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Thread: Big Cottonwood Canyon Photoshoot and Near Disaster

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    Newbie ninjazombiemaster's Avatar
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    Default Big Cottonwood Canyon Photoshoot and Near Disaster

    Hey Guys,

    I met up with a fellow Z driver and drove up Big Cottonwood Canyon, a 15-mile run southeast of Salt Lake City with a total elevation change of over 4000 feet.
    We were up for a good cruise, and trying to get some sweet photos. Here's what I managed with my phone.
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    We also took another drive through Butterfield Canyon, a low elevation canyon near the copper mines in the southwest region of the valley. I haven't gone through the photos there yet. It was raining, and made for quite an exciting drive through wet, narrow, tree lined roads that are not common in Salt Lake.

    My buddies car is a 280z, NA. We purchased our cars about the same time last year. Its amazing how different they sound and drive. His engines tone is very different, much quieter, revving at a higher pitch, but idles at a lower drone. Mine is very loud, and sounds more like a gigantic lawn mower.

    His suspension, chassis and clutch are much more rigid. My car is soft in comparison. Neither of us enjoyed driving the other's car. His actually felt slower to me! But who knows. We didn't drag race..

    Anyway, back to the story. Once we reached our turning point in the canyon, my car made it about 10 feet down before my engine died. Must've been the elevation. I turned the key - and nothing. Here I am, rolling down the canyon with my engine totally dead. Now, its all downhill, pun intended from here. It didn't hit me immediately, but without my engine on, it has no vacuum; Without vacuum, brake boosters cannot function. Here begins a 4000 foot descent down a 15 mile canyon with no power braking. By far, one of the most frightening experiences I've ever had. While I could slow the car manually, not nearly as quickly as the driving conditions necessitate. Nevertheless, keeping my head calm got me safely to the base of the canyon, where my car started suddenly and continued with no further issue.

    The entire experience was captured by a dash cam.. although it looks much slower in the video than it felt in person.
    https://www.youtube.com/watch?v=_myAS2IAgac
    1973 240z w/ ztherapy round top conversion.

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    That was a ride , glad your OK.

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    I'm curious, is your car an automatic? If not, why didn't you let engine compression slow you down?

    Also, for it to die while running and then restart later might indicate junk in the gas tank.
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    Newbie ninjazombiemaster's Avatar
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    Its manual. I thought engine braking was reliant more on vacuum than the compression and was negligible in effect when the engine isn't running.
    Fuel looks clean. My tank should be in good shape, filter is spotless. I'm blaming the carbs at this point. Next day off I have, I'm gonna re-tune them and see if I get any insight.
    1973 240z w/ ztherapy round top conversion.

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    No more body roll! SteveJ's Avatar
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    Engine braking uses the engine's compression stroke to slow you down. Try it some time on a much more gradual slope.
    Are your fuel lines insulated well? You may have been experiencing some vapor lock, though it's funny that the car would start and then experience vapor lock.
    If it was the altitude, tuning the carburetors wouldn't help. They would need to be re-jetted. Also, you would probably have experienced sluggish performance on the way up.

    As far as checking your gas, some time when you get down to a gallon or two, drain the gas via the bottom plug and see what comes out. Unless you have had the tank boiled and sealed, you might be surprised at what you get out.
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    Newbie ninjazombiemaster's Avatar
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    Performance on the way up wasn't great. But I'll give that a try and see what comes out.
    I don't believe I've ever experienced vapor lock, surprisingly. My car always starts, no matter how hot. Even when my engine is over 200 degrees, and its 100 outside. Sure does make me want AC, though. On that note, though - is it normal for the Temp to sit roughly halfway? My gauge goes from 180-250. My friends 280z would only reach a quarter of the way up. I have the aluminum radiator upgrade, as you can see, and I'm all topped off as far as coolant goes.
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    Torch Wielding Villager gogriz91's Avatar
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    Might be elevation and heat, I had what I thought to be vapor lock in the center part of Yellowstone whereas I didn't have a problem down at Jackson Lake Lodge and in the valley. Got a tow, put an electric pump on to augment the mechanical and no more problems.
    '73 HLS30 129806 ; L-28, street cam, SUs, 5-speed, Koni's, Suspension techniques springs, swaybars, 3.90 R200 LSD

