NA 3.1L=>head & camshaft questions. No shortcuts, max

[zredbaron]

Have to ask...Are you 100% sure the oil pan was full?

No smoke at all when running? So, less than 100 miles total?

 

I keep asking myself too. I can confirm that I had oil at a full dipstick mark during initial break in and carb synchronization, added about a half quart to bring it up to the full line prior to road testing. Less than 100 miles total. Maybe 10 pulls on the dyno. Ran nicely after the adjustments, too.

 

I don't see any other options either, Jon. I'm really confused and will probably remain confused for quite some time!

 

Oh and I was hawking my gauges like it was my job. Constant 170-180 degree coolant temp and consistently high oil pressure, both of which remained true as it smoked and died.

Edited April 21, 2015 by zredbaron

[inline6]

I've had cars that burned oil in the past.  At 500 miles per quart it becomes very noticeable.  How much oil was actually left?

 

At several quarts per 100 miles, there really will be a constant smoke screen.  I think you can rule burning it out - also, go to rear of the car and check the rear panel... if it was burning it, there is going to be tiny oil droplets all over the entire panel.  

 

A leak of some sort is far more likely... to lose that much oil in that brief a period of time.  Look under the car from the engine back for evidence of any leakage.  That much oil leaking is going to coat some portion of the underside of the car.  

 

The coolant system couldn't take on that much oil either.  I think the entire capacity is like a little over two gallons... Easy enough to check if there is oil in the coolant.  Just drain and examine.  

 

I have the kameari chain tensioner.  When it is too tight, it does make more noise, but you really can't put any significant load on the engine by having it too tight.  Cross that one off.

 

Very sorry that this happened.  Do what you can to distract yourself from it... until the emotional part dies down.  Don't dwell in it. You'll get it back to where you want it to be.

 

Just watched the video.  Are you running an open exhaust?

Edited April 22, 2015 by inline6

[steve260z]

Then no drain bolt or crack in oil pan

[zredbaron]

Thanks for sharing your experience with the chain tensioner, Garrett. Yes, it was open exhaust. Here is the same idle from 2011:

https://youtu.be/by_gtw18cLo?t=1m30s.

The car was soooo much smoother last go-around, but I still think that the fancy fuel being fresh is the main difference. (The perceived friction in my mind, however, is a different matter.)

 

I talked to two engine builders, Ray in VA who built the head and Dave Rebello since at a minimum I'll be needing to order some new forged piston(s) and valve(s). Both builders immediately discredited oil as the cause and fixated on "something happening" in cyl #1. A failure in the valvetrain, a rock bouncing into the intake... something.

 

I didn't measure how much oil was in the system and that won't be possible. I drained it and filled it back up with clean oil before I removed the spark plug and discovered the damage (sigh). The dipstick was dry at the time of the event, so I assumed that meant >1.5 quarts were gone. Dave replied that a dry stick doesn't necessarily indicate the system lacked oil.

 

I woke up this morning remembering something that might be a factor: When I was finished mounting the engine block to the transmission and chassis, as I lowered the car one of the wooden blocks that was being used split up the middle and my oil pan was dented from below (in the shallow region of the pan). I would think if it were a problem then oil pressure would indicate as such, but I figured I'd throw it out there.

 

Lastly, I'm totally new to the pacific northwest... does anyone have any engine builder recommendations? I'm fine with hauling to Seattle, Portland or wherever I need to go. I'm not messing around this year, I'm getting this fixed pronto!

Edited April 22, 2015 by zredbaron

[zredbaron]

Any while-I'm-at-it suggestions? Oil pan recommendations, for example?

[bradyzq]

You have my condolences. This is major suck.

 

My guess is valvetrain. Unless I'm missing something (entirely possible...) for a sparkplug to get hit, you pretty much have to have a broken valve stem and a valve head bouncing around in the combustion chamber.

[inline6]

On my engine, I believe the Kameari tensioner will allow the chain to loosen enough to slip one tooth on the crankshaft gear sprocket. That happened to me recently (though I pulled the upper tensioner part out completely when this happened).  

