 15 horse, than to risk damaging the rotating assembly over time. Every turbo is different as far as how much power it will take away. On the 70 GTS series turbo, on a 2JZ Supra, it took away around 25 flywheel hp. On a 61 series turbo it might take away 5-10. These figures have never really been tested on Turbo Buick applications. The only application that is even close, is the 3.0L Turbo Supras, but that motor is a million times more efficient, with regards to head flow, than our 3.8 motors. Results would be close, but not exactly the same.
Just something to think about.

Patrick
 
I would gladly trade that small high end power loss for the chance to run a large and efficient turbo on my small engine and not run into compressor surge at low throttle and airflow conditions. Like you said, Adrian. It's a godsend. :biggrin:
 
Not to burst your bubble but my PTE 6152S turbo surges like crazy under part throttle boost, only the Tornado solved it.

Knowing that it chops off some top end I'd just run the regular cover and use the Tornado.
 
tornado? that thing that they did all those commercial about years back??? don't say it is so? and how does that reduce compressor surge?
 
Hey Donnie, with your turbo setup, does the car still give off that distinctive Fart flutter when you slap the throttle shut or are decelerating?

i don't know about you, but that sound is friggin' awesome!!
 
karolko said:
Hey Donnie, with your turbo setup, does the car still give off that distinctive Fart flutter when you slap the throttle shut or are decelerating?

i don't know about you, but that sound is friggin' awesome!!
Click to expand...

It depends on how much boost I have built up and what rpm I'm at. During a burnout, where I try to keep rpm and boost low, I'll sometimes get the fart flutter sound if I've built up too much boost. At the end of a run when I get off the throttle, It'll be a whoosh from the blow off valve.
 
I will not be running a blow off valve, so i will assume that i will still get the fart flutter sound, it just will not be as bad as it was before with the ported shroud.
 

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The only Tornado I have seen was a finned drum shaped sheet metal thing that fit over the air cleaner stud over the carburator. It turned on the stud when airflow would go through it. The main problem I say with it was the fact that it had no bearing surfaces. As it turned, it rubbed on the lower air cleaner housing and made metal scrappings. Guess where all those metal scrappings ended up going.
 
DonWG said:
The only Tornado I have seen was a finned drum shaped sheet metal thing that fit over the air cleaner stud over the carburator. It turned on the stud when airflow would go through it. The main problem I say with it was the fact that it had no bearing surfaces. As it turned, it rubbed on the lower air cleaner housing and made metal scrappings. Guess where all those metal scrappings ended up going.
Click to expand...

the unit itself "shouldnt" turn at all... the precise fins make the air spin....the idea is to get the air moving efficiently so its not just hitting "a brick wall" and cramming itself in.






if you were jokin' sorry.
 
Royal-T-Ltd said:
the unit itself "shouldnt" turn at all... the precise fins make the air spin....the idea is to get the air moving efficiently so its not just hitting "a brick wall" and cramming itself in.






if you were jokin' sorry.
Click to expand...

Well, that's not what was happening when I found one on a customer's car. The wear on the air cleaner housing was very pronounced. The unit immediately found its way to the round file.

Joking about what?
 
Also if your turbo surges at part throttle, then i would expect that the turbo selection is the problem.

So it is the infamous tornado? wtf? i don't know if i would trust my engine to that tin. just my opinion though.

this my just work for some of you boys, but i would expect something that has been engineered strickly for the purpose of reducing surge to work better and more properly than something that was originally designed to increase fuel mileage.

my 2 cents
 
While my fluids classes are pretty foggy these days, I believe the reason the tornado seems to drastically reduce and even eliminate the part throttle compressor surge for many, is that it reduces the back pressure at the turbo inlet (p1) (due to the it's restrictive aspect, installed before the turbo), moving the compressor into a different area (higher) on the compressor map at lower flow rates... in laymen's terms, the turbo has to work 'harder' at the lower flow levels to overcome the restriction from the tornado, thus pushing the compressor back into a more efficient area, and out of the surge area, of the map. Heck, the spinning motion of the air may have something to do with it too. That's my 'theory'..... but what do I know?? :redface:
 
The only way it stops surge is because it is a restriction and the turbo does not get as much air so it cant get into surge becuase it dont have enough air the compress more than the engine can take. So there forth its restricting the turbo all the time even after its past the surge point.

If the Tornado pushed the turbo up to a more eff part of the map it would surge more because there would be more air.


If your going to run a Tornado, you would be just as well off with a smaller turbo.


Jess
 
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