Dan Baldwin

March 14, 2003

And in reference to the valves hitting the pistons' date=' it appers that was from before he had the Sunbelt cam installed, as not one of the valves was bent and all the guides were in good shape.

-Bob[/quote']

Actually, the big exhaust valve dings WERE after the new cam/headwork. The smaller intake valve dings were the only marks on the tops of the pistons before I installed the new head setup last Winter.

No fault of Sunbelt, IMO, as they just did the head, not the installation, and I was running the cam ~4 degrees retarded.

Anyway, despite the fairly scary-looking exhaust valve dings on the pistons (~.080"?), Chuck at Abacus assures me that all the valves and guides are in GREAT condition. Whew!

Bobby, stock Z06s are not to be allowed to get away. We'll see about those brakes after I recover from this rebuild.

March 11, 2003

50K out of a mostly track motor is pretty good. You got your money's worth out of that one. Take a little extra time and send your crank to Jim Thompson. He can easily take 10 lbs out of it without affecting reliability.

I am more than pleased with the life of the engine, considering the usage and my persisting in running it KNOWING I was losing oil pressure in right-handers.

I'll give Jim a call about the crank. BTW, my pistons now have substantial dings in them from the exhaust valves hitting! When I mocked up the head install last year, I knew I was close on intakes (.045"), but my blob of clay musta moved and I didn't get a clearance on the exhaust valves. Now I know! Abacus says the valves and guides are all fine, though(?!). At least they'll know where to machine the reliefs in the pistons!

The bottom end will need at least 1 rod and 2 (maybe 3) pistons. Seems three pistons had had their skirts machined for clearance, but 3 didn't.

More later,

March 7, 2003

I would contend that in this context' date=' dampen is a synonym of damp, dampner is a contraction of dampener. I will concede that I'm not sure whether dampener or dampner is correct, but I think it's pretty CLEAR what I was describing.

What I don't get is how you can get all pissy about damper vs. dampener/dampner, and then say it's okay to call it a harmonic balancer..[/quote']

Just trying to help! "Dampener" is NOT synonymous with "damper", and "dampner" is an in-between non-word people use because they're not sure. The correct term is "damper". I prefer "damper" to "harmonic balancer", but both terms are acceptable.

J. Soileau, it appears you're pinning the damper such that the two metal parts are rotationally locked to each other. Seems to me that prevents the damper from performing its function of damping crank harmonics. Or am I missing something?

JeffP, is the Euro damper the single groove one? I wonder why it should be any more durable. So now I've got another thing to be nervous about...

Pissy to the end,

March 7, 2003

Thanks for the condolences. I was on the verge of having the engine rebuilt last year when I had the headwork done. But hey, I got a whole season + 1 event out of it! I'll get an oil cooler for it only if the temps are high. I expect they will be, but no reason to spend the money until I know how much cooler I'll need.

PS, I'll know more about the specifics later today. The shop is supposedly doing the post-mortem as we speak.

JJ, so you're going 3.2. 90mm bore with 83mm stroke, I presume?

March 5, 2003

No new tricks on the rebuild other than the comp oil pan. I will have the pistons shaved flat and notched for valve clearance, and might remove one of the layers of the 2mm head gasket for a 1.5mm to make up for the lost volume and a bit more, maybe aim for a 11.2:1 CR. Other than that, I don't know what might gain me much for a street engine running on pump gas. I'm open to any and all ideers for more powah! Reliability and cost are the two primary concerns, though.

March 5, 2003

It's a DAMPER. Not DAMPENER or DAMPNER. It DAMPS crank torsional harmonics, it doesn't dampen or dampn them. Damper damper damper. Or harmonic balancer.

My possibly 30+ year old stock 2-groove one lasted about 38 track days, with 7000 rpm seen routinely and more on a couple of overrev occasions. I installed a new single-row Nismo unit at the beginning of last year, as I could see chunks of rubber missing from the old one. Am I now in greater danger of this new one coming apart? It's the same size as the old one, BTW. Narrow groove, also, unlike the wider groove unit that came in '7?.

March 5, 2003

Drove down to VIR a couple of weekends ago for an instructor clinic with NASA and a 2-day high performance driving event. BobH shared the car with me. Short story: The car ran great for three days, then on my last run on Sunday, the oil pressure went south. Brought it in, we changed the oil, and lo and behold pressure was normal again. Hit the road, continuing my journey southward, but only got 10 miles south of the track before the death clatter came. Fortunately, Bobby came and got my sorry ass. We took the car to his place in Norfolk the next day and got to work on removing the ancillaries. Took the engine out on Tuesday, and stripped it down for delivering to the shop that will be doing the rebuild.

MUCHAS GRACIAS to Bobby for saving my arse and doing more than half the work on the car!

