Lopin18

U would be surprised how many people dont take crankcase ventilation into account. They tested the car today, no more smoke. So hopefully its just working the crankcase ventilation. Thank you btw, i had missed some concepts including the turbo oil return line.

Neat, i was thinking so much i didnt remember that the oil return line from the turbo is another path for pressure to build up. Thanks for the feedback. On monday they will trst the car again to confirm, ill reply back then in the dyno they noticed the valve covers leaking pressurised air, along with oil, but the valve covers were a bit loose, i can imagine the pressure buildup was enough to cause what they saw...

Both hoses from the valve cover go to the oil catch can, PCV valve is joined with one of those valve cover outlets. The catch can itself has 2 inputs from the valve cover outlets. NO outputs on the catch can, meaning no return to the crankcase, no vented filter, no outlet to the compressor pipping. So basically pressure just builds up, theres nothing venting or allowing the crankcase pressure to go anywhere (just the PCV valve, which will be closed during boost)

So, a friend called me to see a GTR with a built RB26 that has been smoking hard under WOT load , it made 480hp, 360tq with the last turbo (precision). on the dyno and they saw smoke coming out of the exhaust housing and then the exhaust pipe. Before that, they thought the turbos were the problem. new turbos, same thing, precision single turbo, same thing. So i went to help, checked compression (all good around @ 170psi), did a leak down, found cyl 1 and 4 giving a loss of around 10-12 psi @ 74psi down to 60 and 70psi to 54, other cyls had 2-4psi loss. This is my only clue. * Checked PCV valve, its fine, plugged it just in case * Took valve cover hoses off (oil catch can has no crank return nor atmosphere vent, its basically a closed box) * Oil return seems adecuate, no rough path to the crank Then, we tested the car, hard wot 1st,2nd and 3rd gear, it only smoked on 3rd gear WOT at high rpms (6500+) and it was a lot of smoke, it blocked the lane behind us. Oil came out of the disconnected valve cover outlets and fell on the turbo and block. As expected. we have to retest with the hoses pointing to the intake side but since they DID see smoke coming out of the tailpipe on the dyno, i can only hope that the PCV being completely closed off could have done something internally with its built pressure on the dyno and burnt oil inside the combustion chamber. I saw some wetness on the pistons from the plug hole, saw no oil or sign of it on the downpipe and exhaust housing. But being realistic... i fear that something is wrong either on the pistons or valve train area. I thought it was the PCV system because i saw the closed box and wondered about the PCV valve etc.But seeing the compression fine but a bad sign on the leakdown. So this left me curious. I thought a cracked piston ringland or a bent valve or bad valve seats would show at all RPM ranges, to different degrees, but this engine only did its smoke screen on 3rd gear, WOT, after 6500 rpms. Any ideas? experiences? i cant open this engine for fun as its not mine so im left with the sad state of not knowing for sure.

PCV was unintentionally ignored, facing the first event it was all quick. Its going to be directed to the catch can now. Catch can is vented to atmosfere. Has a bottom fitting to return oil to pan. I thought the rear vent or drain, wouldnt really hurt anything, whats the generan consensus on it right now? Turbo seals, old holset turbo, used exhaust wheel, i think its out of balance, i keep repairing it every 2 events. Now i bought a new chra to replace the whole thing. I have an oil restrictor on it, but its pretty big, it has a 4mm hole or bigger. Oil temps were indeed sky high, it was a small track, 2nd gear, it was intense and the engine was heating up quite a bit. AFRs are rich, we run around 11.6 - 12 on boost, 100 octane fuel. no EGT right now. im switching from a Z32 chiped ECU to an Ecumaster emu ecu. Apart from all these small things that may add up to big issues. I cant seem to put my finger on the difference between the good results on leakdown etc vs the blowby or smoke im seeing from the valve cover. I keep hearing that the Mobil 1 oil sold in my country is really bad, noone uses it, but i cant imagine that its so bad that it would cook itself and smoke so much. sounds farfetched. Ill correct the pcv valve hole, new turbo, gotta ask around about the turbo oil restrictor. Retuning soon on the new ecu. using knock and a bunch of new sensors to take care of the engine. Just have to figure out this smoke thing. Im almost opening up the engine and rechecking everything. Its not a lot of work for me.