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    Quote Originally Posted by ninjazombiemaster View Post
    Performance on the way up wasn't great. But I'll give that a try and see what comes out.
    I don't believe I've ever experienced vapor lock, surprisingly. My car always starts, no matter how hot. Even when my engine is over 200 degrees, and its 100 outside. Sure does make me want AC, though. On that note, though - is it normal for the Temp to sit roughly halfway? My gauge goes from 180-250. My friends 280z would only reach a quarter of the way up. I have the aluminum radiator upgrade, as you can see, and I'm all topped off as far as coolant goes.
    You might want to talk to the guys at Z Therapy about what can be done to improve high altitude performance.
    What temperature thermostat are you running?
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    Aren't you glad you don't have power steering? BTW, looked like you were going fast enough. Nice Canyon.

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    Quote Originally Posted by SteveJ View Post
    You might want to talk to the guys at Z Therapy about what can be done to improve high altitude performance.
    What temperature thermostat are you running?
    Good thinking. Bruce might have some ideas. Its just the normal 180 Nissan thermostat if I remember correctly. That'd put halfway at 215 degrees. I have a small crack in the exhaust manifold that may be party responsible. Isolating the exhaust would probably be effective.
    Quote Originally Posted by Stanley View Post
    Aren't you glad you don't have power steering? BTW, looked like you were going fast enough. Nice Canyon.
    Haha, yeah. Only time I wish I had it is parallel parking, but I prefer not having it.

    It really is a beautiful canyon though. I have a minute so I'll see if any of my other photos turned out. I am considering an electric fuel pump. Although I don't seem to have vapor lock problems, the added pressure won't hurt, and will make certain.
    1973 240z w/ ztherapy round top conversion.

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    Driving steep roads like that, you REALLY need to understand engine braking. You don't WANT to use your brakes (much) on a road like that, because you'll overheat them possibly to the point of failure! You should have ridden it down in maybe 3rd gear. Your spinning engine would have given you vacuum for occasional power braking.

    FAIW, if I were taking that hill downhill in my 280Z, with my foot off the pedal and the engine spinning way over the 2500 RPM (?) fuel cut limit, the system wouldn't have injected fuel anyway (and therefore wouldn't technically be "running").

    I'm glad you're OK. Phew!
    Last edited by FastWoman; 08-19-2013 at 08:30 PM.
    My last three sports cars while I still owned all three:

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    Here are my favorites from Butterfield.
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    1973 240z w/ ztherapy round top conversion.

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    Frankly, that was just plain stupid. If your engine dies pull over as soon as you can, and don't continue hurtling down the road.
    2/74 260Z

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    Dig it when your tires are squealing like that on a turn you need the motor for some extra torque to keep control. Find a twisty gravel road with wide shoulders and a clear view for oncoming traffic and you'll have the technique down in no time, if you don't have it already. NFS games are good practice too.

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    He needs not to be in neutral and riding his brakes all the way down! (The same would be true with an auto transmission -- slow down a bit, and DOWNSHIFT!) This isn't flat track driving; it's mountain driving.
    My last three sports cars while I still owned all three:

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    I'm a young driver, and a lot of this stuff isn't taught in modern drivers ed classes. They just assume you'll be in a new enough car for stuff to just work all the time. They don't even teach manuals these days.

    Don't know where I heard it, but I was always told to keep the car out of gear - because replacing worn brakes is less expensive and easier then replacing a worn clutch. Perhaps that information was incorrect.
    1973 240z w/ ztherapy round top conversion.

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    As long as the clutch isn't slipping (and badly, at that) there shouldn't be any wear from using engine braking. My daily driving with manual transmission cars always yielded longer brake life than similarly sized automatics.

