Hey guys i'll try to not miss anything and explain my problem in details

so there is EVO with forged built long block (8.5CR)
initially car was running stock Turbo tuned at 19psi, and it was pullin pretty great, quick spool of turbo and kick in was a nice feeling.

after a while car started to loose power slowly.... it was not as funny as before... started to run richer AFRs than before...
anyways i thought it was turbo fault, worn compressor blades or cracked housing or something... so i took and replaced turbo with another one with low milage and great shape. - still same ****...
slow spool, poor power delivery.

did leak test - 0 leak
did compression test - 160psi all cylinders
checked exhaust - it is full 3" Tube without resonator or muffler its a simple tube without anything inside.

i thought there is something wrong with manifold or maybe WG Flapper is not closed good and tight enough, so i adjusted actuator rod to tighten it more.. disconnected vac pipe from it and went for test drive.. still same
it spools slow and goes POO
it was getting 14psi at 5000rpm or so
logs were fine, no timing retard, afrs were spot on, throttle fully opens,

so what i did is, made custom ramhorn manifold, put Ball Bearing GT3076 with T3 .63 Turbine housing.
dropped set of FIC 1200cc
Tial external wastegate with 19psi springs inside
did LEAK TEST and there was 0 leak again

base pull on dyno in 4th gear it holds 18psi (pull was done from 3500rpm to 7600rpm) more or less it looked good.
anyways tuned that ***** pretty conservative at 28psi and got 410whp on pump gas Mustang dyno figures.

to me figures look pretty low even its tuned conservative.
checked logs it does not pull timing, no knock all OK.

went road test car... still same **** slow spool, poor power delivery :P

Cam timing is OK checked myself 3 times (HKS 264 cams)

again

there is no leak (tested at 30psi with compressor air blowing into turbine inlet)
there is no cam timing error
there is no timing retard while doing WOT pull (3-4deg on full peak torque and 8-9deg in higher rpm range)
exhaust is free flowing no bents or restrictions just 3" turbe
intake on turbo is aluminum so no silicone issue there
running stock clean MAF and HKS Air filter (with or without air filter its all same)
wastegate is not leaking exhaust until it hits full boost
there is HKS BOV that does not leak also on Leak test
did compression test again and again 159-160psi all cylinders
car runs 11.5-11.8 AFR under full boost and bit leaner while spool


got really confused
maybe somebody had such experience in past?
does anybody have any idea ?

 

anyone?

 

What octane fuel are you running?

 

timing?

so it runs fine on the dyno but actually driving it runs like crap?

 

Have you factor'd in weather conditions? If it's getting substantially colder the car will run rich and lose power.

 

Sounds like a lot of timing is being pulled when off the dyno. How is your oil pressure ?

-pal215

 

The problem is that you road tested against an angry GTR. Don't do that!

 

it was head issue, replaced head, all ok

 

what was wrong with the head to cause it to lose power?

 

never checked that head, just swapped with other one.

 

What diagnosis pointed to that?