wstar's Journal

wstar

I found an engine! It's from a wrecked 2013 370Z w/ 7AT (so I get the flywheel too) from a local salvage lot. Only 5K miles on the donor car and it's (probably) not damaged from the wreck. Assuming everything goes smoothly (which should be obvious right off the bat and covered by the salvage lot's parts warranty), it's damn near a brand-new engine. Just a hair under $3K after tax and delivered.

The block should get dropped off at Baker sometime Monday, and Jason will be dropping it in and moving over the various bolt-ons next week. Then it will need a quick dyno-tune to make sure my UpRev settings are ok on the new block (not sure where yet), and I'll need to put it on my mini-lift and go over everything carefully to make sure I'm comfy trusting the car, and then hopefully back on track for June 21-22 @ MSR-Houston and June 28-29 @ COTA.

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sig11

Damn that's a good deal! Lucky man!

Eagle

Glad to hear you'll be back up and running soon and for what is relatively very little in terms of cost! Your thread and Megan370s has served as some good inspiration for me to track my 7AT. I just got my car back and the next steps for me are going to be to figure out what I need to do to ruggedize this transmission so i can enjoy quarterly track days without sending it back to the dealer every 12 months.

I'm possibly looking at GTM's torque converter, an upgraded transmission oil cooler, maybe the GTM flex plate and whatever fluids will be best to help this thing soldier on.

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wstar

The first thing I'd do is make sure you have good cooling on the trans fluid. I'm now running a Setrab 19-row Series-6 width cooler for my trans fluid, and I believe it's enough to keep from cooking the fluid under pretty extreme conditions. Most of the kits from the vendors have smaller cores than that. Somewhere deeper in my journal there's some posts about that (e.g. don't buy Stillen's kit, just buy a completely different set of adapters and hoses anyways, because their lines are too large to clamp onto our trans fluid fittings securely - not sure about GTM's).

Keeping the rest of the car cool (e.g. radiator upgrades, uprev fan settings, large engine oil cooler, maybe vent the hood near the front of the engine block, etc) is critical as well, since all temps on the car are somewhat interrelated.

I haven't ever done any trans-parts upgrades aside from cooling. I passed on the GTM valve body job for now because I couldn't get any reliable information on how it behaved from a road-racing perspective (i.e. whether it makes the upshifts too "shocky" for breaking traction on upshifts during trackout (or downshifts while trailing in) - I imagine some street guys and drag racers might actually like that behavior, but I sure wouldn't). I've never even considered touching the torque convertor or anything like that, although after this incident the HD Flex Plate is a little tempting.

Upping 7AT line pressures just a little bit via UpRev is worth it, but don't go too far. ~10% bumps across the board worked well for me with boltons. I also ended up switching my fluid to Motul Multi-ATF, which is one of the very few aftermarket fluids that's rated for our trans from a reputable company. I think it's at least as good as the stock fluid at handling the stress, anecdotally, and I've had it in for a couple of change intervals now. But if you care about dealership warranty issues, who knows if they might balk about using anything but official Nissan Matic-S. GTM has a couple of different PDFs on 7AT fluid swaps and recommended change intervals based on trans fluid temp. Putting in a trans fluid temp gauge (in the side of the pan) is worth it, especially one with a peak hold to find out your high-temp marks for the day. Check out this one: http://www.gtmotorsports.com/Manuals..._Procedure.pdf

At 4 track days a year, you'll be long done with that car before you've put as much wear on it as I have on mine, so you're probably going to be ok if you're reasonably cautious. I was reviewing my records on this stuff a couple months ago, and me and this car have been through about 38 track days in just a little under 3 years (or ~19x full track weekends if you prefer to count it that way). So that's a rough average of a little better than one weekend every two months for the whole 3-year period, plus another ~40K of street miles from back when this car was dual-purpose. Track miles are hard on any car. Having a major failure by this point is not completely unwarranted

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theDreamer

Getting a quick oil change and spacers put on the wife's Z.

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wstar

Jason sent me a pic of my flywheel. Yup, definitely something wrong with the flywheel

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Megan370z

that's a bit worst than my first one ....




Just as a reference,
This is my second flex plate after not even 5000 kms and 1 track day and half.