    Even when I took driver's ed...17 or so years ago...they didn't really teach true manual transmission driving or technique. There were "simulators" that could be used to demonstrate a three on the tree, but how likely was anyone to run across on of those in the 90s? I remember them from when I was a kid, but I've never driven one.

    Anyway, don't worry about engine braking wearing out your clutch. Obviously you won't want to downshift from 4th to 2nd or anything, you'll risk over-rev if you're going too fast. Just try downshifting from 4th to 3rd or 3rd to 2nd while you're slowing down for stoplights. You'll get used to it and it'll be something you do mindlessly before long.
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    Quote Originally Posted by ninjazombiemaster View Post
    I'm a young driver, and a lot of this stuff isn't taught in modern drivers ed classes. They just assume you'll be in a new enough car for stuff to just work all the time. They don't even teach manuals these days.

    Don't know where I heard it, but I was always told to keep the car out of gear - because replacing worn brakes is less expensive and easier then replacing a worn clutch. Perhaps that information was incorrect.
    Allow me to help a bit then...

    You pretty much did everything wrong in that scenario and were lucky that there wasn't a need for any panic stops. As soon as the engine cut, you should've pulled over to a stop as soon as it was safe to do so. Without power assist, your brakes work just fine although it will take a lot more force to get the same amount of stopping power. Use two feet on the pedal if you don't have enough strength using one leg.

    Engine braking could've helped as well, had you put it into say 4th or 3rd gear and slowly let off the clutch (as to not lock up the rears). You've been SORELY misinformed about keeping the car out of gear. Keeping it out of gear has ZERO benefits and more than a few drawbacks. Mainly, you'll get worse gas mileage, wear out your brakes quicker, and don't have immediate engine response to get you out of trouble if the accelerator is needed. The ONLY time your clutch wears is when you SLIP it. An engaged clutch does not wear.

    I recommend you attend a driving school near you. It would benefit you and those around you greatly.

    http://www.tirerack.com/features/mot...t_survival.jsp
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    The question of whether to engine-brake or not is open to debate ONLY ON FLAT GROUND. Irrespective of whether you drive stick or auto -- and irrespective of whether you're towing a big camper with a big truck, or whether you're just tooling along in a little sports car -- Model T Ford or late model Lexus -- you MUST, MUST let the engine carry the braking load on long, downhill grades. MUST! You commented that you smelled the clutch burning, but I can assure you that wasn't the clutch. It was your brakes, which were probably glowing a dull red.

    The problem with riding brakes down a long grade is that friction causes heat, which can cause any moisture in your brake fluid fluid to boil. If this happens, the steam fills the lines, resulting in complete hydraulic failure -- NO BRAKES AT ALL, except for your emergency brake handle, of course. (Most emergency brakes are inadequate for a situation like that.) There's a YouTube video somewhere in which someone was offroading in an SUV down a mountain. The brakes failed in this manner, and they had a pretty scary free-rolling descent to the bottom, ending in a crash. You could hear everyone in the SUV screaming as though they were going to die. Nobody was hurt, fortunately.

    It's unfortunate they didn't teach you this stuff in driver's ed. I second Leon's recommendation for a good course. Hey, no matter how old or experienced you are, there's always something else to learn!
    Last edited by FastWoman; 08-20-2013 at 05:12 PM.
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    Registered User LeonV's Avatar
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    FWIW, as far as engine braking is concerned, I always leave the car in gear until right before I stop, no matter whether the ground is flat or I'm on an incline. In EFI cars, you take advantage of drop-throttle fuel cut by leaving it gear. This is part of the reason why I can get 37mpg out of my '01 Accord.
    2/74 260Z

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    That video was scary! Thank goodness you (and your Z) are okay. You should come to drive licence here...

    Driving licence in Finland - Wikipedia, the free encyclopedia
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    With the engine off as long as it was still in gear there would have been vacuum for the power brakes. The engine need not be "running" to make vacuum just turning. Also, maximum engine braking occurs in gear with the key off at full throttle. Many modern vehicles will hold speed on a downhill by cutting fuel and opening the throttle to increase engine braking.

