How freely a turbo spins?

[Coldandafraid]

I am wondering how freely a turbo is supposed to spin by hand.

Mine has absolutely no shaft play, and when I spin it by hand, I can not feel anything rubbing, or catching anywhere. However, if I spin it fast and take my hand away, it does not continue spinning. It slows and stops very fast, as if, too much fluid friction or something.

Is this normal, or no... possibly the reason I have long boost lag.

 

[Defiant]

Well, it's not being fed oil with the engine off, so it's probably not "fluid drag".
Does it have any symptoms? If not, stop playing with it. You'll get a wart.

 

[Coldandafraid]

hah, no symptoms really, just feels like an extra second of boost lag. So, I was just grasping for a cure.

 

[Defiant]

Did you already check the piping for boost leaks? Are you running an MBC?

 

[FourG63 97GST]

how much miles on it?

It has no shaft play and it spins freely, sound fine to me.
or are you only looking for and excuse to upgrade it?

 

[nhsean69]

If its the excuse to upgrade .... or a excuse to use for the Old lady to let you spend the money show her this post. YOUR TURBO IS TOAST!!! there that should help. Haha, i recently checked mine tho and it does the same thing. T-25 with 70k on it. I have had no turbo lag issues with it.

 

[Coldandafraid]

Yes, no boost leaks anymore. And hallman MBC.

I test drove a 99 gst and couldnt feel any lag... but I bought a 95 tsi and it just seems like about 1 - 1.5 seconds of lag before I go. Of course, it could just be me... this is my first car with a turbo.

But, what I do know, my wifes car is an auto too, and if on gravel, the instant I step on the gas, the tires spin. Where as, on my car, I press the gas hard and it feels like I dont go anywhere for a second. And then turbo kicks in and then it takes off... kind of like, if there were no turbo on the car, it wouldnt move...

And I dumb? Am I imagining things? Is this really just normal? Other thing to note, my vac at idle is 16...

 

[jd1828af]

check you timing. if you are running too lean you egt will be lower and will make you turbo spool slower. check for boost leaks also.

 

[Coldandafraid]

timing belt was changed the day I bought the car... and the 1.5 second lag didnt change. From the time the car was stock, fixed exhaust mani leak, I added mbc, hard pipes, bov, hrc smic... no change in lag.

The turbo does achieve full spool at the proper RPM... its with the auto trans, as I floor it, I dont go anywhere until the turbo kicks in. Like I said, if there were no turbo, the car wouldnt move.

However, from reading an old post, I hear that on turbo cars with the lower compression ratios, before the turbo kicks in the car is slower than a N/A car... so maybe thats all it is.

However, I would like to hear confirmation of this from another turbo auto trans driver... because the 99 gsx/gxt (which ever is the awd version) was an auto too, and I felt no lag. Instant GO as I floored it.

 

[markmakeitso]

Yeah, a car running with turbo comp ratio will be slow until boost comes on. The lower ratio allows more pressure to eventually be forced in.

I'm not sure about what jd1828af is getting at. You talking valve timing or spark? Kinda worried about the EGT info too.

 

[Coldandafraid]

must be that then... but I swear the 99 I test drove was instant GO.

 

[jd1828af]

Originally posted by markmakeitso
I'm not sure about what jd1828af is getting at. You talking valve timing or spark? Kinda worried about the EGT info too.

if you egt is high it will spool your turbo faster than lower temps. you can use the timing to chance the egt somewhat. (at least on my talon n/t i could, it might be different on a turbo car because the ecu can control timing)

 

[vr4gasmtt]

Bringing a dead thread back,

my car has 180k and just as the OP posted it has no shaft play, but when i spin it it spins and stops real quick. My car just lags alot, and the turbo even when the gauge says 10psi, my car doesn't really feel like 10psi.

Boost leaks have been done, and after about an hour of soapy water, I was sad to find that I had no boost leaks. Is it the turbo? Or the motor?