Slow Spool

[jjgrizz73]

Hey guys I know theres been a few threads out there for this but every case is specific. I did a turbo swap on my spyder and upgraded the motor before putting it in. The turbo isnt spooling normally and just creeps up to about 12lbs at redline. I checked the MBC by disconnecting it and it still did the same thing. I checked boost leaks and did fix the ones i found and im pretty sure there isn't any more. HEre are my mods

evo III 16g
580cc inject.
255 walbro
megan fpr
ported 02
tubular exhaust mani.
greddy i/c piping w/ 24r fmic

If anyone has any suggestions or ideas for me to check out i'd really appreciate it! Thanks

 

[fatherbubble]

Did you get the turbo new. It sounds like its bad put your finged into the intake side an see if the fins have play or if there clipped. They couls of been clipped too much an that can cause your low spool up.

 

[kahl23]

When you say "slow spool" when do you see full boost (and what psi is it?) Also, the lower you try to set boost the more apparent boost creep will be, what are you trying to set it at?

Fatherbubble: Clipping is done on the turbine wheel of a turbocharger, not the compressor, if someone has clipped the compressor wheel then that turbo is seriously messed up. What he should be checking for is shaft play, in and out and side to side. A little bit of side to side is ok, any in and out play or excessive (more than a tiny bit, <1/16th of an inch) side to side is bad. Thats because when there is no oil pressure the shaft is unsupported by oil in its bearings and should be able to move some.

 

[Nekoni]

I wish we could see a data log of it. Are you sure it's not set for a lower psi (like 9psi) and it's just boost creeping to 12 at redline?

Edit:
Kahl beat me to it...

 

[magik95]

Did you get the turbo new. It sounds like its bad put your finged into the intake side an see if the fins have play or if there clipped. They couls of been clipped too much an that can cause your low spool up.

I agree. My 14b would slowly creep up to 10lbs of boost at 5k. I took the turbo off and found that the fins had been destroyed by a piece of coupler that had broken off.

Before the turbo would boost strong. Rebuilt the turbo and boost is up to par again.
Fins that are damaged or clipped too much will affect the turbos performance.

 

[res7bequ]

An exhaust leak could also be causing a slow spool. Check for any extra dark spot around the manifold.

 

[topchoice]

Check the wastegate arm for any play/damage. Other members already mentioned what else to do but if that doesn't help try my suggestion.

 

[fatherbubble]

When you say "slow spool" when do you see full boost (and what psi is it?) Also, the lower you try to set boost the more apparent boost creep will be, what are you trying to set it at?

Fatherbubble: Clipping is done on the turbine wheel of a turbocharger, not the compressor, if someone has clipped the compressor wheel then that turbo is seriously messed up. What he should be checking for is shaft play, in and out and side to side. A little bit of side to side is ok, any in and out play or excessive (more than a tiny bit, <1/16th of an inch) side to side is bad. Thats because when there is no oil pressure the shaft is unsupported by oil in its bearings and should be able to move some.

Ok cool, I'm not to knowledgeable on turbo internals. I know engines but turbos are still new to me so all there part names are hard to remember which is what.

 

[topchoice]

Also see if you have any shaft play.

 

[Blindsey]

I would do a boost leak test. At wide open throttle with my 50 trim it would barely boost to 10lbs. Found my throttle body and my EGR valve were leaking. oh by the way a beer can does not work for an EGR block off.

 

[jjgrizz73]

The intake side fins are chipped slightly but not really bad and there is no shaft play at all. I have the boost controller set almost all the positive and it doesnt just build up and creep to 12 it just builds it slow and steadily from 0-15lbs. The manifold doesn't seem to have any exhaust leaks but I will tighten them down again and perform another boost leak test since my Vac. at idle is about 14-15 and I heard its supposed to be higher. Also I just installed the engine and I know the timing is off and there is a 1g CAS on it so adjustment is possible, would this have any affect on boost?

 

[ja12ke]

jjgrizz73 "The intake side fins are chipped slightly but not really bad"

you dont have to worry about the intake side. less material equals smaller inducer size which equals faster spool up.

 

[kahl23]

The intake side fins are chipped slightly but not really bad and there is no shaft play at all. I have the boost controller set almost all the positive and it doesnt just build up and creep to 12 it just builds it slow and steadily from 0-15lbs. The manifold doesn't seem to have any exhaust leaks but I will tighten them down again and perform another boost leak test since my Vac. at idle is about 14-15 and I heard its supposed to be higher. Also I just installed the engine and I know the timing is off and there is a 1g CAS on it so adjustment is possible, would this have any affect on boost?

A few things, first, fix the timing, that could definitely be the source of your woes, then report back. I think that might be it. I say that because it sounds like you aren't creeping, creep is when the wastegate cannot purge enough exhaust gases pre-turbine and the turbo builds more boost than is desired. When you creep you will usually spool up normally, hit your desired psi, stay there for a second, and then slowly creep up, hence the term "creep". A slow linear spool to redline on a controller setting that is supposed to be giving you high boost sounds like either its the aforementioned timing issues or a broken wastegate that's stuck open. If you fix your timing (which you should do, no matter what) and the boosting issue persists, then hook up a pressurized air source, or even a bike pump might work, to the wastegate nipple. Then slowly increase the pressure. This works best if you have a gauge to see at what psi the wastegate actuator arm moves, I can't remember what the stock spring pressure is, I think its something like 11 psi but I could be totally off on that, someone please correct me if I am. If it moves immediately or before the pressure reaches whatever the stock spring pressure is, then it's safe to say that your wastegate is blowing open and causing you to have incredibly slow spool. Hope that helps.

 

[jjgrizz73]

I will def. do that thank you very much, I'll post up the results after the timing fix. Thanks again for the quick help
-Jeff

 

[pj91gsx]

I was working on a car that was really slow because of the ignition timing. I reset the ignition timing it was so much faster afterwards. It needs to be set 5 degrees btc. Also do a boost leak test again put 25 lbs in there and spray soapy water on everything. I will always miss several boost leaks without soapy water.