    Steve

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    Quote Originally Posted by doradox View Post
    With the engine off as long as it was still in gear there would have been vacuum for the power brakes. The engine need not be "running" to make vacuum just turning. Also, maximum engine braking occurs in gear with the key off at full throttle. Many modern vehicles will hold speed on a downhill by cutting fuel and opening the throttle to increase engine braking.

    Steve
    Opening the throttle would decrease engine braking...
    2/74 260Z

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    Quote Originally Posted by LeonV View Post
    Opening the throttle would decrease engine braking...
    You did read the key off part didn't you?
    At low throttle openings you aren't pumping much air. At large throttle openings you pump a lot of air. Which is harder?
    On a recent trip to Colorado we climbed and descended Pikes Peak. The automatic grade braking system in the wife's Denali was most certainly opening the throttle while holding a low gear. You could hear the intake noise dramatically increase when normal compression braking wasn't doing the job. I wanted to see what was happening so I stopped and hooked my scanner up (I always carry a lot of tools when I'm on the road) and continued down. TPS reading verified what I was hearing.

    You have a car. Give it a try.

    Steve

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    Quote Originally Posted by doradox View Post
    You did read the key off part didn't you?
    At low throttle openings you aren't pumping much air. At large throttle openings you pump a lot of air. Which is harder?
    On a recent trip to Colorado we climbed and descended Pikes Peak. The automatic grade braking system in the wife's Denali was most certainly opening the throttle while holding a low gear. You could hear the intake noise dramatically increase when normal compression braking wasn't doing the job. I wanted to see what was happening so I stopped and hooked my scanner up (I always carry a lot of tools when I'm on the road) and continued down. TPS reading verified what I was hearing.

    You have a car. Give it a try.

    Steve
    I would think that an engineer would base a statement like, "maximum engine braking occurs in gear with the key off at full throttle" off something more than one data point. I also like how your responses must always be condescending, is that how you deal with people face-to-face too? Anyway...

    If your wife's truck showed that it would go full-throttle under engine braking, then I think it would be safe to assume that it has some sort of variable valve timing.

    The trapped air within the cylinder acts as a spring when the valves are closed. The main losses of a motored engine are frictional, with the rest being pumping losses past the valves and throttle (ignoring skin friction in runner walls). On an L-series engine, valves have a constant timing and lift profile, so the only thing you can manipulate is the throttle, thus increasing/decreasing pumping losses at the throttle.

    An engine with variable valve timing can alter when the intake valve closes and exhaust valve opens, thus the exhaust valve can be opened much earlier which would then bleed off the work that was done to the air when compressing it. This would be similar to a Jake Brake in diesel truck applications.

    It was YOUR recommendation so go ahead and prove it. With your Z this time and not a modern, computer-controlled truck. Personally, I'd be interesting in testing this myself but both of my Zs are disabled for the time being. My hypothesis would be that engine braking is MINIMUM at wide-open throttle.

    FWIW, here's an interesting tid-bit from Cummins:

    Diesel engines are 'compression ignition' engines, which means that there are no
    external means to ignite the fuel and air mixture, except by compressing the
    fuel/air mixture to cause enough heat to promote combustion of the mixture. The
    compression ratios for Cummins diesel engines are currently around 14:1 for
    larger Cummins engines and 16.5:1 or 17.2:1 for some of the B series smaller
    engines and gasoline engines, for example are about 8 to 1. Since gasoline
    engines are spark ignited, they have less compression ratio, where the diesel
    must 'compress' the fuel/air mixture into a smaller space to create enough heat,
    to initiate ignition.

    A diesel, being a free-breathing engine by virtue of having no valving or
    venturi restrictions (carburetor) offers inherently less braking effort than a
    gasoline (spark ignition) engine even though the diesel engine has about twice
    the compression ratio of the spark ignition engine (which obviously means that
    it requires more effort to force up the piston on the compression stroke), that
    work is given almost entirely back (less friction and heat transfer losses) when
    the air is allowed to expand on the next outward stroke.