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wstar

Got the car back today. It would've been done much sooner, but we had various minor scheduling and parts issues (not the least of which was figuring out very late in the process that the flywheel on the donor motor was distorted and had to be tossed). I've only done a quick testdrive 1 block down the road from the dealership before I loaded it all back up on the trailer, but everything seems perfect. The guys at Baker Nissan did an exceptional job, pretty happy with them (again). Jason is an awesome mechanic

I need to fire it up a few more times here and basically triple-check everything for the usual gotchas like minor leaks, but I don't expect any real problems. That and re-check my alignment, which I was due for anyways. First real abuse test will be at MSR-Houston down in Angleton next weekend (June 21-22). I decided to skip wasting $500+ on a re-tune for now after talking it over with Jason as well. All the bolt-ons are unchanged anyways, and whatever minor variance there might be between blocks, the ECU should be able to adapt to that fine.

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wstar

Yeah, so someone asked on the "visitor messages" thingy here: Nissan 370Z Forum - Conversation Between 12nismo and wstar about whether the engine failure was pulley-related and whether I moved my crank pulley to my new block. The TL;DR answer to that is: I *think* the failure was unrelated to the pulley, but I also did *not* move the pulley over to the new block.

The long explanation, if the above is important to you and/or confusing:

Personally, I don't think the (Stillen, light/underdrive) pulley was a significant factor. My best guess is the flywheel probably started cracking a long time ago, adding some imbalance/wobble to the crankshaft and beginning to cause excess wear in the crank bearings, and then when the flywheel finally got bad enough (when the last bit cracked on that fateful Saturday), we had some major imbalance/wobble/whatever going on that really tore up the bearings, along with the flywheel striking the crankshaft position sensor, which is what caused the engine to go into limp mode at that point.

Even then I think the bearings were merely damaged at that point, but not seized/spun, initially. They didn't really come apart until test-fires and moving the car around around later, off-track (but that was inevitable at that point, they were shot one way or the other)... which brings us back to the Great Internet Pulley Debate (which rages forever on almost every car forum), where pulley-detractors tell us that lightweight pulleys without dampening rings on them will destroy crankshaft bearings over time.

To recap the basic internal/external balancing stuff, open the spoiler (or you can skip this as a TL;DR reduction if you get this part already):



Our engine is an internally-balanced one, meaning the pulley doesn't play a role in basic rotating-assembly balance issues on this car. It *does*, however, contain a rubber vibration-damping ring on the outer face of it. The core of the real debate here is whether the purpose of that vibration damping ring is purely for aesthetic NVH reduction, or whether it has a real dampening effect that partially reduces some mechanically-important crankshaft vibrations from combustion (and if so, how much longevity are you losing if you eliminate this? It could be 5%, it could be 95%!).

Anecdotally, I don't think it's much of a loss, if any, because the pulley kits from NST and Stillen (and others) have sold tons, and we're not hearing about massive lawsuits or even complaints about destroyed engines. It's most likely that the ring is mostly about NVH. Maybe it also reduces some mechanical vibration that matters, but maybe that's not very significant to begin with. For this sort of reasoning, I'm generally of the opinion that you're not risking any kind of large or short-term damage by properly installing a pulley kit on this engine. That and my engine made it through a considerable number of very abusive track miles on such a pulley (and even then, I don't think it was the cause).

However, I can't in good conscience say that without adding 3 important disclaimers/caveats:

1. My car is a 7AT, not a 6MT. Vibrational issues could be different on the two. I tend to suspect that, if there is any issue, 7AT's would fare better than 6MTs. This is because a 7AT has a torque convertor full of transmission fluid bolted to the flywheel at the rear of the engine. I suspect the torque convertor acts like a giant fluid damper on the rear of the engine (e.g. The Original Fluidampr ), offering far better vibration damping than any silly rubber ring on a pulley ever could.
   
   
2. Regardless of all the logical weaseling above, you can't escape a few basic facts: Vibration hurts engines. All engines vibrate. There's a small rubber ring on the stock pulley that may help with some unknown vibrations to some unknown degree. You're tossing that out for a <1% difference in the engine's performance capabilities at the end of the day. Maybe that's worth it, maybe it isn't. How much stress you're putting on the engine to begin with is a big factor. If I were building a 750rwhp turbo monster, I'd probably go in the *opposite* direction and install a heavier replacement pulley that does some serious damping to increase longevity. On an N/A street engine, I doubt you'll ever know the difference (in performance *or* longevity), making the upgrade pointless.
   
