Turbo takes forever to spool.

[1WheelWonder]

Well first off I'm not running a huge t88 or anything like that, I'm using a internaly gated Garrett t28 turbo that has a .86 a/r turbine and a .60 a/r t3 compressor housing. It's not ball bearing but journal bearing. I'm using a turbo xs manual boost controller, my intercooler is 30x9x2.5 (if I remember correctly), cold pipe is 2.5 inches in diameter and the hot pipe is 2 1/4. My problem is that I am not building boost soon or quick enough. When in first gear at WOT it will start to spool at 3 grand but only builds 5psi, 2nd gear spools at 3 grand and makes 6-7 psi, 3rd gear spools at 3 grand and produces 9 psi, and 4th and 5th gear are the same. The turbo starts to spool at 3 grand in these gears but doesn't really start build boost till about 5000-5500rpms. This is a smaller turbo and seems it should build boost a lot quicker than it is. I have no exhaust leaks on or around the manifold, my idle is a steady 21hg and I have yet to detect a boost leak and if it was a boost leak it wouldn't hold boost would it. Any help will be appreciated.

Chris

[Mustangs_Suck]

.86/.60 - correct me if I'm wrong, but aren't those TERRIBLE a/r boost numbers?

As I recall, the larger the a/r, the later the power comes. A small a/r gives you a fast spooling turbo but limits top-end power. A large a/r gives you a laggy turbo with big top-end power.

[crzycav86]

Yeah.. but he's saying that it shouldn't be that bad on a t28.

[Tictakman]

what manifold are u runnin? i was using a bd mani and i was having the same problems. cause was a crack in the tube to the wg.

[1WheelWonder]

Yes as crzycav86 said the a/r's on this smaller turbo I have shouldn't create this amount of lag.

[1WheelWonder]

It's an el cheapo ssautochrome(flame on), but there are no cracks or warped runners, yet.

[WDRacing]

Try this, but watch your boost carefully. Disconnect the boost reference line from the wastegate actuator. Now your wastegate shouldn't open at all. SO boost should hit ALOT harder and not stop building. With a T28 you could have a 1.06 AR which i don't think is even possible, and still have full boost by 5grand. Make sure your boost gauge doesn't have a leak as well.

WD

[1WheelWonder]

If I disconnected my wastegate line and it builds boost does that mean my wastegate is crap, which wouldn't surprise me by the looks of it.

[far1002]

what do you have for fuel control. increasing you fuel down low will help you turbo spool. you might be running real lean down low there fore not creating enough exshaut volume till higher rpms, when your turbo spools or you might just have a boost leak.

[1WheelWonder]

For fuel i'm using a Walbro 255lph pump, Deatchswerks 555cc injectors, PLX M-300 to monitor, and to control them i'm using a SafcII

[far1002]

i see you have a wideband. just add some fuel down low and see what it does. i have a straight T04e and i had the same problem when i first put the kit togehter i just add fuel it made a big difference.

[hannibal]

Slow spool = air not getting to the turbine. If youre sure you have no leaks, look at the WG. I'd try WD's idea.

Could a leak on the intake side cause slow spool (and low boost readings) if youre reading boost from the intake manifold?

[1WheelWonder]

I have yet to get around to anyone's suggestions, but if the wastegate flapper were partial open at all times would that cause the lag or lack of response from my turbo? I say this because I had to make a bracket to hold the wastegate to the compressor housing but because of my mad fabrication skills the flapper wouldn't fully shut and me being newbish figured it would be alright.

[K240]

Im still learning about turbos in general, and correct me oif im wrong, but if the wastegate flapper doesnt close all the way, wouldnt that make the car not build boost the way it is supposed to? like the wastegate is opening earlier than the set spring pressure (ie, 7lbs) ???

[240SicknessX]

if your wastegate flap was not totally seated it would cause the "laggy, late spool" that you describe. I would most definitly start trying to fix the issue with making sure that the wastegate flap valve is properly seated to the turbine housing. Watch when you drive the car after you alterd your bracket, the eariler quicker spool might have you changin up the safc giving a little more fuel down low.

also if you are not using tbolt clamps around on your intercooler piping, check for loose connections and boost leaks. I had a problem with one of my couplings that I did not tbolt.

[hannibal]

I have yet to get around to anyone's suggestions, but if the wastegate flapper were partial open at all times would that cause the lag or lack of response from my turbo? I say this because I had to make a bracket to hold the wastegate to the compressor housing but because of my mad fabrication skills the flapper wouldn't fully shut and me being newbish figured it would be alright.

I think you identified the problem. If the flapper is stuck open even partially, air that should be turning the turbine wheel is just flowing out your exhaust. Say a T28 usually spools up at 2500rpm, if youre waiting til 5000rpm to get boost, about half of the exhaust gas is slipping thru that flapper. Thats not 100% accurate, but I'm just trying to paint a picture.

I assume youve tried boosting without the boost controller installed and had the same problem.

[1WheelWonder]

You would be correct.

[1WheelWonder]

Guys I got my problem fixed. As I stated before I had wondered if my wastegate flapper not closing could cause my problem. Well it was, so I stacked some washers on the wastegate bracket which moved the wastegate enough to close the flapper fully. Now I get the full boost I was wanting (10 psi) in each gear at around 3200rpms. The car feels great now and pulls strong all the way to the redline. Thanks for the help and for listening to me.

[240SicknessX]

good to hear your car runs good now

i had a boost leak from a cracked silicone coupler right after the install, i hit full boost around 4600 rpm, i didnt think that this 60 trim compressor wheel would change that much spool up charictoristics on the t3 .63 turbine housing. I was disapointed to say the least, after a day or two i looked around to find a coupler was split wide open aside from my rough base tune. yada yada yada but now with all leaks taken care of, with the intake runner butterfly valves still there i get full boost at 3700 from my t3(.63)\t04e(.60) 60trim turbo.