 

The car wouldn't rev right and the engine was louder.  I was thinking that the valve adjustment had gone out of wack, so I tightened up the clearances a couple of thousandths.  However, that made the noise worse - so I shut it down.  I bought a bore scope and found that the exhaust valves were tapping the pistons.  That and recently messing with the tensioner led me to suspect the cam timing was messed up - which is what the problem was.  

 

Here is a pic of the bore scope LCD screen:

 

 

Any changes with the tensioner that might have allowed the chain to slip a tooth?

 

G

[JMortensen]

Nissan Comp/Design Products Racing makes the best pan. AZC sells a pan but there was recently some question about how far from the bottom the pick up tube is, so I would check that out when you assemble and maybe modify the the pickup with a little wall around the screen so that it can't pick up bubbles from the sides and has to pull from the bottom close to the pan.

Edited April 24, 2015 by JMortensen

[zredbaron]

Thanks Brady. That's my guess too.

Again, great feedback with the tensioner Garrett, thank you. That's crazy! Did enough of a collision occur to lower / lose compression, or did you luck out? I can't quite make out your image. I didn't touch the tensioner, only the engine builder did. Slippage is possible I suppose. The chain was tight to the touch when I took the pic of the idler gear and since then the bolts haven't moved visually. I would think it would have to slip noticeably in order to jump a tooth, and would also think that all cylinders would be affected equally?

Thanks for the oil pan suggestions, Jon. The Nissan Competition pan seems to be made of unobtanium, it didn't turn up on any of my internet searches, though it steered me to Kameari (again). Evidently the Kameari pan is > $1,500!? Haha! I might be one of the fools who's willing to sacrifice price if I feel I'll get what I pay for, but that's a ridiculous amount for a similar product. Looks like I'll be steering toward AZC. (Now that I think about it, I didn't think to check if Nissan still offers it. Too obvious?)

I had a chance to dig out the copy of my dyno runs from a couple weeks ago. Evidently my memory with the numbers were a little generous! Haha, the poor sap was trying to make up for his heartbreak... The tale of the tape: 235 whp, 205 ft-lbs. Not shabby at all, however comma, the 2008 dyno was 264 whp, 249 ft-llbs with street headers and a lesser, non-oxygenated VP race gas. (Not that I think I had any oxygenation after 3 years, I simply mean that non-oxygenated fuel produced 264 in VA.) I went ahead and attached the 2008 dyno runs for comparison.
 

As JohnC pointed out regarding my A/F ratio, it's awful. [below 3,500 RPM especially, which he called out predictably I might add!]

 

As for the performance: fuel, friction, tune...? I'm not worried about the performance discrepancy at all, it drives like a totally different engine in the most intoxicating way. The purpose of the dyno pulls were to confirm all was well mechanically and timing-wise with the engine so I could confidently tune the carbs, order more jets, burn the fuel drum up and put more miles on the engine before ordering new tires, doing a full tune with fresh gas and competing. I was running the same race gas from 2011 ("fresh" from drum) and didn't have sufficient time to dial in either A/F or timing on the dyno, but certainly improved performance significantly. Sure, the ratio was ugly, but it drove like like a son-of-a-bitch to and from the taco stand. (Cue Al Bundy pose, living the glory days...)

Carburetors: For me, the dyno is to dial in my timing curve so that I can productively be free to tune my carbs week-to-week before races. With timing locked in, I can road-tune the car to respond to the pedal better far than dyno pulls can. WOT doesn't help me for autocross, and leaves me with a car that doesn't drive in mid and low-pedal positions under 4k, not even with a feathered pedal. Butt-and-ears dyno? You bet.

 

Yes, fuel injection is coming... but not for another year or two. I still want to progress via a *tuned* comparison from carbs, and I still plan on larger DCOEs as an interim comparison as well, simply because I want to enjoy competing with carburetors for a couple of seasons before spoiling myself as a driver and going to FI. WOT has never been possible until around 4k with this cam, so there is definitely some area under the curve to be had the day fuel injection arrives.