    Conversly, the spark ignition engine becomes a vacuum pump when being motored
    with the throttle closed.
    2/74 260Z

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    Quote Originally Posted by LeonV View Post
    I would think that an engineer would base a statement like, "maximum engine braking occurs in gear with the key off at full throttle" off something more than one data point. I also like how your responses must always be condescending, is that how you deal with people face-to-face too? Anyway...

    If your wife's truck showed that it would go full-throttle under engine braking, then I think it would be safe to assume that it has some sort of variable valve timing.

    The trapped air within the cylinder acts as a spring when the valves are closed. The main losses of a motored engine are frictional, with the rest being pumping losses past the valves and throttle (ignoring skin friction in runner walls). On an L-series engine, valves have a constant timing and lift profile, so the only thing you can manipulate is the throttle, thus increasing/decreasing pumping losses at the throttle.

    An engine with variable valve timing can alter when the intake valve closes and exhaust valve opens, thus the exhaust valve can be opened much earlier which would then bleed off the work that was done to the air when compressing it. This would be similar to a Jake Brake in diesel truck applications.

    It was YOUR recommendation so go ahead and prove it. With your Z this time and not a modern, computer-controlled truck. Personally, I'd be interesting in testing this myself but both of my Zs are disabled for the time being. My hypothesis would be that engine braking is MINIMUM at wide-open throttle.

    FWIW, here's an interesting tid-bit from Cummins:
    My one data point dis-proved your hypothesis. That's all it takes. Also my Denali doesn't have variable valve timing or cylinder deactivation. It's a relatively simple analysis to do if you remember your thermo. Draw a box around the engine and account for inputs and outputs. I wouldn't exactly say I recommend it either. That's a lot unburned of fuel/air mix washing the cylinders down in a carbed car.

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    Ninja, it is well you and everyone else on that highway are safe. You were foolish but lucky. Here's another perspective: coasting down grade in neutral is not only dangerous, but also against the law in many states for just that reason. Your video has provided proof of at least one driving infraction, maybe more. Surely a driving course or the study to acquire the privilege of a dr. license would advise that it is the responsibility of the driver to be well acquainted with the laws and driving considerations of that state or any through which one drives. Youth or blame are not excuses for ignorance. Such laws are easily accessible online. The ensuing debate about downhill engine braking in a properly functioning vehicle is productive, but mute in this case when the driver should have immediately put on emergency flashers and pulled off to ensure everyone's safety. Your recorded comments demonstrated that you did recognize but ignored the fatal possibility of filming your own death. Perhaps having an in-car camera and the present day propensity to record and publicly share bizarre, exciting, risky, and even illegal behavior were motivation to discard common sense and consideration for others, including your buddy in front of you, whom I'm sure would have come back if you had put on flashers, flashed headlights, or better yet, pulled off. Sorry. I don't mean to be rude. I hope you will give serious retrospection rather than defense, and I'm glad you survived to openly and honestly present the topic for discussion and education. This thread will perhaps save lives. "Live and learn," yes, but better yet, "learn and live!"

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    ^All things given, filming his own death could've been the best case scenario had he lost control or under steered into oncoming traffic (there were plenty in the vid, including bikes). I also saw plenty of shoulder spaces on some stretches, that's where the vid should've stopped. Sorry to say you've risked many lives in danger, I'd hate to see a biker or a car full of family & kids in a fatal collision when the fault is 100% on the OP.

