ka compression #'s, what could it be?

[blackoutt]

So I did a compression test today on my 95 ka24de with "115k" miles to the best of my knowledge. The last 1,500 or so of which have been turboed at 7-8 psi tuned with an apexi afc neo and AEM uego wideband, stock fuel system, stock maf. My symtoms that lead me to the test were: 1. oil blowing out of the breather on my valve cover, only a breather because a catch can plumbed in any manor would cause severe exhaust smoke (the only symptom prior to a trip 3 hours away) 2. general oil leak/s all over motor, and burning oil. (took 5 quarts to drive 3 hours home) and 3. Loss of power, (no sht right).

My readings were (dry)

1:75
2:80
3:85
4:90

I then followed that up with a small amount of oil in each cylinder (wet)

1:80
2:90
3:100
4:120

I can't decide if its a head gasket, piston rings, valve seals, or combination of those. mainly due to the odd patterns that emerged. give a zilvia noob some love.

[240sxfamily]

So I did a compression test today on my 95 ka24de with "115k" miles to the best of my knowledge. The last 1,500 or so of which have been turboed at 7-8 psi tuned with an apexi afc neo and AEM uego wideband, stock fuel system, stock maf. My symtoms that lead me to the test were: 1. oil blowing out of the breather on my valve cover, only a breather because a catch can plumbed in any manor would cause severe exhaust smoke 2. general oil leak/s all over motor, and burning oil. (took 5 quarts to drive 3 hours home) and 3. Loss of power, (no sht right).

My readings were (dry)

1:75
2:80
3:85
4:90

I then followed that up with a small amount of oil in each cylinder (wet)

1:80
2:90
3:100
4:120

I can't decide if its a head gasket, piston rings, valve seals, or combination of those. mainly due to the odd patterns that emerged. give a zilvia noob some love.

We had the EXACT same problem. We did the head gasket, put it all back together, and NOTHING. just cranked. Pulled it all apart, piston rings where fucked.

[aled]

I'd say its a mixture, between the piston rings and valve seals.

[let5l1de]

real simple and easy... rings are worn or broken and maybe even excessive piston to wall clearances.

KA pistons have thin ringlands which crack or completely break when boosting typically higher numbers (above .75 bar or 11psi est...). It's possible to have this occure in engines boosting lower numbers especially when a severe knock or improperly tuned engine is pushed hard.

~m

[fliprayzin240sx]

Either way, engine is done...time for a rebuild or get another engine.

[blackoutt]

Yeah I figured I was screwed. I still wanna stick with KA-T though. I'm currently deciding whether to rebuild on my own with the help of local machining, buy reman shortblock and head and assemble myself with arp head studs and nicer hg, or just buy a built longblock and save myself the time and stress. On top of any of those options I'll be adding alum radiator with electric fans, walbro 255, sr injectors, and bigger maf. Possibly better tuning, but I thought mine was pretty decent for just a fuel controller and 8 psi. around 14.5 afr cruising, and 12 under boost.

[let5l1de]

Yeah I figured I was screwed. I still wanna stick with KA-T though. I'm currently deciding whether to rebuild on my own with the help of local machining, buy reman shortblock and head and assemble myself with arp head studs and nicer hg, or just buy a built longblock and save myself the time and stress. On top of any of those options I'll be adding alum radiator with electric fans, walbro 255, sr injectors, and bigger maf. Possibly better tuning, but I thought mine was pretty decent for just a fuel controller and 8 psi. around 14.5 afr cruising, and 12 under boost.

do not buy a manufactured engine. You will rest assured not to crack or break a ring land with aftermarket pistons. if you are on a really tight budget, do the following. (not in a any particular order)



Purchase forged pistons of your choice and compression ratio
have your stock rods and crank checked for straightness, cracks, etc...
hone/bore cylinders and deck block surface head
rebuild the head if funds allow
ARP head studs
aftermarket head gasket of your choice
assemble with bearings, gaskets, etc.....
all the fuel upgrades mentioned....


this build will not safely break any hp/tq records but will surly hold the 12psi without blowing a hg or ringland...

~m

[project-D180]

make sure to get ya crank balanced n get your main honed if your budget allows it

[blackoutt]

I've been looking into it a lot and think my budget might allow me to spring for a built longblock from handcraftedracing.com, anyone heard anything good/bad about em? I'm not looking for hp and tq records, just enough to break loose when I want and (more) reliability.