 

Hanging onto carburetors is a product of my amateur perspective and my desires. If there are opinions out there that carburetors are *foolish,* I'm formally asking for them! There are reasons that I'm in the same boat again with this engine, but I don't know what the reasons are. I find it plausible that an "ok" carb tune under load might be fine, but the break-in moments when the engine has never turned over before and isn't under load... perhaps those moments are more crucial than I realize?  (JohnC, were you holding back?)

Perhaps: [amateur with carburetors] + [engine with tight tolerances] = [margin for damage/failure]?

I don't think so, but I don't know. I keep referring to the first build in my memory and on YouTube. I was "more" of an amateur in 2011, and that engine purred from birth. The data points conflict, so a proper conclusion cannot be drawn. Productive criticism and debate aside, I'm particularly pleased with shapes of what the curves are trying to be. Despite the poor tune, I remain encouraged that VE has improved.

 

Regardless, it's on! I'm in a new town all as a single guy staying in a hotel, but I found a storage unit for my Z that gave me permission to pull the engine out, keep a drum of fuel, etc.

[side note -- in this case it was very challenging being an honest, responsible citizen in a free economy. I was judged and rejected by several owners because they have had "rif-raff" type tenants abuse their storage units in the past. I finally found a guy that appreciated my honesty so much he said yes. And a handshake. The way men used to shake hands. ]

Very fortunate I brought my cherry picker with me in the front of the trailer! Zed willing, I'll have the block out this weekend...

Edited May 1, 2015 by zredbaron

[ryant67]

Good stuff, glad you are going to keep at it!  These cars are too much fun when running to let a few setbacks (admittedly, heavy ones in your case...) stop you.  Hope everything goes smoothly, third time's a charm!

 

[zredbaron]

Good stuff, glad you are going to keep at it!  These cars are too much fun when running to let a few setbacks (admittedly, heavy ones in your case...) stop you. 

 

Cheers to that! For a quick moment, my heartbreak wanted me to run away and pursue something safe that wouldn't risk failure or being disappointed again. And then after about half a second I grunted and plunged myself aggressively back into the arena. I knew I'd never stop longing for its pursuit.

[inline6]

Thanks Brady. That's my guess too.

 

Again, great feedback with the tensioner Garrett, thank you. That's crazy! Did enough of a collision occur to lower / lose compression, or did you luck out? I can't quite make out your image. I didn't touch the tensioner, only the engine builder did. Slippage is possible I suppose. The chain was tight to the touch when I took the pic of the idler gear and since then the bolts haven't moved visually. I would think it would have to slip noticeably in order to jump a tooth, and would also think that all cylinders would be affected equally?

 

Thanks for the oil pan suggestions, Jon. The Nissan Competition pan seems to be made of unobtanium, it didn't turn up on any of my internet searches, though it steered me to Kameari (again). Evidently the Kameari pan is > $1,500!? Haha! I might be one of the fools who's willing to sacrifice price if I feel I'll get what I pay for, but that's a ridiculous amount for a similar product. Looks like I'll be steering toward AZC. (Now that I think about it, I didn't think to check if Nissan still offers it. Too obvious?)

 

I had a chance to dig out the copy of my dyno runs from a couple weeks ago. Evidently my memory with the numbers were a little generous! Haha, the poor sap was trying to make up for his heartbreak... The tale of the tape: 235 whp, 205 ft-lbs. Not shabby at all, however comma, the 2008 dyno was 264 whp, 249 ft-llbs with street headers and a lesser, non-oxygenated VP race gas. (Not that I think I had any oxygenation after 3 years, I simply mean that non-oxygenated fuel produced 264 in VA.) I went ahead and attached the 2008 dyno runs for comparison.

 

As JohnC pointed out regarding my A/F ratio, it's awful. [below 3,500 RPM especially, which he called out predictably I might add!]

