Forums/Z31P/z31-performance-upgrade-forums engine-mechanical-aa/Have to tear the motor down for rebuild..
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grahfz: (2006-07-01 01:40:11)
I've lost ~30psi compression (some worse, some less) across all six… still acceptable compression, but in the little bit of mileage I've put on this motor between tests, not acceptable.
It's getting lots of blow-by. Smoke coming out of the valve-covers and blowing the dipstick out. I can feel the engine pulsing through the covers as well.
Burns oil as soon as you start it as well… fouling out the plugs too.
And it's also developed a rod-knock. pretty badly too.
All of this is pointing at something in the oiling system, to me.
so, 15k miles on this engine, and it's down for a rebuild.
t70: (2006-07-01 01:42:34)
OUCH!!! That's awfully depressing.. I didn't replace the oil pump in the vg30 when i built it -- hope it doesn't bite me in the ass. I would have replaced it but my poor buddy who owns the car was expecting to spend much much less than he has so far.
G-E: (2006-07-01 02:06:03)
how was oil pressure? aside from oiling problems like sludge or blocked passages, was everything cleaned/flushed before?
there's first of all no way 15k should wear out rings so much to have blowby.... but having excessive blowby does cause a bit of oil cooking, especially where there isn't that much
also I'd really like to know if you you were running hot/lean
grahfz: (2006-07-01 02:06:59)
I put a HP/HV pump in it when we built it.
Oh, I'm adding it up, and I'm going to have another 2-3k in it by the time that I'm done.
grahfz: (2006-07-01 02:09:36)
not running hot/lean at all. Only 4-6psi of boost w/ a walbro. shouldn't have been a problem, plus I was watching the LM-1.
Oil pressure, is still well above FSM specs.
the whole engine was pretty much new.. but yeah, we tore it down and had it cleaned.
- edit* as an addition.. the compression tester was coming back with good amount of oil on it from some cylinders.
BLOZ UP: (2006-07-01 02:26:28)
rings may not have seated right…
MrwassmanNA2T: (2006-07-01 02:36:53)
unfortunatly, sounds like it
grahfz: (2006-07-01 02:47:37)
motor was perfect until the upgraded turbo. Hell, during that whole ordeal, I tested compression, averaged ~181psi
G-E: (2006-07-01 04:14:37)
try nissan rings this time? heh
grahfz: (2006-07-01 21:39:14)
heh, they were nissan rings.
G-E: (2006-07-02 00:19:27)
then all I can think is you didn't break it in properly
j30_vg33et: (2006-07-02 00:21:52)
I've got some spare Total seal rings laying around here for sale… Didn't use them cuz file to fit was just tooooo much of a PITA.
t70: (2006-07-02 05:30:39)
it's not that difficult.. i just use a ring file… takes about an hour to do all the rings perfectly. Less time if you've done it before… took me an hour to file fit and assemble the bottom end of a 4g63.
grahfz: (2006-07-02 15:49:36)
Thanks, but I'll get them with the pistons.
j30_vg33et: (2006-07-03 00:25:13)
If you call Beeri at Arias he's already got a set of +0.5mm VG33ET 8.5:1 compression forged pistons designed. They use the 21mm stock rod pin diameter too, which is nice. The pins is tool steel, and narrowed for weight.
On my set, there's never any piston clatter. Also, clearly, I had them coated at Swain, which isn't included in his price.
grahfz: (2006-07-03 00:32:34)
holy carp. That's exactly what I'm going for too. 8.5:1, and more meat above the rings.
mind sharing how much they were, get the total seal rings with them?
.5mm, that's .020 right? I'm going to take the block to the machinist and see just how big I can go… ;D
it's nice to actually see the type of work they do. The clean stock piston looks like a 9:1 vg33 piston, the dirty one HAS to be a vg30 piston ;D
I don't know if I like how they dished the piston out.. are those edges sharp at all?
oh, and how long did it take for you to receive them?
t70: (2006-07-03 01:18:22)
I only use arias pistons myself in all my engines.. they are very well constructed. I have never seen a coated arias piston before though… all mine are just basic customs. I usually get Atomic speedware to design them for me - Nick Arias III does the design. if you want a good price on them -- let me know as I buy them for cost.
Alex86na2t: (2006-07-03 01:56:50)
Like i said before, Nick Arias 3 is great. My pistons cost $830 shipped. And that is with lightweight machinging to the skirts. I suggest going with a 93mm bore like the escort racing engine uses. That would be very interesting. Brings it to a 3.4L.
grahfz: (2006-07-03 01:59:04)
93mm is what I'm aiming for.
