Canada 1993 gtr ready for action
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More assembly going on, with all sorts of "bolt right on bro" scenarios going on here. Smartly, PTV clearance was checked. And I say smartly because it turns out that the intake was 0.009" from piston meeting valve. This is 0.23mm. This is very not okay. A fast meeting was facilitated between engine builder in Australia and engine builder in the USA which was actually incredibly helpful and constructive actually, various ideas thrown around to get around this issue including: 1) Retard the cam timing which would have brought the exhaust valve closer to meeting piston (it was 0.065") which was uncomfortably close to begin with, and change the cam profile making it 'laggier' 2) Much larger head gaskets which would reduce compression, but half the point of this was to increase compression. 3) New set of pistons ($$$$$$$$$$$$$$$$$) 4) All of the above 5) Get ghetto The concept is you get sticky sandpaper and stick it back to a valve, slightly larger than the valve you/I'm using, like say from a LS3/rectangle port head. You now have a very super advanced flycutting tool to modify your pistons in your block. Then you install it in your head, and attach the other end of the head to a drill. Then you just replicate your valve smashing into a piston with your spinning drill. This is the result. Repeat many times. It is strongly recommended you have some kind of fixed stop when doing this for extremely obvious reasons because if you press too hard then you're well into apocalyptic repercussion land. The minimum clearance on the intake valve is now 0.075" this is still in the "Too close to be really comfortable" and into "It should be fine" land. Supposedly in the real world the clearances will be slightly bigger. Guess this is what happens when people push envelopes for N/A engines instead of adding boost! Time to move onto the new, upgraded, higher ratio roller rockers from Yellaterra, all tapped and threaded with a stronger bolt for better stability. Very nice. Lets see how they fit. For f**ks sake. Time to bring the grinder out for these aftermarket, machined and CNC'd heads. Looks like the new, beefier rocker from YellaTerra has gone from Bolt on part to "Bolt on part". Well, lets see how this bolt on crank scraper and windage tray goes then, shall we? There actually is more clearance than they specify for this thing, but seeing it all move as you check it is terrifying when you see it all so very very very very nearly hit things. But after all, this is what the item is designed to do after all and actually did bolt on perfectly and have enough clearance to everything and some very clear and direct instructions. So +1 to Improved Racing I suppose. As above with the windage tray on. Photo of breaker bar wonkiness for added lols. Next up: Oil pump/front cover/water pump/sump and then it's time to actually install the heads, pushrods, head bolts, valve cover gaskets and such is all there and ready to go. (except the oil pump bolts which were previously longer for more clearance with the previously perfectly installed double row timing chain). There's definitely a sense that someone other than us has been here before and done everything perfectly, or at least considered it and came up with working solutions. Perhaps the previous cam was 6deg advanced to avoid PTV issues with the milled stock heads? In any case when I attempt to sell this stuff the buyers are going to be very directly informed. -
my catch can is pretty easy to empty but it overflows due to the blowby/crank case pressure etc. max I have drained is ~600ml even with a ~2.3L capacity. So it is not just about having to drain it out its the mess it makes down the firewall and under the car and rear passenger tyre from the overflow oil being blasted by screamer + air in general. Ending up on the ground cleaning the oil up and having oil on your arms when everyone else can chill and watch the other sessions gets old fast -
Yeah - the secret learned a long time ago is that the RB likes to belch oil out the covers, and/or starve the pump because it drowns the head in oil, because the upflow of crankcase gases from piston blowby comes up through the oil drain holes in the block and prevents the oil from flowing back down. The external vents from sump are about creating an alternative path/much more XS area for gas flow to decrease the gas velocity up through the oil drains and allow the oil to get back down. So, it's not about pressure at all. It is about flows - gas up and oil down - or when it's not working, gas up and oil not going where it is supposed to after it arrives at the top, except out through the cam cover vents. And regardless of whether the catch can is vented to air or vented to the turbo inlet, it must still be vented because a sealed system would blow out the crank seals, or something equally bad. -
I just used a can that's easy to empty after every session and pour it back into the fill hole. Takes about 40 seconds when you have 40 minutes between runs :p I don't see how changing any catch can stuff will reduce pressure if the system is sealed. And if it's vented - Does it matter where it's vented with regards to overall pressure?
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Welp, too late already committed to the cam cover breathers to be welded on. I did think about adding a catch can in line with the drivers side sump breather as a phase 2 along with a drain to the sump on the original catch can but with an inline ball valve so I can have it closed if needed. Likely a single breather would have been enough but I think I’m overcompensating to hopefully not have to empty my catch can and clean up oil over flow every session. out of curiosity has anyone actually measured crank case pressure before and after various mods? I’m considering adding a sensor for science
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