r33_racer

Did it sound like it was detonating when it was overboosting?

Leave that drain where it is. It's fine. Just put 1 x -12an weld on fitting on the inlet side of sump and hook that up to your catch can. This will give the excessive crankcase pressure an exit to atmosphere without carrying large sums of oil with it.

I believe he means the std rb25 VCT drain at the front of the head on exhaust side. You really need a bung welded on the inlet side of the sump as high as practically possible. I wouldnt drill a hole in the block itself.

Your rings on your cp pistons are not sealing as good as the oem ring set on the factory pistons when it was just a 25.

Your problem is excessive blow-by and its stopping the oil in the head from returning to the sump in a regular manner, both your crankcase internal vents and internal head drains are working as vents so the oil is being trapped in the head and then being blown out your cam covers lines into your catch can. You want to put a breather line off the inlet side of your sump -12AN is a good size, above oil level and run it directly to your catch can. Your cam cover lines should be atleast -10AN.

Hooray for the pistons turning up! Not so much for the hand surgery.....does not look enjoyable! Coincidentally my old man just had surgery to fix his carpal tunnel syndrome in his right wrist. Apparently its quite common in mechanics and tradies who often use hand tools. Shunting spanners, ratchets and breaker bars with the palm of your hand to crack nuts/bolts is a primary cause! So there is something to be weary of in the future!

Well it seems like the logical explanation. There doesn't really seem to be too many other obvious options left that explain the problem.

Should be more like almost double those figures for the sort of rpm/boost you would be running. Like around 80-90 lbs. Perhaps with your new aggressive valve train/cam setup the valve springs were not spec'd correctly and your getting some valve float in that upper rpm range.

I wasn't saying the Nissan OEM rings are the ultimate setup. Just that they tend to seal better then newer age thin rings supplied with most forged pistons these days. No doubt if the stock rings are 10 years old they could be due for refresh. What sort of issues do you have? Breathing issues? Unfortunately every engine is different, some maybe more rigid then others and help provide a truer bore for the rings to seal on easier. The RB25 vct drain shouldn't act like a vent as the venting of the engine occurs on the inlet side not the exhaust side, that is the drain or return side for the oil. Its natural direction of flow is blow-by up the inlet side of the engine and oil drains down the exhaust side, however that is when the engine is running in a normal condition where it doesn't have excessive blow-by which is forcing itself up both sides so it can escape out the cam cover breathers. I guess in that situation an RB25 would have the slight advantage over the RB26. Thin rings work fine in N/A engines, simply because they don't see the same high cylinder pressures and temps that exist in turbocharged/supercharged engines. It's similar reasoning why forged pistons for turbo cars are beefed up everywhere so they can handle the extra horsepower which presents itself in the form of higher pressure/heat. All of what I have discovered is only from my own experience. We went from one engine with thin rings breathing heavily whilst making 600rwhp on alcohol to the same engine but with new pistons with the thicker rings to not breathing at all, and by all I mean no visible fumes and the can inside is perfectly clean and the air filters nice and dry instead of soaking with oil residue.

The fact of the matter is the radial width does change how well the rings seal. A thicker ring has more sealing surface area against the bore at any point while going up and down the bore, being thicker it has more tension and sealing ability on every cycle where expanding gas isn't helping push it against the bore, it can handle and transfer substantially more heat from the piston into the bore for cooling ultimately giving it a longer lifespan whilst keeping a much better seal (less blow-by) for that duration. Your idea of a fix is just a band-aid solution like the rest of them and that may in fact be good enough for a lot of people. However there will be people who want to know what the real cause is and then fix it at its root. The most effective band-aid solution I have found is to run a single -12 vent from the inlet side of your sump pan and run that to your breather can, combined with your lines from the rocker covers that helps vent the excessive blow-by from the crankcase and head which stops excessive oil accumulating in the head (which previously could not drain to the sump via internal returns as the crankcase was in positive pressure) which would normally get carried out of the rocker cover breathers into your catch can, filling it up and blowing it out all over your engine bay.