   
3. Jason (the mechanic who did the swap, and who I think has a trustworthy opinion about all car things) recommended against moving the pulley over to the new engine when moving all my other stuff over, because he thought it *could* have been a factor, and it's not worth the risk if it was. While, academically, I may believe it to not be a major contributing factor in the failure, I don't believe that strongly enough to tell him "No, put it on anyways", especially given that I could end up destroying this replacement block in a short period of time via something totally unrelated and coming right back to him with it, at which point he'd get to say "I told you so" about the crank pulley whether it was the issue or not, because that's only fair at that point. So he put my stock crank pulley on the new block, and that's what I'll be running for the foreseeable future (until I kill this engine in some new and imaginative way!).

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BGTV8

Have just come across this thread and read selective bits from it ....

To add my 2-cents worth to the pulley debate, on a DD that sees a "big" rev every now and then .... probably not significant, BUT in a competition car, an un-damped pulley is an engine killer in my book.

Back in the 80's, when I built the race-car I have come back to (is an historic 70's sports car, Buick 215 V8 engined), I ran without a crank-damper for the first 3 seasons and lost 4 engines (crank main-bearing failure each time), at which time we moved to dry-sump AND a damper.

We've had engine failures since, but never crank main failure - usually down to running the rod-bolts a tad too long (Carillo's are lifed at 80 hours, but we now replace rod-bolts (7/16" now rather than 3/8") every 40 hours as a precaution.

You only have to speak to the guys in the UK (IES - who prepare the GT3 NISMO GTR and also the 370Z GT4 engines for RJN Motorsport who run these cars in the Euro GT3/GT4 and Blancpain championships for NISMO) and they NEVER run an engine without a damper.

In the USA, talk to JWT who build the Grand Am engines for the Nissan 370Z runners, or Unitech Racing who built the Fontana Racing 350Z's - they all have recent experience of VQ race engines and I am quite confident they will specify a quality damper. In Canada, Sasha Anis also has a wealth of information about the VQ engine in competition-spec.

The NISMO engineer in Melbourne who assembles the VK engines for the Nissan Motorsport Altima's in the V8SuperCar series also specifies a motorsport damper and these are 5-litre engines making 650hp.

If it is good enough for those guys, it is certainly good enough for me, BUT as always, make up your own mind and tread your own path.

RB

theDreamer

12nismo is cobb in Houston.
He is getting his pulley put on this week so wanted to make sure your engine failure was not related.

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wstar

Apparently he's already doing it. Unfortunately I don't have any easy answers for him, hence my huge diatribe above! Maybe an appropriate closing statement would be: if I could rewind time and start over, I'd still have put the same pulley on my (7AT-, NA-, track-) car back when I did.

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12nismo

Just got the kit installed and I'm very happy with the results...as long as the motor holds up, lol.

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VoBoy

so just curious, what's your preventative don't blow up the engine plan in the future? flywheel replacement every 1 to 2 years?

wstar

Well, I'll certainly at least pull the starter and access covers and take a look at it from time to time. I suspect there was a good amount of lead time between the first crack and the bad situation at the end, but "inspect the flywheel" was never really on my track prep checklist before

I've got my old block back at home now with an engine stand as well. I plan to get that one rebuilt stronger and then drop it back in the car at a later date. Once I get to see the extent of the damage I'll know how much basic work needs doing and whether the block needs to see an engine rebuild shop first (probably). Once the block is basically sane, I'll probably drop in a bunch of upgraded parts for durability (e.g. Nismo oil pump, GTM HD flex plate, custom water inlet/outlet stuff with good fittings and no stupid heater connections, etc). Depending on time contraints, budget, and craziness, I might go further and build it up into something awesomer (e.g. one or more of 4.0 stroker, lots of forged high quality internal bits, dry sump, custom race ECU, etc). Right now the budget picture is pretty bleak while I recover from replacing the engine in the first place, but that will turn around in a few months.

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