This will be a weird one: RB25 Neo head on rb25 neo block with 26 internals (CP, Eagle, ACL, ARP, Cometic HG 2.5mm), enlarged oil returns, blocked feed, 1.1mm on the other one. VTC inactive. Rear head vent to crank, big catch can vented with oil return to pan and vents to crank and valve covers, Jun oil pump. Tomei baffle box on the oil pan. This was fully done with everything i saw around. Everything was done as perfect as i could. Ever since day 1 ive had a weird white vapor coming from the valve covers (pcv valve hole open to air, i never got it into the catch can), like a light smoke, almost like something burning slowly. And a tick on the head after warm up (i meassured valve to cam clearance as best as i could and its within spec, but im guessing one was too tight maybe...) i ignored it for now. Compression was fine after initial start and break in, 175 psi. Anyways, i made over 450hp with clutch slipping, a lot of things happened, in the end it was ran hard, it worked. Last weekend i went to a drift demo we had. PCV hole was open to air still, engine squirted oil on the bay, oil temp was around 270-290, it was hot as hell. oil pressure was fine all the time, blew the turbo seals BUT i had more white smoke comming from the pcv hole now. shut down, it kept smoking for quite a while, like something was burning. i dont know what that is, maybe its the shitty mobil 1 mineral oil? i dont know. Due to the turbo smoking, i towed the car home, in my mind i broke a piston ringland. But not i didnt. still have 170 psi compression, leakdown @ 75 psi was only showing 2% - 4% according to the instructions on the leakdown tester (4-8 psi loss), compression test was done cold and hot after rolling the car to the shop. leakdown was made cold. This was quick check while hot: at home, 8pm, i shined a light on the pcv hole and i could clearly see the smoke being pushed out, giving it throttle it clearly pushed it harder. So what now, compression is fine, leakdown is fine, but engine seems to be smoking from the covers for some reason. im leaning towards BAD oil doing something weird under heat. I supposed blowby would be noticeable on the leakdown, but its fine right? (75psi in, 72psi held, it was never over 8psi difference), maybe i dont really grasp how blowby works vs these tests or something.... Any ideas?

Taking lots of notes lol. Thing with response is that im running Achilles 123s and similar grippy tires and it would be better for me to get a better torque curve down there.(our track layout keeps giving me a hard time when i have to get the power back up to spin those tires after they heat up, they are insanely grippy and i have to keep up with the high budget setups here) Right now i have low torque on low end, clearly due to the turbo selection as far as im seeing now after watching responses and dyno sheets from setups used around here. AHh that damn dyno sheet didnt have the torque line, ill try to get it. Now diving into that huge thread from hypergear.

So im trying to refresh my setup to get more response, torque, this is purely a drift car, but i cant seem to decide what would work out to achieve my goals.... I was planning to get tomei cams, 260 9.15mm, but as far as ive seen the stock ones give a better low end/mid torque setup, springs and retainers ill hold it off for now since i dont wanna rev more, i want low end torque.... exhaust manifold ive been reading that the stock one being a log style, would give better spool.... only thing that comes to mind right now is a standalone ecu and switch from 100 octane to VP fuels 109 octane or VP 113 with lead and give it more timing.... maybe even switch the headgasket to a thinner one to get 10.5:1 CR What are the options for these engines to improve it torque wise and in the low rpm range? RB25 Neo specs: -Rb26 Crank, CP 26 Pistons, Eagle rods -RB25 Neo head, quench pads removed, 2.5mm cometic HG, compression ratio is around 9.5:1 -Stock exhaust manifold, Godspeed intake manifold -Holset HE351 turbo -550cc rx7 injectors -Z32 ecu, chipped -Oil control mods, crank collar, jun oil pump, restrictors etc etc. Last time i broke the exhaust poncam installing it so im back to stock cams. But now im stumped. i dont know whats the best plan, budget is not very big and the turbo selection was made because i can easily repair and replace that turbine without hazzle (im in a Caribbean island), thats the dyno sheet, its pretty close to my last dyno on a stock rb25 neo, before mixing the rb26 forged parts. Compression ratio stayed pretty much the same so i guess thats why. (Stock is 9.5 i think right?) and i had 450hp @ 23psi before, so im pretty much in the same position as before. That was last friday, i broke the clutch on sunday, it was slipping so i think thats why the dyno sheet has a weird peak in 2 places. speed remained constant so thats why we ignored that we had a clutch problem but it was definitely slipping on the track @ WOT

Jeez, how dumb do i feel now, i checked that page like 20 times but i didnt notice the big note. Thanks man!

