My rod bearings after a HPDE

[aquariuscsm]

What`s weird about these cars,is that the 1990 manual states 4 5/8 quart capacity,while later models spec 3.8,I think? If I only put in 4 quarts,it doesn`t register full on the dipstick. I have to have a full 4 1/2 to get to the full level. Wonder why the difference in capacities? I wonder if you just need to use more oil? If I were racing,I`d use a dino racing oil like Pennzoil or Valvoline.

 

[A_Harman]

My .02:

Stop trying to fix this thing by juggling oil viscosity. That's like trying to put a band-aid on a slit throat. If oil is not being supplied to the bearing, a little higher viscosity is not going to matter. The difference in bearing life can be measured in milliseconds.

Sounds like you need to get serious about checking journal sizes and bearing clearances. Do the rod bearings have adequate crush in the rods? Are the crank journals round and smooth? Is the vertical rod clearance within service manual specifications?

Get the engine built right, then add sump volume, and an Accusump.

 

[electrolover]

i agree if you had a knocking problem replacing bearings wont fix it. you need to size the rods and turn the crank. try clearancing the crank an extra thou. ask your engine builder about oil system mods. also mod for faster oil return to the pan, like sometimes enlarging oil return holes in the head. carcraft built a 300z, they called fairlady z. in that they completely polished the inside of the block and heads to remove casting sand and speed oil return. its something you can do your self with a grinder and cartridge rolls.
thats about all the help i can give ya because im a sbc boy when it comes to hotrodding. the only reason i remember the fairlady z car is because they stole my idea of a multi peace splined crank and roller bearings for the rod and main.
they stole my idea and built it before i even got a chance to think about having one made

 

[VG30DETT]

Yes you guys are correct about fixing the root of the problem..I used a higher viscosity the 2nd time around as sort of a sanity check if rod bearings did fail again. Hopefully it is a useful example for those people who always blame oil for engine failure

The bearing clearances were to the service manual specs, and all brand new bearings were used to achieve proper crush. Remember, the knocking problem did not occur for years of spirited street driving until the HPDE with exposure to high RPM and Gs. I still have not torn the engine down since the last incident to investigate which bearings suffered this time. I agree that when racing, bearing clearances should be slightly changed for better performance, but after taking care of oil starvation first of course. Effects of removing casting sand would probably be negligible, but if I have the time I would do it for perfection.

I am working on a dry sump retrofit currently. It will be a challenge the way I want it, but it is something I consider a must. I really want to get back on the track and enjoy driving at the limit without being towed home!

 

[A_Harman]

I recently read a tech article about the Nissan GTR, in which they said that its engine has drain hoses from the cylinder heads that cross over to the other side of the oil pan for drainage. (Driver side head drains into pass side of the oil pan & vice-versa.) Pretty elegant feature, I thought. They are taking advantage of lateral acceleration in cornering and using it to force the oil back to the pan.

What are you planning to do with the engine before you put on your dry-sump oil system? I recommend a remanufactured short-block assembly from a reputable supplier. One with a good warranty. Even though the warranty is probably going to be void because of track use, at least it would show that the builder stands behind his work. What can you get from Nissan?

Or if you want to rebuild the shortblock yourself, get a new crank and con rods from Nissan. They would be the most likely to have journals and big end bores that meet factory specifications for diameter, roundness, and surface finish.

As long as you have a steady supply of clean oil at a safe temperature, you should not need to do any special tricks with bearing clearances, but if they were set to the low side of the factory specs, it would minimize the flow required from the oil pump to maintain pressure.

 

[salgra]

Has anybody noticed that, according to the post of aquariuscsm on the third page showing the oil page of the manual.
nissan seems ok using a 20 weight engine oil in the hottest condition's? as you can see. 20w-20 in the most left bar.

 

[salgra]

Offcourse i meant the far Right bar

 

[morris]

ask big Qs but no info as to the bearing clearance? stock clearance is NOT made for severe use. any time you push a engine past the stock settings, you need modded oiling system. DAAAA. turbos big boost. but no detention? bet so.

 

[yonyon]

Originally Posted By: bruce381
unless that first rod on the left is the last to see oil pressure i would say bearing material falure


Wait, wouldn't the first to see pressure also be the first to see air?

 

[JosephHarmon]

Detonation will distort the upper thrust half of the bearing when it bangs the center then the edges where the insert halfs split can pinch in & scrape the oil dry off the journals causing failure.

 

[Gene K]

Originally Posted By: IndyIan

Also FWIW, I foamed the oil on my Neon running high rpms and cheap dino a bit over a half quart over full. It turned the oil light on, but seems that little damage was done.


Thats why they ran them low of oil in Showroom Stock. They foamed even with synthetic and normal fill level. You had to run them low to keep oil out of the crank.


PS I agree with Joseph Harmon... possible detonation damage. Check the pistons and ring lands on those cylinders as well.

 

[dja4260]

You said that you overfilled.

Overfilling causes the oil to become aerated. That is worse then underfilling and could cause damage to your mains. This happens in BBC's.

 

[3311]

I think your engine saw multiple, brief starvations. Maybe every time you accelerated out of a turn? Who knows.

