4agze and sc12 questions

**caibs** · 19-01-2006, 02:00 PM

ok heres the story so far.
i got a 4agze which is blowing a bit of smoke under acceleration. i did a dry compression test on it and all cylinders came up fine (doesnt mean ya oil rings are good though). anywho, i was going to pull the motor out today but as soon as i pulled the intercooler piping off i found oil in the piping. so, now i'm thinking that the seals in the blower are possibly gone and thats the cause of the smoke.

the real question is; can anyone tell me if these sc12's are self oiling? or do they have an external source (err.. the sump)

also, is there any way to test one of these bastards to see if they're goin alright? it makes 5 pound boost instantly and then slowly climbs to 8. i was just under the impression i had belt slippage, but maybe not? i dunno.

any help would be appreciated.

cheers.

**wiso** · 19-01-2006, 02:58 PM

hmm thats the way they are, you always get a fair amount of blow back oil in the intake lines, it just all comes from the cam cover breather (i am pretty sure) you just give it a clean out every now and then, run some fuel through your cooler a few times till it comes out clean. are you booting it abit? your smoke could just burning fuel, they tend to run pretty rich, so when you floor it you will get some black smoke, nothing major hopefully

and yes the sc are self oiling, they have their own suplly, there is a 17mm bolt at the botto for draining it and they are filled through the dipstick they have, you'll find that on top of them, it a yellow wing nut.

nah they also do that, they will ussually instantly hit about 5-6psi then after the revs get to about 4000ish they will begine to climb to about 8psi, this is cause of the relitave cranks speed to turn to sc.

**4agte** · 19-01-2006, 02:58 PM

they have their own oil supply

it is quite normal to have oil in the i/c and inlet hoses from blow by and its quite easy to adjust your s/c belt to make sure it dosent slip

**caibs** · 19-01-2006, 03:32 PM

arr k so it does have its own supply.

i know how to adjust the belt though, not that stupid - just too lazy to tighten it haha.

the smoke isnt fuel, if it were just black smoke i'd be relieved, but its white/grey so a little bit more sinister. and yeah, she gets cained so it was gonna happen eventually i guess.

i thought the boost was instantaneous, not progressive because its a roots type blower? maybe its just the clutch on it or something, dunno. doesnt really bother me coz it still goes pretty good haha.

i've started pulling the motor out, just need to unbolt the block from the box and get the rest of the loom outta the way. hopefully it just needs a new set of rings and bearings. time will tell.

cheers for ya help cobba.

**Starfire** · 19-01-2006, 03:38 PM

The 4AGZE is pretty filthy actually when it comes to blowby and crap from the breather. Due to the positioning of the hose the entire inlet tract gets coated with a crapload of oil, especially if you overfil the engine with oil.

Invest in a catch can (largish one with a decent seperator in it) and take out all of your inlet piping/IC. Spray them with degreaser and wash with water. Make sure that they are good and dry before you put them back on, youll find plenty of sludge in there - especially if they havnt been cleaned for a while.

The Supercharger has its own oil supply and uses a very low viscosity gear oil (almost like water). It only has 120ml or so in it. Theoretically it never needs replacing but its not too hard to do. Toyota charges an arm and a leg for the stuff, but Holden sells a supercharger oil for their 3800 engines for about $25.

**wiso** · 19-01-2006, 09:02 PM

Originally Posted by caibs

i thought the boost was instantaneous, not progressive because its a roots type blower? maybe its just the clutch on it or something, dunno. doesnt really bother me coz it still goes pretty good haha.

the speed of the charger is relative to the crank speed. theoreticly the faster the faster the crank turns the faster the charger turns, the faster the charger turns the more boost it produces, the charger needs to be turning at a certain speed to produce the full level of boost, and it doesn't reache them speeds until the crank is turning fast enough

fuck it i give up, i just confused myself

**caibs** · 20-01-2006, 01:12 AM

arrrrrr yep i think i understand. basically when it first starts spinning it makes the largest portion of boost (5psi for example) but isnt operating at full capacity until spun harder.

either way, i got sidetracked and started drinking. the hard part is finished though.

**takai** · 20-01-2006, 01:23 AM

You would be doing extremely well to have your supercharger oil leak into the charger lobes without catastrophic failure. I would be looking at the PCV.

**caibs** · 20-01-2006, 01:25 AM

aint no pcv to look at.

she vents atmo and breathes quite heavily if you catch my drift.

**oldcorollas** · 20-01-2006, 01:28 AM

Originally Posted by wiso

the speed of the charger is relative to the crank speed. theoreticly the faster the faster the crank turns the faster the charger turns, the faster the charger turns the more boost it produces, the charger needs to be turning at a certain speed to produce the full level of boost, and it doesn't reache them speeds until the crank is turning fast enough

fuck it i give up, i just confused myself

just to clarify

engine is positive displacement
supercharger is positive displacement.

they both move their fixed volume per revolution. theoretically..

however, at low rpm, intake velocities of the engine are low, AND the valve overlap is an issue, whereas for the SC, it still happily pumps away.. and at lower speeds is more efficient..

so it's more likely that you are losing boost thru the exhaust down low, then things get hapy, then up high you lose boost as the SC becomes less efficient..

that make sense?