Important to PUSH the Northstar once a week? - Page 2
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Northstar Engines and System Technical Discussion Discussion, Important to PUSH the Northstar once a week? in Cadillac Engine Technical Discussion; Thanks for the information. I am still from the old school of cast iron blocks and an aluminum engine somewhat ...
  1. #16
    peatea's Avatar
    peatea is offline Cadillac Owners Member
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    Thanks for the information.
    I am still from the old school of cast iron blocks and an aluminum engine somewhat worries me.
    I baby my northstar around town but when I hit the road I treat it like a road car.
    I am not afraid to push it.

    Pat

  2. #17
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    I drive it pretty easy usually around town. Afterall, your mileage DOES go into the crapper when you hot-foot it around all the time. But on almost every freeway entrance (if there's not a slow Honda or Acura in front of me), I'll let that Northstar run, baby! I grew up on iron-block pushrod engines, so I was never used to the DOHC nature, but the sound of four camshafts singing in harmony is just unmatched! Did you know that a full 250 lb*ft of torque is available at JUST 1000 rpm??!! That's big-time! The Northstar is incredibly flexible for a DOHC design. You can lope around at just above idle if you want, but it'll open up and run if you let it!

    Remember, when you floor it, you're not "pushing it hard", you're really letting it run at its potential. Marine and aircraft engines run at WOT all the time. Northstars make great marine and light aircraft engines.

  3. #18
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    I have to agree with pushing the northstar. If the results of those cycles are true, then what could a little redlining possibly do to it, if it can survive all that. They are really designed to last, if you take care of them.

    I was realizing the importance of WOT-ing and engine, or at least really pushing. My fleetwood never gets pushed, it only gets driven once a week, and about 1 a month on the highway. I pulled it out of the garage, and revved it a couple of time. Nice little puffs of smoke. Next time i have it out i am going to really slam it down.

  4. #19
    Katshot's Avatar
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    What GAS-BURNING engines do you know that are run at WOT constantly?

  5. #20
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    Originally posted by Katshot
    What GAS-BURNING engines do you know that are run at WOT constantly?
    Marine engines and light aircraft engines come readily to mind. I'm sure there are others, but I can't think of any now.

  6. #21
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    It seems that some ricers have to be at WOT to stay at highway speeds :-D .

    In response, i would have to agree that most aircraft engines run at high RPMs, but i dont think they run at WOT. IMO, i dont think there are any engines that run at WOT constantly. My relatives own a marina, and most of the engines that are in there are simply small block chevys, chryslers, and fords with marine conversions (such as wet manifolds, brass water pump, and other things i cant think of). Sure, some can endure more WOT than others, but there is no engine (that i know of) that is specifically designed to be at WOT all the time. End of story.

  7. #22
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    While most engines are not designed for full-throttle use, the Northstar IS designed for this. Read below, from a statement by a friend of mine, a GM Powertrain engineer who worked on the Northstar project back in the late 1980s and early 1990s:

    =====
    The 300-hour test I referenced is run at full throttle, maximum power, maximum RPM. On a Northstar we don't usually bother with the LD8; we run everything at 6000 RPM, 300 HP continuous, for 300 hours. That is like driving 150 MPH for 300 hours, or about 45,000 miles actually. If you can drive the equivalent of twice around the world at 150 mph, you are not the average customer. Besides, that test is just used to rapidly accumulate high load cycles on things like pistons, bearings, cranks, and block bulkheads.

    There are many other dyno schedules we use to validate the engine for strength, longevity and gasket endurance. The gasket endurance test is particularly interesting because the engine is in a dyno cell and it is hooked to a large industrial chiller on one cooling system and a short-circuited radiator/hot water tank on the other. The schedule is run at WOT and about 4400 RPM (peak torque). The engine cooling system is short-circuited and the coolant gets to about 260 F. The engine goes to idle and is shut down. The cooling system is automatically switched and the engine is flooded with coolant from the chiller at -20 F. Frost literally forms on the block as the temperature drops. When the core of the block gets to -20 F the engine is started and immediately goes to WOT at 4400. It climbs back to 260 F from -20 F in about 6 minutes. Now for the killer: that is one cycle. A full test is 1200 cycles. Routinely run 1600 cycles to establish statistical significance of the data. If you know a customer that can mistreat an engine worse than that I would like to know how they are doing it.
    =====

    That coolant cycle test is the one I mentioned. I got my facts wrong, though. I said they do it 300 times, they really do it 1200-1600 times. My bad.

    The Northstar is a high-speed, high-performance engine. It LIKES to live in the upper ranges of the tachometer. This ain't no small block Chevy!

  8. #23
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    Those really are tremendous results.

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    seduxion is offline Cadillac Owners Member
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    yes very impressive... i wonder ho wmany other engines can do that.