Its in the RB30 guide mate. Download it and have a look.

Mate you are the first person to identify this as the real issue/fix that I have come across! I have been waiting for a while now to see who else would catch onto this. I figured this out a while ago with our race car engines. When we build our engines we don't use Nissan rings, just the old school approach of 1/16", 1/16", 3/16" rings. We go one step further and run a second gap less ring and we run the second ring gap tighter then the top. With this setup we don't see any breathing at all. Breather can is dead dry, the filters barely vent any fumes at all, only a little while she is bedding in on the dyno. The rings get bed in hard and quickly on the dyno, loaded up and heat cycled a few times, works perfectly! The venting of the sump and covers as has been covered before is an adequate band-aid fix, as is the mines rocker cover baffle setup. However, as stated these fixes simply alleviate the excessive blow-by carrying oil out into your engine bay and making a mess. The real issue is the poor ring seal you are getting which is causing all these issues in the first place. Get the engine to seal up and that will fix the issue! The problem is no piston manufacturer makes their product to suit thicker rings (like std Nissan rings), they all use thin rings which just don't have enough tension or meat to handle the rigors of a blown engine. The only answer is to order custom pistons which isn't really that much more expensive, it just takes longer. Maybe now people might start believing me if others on the forum start seeing it as a good thing. People these days are so skeptical, show them in person and they don't know what to think, but let them read it on a forum mixed up with a lot of bullshit and its suddenly taken as gospel! Its crazy!

crazy phantom problem! How frustrating

ACL/Ross forged pistons.

Precisely what he said.

You could deduce quite safely that if an RB crank fits into the RD28 block then surely the inverse would be true. I can tell you that the main tunnel is the same size, I'm just not sure if the big end journals are or not.

Yeh, two flats, to a spline to gears. Obviously the better setup is an external single stage pump. Then limiter bashing wont matter at all!

Total seal are pretty well bang on. The hype with pressure build up and ring flutter is essentially hogwash for the most part and doesn't really appear in 95% of applications, more so just the very high end people; the other 5%. You can gap your rings almost anyway you want, looser or tighter, so long as you are in the ballpark where the manufacturer has spec'd them you will be okay. My ring manufacturer (Aussie bloke in Melbourne) tells me to gap my rings tighter on the second FYI.

Its probably abit too late now, however I always run the second ring tighter then the top. Usually use bore x 0.0065" for top and bore x 0.005" for second ring gap. Never had any issues nor any signs of butting. Having a loose second ring gap is only encouraging the gasses to get past the rings easier. That doesn't make much sense.

haha I'm here! Yeah, Noel and Mike are spot on. Im stretched a little thin atm. However I have fixed the issues I had on the dyno the first time. Its just a matter of getting time to go back to finish off the tuning. Currently fabricating a whole exhaust system on my old mans HR holden w/ stroked LS1 to 383CI, then I have my uncles 56' chevy to fit new 434CI stroked small block into and fab up exhaust system and fuel system. After that is Dads 57' chevy which a 632CI BBC with a 4L80e box to go into it and then exhaust system and fuel system to suit. The two Chevy's need to be done before April for a charity event we were hoping to attend at Harry's. So my car has gone on the burner again until further notice unfortunately! If I get some time in the next couple of weeks I will attempt to get it tuned!

Awesome stuff mate!

Mate that is unfortunate! I read the thread, who the hell is TRP? Clearly they cant be known building tough motors if this one was stuffed before it even ran! How dodgy is their workmanship! Sorry to hear about your bad luck with that buy mate!

He has made some manifolds with 1" pipes... He was testing them on sr20s a few years ago mainly for street and drift cars where response was favoured. I think he said he found it was only good upto a certain power level before it became too restrictive. Can't recall all the details, it was a while ago now.

Ok. The nuts look like arp. But usually there is the Allen hex in the top, but those seem to not have it. Curious to know what they are.

Quick question. Are those main studs in upside down? Or they some non standard type? Shouldn't there be a hex in the top?