# over spinning a turbo V charge pipe left open.
**URL:** https://forums.speedlife.net/t/over-spinning-a-turbo-v-charge-pipe-left-open/70282
**Category:** NYSpeed Automotive
**Created:** [July 9, 2009, 6:54am UTC](https://forums.speedlife.net/t/over-spinning-a-turbo-v-charge-pipe-left-open/70282 "2009-07-09T06:54:58Z")
**Posts on this page:** 20
**Page:** 1
### Author:  [@somedude](https://forums.speedlife.net/u/somedude)
#### Post date: [July 9, 2009, 6:54am UTC](https://forums.speedlife.net/t/over-spinning-a-turbo-v-charge-pipe-left-open/70282/1 "2009-07-09T06:54:58Z")
I have been battling a vehicle speed sensor issue for nearly a month now, and in desperation I swapped my turbo SHO back to stock. By that I swapped in the stock injectors, MAF and unplugged the tweecer (tuning device). So as far as the computer is concerned the car is stock. I left the 2.5" charge pipe open and have the stock maf drawing air from the front of the car. My question is about overspinning the turbo from not haveing any restriction on the pressure side. I have been trying to take it easy on the car but it is just so ungodly slow because it is leaning out because of the cams and intake work that it is hard not to beat on it + the intake is ferocious. Can I over spin the turbo driving it without restriction on the intake side? the typical intake shreek is not there since it will not build boost so I would assume there is not enough exhaust flow to be a concern. thoughts?
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### Author:  [@LXIFLYBY](https://forums.speedlife.net/u/LXIFLYBY)
#### Post date: [July 9, 2009, 1:35pm UTC](https://forums.speedlife.net/t/over-spinning-a-turbo-v-charge-pipe-left-open/70282/2 "2009-07-09T13:35:53Z")
Yeah itll spin wayyy too fast without any air resistance to the compressor side. I wouldnt reccomend it at all, itll most likely trash the turbo rather quickly
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### Author:  [@newman](https://forums.speedlife.net/u/newman)
#### Post date: [July 9, 2009, 1:46pm UTC](https://forums.speedlife.net/t/over-spinning-a-turbo-v-charge-pipe-left-open/70282/3 "2009-07-09T13:46:49Z")
I’m more surprised that you converted the car to NA because of a VSS issue…
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### Author:  [@b5a4](https://forums.speedlife.net/u/b5a4)
#### Post date: [July 9, 2009, 2:19pm UTC](https://forums.speedlife.net/t/over-spinning-a-turbo-v-charge-pipe-left-open/70282/4 "2009-07-09T14:19:30Z")
FWIW he only went back to stock so he didnt need the tweecer. Trying to see if that was the cause of his problems.
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### Author:  [@Nivek](https://forums.speedlife.net/u/Nivek)
#### Post date: [July 9, 2009, 2:44pm UTC](https://forums.speedlife.net/t/over-spinning-a-turbo-v-charge-pipe-left-open/70282/5 "2009-07-09T14:44:24Z")
> [@newman](#):
>
> I’m more surprised that you converted the car to NA because of a VSS issue…
i was thinking that too.
but isnt this also your 5th transmission too… maybe something is missing in the transmission?
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### Author:  [@somedude](https://forums.speedlife.net/u/somedude)
#### Post date: [July 9, 2009, 2:44pm UTC](https://forums.speedlife.net/t/over-spinning-a-turbo-v-charge-pipe-left-open/70282/6 "2009-07-09T14:44:47Z")
> [@newman](#):
>
> I’m more surprised that you converted the car to NA because of a VSS issue…
I that had to be done is swap injectors and MAF. it took a hour and twenty min to do. like B5A4 said I did this to eliminate the tweecer (tuning device) as a suspect. so far I have replaced the sensor, the wiring from the sensor to the PCM, and the PCM.
and now as of today the car will not let me pull codes now. FML I don’t know how to fix this car. I PM’ed gary about it. I serously don’t know what else to do.
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### Author:  [@Viper966](https://forums.speedlife.net/u/Viper966)
#### Post date: [July 9, 2009, 3:19pm UTC](https://forums.speedlife.net/t/over-spinning-a-turbo-v-charge-pipe-left-open/70282/7 "2009-07-09T15:19:55Z")
How do you not have a daily driver to drive while you fix the issue and not risk overspinning the turbo???