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    Newbie ninjazombiemaster's Avatar
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    Quote Originally Posted by Kennymonster View Post
    Sorry to say you've risked many lives in danger
    Quote Originally Posted by alternativez View Post
    Ninja, it is well you and everyone else on that highway are safe. You were foolish but lucky. Here's another perspective: coasting down grade in neutral is not only dangerous, but also against the law in many states for just that reason.
    Quote Originally Posted by LeonV View Post
    You pretty much did everything wrong in that scenario and were lucky that there wasn't a need for any panic stops. As soon as the engine cut, you should've pulled over to a stop as soon as it was safe to do so.
    Quote Originally Posted by LeonV View Post
    Frankly, that was just plain stupid. If your engine dies pull over as soon as you can, and don't continue hurtling down the road.
    Yes, I get it. It was dumb and dangerous. If I ever find myself in that situation I will act differently, however, what has already happened cannot be changed, and was in a moment of emergency I wasn't prepared fully for at the time. What is important is I learned from the situation, and everyone came out okay.
    1973 240z w/ ztherapy round top conversion.

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    Quote Originally Posted by Virto View Post
    they didn't really teach true manual transmission driving or technique. There were "simulators"
    How many drops is this for you, Lieutenant?

    Quote Originally Posted by LeonV View Post
    I always leave the car in gear until right before I stop, no matter whether the ground is flat or I'm on an incline.
    Me too. And I don't use the clutch to take it out of gear. Once you slow down to the point where the gear train is unloaded it slips out easily.

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    It's awesome bartsscooterservice's Avatar
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    The engine dying must be some other problem. There must be enough oxygen there, your buddies car keeps running..
    HLS30 32581, 5/71 Matching numbers

    Jay Leno : You know one week after the Americans have walked on the moon, the Japanese introduced this sports car, and…if you’re a car guy pretty equal. I mean walking on the moon was pretty good, but how many times you’d gonna walk on the moon? But here was an affordable sports car that had real performance and looked like it cost a lot more than it did.

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    Quote Originally Posted by ninjazombiemaster View Post
    What is important is I learned from the situation, and everyone came out okay.
    Absolutely! Please don't feel beaten upon. I think we all did dumb things in our youth. I think this was just a teachable moment. I would like to think that someone would take the time to have the same sort of talk with my own kids over this sort of thing.

    As for engine braking technique: It's pretty much flat where I live, and I'm of the mind that brakes are easier/cheaper to service than clutches. So I, too, leave my car in gear as I'm rolling to a stop. I don't do any downshifting unless there's really a need (e.g. I'm towing a trailer and want to keep an excessive load off the brakes). Doing this extends the life of the brakes and makes no difference to the life of the clutch.

    And rolling down a long grade (your situation), I will drop a gear or two, such that I can coast down at approximately the speed I want without using the brakes. I think 3rd would have worked fine for the grade you took. If you remember seeing any caution signs that said "Grade. Use low gear," that's what that was all about, whether automatic or stick.

    FAIW, I remember once driving down a grade about that long, but actually much steeper, with sharper curves, in a Dodge Ram 2500 truck, towing a rather heavy 30' camper. The entire rig was 50 ft long. My heart was pounding the entire way, and I needed about an hour at a diner to chill after I reached the bottom. I think I did it in 1st gear (automatic transmission) at approximately 35 - 40 mph, with the engine winding up within maybe 1000-500 RPM of redline. And if I could have avoided that situation, I would have avoided it. Unfortunately there was no warning before I was committed to it -- only a sign telling me I'm in deep @#$% for the next several miles, with no pull-offs available. (Thanks for the useful info, Arkansas!) Nobody was impatient with me. I think everyone on the road understood that doing it any differently could have resulted in someone's death. Mountains are different: Gravity is not your friend. Nobody will fault you for doing what you have to do to stay safe.
    Last edited by FastWoman; 08-23-2013 at 07:40 AM.
    My last three sports cars while I still owned all three:

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    1966 Ford Mustang Coupe (sold)
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    The correct thing to do would have been to stop the car and get it running before descending. Barring that, descending a little at a time allowing the brakes to cool at regular intervals.

    Using engine braking on a non-running carbureted engine is a good way to fill up the exhaust system with gasoline.