Poncams seems to be a set everywhere i look, procams tho are sold individually, but now that u mention the ramp rates etc... i dont know much about cams. If i get a procam 260, 9.15mm lift, what makes it different from say a poncam? ramp rate, i thought cams only had 2 variables, duration and lift. Kelfords are out of my budget for now. Seems my option would be to get an exhaust procam or just go with the intake camshaft only. Dont know what that would mean.

Lol whats the recommendation for kelfords? This is a drift car so im looking for low-mid response

While installing the exhaust one i didnt notice that the lobes where in the wrong position so the last one was under pressure and it snapped.... f**k me Now im trying to see how to replace it. i cant seem the find the exhaust only poncam. RB25 Neo, 260 dur poncam type B 9.15 mm lift. All the ones im finding as a single cam are the procams, can i actually replace my broken poncam with a procam with the same duration and lift without issues? or is there something different? i keep reading the poncam is adjusted to stock timing etc but i dont see that on the procam so its kind of confusing.

Currently doing mains, soon to do rods. Ive miced and used a dial bore. Ive gotten a wide range of clearances, so i cant decide how to go with it... Ive got HX y and H shells on hand, ACL Race Series. I can either go all 0.0025" (ranging within 0.0002) or 0.002" (same as before), cant decide which way to go, this engine will have over 450hp, revved to 8k or maybe 7.5k to be safe. Purely a drift engine. First time going this deep into an RB, last time i got a stock engine refreshed with full HX, dont remember my clearance but it was loose, engine lasted a year until oil starvation got it. * Jun Oil Pump *RB25 Neo head *RB26 crank/Eagle rods/CP pistons in RB25 Neo Block.

Thanks, did, new set on the way, ill reuse the other good shells to get clearance on another engine (they are HX). Sigh, im so annoyed at this mistake. Im thinking one of the rags used to wipe the engine had a particle in them, or an oil galley. Dont know but big annoyance.

God damnit, even as clean as i tried to be a small aluminum debris got squished on a main bearing non grooved side (bottom of the engine). I tried to remove it with a sharp thin box cutter and got it out but left a tiny hole. The sharp edge took out a bit of the bearing, ill say its about a 0.5x0.5mm lil hole, depth: it isnt really deep but i do think it went through the coating and the first layer of the bearing, dont know if copper is seen. So im wondering if it matters really, i think it wont affect the general oil film but i dont know if im risking delamination from that small gouge.

Anyone have lying around a set of stock valves for a 26? I just need 2 exhaust and 2 intake valves. Maybe a bucket lifter since mine collapsed.

Ok, so finally got the block machined etc etc etc. Got the bottom end done, torqued etc. Today i did a dummy assembly again. Block got decked, piston deck clearance was affected, so the piston stands right now at 0.3mm over deck. Repeated the same thing as before, clay on piston 1 and 6 this time. Torqued the head im gonna use (it was decked before, this time it was straight so no further decking was done). Stock used HG, ARP, all of them, to 80 ft/pounds. This time i got more valve contact on intake and exhaust, intake was just a touch logically, exhaust went down from 3mm to 2.5mm, this time i used a good caliper to measure it and i repeated it on piston 1 and 6 just to be sure. So im positive i have 2.5mm piston to valve clearance. Next up im ordering a HG, prolly going 1.4mm Tomei, work the head combustion chamber to get the compression down (im removing both quench pads for a change, ive found over 3 stock neo engines that completely melted the intake side of the piston and its always limited to where the quench area is, i dont know if theres something with temps and the quench area intake side but.... i took a look at a VERY expensive RB26 head that a friend has, this thing is revved to 11k rpms and had over 1k hp, a local record setter so im taking if from his head that removing them isnt a leap to hell, im no expert in this im just using the quenches to avoid a suspicion i have and to get those ccs i need) ill set the engine up soon. Thanks to the people who always leave a trail of tips and info to pick up, hopefully this helps out someone someday. Edit: Oh yea, first test was with Stock Rb26 pistons, this test was with SC7310 CP Pistons.

