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[ 9 posts ] |
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Blacktop 4AGE Oiling System Research
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Fred
Moderator
Joined: Tue Jan 15, 2008 2:31 pm Posts: 15080 Location: Home sweet home!
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So, I just did some blacktop oil return and coolant routing investigation, and I'm a bit shocked. Those big drains you can see in the head gasket don't do s*** until the head is half full! Which leaves the two small ~12mm ones rear and mid-front to do the work. Furthermore, adding external drains to it is really tricky, difficult but possible at the back on the intake side, but hard core/impossible at the front on the intake side. Another thought crossed my mind, too, contrary to every engine I've ever seen, (see next post) the right place to take your breathers off is smack in the middle of the top of the engine and up high, which would also require some custom fab etc but would ensure that even in a nasty flood of overflowing, it'd stay dry. That could be emulated by taking the breathers off the usual places, routing them together and upward, and plucking it off the middle of that. This quite possibly would have saved me on the ute at Hampton Downs. I guess the equivalent is to take the LHS breather and route it upward and RIGHT and away, and vice versa for the RHS breather, otherwise it's just a giant funnel out of the engine and into the guard :-D You heard it all here first. Probably. I guess the purpose of that central "drain" isn't a drain at all, what in fact is, is the channel through which blow by can escape through the head and breathers, and for that it'd work admirably. I'd probably leave that completely alone even though it has big potential to get a lot of oil out of the head. I wonder what 16v shit is like? For the 20v, the entire intake side is all ports, and the gaps between the ports align with the head bolts, and the area below the ports is 100% cooling, which only leaves these two tiny areas at the front and back, but the back one is ultra tiny due to the shape of the casting and the cam belt etc. I wonder if the inter port gaps can be used in some clever fashion - maybe, just maybe. I think I'll have to get some sort of table setup and take this smoky blacktop apart. Thinking about this all from a FWD perspective- Cruising - no big drama, RPM low, oil level approximately flat, oil able to casually drain out of both left and right side front drains (front and back of engine, exhaust/LH side)
- Braking - no big drama, regardless of RPM, oil pushed at in excess of 1g toward the drains means excellent oil return, if insufficient, the rather high centre passage will come into play much earlier due to the effective angle of the surface of the oil
- WOT Acceleration in 1st gear - no big drama, only lasts a second or two, later gears pull very low Gs, much like cruising, but RPM in the 6k to 8k+ range, both oil returns will be working hard with some minimal pooling in the head at the intake side due to mild Gs.
- Hard Turning Left - no big drama, high effective to-sump pressure driving oil out of head through RHS drain at front of engine, if feed was excessive, and corner was long, loss from breathers could occur, but most corners just aren't.
- Hard Turning Right - no big drama, exactly the same as left, except LHS drain at the rear of the engine is used.
Summary: Not great while turning, mediocre while accelerating, great while braking, fine while cruising. The same set of states in an unmodified RWD configuration- Cruising - no big drama, RPM low, oil level approximately flat, oil able to casually drain out of both front and rear LHS drains
- Braking - no big drama, high effective to-sump pressure driving oil out of head through front LHS drain, if feed was excessive, initial speed was high, and RPMs kept high, loss from breathers could occur, but would not be sustained for more than a few seconds at worst.
- WOT Acceleration in 1st gear - no big drama, only lasts a second or two, later gears pull very low Gs, much like cruising, but RPM in the 6k to 8k+ range, rear LHS oil return will be working hard with some minimal pooling at the rear of the head as supply exceeds expulsion.
- Hard Turning Left - Terrible, we have a problem! Oil will pool heavily in the RHS of the head where it has NO drains whatsoever. This will take seconds to build up, but once it does, oil will be lost from breathers which are very poorly placed for this scenario, and the head will remain full of oil. This is bad for your bottom end too, as while it's in the head, it ain't in the sump, and your pick up will be sucking air to some degree after the oil volume in the sump has been reduced sufficiently. This is the scenario that drives modification of the head.
- Hard Turning Right - Exactly like FWD braking, regardless of RPM, oil pushed at in excess of 1g toward the drains means excellent oil return, if insufficient, the rather high centre passage will come into play much earlier due to the effective angle of the surface of the oil
Summary: Disastrous while turning left, great while turning right, mediocre while braking or accelerating, fine when cruising.