 

As for the performance: fuel, friction, tune...? I'm not worried about the performance discrepancy at all, it drives like a totally different engine in the most intoxicating way. The purpose of the dyno pulls were to confirm all was well mechanically and timing-wise with the engine so I could confidently tune the carbs, order more jets, burn the fuel drum up and put more miles on the engine before ordering new tires, doing a full tune with fresh gas and competing. I was running the same race gas from 2011 ("fresh" from drum) and didn't have sufficient time to dial in either A/F or timing on the dyno, but certainly improved performance significantly. Sure, the ratio was ugly, but it drove like like a son-of-a-bitch to and from the taco stand. (Cue Al Bundy pose, living the glory days...)

 

Carburetors: For me, the dyno is to dial in my timing curve so that I can productively be free to tune my carbs week-to-week before races. With timing locked in, I can road-tune the car to respond to the pedal better far than dyno pulls can. WOT doesn't help me for autocross, and leaves me with a car that doesn't drive in mid and low-pedal positions under 4k, not even with a feathered pedal. Butt-and-ears dyno? You bet.

 

Yes, fuel injection is coming... but not for another year or two. I still want to progress via a *tuned* comparison from carbs, and I still plan on larger DCOEs as an interim comparison as well, simply because I want to enjoy competing with carburetors for a couple of seasons before spoiling myself as a driver and going to FI. WOT has never been possible until around 4k with this cam, so there is definitely some area under the curve to be had the day fuel injection arrives.

 

Hanging onto carburetors is a product of my amateur perspective and my desires. If there are opinions out there that carburetors are *foolish,* I'm formally asking for them! There are reasons that I'm in the same boat again with this engine, but I don't know what the reasons are. I find it plausible that an "ok" carb tune under load might be fine, but the break-in moments when the engine has never turned over before and isn't under load... perhaps those moments are more crucial than I realize?  (JohnC, were you holding back?)

 

Perhaps: [amateur with carburetors] + [engine with tight tolerances] = [margin for damage/failure]?

 

I don't think so, but I don't know. I keep referring to the first build in my memory and on YouTube. I was "more" of an amateur in 2011, and that engine purred from birth. The data points conflict, so a proper conclusion cannot be drawn. Productive criticism and debate aside, I'm particularly pleased with shapes of what the curves are trying to be. Despite the poor tune, I remain encouraged that VE has improved.

 

Regardless, it's on! I'm in a new town all as a single guy staying in a hotel, but I found a storage unit for my Z that gave me permission to pull the engine out, keep a drum of fuel, etc.

 

[side note -- in this case it was very challenging being an honest, responsible citizen in a free economy. I was judged and rejected by several owners because they have had "rif-raff" type tenants abuse their storage units in the past. I finally found a guy that appreciated my honesty so much he said yes. And a handshake. The way men used to shake hands. ]

 

Very fortunate I brought my cherry picker with me in the front of the trailer! Zed willing, I'll have the block out this weekend...

 

There is some nice art here  - thanks for it.

 

Here is the oil pan that mortensen was speaking of.  Seriously consider it.  I got one not that long ago... I think 4 to 5 weeks is lead time much cheaper than the Kameari one.

 

The shiny "sliver moon" on the right side of my pic indicates exhaust valve to piston contact.  My leak down before and after the chain being off a tooth is the same 2 to 5 % across the cylinders. I think I got lucky, but will have to check again after some more miles to know for sure.  

Edited May 1, 2015 by inline6

[zredbaron]

Glad to hear all that typing wasn't just hot air! The art comment was unexpected, thank you. Super glad to hear you got lucky with your compression!

 

Hmm, I'm surprised I missed the competition pan on DP Racing's website. Jon, you were referring to the AZC pan and not this pan, correct? Looks like the comparison is $300 cheaper for a cast-aluminum pan with potential pickup issues vs. an $800 forget-about-it solution. Hmmm. Negligible performance difference? I would think aluminum would transfer heat better, but I don't see it being an "issue." Any other experience is of course welcome! 