  10. #25
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    Unfortunately,
    Many (if not all) the tests that engineers run on test engines are NOT directly applicable to production engines run on the street.
    As for engines run at WOT, Many aircraft engines are run at a NEAR full-throttle for the following reasons:
    1. Better fuel efficiency
    2. Less wear on the engine
    3. More effective use of the engine's power
    Aircraft engines that are run this way are are usually in the more expensive aircraft because in order to do it, you must have a variable-pitch prop.
    Marine engines are NOT run at WOT. They ARE generally run at a relatively high throttle angle due to the constant load produced by the water. True, once you get the craft on plane, it is easier to maintain speed but overall there is a large load placed on the engine constantly. Oh, and the different materials used in the engines (brass, bronze, etc.) are used because they are non-sparking, and less likely to corrode, not because they are more durable.

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    Oh yeah, I forgot. As for engine durability, the Northstar is well designed but I don't recall seeing it doing too well in the actual competition.

  12. #27
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    Originally posted by Katshot
    Unfortunately,
    Many (if not all) the tests that engineers run on test engines are NOT directly applicable to production engines run on the street.
    The tests are usually run on engines that are hand-built, necessary because the production tooling isn't in place. In a subsequent conversation with my friend at GM, he said that production engines are actually more consistent than the hand-built ones. The production tooling and process can put a group of engines together much more consistently than a single person or group of people can.

    Seeing the results of durability tests on hand-built pre-production models is impressive, and I think that track record only gets better in the real world. Yes, some engines have issues -- it's impossible to build a perfect engine that will never have defects, but it's getting closer as time goes on. I do think that the track record for the Northstar, being essentially a clean-slate design, is impressive. The reliability of, say, a 350 Chevy is pretty good because they've had 30 years to tweak and improve the design. The Northstars had a production run starting in about 1993 and continuing on to 2000, essentially unchanged. In 2000, they changed the combustion chambers and piston tops to effect a slightly lower compression ratio, enough to recommend straight 87-octane. For 2004, they're adding variable valve timing, on BOTH the intake and exhaust camshafts.

    It's a world-class design that had to have the bugs worked out for sure. Caddys first high-compression V8 in 1949 probably wasn't stone reliable either. It takes time to see what the issues in the real world will be and how to improve them.

    I don't know if I spoke to your comment or not...I just started rambling. What do you mean, "actual competition"?

  13. #28
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    There's an actual competition among factory (and non-factory) cars that just runs the cars flat-out on a banked track until they blow. I remember reading about it a couple years ago in a magazine. As I recall though, there weren't any Northstars there.
    Oh, as far as the production engines vs. hand-built units. I agree that mass production of engines leads to greater consistancy BUT, that also means that if there's a flaw in the manufacturing process, you get a WHOLE LOT of engines with the same flaw. This is what has caused problems several times for Cadillac. I'll agree that IF the engines are built EXACTLY as designed, you'd have some great engines. The problem is making that happen. I remember a couple years ago, one specific issue was that the holes for the head bolts weren't drilled quite deep enough in the block. This in turn caused head bolt torque to be reached before proper head gasket clamping load was attained. Guess what that caused? How 'bout several THOUSAND Northstars with head gasket failures, broke-down Cadillacs on the roads, pissed-off customers, service bulletins, recalls, legal notices, etc. etc. etc.
    So you can see how a TINY screw-up in manufacturing can keep a GREAT DESIGN from being a GREAT ENGINE.

  14. #29
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    Yeah, absolutely, the process has to be nailed down before production can start. I don't remember reading about that endurance run. If those other vehicles can run at redline for 300 hours, then I'd say that they've matched what the Northstar was designed and validated for.

    I've also never heard of thousands of Northstars blowing head gaskets because of a manufacturing flaw. If there's an article somewhere, that'd be an interesting read. I know that mine's performed flawlessly for 112,000 miles. Only major thing has been an alternator. Recently, I think the water pump is starting to weep, so I need to change that, which I'm happy to do after working on my old Cutlass. Water pump change on that car was about a 4-6 hour job. On the Northstar, about 45-60 minutes, including draining the fluid.

    After I get the water pump changed, I'm looking forward to the next 100,000 miles! I think low mileage is overrated anymore. The car with the least mileage we own is the Cadillac (112k). My Nissan truck has 173k and both vehicles run like brand new. Manufacturing and production have sure come a long way since a few decades ago. I remember when people would throw the car away (or at least change engines) at 90-100k.

  15. #30
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    Yeah, you're right. Today's car buyers/owners are spoiled. Cars last SO MUCH LONGER now than just back in the 80's let alone the 70's or earlier. Thank corriosion resistant metals and better finishes.

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