 

[morris]

not a great thing to happen, BUT it looks like the bearings did what then are ment to do. that is protect the crankshaft. stop using water for oil, min diesel 15w-40 and get a real oil sump, and oil pump, min 6 qts if you are going to race. ill bet the factory says to not run the engine that hard and that long. the high performance cars that chrysler made had a note: saying do NOT run the engine at top rpm for more than 15 seconds. you see you DIDNT have a REAL race engine.

 

[SteveSRT8]

Hey, in the ole daze we used to run them a quart LOW at the strip!

He needs an accumulator. Go to Summit racing and get one, they're cheap and easy to install.

No more oil starvation, and it makes a nifty pre-luber as well with a remote switched valve!

 

[Jarlaxle]

Originally Posted By: Gene K
Originally Posted By: IndyIan

Also FWIW, I foamed the oil on my Neon running high rpms and cheap dino a bit over a half quart over full. It turned the oil light on, but seems that little damage was done.


Thats why they ran them low of oil in Showroom Stock. They foamed even with synthetic and normal fill level. You had to run them low to keep oil out of the crank.


PS I agree with Joseph Harmon... possible detonation damage. Check the pistons and ring lands on those cylinders as well.


The cast-aluminum oil pan is a culprit here: it was thicker than the older stamped pan, raising the oil level just enough.

 

[friendly_jacek]

Originally Posted By: salgra
Has anybody noticed that, according to the post of aquariuscsm on the third page showing the oil page of the manual.
nissan seems ok using a 20 weight engine oil in the hottest condition's? as you can see. 20w-20 in the most right bar.


This is weird. I never heard of 20W20 oils before.

 

[aquariuscsm]

Originally Posted By: morris
stop using water for oil, min diesel 15w-40


^^2nd.

 

[DoubleWasp]

From what i know of the the VG30DETT and DOHC V-engines in general, you almost certainly lost out due to oil starvation.

Coming to what someone was saying about the GT-R; it does not have cross tubes exactly. It actually has two small electric pumps to forcibly pull oil out of the valvetrain area.

When Steve Millen was racing his 300's, he actually had to relocate the PCV system from the cam cover to the valley in order to stop the oil from flooding up into the PCV system and being consumed by the engine. This mod is also now a factory arrangement on the current GT-R.

DOHC V-engines of all types, including our DOHC Ford V8s are notorious for filling the valvetrain area with oil during high rpms, taking it away from the sump. A proper dry sump system for these types of engines usually has 2 full stages or 2 mini stages dedicated to the cylinder heads to extract the oil from them. In between this condition, normal sump demand by the rest of the engine lubrication, low sump capacity, and the G-Forces, I'll say you never had a chance.

You might only be on street tires, but even street tires can tolerate momentary G-Forces well above 1G, in which the oil is more likely to climb up the cylinders than stay on the bottom of the sump.

If it were me, I would get an Accusump or other brand of accumulator, oil temp guage, and either one or two large oil cooler(s). People don't like to think of the oil system as a cooling system, but it is. The engine oil gets a whole lot closer to the hot engine parts than engine coolant ever does. Have you ever seen an FC Mazda RX-7 or Porsche oil cooler? Massive. Their OEM coolers are preferred over any aftermarket designs.

Look at any factory racer, or racing package, and you are guaranteed to find one serious oil cooling system. Gotta upgrade.

Just ask yourself; do you really feel comfortable letting this weak [censored] manage your engine oil cooling duties?

http://z32.wikispaces.com/file/view/Used..._Oil_Cooler.jpg

I think the power steering cooler on my van is larger than that.

 

[OVERKILL]

Originally Posted By: DoubleWasp
From what i know of the the VG30DETT and DOHC V-engines in general, you almost certainly lost out due to oil starvation.

Coming to what someone was saying about the GT-R; it does not have cross tubes exactly. It actually has two small electric pumps to forcibly pull oil out of the valvetrain area.

When Steve Millen was racing his 300's, he actually had to relocate the PCV system from the cam cover to the valley in order to stop the oil from flooding up into the PCV system and being consumed by the engine. This mod is also now a factory arrangement on the current GT-R.

DOHC V-engines of all types, including our DOHC Ford V8s are notorious for filling the valvetrain area with oil during high rpms, taking it away from the sump. A proper dry sump system for these types of engines usually has 2 full stages or 2 mini stages dedicated to the cylinder heads to extract the oil from them. In between this condition, normal sump demand by the rest of the engine lubrication, low sump capacity, and the G-Forces, I'll say you never had a chance.

You might only be on street tires, but even street tires can tolerate momentary G-Forces well above 1G, in which the oil is more likely to climb up the cylinders than stay on the bottom of the sump.

If it were me, I would get an Accusump or other brand of accumulator, oil temp guage, and either one or two large oil cooler(s). People don't like to think of the oil system as a cooling system, but it is. The engine oil gets a whole lot closer to the hot engine parts than engine coolant ever does. Have you ever seen an FC Mazda RX-7 or Porsche oil cooler? Massive. Their OEM coolers are preferred over any aftermarket designs.

Look at any factory racer, or racing package, and you are guaranteed to find one serious oil cooling system. Gotta upgrade.

Just ask yourself; do you really feel comfortable letting this weak [censored] manage your engine oil cooling duties?

http://z32.wikispaces.com/file/view/Used..._Oil_Cooler.jpg

I think the power steering cooler on my van is larger than that.





Great information

and dear Jesus that's a small cooler!