Ok this comes from recent observation of what i was doing. I have a RB26 head and a Neo 25 Head. And a 26 Tomei headgasket. On the RB25neo with VTC, the front intake side of the head has a hole for Coolant and another one for VTC, when i matched the 26 Headgasket to it both holes get mixed. As the HG is the same as the rb26 block, if u use the RB26 block with the 25 head i think you would have to do something about its VTC oil feed as it will receive Coolant. Do this, grab your head gasket, the block and the head. and try to match the HG on the Block, you will see what i mean, then try to imagine whats gonna happen when u mate both pieces, that should help you decide which headgasket to use.

Ok i cant edit the post. New findings on HG and Heads. If im to use the 26 head on the Neo block, i have to block off the VTC feed and i have to add material to a corner since you get a very thin seal (3-4mm) between the 26 head and the neo block on the coolant passage. In this combo i can use either headgasket, the holes dont match but i think coolant flow should work out (but its gonna be restricted) RB25 Neo head with Neo Block, same, cant use the 26 headgasket, you would mix the oil and coolant and u would have to block it off and lose VTC.

Ok, so i got to work on the engine. Tested: RB25 neo Block, RB26 Crank + Neo Rods + 26 Pistons (All OEM), Neo head (kind of confused, ill say why later), used old stock headgasket, ARP Studs on head. Torqued crank with old bearings to around 50ft, then loosened to 30 ft to avoid any damage since these are old bearings on a diff crank etc... Torqued the head with 4 arp studs. 2 on the 2nd row from the front, 2 on the second row from the back. Torqued to 50 ft. Gave it plenty of clay all around. Engine was 100% on timming. Everything bolted down. Only Main studs and head were torqued to mild settings, but i suppose it was enough. Results: Almost no valve to piston danger. Only one exhaust valve got into the clay and it was on its closest, almost 3mm away from the piston. Quench area pressed the clay but it was very big. I didnt pay much attention to that but from the pictures i took i think it has a 1.5mm space between the piston/head quench. Im just wondering why im getting such a huge space on the quench area. Ill retry the test with the forged engine done and ill torque properly everything and ill be CCing the head i used to confirm this is the Neo head because i found it weird that i had so much clearance (pretty sure it is physically but i wanna recheck). All in all, im confused, i was expecting it to be waaaaay closer and the quench area has me thinking, but im sure i gave it enough torque to squish that HG. I think its safe to say that i can use the head, ill only work out its CCs to lower compression. Also i got a RB26 head, but its being welded to repair dropped valve damage and i gotta order lots of parts to fix it. Ill try the neo head and i think ill use the RB26 head when its ready, but i will test the neo head on the running bottom block. Oh yea, those pistons and rods were in another block with an RB25 crank, they sat like 1mm below deck, when i used the 26 crank, they were pretty much flush with the block. So Im wondering really hard why i had such a big quench.

GTSBoy That would be the correct way but i cant fork out 1000usd for forged pistons, that doesnt include all labor and work. But i have 2 plans currently. I was given forged 26 internals and a 26 crank. So i can do a full 26 but i dont have the head. Hence the neo head. Ive been speaking with local tuners and porters. All of them fall back into "How is the valve clearance" So im gonna try that, i think its a safe and productive research. If it has clearance then ill just increase the CCs on the neo head from 51.5cc to 60cc. That should give me 9.5:1 CR. I COULD use 11:1 with fuel, but i dont like it, even if im getting all this for free i dont want to blow the engine for giggles. Btw as far as ive read all 25,26,neo blocks are the same height no? I know the 26 crank has 73.7 stroke compared to the 25's 71.7 stroke. Neo pistons have a unique design, 26 has a lower piston pin. Comparing neo vs 26 seems to have no meaning due to the different design. Rods are all the same as far as ive read. Second plan is to rebuild a stock neo, since i have more than enough parts. That was the initial plan, until i got this donation. Hehe.