_________________DIYEFI.org - where Open Source means Open Source, and Free means Freedom FreeEMS.org - the open source engine management system FreeEMS dev diary and its comments thread and my turbo truck!n00bs, do NOT PM or email tech questions! Use the forum! The ever growing list of FreeEMS success stories!
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Wed Jul 27, 2016 5:12 am |
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Fred
Moderator
Joined: Tue Jan 15, 2008 2:31 pm Posts: 15080 Location: Home sweet home!
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I realised while writing the above that I'm not the first to think about joining the two side's breathers together and taking off that joint volume. Nissan sort of did it on their R32/R33/R34 (real) GTRs. Here's a cropped close up of the factory Nissan setup:  Original scaled down: http://stuff.fredcooke.com/NissanSkylin ... maller.jpgOriginal large image: http://stuff.fredcooke.com/NissanSkylin ... ineBay.jpgAnd these characters at FEAT have improved upon it further with their R32:  Original: http://stuff.fredcooke.com/NissanSkylin ... ineBay.jpgIt could probably be made to look a bit neater with the right sort of central enclosure and fittings, but the FEAT setup is excellent in terms of keeping the oil out of that hose even when the head is suffering from major flooding at high RPM with max blow by, etc.
_________________DIYEFI.org - where Open Source means Open Source, and Free means Freedom FreeEMS.org - the open source engine management system FreeEMS dev diary and its comments thread and my turbo truck!n00bs, do NOT PM or email tech questions! Use the forum! The ever growing list of FreeEMS success stories!
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Wed Jul 27, 2016 5:39 am |
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ivan141
LQFP112 - Up with the play
Joined: Sat Sep 29, 2012 9:16 pm Posts: 148 Location: Rotterdam, the Netherlands
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16V 4AGE's suffer from similar difficulties with the crank ventilation. The vent is situated in the top-middle of the intake side cam cover, if you take a looong right hander in an AE86 you're likely to leave a smokescreen. The later smallport 16v's had an added external oil drain, but those only came in FWD cars. Restrictors for the head oil feed were made by HKS for high RPM 4AGE applications to help combat these problems.
_________________ FABRICA MI DIEM, PVNC!
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Wed Jul 27, 2016 7:38 am |
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Fred
Moderator
Joined: Tue Jan 15, 2008 2:31 pm Posts: 15080 Location: Home sweet home!
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That'll teach me for not mentioning the restrictor head feed situation! If they are entirely unrestricted in the first place, then yes, that's an important step. If they already have restriction in place (as the vast majority of engines do) then reducing flow is scary to me. Here's a shot of the factory restrictor in my Mazda 4 pot, it's 2.5mm ID:  Based on that, I'd say ~2.0mm would be an appropriate size for the blacktop 4AGE to use, if anything. I see "mototq" recommending that the hole size is a whopping 3mm! Nevertheless, a restrictor only increases the time to trouble it does not and cannot solve the actual issue, which is well distributed drainage. And given that in FWD format these things are happily trackable (I've done it) with zero oil issues through the crappy little twin ~12mm holes, you've got to wonder just how much restrictor is a good idea. It's obviously not flowing huge amounts of oil into the head or there'd be a general issue even in FWD layout usage. EDIT: Another data point for sustained high revs, I once drove my ex's AE111 home down the motorway at the speed cut of 180kph the whole way and at no point did it accumulate oil in the head to the point of inhaling it. I've actually spent a bit of time studying all of my performance engines recently. This spurt of research was triggered by the issues I had with the ute in the sweeper at Hampton Downs. But the ute engine actually has the best setup of the lot, aside from the fact that it only drains down the intake side of the head. It'd have roughly 4x the drainage compared to the little 4age's 2 small holes (ignoring the high rimmed centre hole which doesn't count until things are badly out of hand). And it still filled up, but only on the sweeping right hander, no where else :-) Volvo redblock: 3 smallish ~15mm holes between the three bores on the uphill side of the slant engine with head internals cast to create a level playing field. Nissan RB: 2 very generous odd shaped holes, but both at the rear of the head, one on each side. Great for straight line abuse, terrible under brakes, and mediocre to bad while cornering hard for sustained periods. Ute engine, as discussed, 4 massive drains on the RH/Intake side of the head when RWD I guess a few photos of the 16v external drain is in order for comparison:   If you can find a better picture, slap it up here! :-) Next up, cooling systems, though I'll probably hold off publishing that until I have my gearbox-engine interface sorted and can mock things up in the vehicle and see how much space there really is.
