I think i might need a new motor help please

Hey all

Well my problem is that after a fairly high speed run for about an hour and a half doing around 160k my k11 started to run like crap down low. But when im on boost 8psi she runs fine! And today it has started to over heat! I will admit its not the best setup! Its got a standard manifold cut and flipped,non intercooled, standard computer with a heap of timing retardation, with a t28 running 8psi and standard injectors with an r33 fuel pump pushing 60psi on a rising rate fuel reg at idle . It always was really laggy but now it sounds to be only running on 3you cylinders! Please help there is so many things that could be going wrong but as its my daily I can't really pull it apart to find out

8psi on standard ECU? Gees

Believe me you can tell the difference between fuel from different servos. Oh and the motor standard un opened with 130000ks

i would guess a burnt exhaust valve personally shorty, you will be getting some very high EGT with that much spark retard! unless your 160 kph run included some big hills ?

Well yes there are some big hills in then run I did! I do have and air fuel meter and to sit at that speed it was reading rich.

you,re usually off boost at that speed eh, but if you floored it up a big hill then you will be on full boost, and those stock injectors must have been near maxing out!
compression test would be the 1st step i guess

But would a burnt valve make it overheat? because it didn't start over heating straight away

not really no, but it would make it run on 3 at low revs (then run on 4 as the revs increased), and would need more throttle to maintain the idle, have you tried pulling the plugleads to pinpoint which cyl ?

Checked you water level. Overheating could be a blown headgasket.
8 PSI is a lot of boost for a stock motor imho. I've blown two headgaskets and I only run 4.5 and I know my mixtures were ok.

Metal HG is the way to go. I'm using one and no problems at 10psi, even when the NIStune ECU map was like crap. Now boosting without worries of a blown HG.

And when people say that you need to o-ring the cylinders for proper seal, not true. I just took the head off, cleaned the block and head, put some Hylomar Blue on the block, installed the HG, put more Hylomar on the HG and installed the head. Had to do two re-torques on the head bolts but its ok. And i didn't machined the block/head for "proper" finish.

You can tell by noise too if a valve is buggered