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### Author:  [@neonglh](https://forums.speedlife.net/u/neonglh)
#### Post date: [July 9, 2009, 4:36pm UTC](https://forums.speedlife.net/t/over-spinning-a-turbo-v-charge-pipe-left-open/70282/8 "2009-07-09T16:36:31Z")
I want to know if it will really over spin or not. I heard this before too.
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### Author:  [@reliant\_turbo](https://forums.speedlife.net/u/reliant_turbo)
#### Post date: [July 10, 2009, 6:49am UTC](https://forums.speedlife.net/t/over-spinning-a-turbo-v-charge-pipe-left-open/70282/9 "2009-07-10T06:49:20Z")
take the wastegate spring out of an external wastegate or remove the wastegate can if you are using an internal wastegate. that will make sure it doesnt overspeed the turbo.
if you spin the turbo up with all the piping disconnected, it may puke alot of oil out of the compressor depending on the condition or the type of seal that it has.
brian
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### Author:  [@somedude](https://forums.speedlife.net/u/somedude)
#### Post date: [July 10, 2009, 8:16am UTC](https://forums.speedlife.net/t/over-spinning-a-turbo-v-charge-pipe-left-open/70282/10 "2009-07-10T08:16:53Z")
> [@Viper966](#):
>
> How do you not have a daily driver to drive while you fix the issue and not risk overspinning the turbo???
I do.
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### Author:  [@newman](https://forums.speedlife.net/u/newman)
#### Post date: [July 10, 2009, 8:22am UTC](https://forums.speedlife.net/t/over-spinning-a-turbo-v-charge-pipe-left-open/70282/11 "2009-07-10T08:22:12Z")
Why don’t you just buy a friggen standalone or something and ditch that stock crap and piggyback.
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### Author:  [@brent\_strong](https://forums.speedlife.net/u/brent_strong)
#### Post date: [July 10, 2009, 8:23am UTC](https://forums.speedlife.net/t/over-spinning-a-turbo-v-charge-pipe-left-open/70282/12 "2009-07-10T08:23:59Z")
> [@newman](#):
>
> Why don’t you just buy a friggen standalone or something and ditch that stock crap and piggyback.
Spent all his money on 12 transmission rebuilds. :mamoru:
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### Author:  [@Nikuk](https://forums.speedlife.net/u/Nikuk)
#### Post date: [July 10, 2009, 8:28am UTC](https://forums.speedlife.net/t/over-spinning-a-turbo-v-charge-pipe-left-open/70282/13 "2009-07-10T08:28:07Z")
Wait, what?
Nothing mechanical has changed as far as the exhaust right? So you’re feeding less exhaust gases / pressure through the turbine - since you’re combusting less charge because you’re running in vaccuum as opposed to positive manifold pressure…
How exactly are you over spinning the compressor by leaving it open? It’s not a fucking pinwheel in the breeze…? It’s turbine driven.
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### Author:  [@Saxon](https://forums.speedlife.net/u/Saxon)
#### Post date: [July 10, 2009, 8:36am UTC](https://forums.speedlife.net/t/over-spinning-a-turbo-v-charge-pipe-left-open/70282/14 "2009-07-10T08:36:53Z")
there is no resistence between the compressor housing and intake like there normally would be so it makes that wheel that much easier to spin is the theory
lately people have been contesting it and sayings its a myth
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### Author:  [@newman](https://forums.speedlife.net/u/newman)
#### Post date: [July 10, 2009, 8:38am UTC](https://forums.speedlife.net/t/over-spinning-a-turbo-v-charge-pipe-left-open/70282/15 "2009-07-10T08:38:57Z")
Eh, don’t agree ^^^
In it’s simplest form, the torque balance on the shaft is described as
alpha \* I = turbine torque - compressor torque - drag and other losses
The I is constant.
Centrifugal pumps, as anyone who has ever read a compressor flow chart will attest, require a driving torque that is a function of both the mass flowrate and **head pressure**. When the car is boosted, the torque on the compressor side is much than the torque when the car is NA.
This means that the net rotational acceleration will much higher, and the steady state RPM where the torque balance is equal to zero will be higher.
That said, I’m unsure of how quickly the parasitic losses will increase as a function of alpha to create a steady state condition. It may be 1000 RPM, it may be 25000… I can do nothing more than speculate. If you look at any compressor map, the efficiency of the compressor is typically pretty bad at a pressure ration of 1… It’s certainly cause for concern.