But you haven't seen how close some of the water passages are, have you?
I have.
Alex86na2t: (2006-07-03 02:01:58)
You have me curious now, please post a pic. Do you have your block or heads O-ringed?
grahfz: (2006-07-03 02:06:06)
I can take pictures when I tear the heads off of it.
I know .060 over has been done. But in a forced-induction motor that WILL see detonation?
Alex86na2t: (2006-07-03 02:24:56)
I just hope you get it done by sept and come to SEZS so i can see it. I am trying to get my fuel control done by then but $$$$$$ has put a damper on me lately.
grahfz: (2006-07-03 02:27:56)
I'll probably either be done, or almost there…
The way it's looking right now, I'm going to dump another 2000$+ into this car.
Jason84NA2T: (2006-07-03 02:37:54)
[quote]Alex86na2t wrote:
I only use arias pistons myself in all my engines.. they are very well constructed. I have never seen a coated arias piston before though… all mine are just basic customs. I usually get Atomic speedware to design them for me - Nick Arias III does the design. if you want a good price on them -- let me know as I buy them for cost.
Like i said before, Nick Arias 3 is great. My pistons cost $830 shipped. And that is with lightweight machinging to the skirts. I suggest going with a 93mm bore like the escort racing engine uses. That would be very interesting. Brings it to a 3.4L.
A company called VT engines east of me in Lansing used to make a VG37. They would use 93mm pistons and weld and offset grind the crank. They changed ownership and no longer have any of the info though. I'm not sure if it was intended for use in a forced induction application or not…
Alex86na2t: (2006-07-03 02:45:17)
i have always wondered if you could bore out a regular vg30 block (87mm), to make a vg33(91.5mm). It was a big delima when i was ordering my pistons. i wanted 91.5 but i was afraid that i would bore away all of my cyl wall. So i decided to settle with 89mm. i would rebuild my engine in the future to 93mm if i could. I still wonder.
t70: (2006-07-03 02:45:19)
I'd be very nervous of being that close to the coolant jacket. The engine that is in the 300zx now was only built up because when i tore it down -- discovered a leaking head gasket and pulled the heads -- i discovered MAJOR scoring on the sides of the piston skirts -- indicating that they were having cooling issues..... and that was on a stock block and pistons… so imagine how much worse it could get with an extreme bore increase. I realize that forged pistons cool better but.... i would still be nervous. As for detonation -- the larger the bore the less likely it is to detonate assuming proper engine cooling.
grahfz: (2006-07-03 02:50:39)
Yeah, 20-30 is more reasonable.. the 'service limit' on these guys is 20..
maybe the oil squirters had something to do with the skirt temps?
t70: (2006-07-03 02:59:15)
quite a strong possibility… i don't recall there being oil squirters in the block actually… FRIG!!! It was a junkyard motor and not the original… so it is possible it wasn't the turbo motor… at the time I really didn't know anything about what i was getting myself into so I just built it like I built normal engines… FRIGGITY FRIG FRIG!! I've got to tear down the motor again this winter anyway and do some massive porting/cams/valves/springs etc.. So I'll have a look under it then… Though that would explain why i'm having to pull timing… hmmm didn't even think of those bloody squirters till you mentioned it…
G-E: (2006-07-03 07:32:02)
vg30e didn't come with squirters, pretty sure most if not all vg33 didn't either
the de/det/dett did
grahfz: (2006-07-03 15:06:53)
I meant the ones on the rod.
t70: (2006-07-03 17:35:01)
phew! man.. that kinda scared the crap out of me… I thought it a bit weird that there wasn't any mention of oil squirters in the haynes manual. That's a huge relief.
TurboZkid: (2006-07-03 19:03:24)
this might sound stupid..but im new does this piston setup require boring…and how much if so?
grahfz: (2006-07-03 19:06:32)
yes, too much for a vg30 block. should be fine on a vg33.
consult your machinist.
cheezmonta: (2006-08-20 11:54:37)
Kind of off topic a bit. About the oil squirters.
Has anyone actually tried to put them in on a VG30E(T)? I was looking at my buddy Scot's torn down VG30DE and it just looks like they're tapped into the main oil galley. Seems simple enough to have the machine shop do.
Also was reading up on the oil squirters a bit. The VG30DE(TT) all used a small diameter open squirter but the SR20 uses a small check valve squirter that only lets oil squirt above something like 25-28psi. I assume for when the motor is building more oil pressure due to higher revs aka racing.
I'm about a year (fingers crossed) from tearing into my motor to do any hands on with this but maybe someone with a block ready for machine work would be interested.