just questions in general I cannot figure out

3rd gear WOT run, my boost target is 20 PSI, boost holds steady to about 4800 rpm, then its a steady decline down to 12 psi
kkk24 turbo on a 5 cylinder Volvo

after logging my turbo solenoid duty cycle goes through the roof trying to hold boost, so im assuming the ECU is doing its job properly

so far I have adjusted wastegate
replaced turbo solenoid
smoke tested entire system from MAF to intake manifold, and intake manifold
verified multiple times that the ECU is doing its job

is there any way to tell if my turbo is on the way out, I still have no shaft play, no odd noise, no oil leakage

I have tuned atleast 4 other Volvo's of my exact model with the same mods done, and they can hold perfect boost to redline
the only thing I have noticed when logging a comparable vehicle is that in general my duty cycle is higher to meet requested boost then others which would lead me to a boost leak, exhaust is a total straight pipe from the turbo

you know, I never really thought about that, I did leak test the vacuum/pressure side of it, but to remove it on my car means removing the turbo.... I have been thinking of upgrading to a forge one anyways, and that would probably pass my smoke testing also I have been doing

any tricks I could do to possibly tell? I do have access to OEM diagnostic tools/ memory logging now finally for this vehicle

think he is talking about the newer k24 found in volvo R models, capable of pushing  closer to 400hp out of the box, even ~450hp with the right compressor wheel, and not the REALLY old one found in audi s2 etc. 

The K24-7000 will not do 400hp on 98 RON, forget it. 350-360 hp is the limit for this turbo, when running locked wastegate.
Don't smoke test, instead pressure test. The problem could be occurring only at higher boost pressure, and your smoke machine probably works only at 5 psi.
Put 16-17 psi in there and see how it likes that.

Also make sure your cat is not loose or blocked.

thanks guys for the input, pressure test passed perfectly, we have a nice machine for this!, still does not mean the diverter valve is not leaking

i tried to remove it in the vehicle, its NOT happening, the bolts are frozen BAD, and it faces directly at the block so im forced to use shallow swivel allens... i plan on doing some porting to the manifold and such, and possibly upgrading the compressor wheel so i am probably going to go with a forge valve at the same time

the car has a 3 inch straight pipe with a straight through 3 inch muffler, i suppose i could hook up a backpressure gauge for kicks, its easy enough

i have heard of the sleeves cracking on these motors are upwords of 400+ hp, but it seems to be area specific, and even totally random as i have seen it happen to stock vehicles.

this turbo can probably handle 400hp with probably the worst EGT's you will ever see and who knows what the turbine RPM is, definitely way over what was ever meant for.

time to do some more testing and report back

Boost profile K24-7400, 100% wgdc after 5500 rpm on Audi 2.2T motor:

5000 - 268kpa
5500 - 265kpa
6000 - 250kpa
6500 - 240kpa
7000 - 230kpa

Boost profile K24-7200, 100% wgdc after 5500 rpm on Audi 2.2T motor:
5000 - 283kpa
5500 - 280kpa
6000 - 273kpa
6500 - 268kpa
7000 - 255kpa

To reach 400 hp these engines need at least 1.65-1.7 bar to redline if using the standard (9.3:1) compression ratio.
At 8.5:1 CR they can make a bit more, but no way to hit 400hp on K24-7200 turbo, never mind on the smaller K24-7400.
Full boost on K24-7400 about 2900 rpm, Full boost on K24-7200 3500 rpm in 3rd.

ugh.. choke that turbo..  
actually ive tuned none myself, but ive seen a few 2.5l 20v engines on the dyno around the 400hp mark over here in "the land of the volvos", mostly on 98ron or V-power (99ron)

these turbos dont really like the boostlevels you are describing, and never operate that high in the volvo cars due to the increased engine volume + flow, the compressor flow is no doubt higher in lower PRs, and you wont max out the turbine below 400hp on 98ron.

if what youre saying were true for the cars in question, Volvo would have stuck with their MHI 16t/19t turbos, and not step it up a notch to these.. since the MHI turbos were really solid units which produced the widest of torque-bands..

worth mentioning is that a stage 1 chip for these cars yield 354hp/493Nm.. on 95ron.
using 98 ron on top of that, combined with lowering backpressure from a better downpipe + exhaust and you are there.

On swedespeed lol