 

And in other news... the engine is out! I had a chance to pop off the valve cover and found #1 exhaust's rocker arm split in half at a minimum. I also found oil throughout the header runners for cylinders #1-3. Pics below.

I wonder what the heck happened in that cylinder? Not knowing what caused the failure, it looks like the CNC rocker arm took one for the team in a very neat, let-everything-else-live sort of way. Maybe it was the failure, but then again maybe it saved the head and cam from further damage? Hopefully the engine builder will be able to make a determination.

 

Edited May 4, 2015 by zredbaron

[JMortensen]

Yeah, the DP racing pan is kind of the known standard; you pay and it works. The cast AL pan is friggin heavy too. 

[tube80z]

On your pic I had a similar failure but for a very different reason.  I had the front sprocket break a chunk of cam and slip and that broke a rocker similar to what you have along with bending some valves.  What I wonder is it possible something got into the cylinder and caused enough of a jolt to break the rocker?  Have you been able to look into the cylinder at all?

 

It sucks when stuff like this happens but when you've done it for long enough it happens to us all.  Not that we enjoy it any more than you are.

 

Worry, hope the the luck improves!

 

Cary

[inline6]

It looks like those cnc rockers (that one anyway) has had holes drilled through it... perhaps to decrease weight.  I don't see those holes in the earlier pics of them you put in the thread.  Am I seeing that right?  Did they come that way?

 

Did you pull the valve retainers for that one valve, or were they jettisoned during the failure and that is how you found it?  I'm coming up with theories...

 

As an aside, I noticed you said that the engine doesn't deal at all with WOT below 4k RPM.  I've been working on tuning in recent weeks and have been chasing after that same issue (if I recall correctly, we have the same cam).  Been using a LM2 data logger and making changes one step at a time.  A vexing problem has been its inability to deal with WOT in higher gears (3rd, 4th, 5th) and lower RPM's (less than 4k in 3rd - I don't even attempt such a thing in 4th or 5th anymore).  I have found a combo that allows full throttle in first without issues and once the revs are up, I'm all good. 

 

(Edit: Nice - I just saw your AFR curve... that is the same mountainous beast I am dealing with!   )

 

Still, the Mikuni's (44's) are losing their aura.  FI is going to happen sooner rather than later.

Edited May 5, 2015 by inline6

[zredbaron]

Thanks for the collective encouragement and support, guys. It isn't expected, but it sure does help. Thank you. 

 

I had the front sprocket break a chunk of cam and slip and that broke a rocker similar to what you have along with bending some valves.  What I wonder is it possible something got into the cylinder and caused enough of a jolt to break the rocker?  Have you been able to look into the cylinder at all?

 

Ouch! I still can't believe how fortunate I was to have a rocker arm break so cleanly. I think you're right, I think something got in there.

 

When I put a flashlight into the exhaust port, I saw several very small, shiny dings (~.1mm thick, ~2mm long) in the otherwise very oily port, all concentrically parallel along the cored passageway toward the port. (Does that even make sense or is that technical nonsense? LOL!) It's really odd, actually. Maybe a piece of rock or nail found its way past the carburetor but found the valve seat, snapping the rocker arm and glancing the valve into the spark plug? Conjecture, but it's my running theory.

EDIT -- Oh, and the broken rocker on an exhaust valve would explain the missing oil, right? If oil could enter the combustion chamber due to the damage, then it would have an open path out the exhaust leaving the headers quite oily? The missing oil was on the road behind me?

 

Unfortunately I didn't have my USB boroscope to investigate the valve. I do remember seeing 3-4 black bits on top of the piston, next to the busted-up valve reliefs. The resolution and light didn't allow me to make out if they were just broken bits of the spark plug or if something else was present too.

 

It looks like those cnc rockers (that one anyway) has had holes drilled through it... perhaps to decrease weight.  I don't see those holes in the earlier pics of them you put in the thread.  Am I seeing that right?  Did they come that way?