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    Keeping the speed down seemed to help me once, in the old chevy truck, heading South from Oregon on the coastal route. That's a long downgrade with curves. Smelled the brakes, felt them starting to fade. the truck tops out about 75 with the 230 and a 4 point something rear end. Got it stopped on a truck run-off and saw them glowing red. After they cooled off I took it real slow - 2nd gear with frequent stops, no proble When I got back did a full brake job on it.
    Another time in the truck, had a job in the Hollywood hills. Very steep narrow road with tight curves. Felt the brakes about gone at the top of a hill. Got out, tightened up the adjustment, brakes ok again.
    Wonder how a z with stock brakes will do on Pike's peak for example? Is it safe to go as fast as traffic, driving ability, and the road will allow, or is it necessary to use take it slow, use engine braking, or stop every 5 minutes or so for a cool-down? What brake mods would you need to really stand on the gas on the way down? How would a rally driver in a Z take that downhill if their brakes were stock, for the best time?

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    Quote Originally Posted by bartsscooterservice View Post
    The engine dying must be some other problem. There must be enough oxygen there, your buddies car keeps running..
    Hes got a 280z with EFI. It should be much less effected by altitude.
    Quote Originally Posted by FastWoman View Post
    Absolutely! Please don't feel beaten upon. I think we all did dumb things in our youth. I think this was just a teachable moment. I would like to think that someone would take the time to have the same sort of talk with my own kids over this sort of thing.
    No worries. I live in a valley with many steep hills, and this has all been valuable information.
    1973 240z w/ ztherapy round top conversion.

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    Quote Originally Posted by Stanley View Post
    Wonder how a z with stock brakes will do on Pike's peak for example? Is it safe to go as fast as traffic, driving ability, and the road will allow, or is it necessary to use take it slow, use engine braking, or stop every 5 minutes or so for a cool-down? What brake mods would you need to really stand on the gas on the way down? How would a rally driver in a Z take that downhill if their brakes were stock, for the best time?
    Strange questions. A stock Z would do fine if driven intelligently. During mountain driving, if done properly, brakes do not get overheated and do not need to cool down. Wind up the engine, and let it do the work. Even feathering the accelerator will accelerate the car pretty dramatically. (No need to "stand on the gas.")

    When driving down a grade, just remember that gravity is shoving you forward, so you don't have the same braking potential before you lose traction and slide off the embankment. Unlike on a flat track, mistakes are often fatal.

    I actually did some google searches to find out how suicidal people might race cars downhill. I came up with nothing. There are UPHILL races, but not downhill. I'm sure there's a very good reason for that, namely that when racing uphill, you can stop on a dime, but when racing downhill, you can go skidding off the road with even moderate braking and can plummet to your death. So if you want to know how the autocross racers do it, I suspect the answer is that they don't.

    It's sort of like asking what techniques track and field athletes use to get the best time when sprinting across an ice rink. Or maybe it's like asking how people race their mules down to the bottom of the Grand Canyon.
    Last edited by FastWoman; 08-23-2013 at 03:22 PM.
    My last three sports cars while I still owned all three:

    2001 BMW Z3 Roadster 3.0i soft/hard top (sold)
    1966 Ford Mustang Coupe (sold)
    1978 Datsun 280Z (enjoying very much )

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    Quote Originally Posted by Captain Obvious View Post
    How many drops is this for you, Lieutenant?
    32, ... simulated.
    "How many combat drops?"
    2 including this one.
    1970 240Z HLS30 01955 March/70

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    Quote Originally Posted by grannyknot View Post
    32, ... simulated.
    "How many combat drops?"
    2 including this one.
    Haha!! Finally!!

    That took way longer than it should have!

    (It was 38 by the way... )

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    Quote Originally Posted by FastWoman View Post
    but when racing downhill, you can go skidding off the road with even moderate braking and can plummet to your death. So if you want to know how the autocross racers do it, I suspect the answer is that they don't.
    Good point. Pike's hillclimb has some downhill sections though, along with flat and uphill sections. I've watched a lot of videos of that race. Seems like every year at least one car plummets off the road. Hope to drive it someday, why I was asking. Would like to be there for the race, just to watch. It's a hell of a race.

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