Ill do it indeed, just wondered if i could get someone with first hand experience. Im pretty much a newbie when it comes to these measures, ill have to read a bit how to. Even if i get clearance, i still havent figured out how will i go about lowering compression, i dont want to mess with the quench pads, specially since i have dome pistons and i dont know if that combination would cause issues (detonation wise, mixture quality and burn etc.) I cant use the RB26 head because there are none here (Dominican Republic) and whoever has one wants quite a bit of money. Ill post back soon when i test all this out.

First off, ive read a lot.... i just need some info that noone has so far shared in old posts... everyone just changes plans or has the engine done but doesnt go into detail of what they experienced. And a lot of users seem to recommend using the Neo head on RB26s but no info on what really has to be done etc. Right now i have a RB26 crank, forged rb26 rods and forged rb26 pistons, plenty of RB blocks and several Neo Heads. Hence why im trying this out. I got a RB26 head but its damaged extensively. I know they fit. Some have done it but i havent had the confirmed info about this: - CR seems to be around 11:1 - Some have gotten valve damage, others havent. Has anyone heard for sure or has confirmed information of what the CR is on this combo? Or what work was done to lower the compression? I know if i open up the head from 51.5cc to 60cc ill go down to 9.2:1 according to calculations with Deck Piston Height to zero and a 1.2 HG. Also what about the piston to valve clearance. Some seem to hit valves but Mr Bizzle removed the quench pads and had some work done which i dont know and ran this combo for some miles. I have zero experience dealing with Piston Valve clearance, but ill test with clay soon if i dont find info. A friend of mine did this same combo but with an RB25 crank w/ rb26 pistons and Neo head, i think he should have been 1 or 2 mm below deck (piston/deck height) due to the stroke difference and he ran it for a couple of miles on stock ecu and had massive detonation damage, broke ringlands and melted the quench areas but no valve hit. http://forums.hybridz.org/topic/88037-rb26-crankrodspistons-in-rb25-neo-block-crazy-compression-ratio/

Thanks, now i can sort of get an idea of how the RB likes timing. A friend had a Neo too, revving it up to 8k for several years, not a problem ever, but im not in the same range of income as him soo i probably wont go up so far, maybe ill add so i can stay of the limiter more. On the other hand, i set base timing to 15 on the second mark of the pulley (if i remember correctly) so that would mean im running 20 which makes things more aggresive. Im not tuning it myself, i have a well backgrounded tuner doing the work. Im just learning about the RB to have an idea of how close or far we are from safety. Ill be enabling the VTC soon and going back on the dyno, surely ill set the timing to 15 base and retest on the dyno everything. Amazingly we didnt see any knock and when we added some degrees on the high rpm/load section of the map, we saw torque improvement, so i think we are safe as far as audio from the knock headphones and tq band goes. I will try to get the map up here for you guys to see after i check the base timing to confirm it. Maybe ill do a run on the street and bring the map with the trail from the run. For knock detection im using a SR20 Knock sensor, bolted to the block close to the stock knock sensors, with headphones and amplifier connected, i can hear everything, most of the time the injectors, but neither i or the tuner heard anything at any range other than the injectors. So i think we are safe in that part.

Im trying to understand this engine, i really dont want to test how far the timing goes, since the fuel here isnt that safe.... not trustworthy. So. i got 360hp/310tq @ 18 psi on a Holset HE341 turbo. VTC Disabled. Running on 100 octane fuel. stock engine with a greddy copy intake. I understand that this Neo rb25, comes with stronger head parts. solid lifters etc.... 2 simple questions: - How safe is it to race this engine up to 8k RPMs, ill be drifting it. So far im running 7600 rpms. Not a hitch on my last event. Running Castrol full synthetic 10-50w - Timing map, 5000-6000 rpms high load im seeing 27-25 ignition timing, on the 6000+ range high load im seeing 23-19 timing. How are those numbers for an engine like this one? Are they low, high? What timing numbers are you guys seeing on ur setups with 98+ octane fuel and how much hp/tq, Edit: Interesting, seems that the Stagea RB25 Neo, the first mark on the crank pulley is the TDC 0 Mark, ill have to do the timing again. Im interested to know so i can have an idea of how this engine behaves and what timing numbers are low/safe/high for it. On the last tune/dyno runs, we used headphones with knock sensors, we heard no noise at all other than injectors and normal noise, no knocking at all. Thanks in advance.