Moral of the story: Don't expect to get more than ~50,000 miles and about 50 hard track days out of an L-series engine with a stock oil pan and no oil temperature gauge (though the sensor is in place in the oil drain plug, the gauge remains on a shelf at work). Oil pressure would fall during hard right-handers from day one, so clearly I was living on borrowed time. It's testament to L-series engines and to the guys that put it together for me back in '94 that it lasted as long as it did.

This time there WILL be a competition oil pan and I'll run an oil cooler if necessary. Maybe I'll get 100+ track days out of this rebuild!

February 14, 2003

You need the little Borg-cube device, available cheap at your local auto parts store. It's just a little metal cube, with pins of different number, size, and spacing on it's 6 sides. Put it on an extension on a ratchet, and screw the caliper piston back into the caliper.

Dan

February 13, 2003

Wait a minute, those pics are of a rwd AE86, what gives? I love those, very lightweight. Would make a killer autoX car! Oh, I got it, the ENGINE is out of a fwd corolla.

I love it! I was looking for one as a daily driver but found a '91 240SX first.

The Corolla's gotta have a ton more potential. Aren't they like 2200 lb.?

February 12, 2003

Most basic L28 swaps into 240Zs use the 240's SU carbs (not the '73 flat-tops!). That's the easiest way to do it, for sure. Zero wiring worries. 5-speed is highly recommended, the ratios are a lot closer than the 4-speed and you can run much shorter diff gearing. Be aware there's a big 2-3 gap in the 5-speeds thru 1979, and the '80+ ZX trannies have tall 1st and 5th gears. Something to consider, the '80+ 280ZX non-turbo blocks have flat-top pistons, so it's easy to get a decent compression ratio by swapping on a 280Z N42 or N47 head (easy way to get 9.8:1 CR), or shaving .080" off the 280ZX P79 head (shim cam towers and be aware of geometry and timing issues if you do this).

February 11, 2003

Since the subject has been brought up (again), I may as well mention that John's 305hp race motor, Norm's 12.88@106 street motor, and my 235rwhp street motor, all have N42 heads. Where are the big P79 numbers? (just askin', I don't think the n42 is the livin' end, necessarily, and of course the heads on our motors have been tweaked a bit)

February 7, 2003

240Z, no doubt about it. 500 lb. lighter than the 280Z, huge difference. Nicer looking bumpers, too:) Forget the ZX. Semi-trailing arm rear suspension is not as good as the earlier Zs' Chapman struts, not to mention aesthetic issues.

It's a LOT easier to swap bigger, more powerful motors into a 240Z than it is to swap the 240Z's light weight into a later-model Z or ZX;)

February 5, 2003

Another ditto on the fragility of these motors. Two of them expired last year at time trials events. My L6 has been doing these kinds of events (47 track days) since 1995, no problems! One of the victims felt the very-tight the bearing clearances were to blame. Both instances were bottom-end failures, BTW.

How could Ford have built a motor so big and heavy, with so little (relatively) displacement, and still have reliability problems? GM (not that I'm a fan) had the right idea. Of course they still lost the war!

February 5, 2003

I'd go with the LT1. Or LS1. Or LS6! Basically, the DOHC 4.6 gives up as much in displacement as it gains in revs (4.6 liters at 7500rpm roughly equivalent to 5.7 liters at 6000rpm). But it has way less low-end torque and it is VERY bulky, which is why the Cobras had to have another bulge on top of the already-very-high Mustang hood.

Also, the OHC and DOHC Ford motors weigh enough that the Mustang went from 3200lb with the 302 to 3300 lb with the SOHC GT motor and 3400 lb. with the DOHC Cobra motor. It's gotta be heavier than a small-block Ford, or a small-block Chev. Just about all the increased weight in the OHC and DOHC motors is up high, as well. If it was me, I'd rather have an OHV small-block (Chevy or Ford) in my Z than the 4.6 DOHC motor.

February 3, 2003

You could call Larry at Carbotech (http://www.carbotecheng.com). Tell him your intended usage and he'll recommend a compound. He carries Hawk and his own line of Panther compounds. I'm using Panther XPs for my track/street car. I believe he'll make shoes for you, too (I've got rear discs now). I used to always use Nissan shoes back when they had asbestos (NLA, I think), and they worked fine on the track, believe it or not.

February 3, 2003

Originally posted by empracing:
na or turbo the 90a will still flow better and sqwish better too. change the cr with pistons not chambers .run the god dam 90 .

p.s i really wish i had the time to get these bloody things flow tested to end this silly debate.

Flow testing can show basic steady-state flow characteristics, which can be an indication of performance potential. Results are certainly not definitive, though, just a part of the picture.