Because of that, I would not risk an expensive turbo and would figure something else out…
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### Author:  [@Nikuk](https://forums.speedlife.net/u/Nikuk)
#### Post date: [July 10, 2009, 8:39am UTC](https://forums.speedlife.net/t/over-spinning-a-turbo-v-charge-pipe-left-open/70282/16 "2009-07-10T08:39:32Z")
> [@alpha earl](#):
>
> there is no resistence between the compressor housing and intake like there normally would be so it makes that wheel that much easier to spin is the theory
>
> lately people have been contesting it and sayings its a myth
thats my point… there is no resistance to the compressor wheel, but does that mean that the compressor is no longer connected to the shaft? The compressor doesn’t drived the turbine, it’s the other way round. The theory that the compressor will spin too fast implies that the turbine wheel is spinning too fast, when in reality it’ll be spinning slower…
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### Author:  [@newman](https://forums.speedlife.net/u/newman)
#### Post date: [July 10, 2009, 8:54am UTC](https://forums.speedlife.net/t/over-spinning-a-turbo-v-charge-pipe-left-open/70282/17 "2009-07-10T08:54:41Z")
> [@Nikuk](#):
>
> thats my point… there is no resistance to the compressor wheel, but does that mean that the compressor is no longer connected to the shaft? The compressor doesn’t drived the turbine, it’s the other way round. The theory that the compressor will spin too fast implies that the turbine wheel is spinning too fast, when in reality it’ll be spinning slower…
No, the theory is that when you have a driving force, and you decrease resistance force in the opposite direction, the net acceleration will increase.
Think of it like this:
You put 2 cars on identical hills.
Both cars are turned in neutral, so both cars are undergoing the same driving force, gravity.
Car 1 rolls down the hill with it’s brakes applied slightly but a steady amount (creating boost pressure is essentially like “putting the brakes on”).
Car 2 rolls down the hill with no brakes.
Car 1 will reach a lower top speed than car 2, because it’s force balance looks like:
M\*A = component of gravity parallel with hill - braking force - drag.
Whereas car 2 will look like:
M\*A = component of gravity parallel with hill - drag.
However, drag is a function of speed, so since Car 2 is moving faster the value for drag increases, so it’s not going to increase in speed in an amount that corresponds exactly to the change in net force parallel to the hill.
Car one represents the car with the turbo connected normally
Car 2 represents the OP’s scenario.
However, that’s not a perfect example, what you have in the real world is
Less exhaust gas on NA car: Less incline of the hill of car 2
Variable compressor loading in boosted car: Variable braking force in car 1.
As the turbine wheel speeds up because the torque required to spin the compressor has decreased, the system’s net drag/losses increase
So after all that is said and done, is it spinning any faster? **I don’t know, but it CERTAINLY could be.** And because of that, I wouldn’t risk it.
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### Author:  [@Southtowns27](https://forums.speedlife.net/u/Southtowns27)
#### Post date: [July 10, 2009, 8:56am UTC](https://forums.speedlife.net/t/over-spinning-a-turbo-v-charge-pipe-left-open/70282/18 "2009-07-10T08:56:16Z")
This needs to be a Mythbusters episode
Or invest in a turbo tach
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### Author:  [@Nikuk](https://forums.speedlife.net/u/Nikuk)
#### Post date: [July 10, 2009, 9:33am UTC](https://forums.speedlife.net/t/over-spinning-a-turbo-v-charge-pipe-left-open/70282/19 "2009-07-10T09:33:37Z")
Newman, yea I understand that completely,and I obviously don’t know the concrete answer either.
From an academic standpoint I don’t think it’ll be that big of an issue.
I say this based on the fact that IDK what turbo the OP runs, but I know that mine for example isn’t going to overspeed until 117-132k rpm (load dependant) WITH a load (air mass) on it. This leads me to guess that with NO Load there is no way its gonna spin THAT high consiering that I’m putting 1pr worth of combustion through the turbine, not 3-4pr worth.
The missing function is how much of a braking effect does the compressor housing have in a closed circuit.
To the op’s concern, I WOULD try it if I was stuck on the side of the road or something, but otherwise there is really no reason to do it.
Srsly, there are other ways to troubleshoot a VSS…
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### Author:  [@boardjnky4](https://forums.speedlife.net/u/boardjnky4)
#### Post date: [July 10, 2009, 9:37am UTC](https://forums.speedlife.net/t/over-spinning-a-turbo-v-charge-pipe-left-open/70282/20 "2009-07-10T09:37:03Z")
what is the wastgate setup like? there has to be a way to rig it full-open.
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