_________________DIYEFI.org - where Open Source means Open Source, and Free means Freedom FreeEMS.org - the open source engine management system FreeEMS dev diary and its comments thread and my turbo truck!n00bs, do NOT PM or email tech questions! Use the forum! The ever growing list of FreeEMS success stories!
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Wed Jul 27, 2016 8:09 am |
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Fred
Moderator
Joined: Tue Jan 15, 2008 2:31 pm Posts: 15080 Location: Home sweet home!
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Here's the HKS oil pressure up kit with spring, washer, and restrictor plug: https://www.nengun.com/hks/4a-g-partsAnd here's the image, cached:  I won't be taking the head off my first engine anyway, so no chance of a restrictor going in. But if I can safely machine some drains into it while it's still on the block, then I will.
_________________DIYEFI.org - where Open Source means Open Source, and Free means Freedom FreeEMS.org - the open source engine management system FreeEMS dev diary and its comments thread and my turbo truck!n00bs, do NOT PM or email tech questions! Use the forum! The ever growing list of FreeEMS success stories!
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Wed Jul 27, 2016 8:26 am |
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Fred
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Joined: Tue Jan 15, 2008 2:31 pm Posts: 15080 Location: Home sweet home!
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A little more context: User 'piimae' modified his 16v head for drainage from the rear right hand side, not quite how I'd like mine, but good enough in a sustained LH cornering situation with mild to wild acceleration. Here are his pics:    He also made some comments about his usage: Quote: (18:48:08) piimae: I've never had any issues with breathers and oil spills on any of my 16v's btw (18:49:43) piimae: I made an oil drain in the back of the head on the intake side (18:50:42) piimae: also I'm using the stock 10mm intake breather plus a 16mm or so from the middle (18:51:04) piimae: zero issues (18:51:56) piimae: not that many long high speed turns on the track I prefer though (18:54:43) piimae: not that you'll be going "high speed" in a 4ag anyway ;) (18:55:34) piimae: I prefer the slower, more technical tracks.. well did anyway before turbo <SNIP> (20:06:26) piimae: oh and no block restrictors <SNIP> (23:12:39) piimae: the holes that feed the lifters & cam journals are tiny, 1-1.5mm max out of memory, 16v that is.. <SNIP> (05:30:04) piimae: fredcooke: kytkinpotku.org/rusina/img/headdrain1.jpg 2, 3.jpg (original source, cached by me above) (05:30:25) piimae: it seems I misremembered the size, looks more like 10-13mm ID (05:30:32) piimae: anyway, zero problems still If the 1-1.5mm max is correct, that totally explains the lack of block-head restrictor. I can't go and measure right now (because I got the wife to lock me out of the workshop, lol) but I think the Mazda cam journal and lifter bore feed holes are around 3mm or so. Which would explain why the Mazda has it. I'm guessing the RB heads have decent sized holes into their cams/lifters, too. Solid lifter RB26 has only one feed to the head, instead of two in other RB engines, presumably just for the cam journals, relying on splash/flood/spray/splatter/fling to lube the solid lifters. I had a poke around for photos, and the feeds at the front end of the cams look bigger than 1/1.5mm to me, but perhaps he meant out of the cams into the other journals. A few things from this Tomei RB product link: http://www.rawbrokerage.com/tomei-oil-g ... rb26-rb30/They claim stock RBs have two 2.0mm holes and reduce that to two 1.5mm holes. roughly 1.77sq mm each, 3.53sq mm combined. 4.91sq mm for the Mazda factory restrictor. 6.28sq mm for the stock RB restrictors IF their information is correct. Now given the RB head is feeding the same bore size, same valves, 1.5x as many, 6.28sq mm compares favourably to 4.91sq mm in the Mazda. Yes, it'll push more oil into the head, but it also needs to. How do we compare a smaller 4age in terms of required flow path? Not sure, hence my guess of 2.0 which would yield exactly PI sq mm, 3.14. If the Tomei kit doesn't hurt an RB then I'd confidently say that, aside from the VVT pulley, a 2.0mm restrictor couldn't hurt a 4AGE either. Here's their picture illustrating one of the issues: 
_________________DIYEFI.org - where Open Source means Open Source, and Free means Freedom FreeEMS.org - the open source engine management system FreeEMS dev diary and its comments thread and my turbo truck!n00bs, do NOT PM or email tech questions! Use the forum! The ever growing list of FreeEMS success stories!