Just curious, what's your quickest/fastest NA ET with the P90 vs. N42? Dyno comparisons? The benchmarks I know of for N42-headed cars are 12.88 @ 104 (correct me if I'm wrong, Norm) in a 2.9 liter ~11:1 CR motor, 235 rwhp in my 3.1 liter 10.8:1 CR motor, and 315 flywheel hp (correct me if I'm wrong, John) in a 3.0 liter 13.5:1 race motor.

I'd agree that the debate is somewhat silly, because from what I've seen/read/heard there's not enough between the two heads to inspire impassioned debate. If I were building a new all-out motor and I had either head (P90 non-hydraulic or N42) lying around, I'd probably just use it.

January 31, 2003

Have you contacted the ACLU? No kidding, it'd be worth a shot to try to get some legal/political muscle behind your cause.

January 31, 2003

Originally posted by Mikelly:
This stress tester (He calls it is demolisher) actually has four posts with Hydraulic pistons that have steel inserts that can be swapped for differing sizes... We put it in this vise like contraption and load the part in opposing angles (We did 8 in all) and test welds and such. We didn't max the system out as he has done well over 100,000 pounds presure on stuff designed for special customers.

Fun w/ hydraulics! That certainly does something to instill confidence. Would be nice to see pics of the tests if you have them. Were you able to hold the inner pivots and apply fore/aft thrust loads at the outer pivots?

BTW, it looks like the threads on your rear control arms are only subjected to bending if there's a sway bar involved.

Thanks for chiming in, katman. It looks like the arm I linked to does share the shear and bending between the two outboard heim joints instead of all of it going to the forward one. Looks like the longitudinal distance between them is fixed, right?

Honestly, I feel a lot better about both the previously linked-to arms (who makes those?) and Mike's after this discussion.

Eventually, I'd like to get some rear adjustability beyond what I've got with the Al/delrin eccentric bushings. Rear end is somewhat out of whack after last year's "incident" at Turn 6 at Watkins Glen. The eccentric bushings got me somewhat close, but both rears are about 1/2" offset to one side with the toe and camber set where I want them.

January 31, 2003

Unbelievable. This is one short step away from thought-crime. I hope none of you out there has any illusions that we live in a free country. Freaky. I am ascared now. If you ask me, any crime in which another human being is not physically assaulted/kidnapped/threatened/etc. is not worthy of more than a few weeks in the slam. TWO YEARS?! And nobody was injured/kidnapped/threatened/other by you? I feel sick.

Here's some recommended reading for ya:

Nabakov's "Invitation to a Beheading"

Kafka's "The Trial" (of course)

Dostoyevsky's "Crime and Punishment" (although the protaganist was actually guilty of something worthy of detainment or worse in this one)

January 31, 2003

Originally posted by Mikelly:
at 78,000 pounds presure the only problem I had was one split tube. It was the longest tube, but then again, it was 78,000#.

Just read this again. Was this test done at Boeing or something?! Seriously, 78,000 lb is, well, difficult to believe. How was it loaded?

Potential problems with the Az Zcar rear arm and the rear arm I linked to a couple of posts up have to do with bending load in the outer heim joints, where they screw into the arms. The distance from those spherical joints to the arms appears small on those arms, but calculations show the bending moment and stress in the threaded section to be not insignificant. Mike's arms do avoid this somewhat, as the adjustable turnbuckle parts carry appear to primarily carry axial loads and shear, with bending pretty minimal (at least if there's not a sway bar involved). BUT, the triangulation is still FUNDAMENTALLY wrong. It should look more like the AZ Zcar and the arm I linked to. That would make me feel a lot better about this piece. The front arm, with big sway bar bending loads being taken by a threaded rod, I dunno. I guess if the rod is big enough, but has any analysis been done to determine how big "big enough" is?

Brake brackets, suspension parts and the like should be subjected to analysis by qualified structural engineers, and an engineered structural test program. If only one of the two is done, factors of safety should go way up. There's a lot of stuff out there that looks right but is bad wrong, that has never been subjected to any kind of structural analysis or test. None of it goes on my car.

So, anybody want to give me a consulting job?

January 30, 2003

Glad to hear it's been tested and that there have been no failures. Fatigue failures can take a while, though. I wish my ASCII art had come through. I still would much rather see it without the "node" at the midpoint of the long tube. Picture the rearmost diagonal tube going straight forward from its aft end, meeting the aft end of the forwardmost diagonal instead of angling over to the long tube. And then picture the inboard end of the middle transverse tube angling back to the aft end of the longtube (instead of joining it at its midpoint). That would be a more efficient structure, and wouldn't be much if any more difficult to produce, I think. Somebody makes them like this (don't remember who), I put a picture of one on my gallery at 240Z.org here: http://www.classiczcars.com/photopost/showphoto.php?photo=3164

For adjustability, do you have opposite-threaded rods coming out of the inner and outer welded pieces, with a turnbuckle connecting them? I just wonder about bending loads from a rear bar working those connections (same issue with the front arms). I wonder if there's an easy way to mount swaybar links to the bottom of the strut housing, or coaxially with the CA outer pivot? That would eliminate the out-of-plane bending load, and the turnbuckle would be loaded axially only (ideal).