 

Did you pull the valve retainers for that one valve, or were they jettisoned during the failure and that is how you found it?  I'm coming up with theories...

 

Yes, Brian's final design has significant weight reliefs. I don't suspect the rocker arms at this point, but who knows. I didn't touch any of the valvetrain; I snapped a pic exactly as I found it for this very reason. I always appreciate additional theories!

 

 

As an aside, I noticed you said that the engine doesn't deal at all with WOT below 4k RPM.

 

I'll refer you to Dan Baldwin on this one:

 

Every biggish-cammed highish-hp carbed L6 build I've seen does that, it's due to reduced V.E. and multiple carburetion in that rpm range. I.e., air comes through venturi once, gets fuel, then some air gets pushed back through the venturi due to late intake valve closing and picks up more fuel, then gets drawn through again, picking up still more fuel, at the next cycle. With fuel injection you could improve the A/F ratio, but you'd still have a big torque dip there, as it simply doesn't breathe well at that rpm. What works great at 6500+rpm doesn't necessarily work all that great at 3800rpm...

 

 

To dramatize it, I've accepted that the carburetors are basically telling us "Clatter all you want, I will not and can not rape that village." I've referred back to this VE limitation a number of times, both for tuning and the realization that this limitation is what makes the car all the more awesome when it's an "on" day and all the more classic / manual when it's an "off" day (still awesome).

 

So for me, road-tuning a carbureted, aggressive L6 has two basic components: above 4k for AFR / power and below 4k to minimize feathering regardless of AFR so I can get back in the power band! Makes it much more driveable on course, too.

 

[...case in point...]

...but FI is coming! Agreed. 

Edited May 8, 2015 by zredbaron

[bradyzq]

Looking at the dyno graphs' shapes rather than the actual numbers, it seems that on your recent build, you maintained 90% or more of your max torque between 4200 and 6700RPM or so, which is slightly better than your 2008 engine which held 90% or more between about 3900-6200.

 

I seem to remember that you have a badass ignition system (Electromotive?) If I'm wrong and you still have a single coil and dsitributor, that can make the difference between lighting off a mixture that's way lean or rich, or getting a misfire/stumble.

[inline6]

I'll refer you to Dan Baldwin on this one:

 

Every biggish-cammed highish-hp carbed L6 build I've seen does that, it's due to reduced V.E. and multiple carburetion in that rpm range. I.e., air comes through venturi once, gets fuel, then some air gets pushed back through the venturi due to late intake valve closing and picks up more fuel, then gets drawn through again, picking up still more fuel, at the next cycle. With fuel injection you could improve the A/F ratio, but you'd still have a big torque dip there, as it simply doesn't breathe well at that rpm. What works great at 6500+rpm doesn't necessarily work all that great at 3800rpm...

 

Interesting... I was starting to suspect "reversion" and came across another hybridz post (sometime during the hours and hours of searching/reading) where another member addressed their "bog" issues completely by adjusting the cam timing.  My engine builder spec'd out the cam timing with three different settings on my adjustable cam sprocket.  One of my recent tuning changes was to retard the cam a touch to see if it improved the wide open throttle (WOT) below 4k situation.  Retarding the cam changes intake valve opening and closing times relative to piston position, so it has an impact of the amount of reversion.

 

Ah... so when you pulled off the rocker cover, the number one valve (exhaust) was as pictured: valve keepers missing and valve bent (it looks bent to me...).

 

You mention a rock or a nail... Were you running without an air filter?  How about a pic of the number one spark plug?

Edited May 7, 2015 by inline6

[ryant67]

Just a random thought, along the line of what Inline6 just posted...  You run one of those TWM air boxes, right?  I recall reading about someone using one of those and having a rivet inside the box break loose and getting sucked inside the engine via the intake.  Might be worth giving it a good look over, if you were running it when the failure happened.  

For reference, post #12
http://forums.hybridz.org/topic/59069-intakeair-filter-for-triple-mikunis/