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Wed Jul 27, 2016 11:56 pm |
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Fred
Moderator
Joined: Tue Jan 15, 2008 2:31 pm Posts: 15080 Location: Home sweet home!
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Some photos I took yesterday to go with this write up: Small left front stock drain: https://twitter.com/FredCookeNZ/status/ ... 2295248896Small left rear stock drain: https://twitter.com/FredCookeNZ/status/ ... 9534497792Central left non-drain over exposed: https://twitter.com/FredCookeNZ/status/ ... 7540695040Central left non-drain under focused: https://twitter.com/FredCookeNZ/status/ ... 6525603841Where you can't put an oil drain on the right front: https://twitter.com/FredCookeNZ/status/ ... 5042397184Difficult place where you could put an oil drain on the front right: https://twitter.com/FredCookeNZ/status/ ... 2969063424Right rear oil drain location, left of 'O': https://twitter.com/FredCookeNZ/status/ ... 0282833921Inlined, read tweets for better descriptions:       
_________________DIYEFI.org - where Open Source means Open Source, and Free means Freedom FreeEMS.org - the open source engine management system FreeEMS dev diary and its comments thread and my turbo truck!n00bs, do NOT PM or email tech questions! Use the forum! The ever growing list of FreeEMS success stories!
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Thu Jul 28, 2016 6:53 am |
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Fred
Moderator
Joined: Tue Jan 15, 2008 2:31 pm Posts: 15080 Location: Home sweet home!
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So, first hand, tonight, I saw this RB25DET engine's left front factory side-drain: https://twitter.com/FredCookeNZ/status/ ... 2569020416 Apparently there are more than what I thought, small holes, all the way down one side, that can be enlarged somewhat. Hopefully I'll see these first hand sometime soon :-) cough, Rob, cough. Links welcome. Ignore the topic, it's good background info to compare with. Quote from an SAU thread: "ever since i blocked off my oil line and restricter the other I have had major lifter noise when the car is driven slowly and cruising to work. As soon as i start hitting boost or idle in traffic for a while (engine gets warmer) the lifters stop making noise." Not too surprising, TBH. There is no way I'd have done that with HLAs still in there. I'd be scared for the camshafts, too, as the HLAs should pump up and work so they must literally be starved of oil to make any noise at all. Ugh. Here's a couple of pics, first raw, then with my markings. The two big ones on the right are definitely oil drains. The top one on the left I'm unsure about EDIT: Pretty sure this is coolant, not oil. The lower 5 have to be what Rob was describing earlier. They're on the down hill side of the slightly slanted engine. Please confirm/deny what you know :-D  
_________________DIYEFI.org - where Open Source means Open Source, and Free means Freedom FreeEMS.org - the open source engine management system FreeEMS dev diary and its comments thread and my turbo truck!n00bs, do NOT PM or email tech questions! Use the forum! The ever growing list of FreeEMS success stories!
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Thu Jul 28, 2016 11:04 am |
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Fred
Moderator
Joined: Tue Jan 15, 2008 2:31 pm Posts: 15080 Location: Home sweet home!
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RB wise, I came across the below photo from this thread: http://www.sau.com.au/forums/topic/4523 ... rs/?page=1Some interesting stuff being done in that thread. Not sure about all of it, but worth investigating anyway. 
_________________DIYEFI.org - where Open Source means Open Source, and Free means Freedom FreeEMS.org - the open source engine management system FreeEMS dev diary and its comments thread and my turbo truck!n00bs, do NOT PM or email tech questions! Use the forum! The ever growing list of FreeEMS success stories!
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Thu Jul 28, 2016 12:14 pm |
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