Note: These are my IMPRESSIONS based on what I see (and my experience in structural design and analysis), not the result of any analysis.

January 30, 2003

Yeah, that's what I meant by the "long tube", the one that is axial with the inner bushings. The one you show *looks* (note emphasis, as in I haven't done any real analysis on either) better. For a strictly tubular one, I'd rather see something like this (here's hoping my ASCII art isn't too too horrible) for the inner part. This would be MUCH stiffer and stronger.

.____| Rear Inner Pivot

| / |

.| / |

|

| Forward Inner Pivot

January 30, 2003

Hate to have to say it, but the triangulation on those arms is wrong. It puts the long tube in bending, a BIG no-no, and not necessary. Also, I don't know about the threaded rods(?) in bending, particularly if a rear sway bar is used. I'm not saying the design is inadequate, I haven't done any analysis on it. But it looks bad. I've seen more than one aftermarket suspension component failure at the track (mostly Mustangs), and it AIN'T pretty.

Not meant as an attack or anything, just an observation.

January 29, 2003

Originally posted by LT_ZT:
yeah i was leaning more toward the 2.8 becuase i like the faster higher revs.

Gotta comment on this (AGAIN). Theoretically, an L28 will have the same peak piston acceleration as an L31 with the L28 spinning 2.85% faster. So if piston acceleration is what limits redline rpm, the L28 would have a 2.85% higher redline. BUT, the L31 has 12.5% more displacement, so the L28 wouldn't spin fast enough to make more power, and it would have ~12.5% less torque everywhere, and best-case would have ~9% less peak power. And that assumes custom pistons that have the same strength. Stock, Nissan gave both the L28 and KA24E engines a 6500 rpm redline, though the KA24E has a much longer stroke (96mm vs. 79mm). Basing L31 redline on KA24E peak piston acceleration at 6500 rpm gives a 7130rpm redline, higher than the L28. No question which would rev up faster (L31). Even with a turbo, displacement is your FRIEND. If you want to maximize hp, you want to maximize displacement. The idea that strokers rev up more slowly is a myth, and any loss in maximum rpm is generally MORE than offset by the increase in displacement.

If I were trying to make 500hp with an L-series engine, the first thing I'd do is maximize displacement.

Whatever you do, keep us posted!

January 29, 2003

Ditto what Bob said regarding having headwork done. Sunbelt rebuilt, ported, did some mild cc shaping, and installed a 302deg/.550" cam for my application, which is pretty similar to what you want. BTW, the KA24E pistons are dished, it's really more like a .019" raised ridge around the edge of the top of the piston. Have it machined off, this will give you more flexibility on head gasket thickness. My unshaved pistons stick up .022", removing the ridge would reduce this to .003" without really affecting compression ratio. You might also have the pistons notched for valve clearance, as with my cam I've only got ~.045" min clearance between the pistons and intake valve, even with the cam timing slightly retarded. I have no experience with downdraft Webers, but have heard from reliable sources that they're not as good as the stock SU carbs. I got a decent boost in high-end power when I switched from stock 1 3/4" SUs to 2" Jag SUs, but nothing like what I got when I went from 2" SUs to 45mm 3X2 carbs. If cost is an object, I'd recommend a used set of triples. Otherwise, FI with triple dual throttles.

I guess 11.5:1 might be OK on 96octane race gas, but Norm (resident giant-killing 1/4miler) has had piston ring lands fail (due to detonation?) above 11.2:1 on 93octane pump fuel. You might consider 100+ octane race gas. Or you could find out what flavor VPRacing fuel John Coffey is using in his 13.?:1 3.0 liter race engine, but you might want forged pistons at that CR level. I'm running 10.8:1 CR on 93 pump fuel at the moment, no problems.

Here's a link to rear wheel dyno results for my car (I can never seem to get these to appear in my posts): http://www.classiczcars.com/photopost/showphoto.php?photo=2274&papass=&sort=1&thecat=500

The leaning out at higher rpm has been cured with smaller air jets since that dyno run, which netted me 5 more hp (went from 228 to 233 on those dyno runs).

It is a lot of fun to outrun Z06s, Viper GTSs, 911 turbos, Cobra replicas and the like in an old Datsun:)

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Posts posted by Dan Baldwin