: Important to PUSH the Northstar once a week?



BeelzeBob
01-28-03, 11:35 AM
When I owned my '95 ETC, the dealer told me to hit it hard once a week. I was reluctant, but did so once every two weeks. They told me it was very important for the Northstar engine. Not only does it clear out carbon - but it does something else..

Does anyone know what this 'something else' is? I trusted my dealer so I did it and had no problem doing it. But, I can understand why one may believe that the dealer just wants you to beat on your car to break it..

Any thoughts?

Katshot
01-28-03, 01:43 PM
Yeah, it increases the possibility that you'll need their service department.
Blowing out the carbon is ok but there's no other benefits I've ever heard of. Maybe he was talking about drying out the exhaust?

Devil_concours
01-29-03, 12:08 AM
i don't know. hard acceleration is never good for transmission. Correct me on this if i'm wrong.

Chuck C
01-29-03, 02:02 AM
besides, dealers have a tendency to talk off the top of their heads :rolleyes:

Cbody
01-29-03, 10:53 AM
Originally posted by Chuck C
besides, dealers have a tendency to talk of the top of their heads :rolleyes:

Well that's the nice way to put it ;)

Personally I believe it's a load of bull. I cannot fathom how "hitting it hard" could be of any benefit. Now "back in the day", when say your cad was carburated, and was only used for idling around town that has more of a basis in reality, but considering the tight nature of the PCM controlling all aspects of the engine I find it almost absurd that the engine would *need* any kind of driver influence to remedy any aspect of it's operation. As long as any EFI engine reaches operating temperature during operation then that's really all that it needs. If you need to run it *longer* in order to reach operating temp then that I could understand, but running it *harder* isn't exactly beneficial.

I'd love to know the reasoning behind the dealers statment.....I've been proven wrong more than once (a day), but I suspicion that the dealer is essentially full of it.
Jay

jadcock
01-30-03, 09:31 AM
Sure, idling the car around all day and pampering it is a sure way to keep your suspension and paint like new, but your engine hates idling. It'll do it forever, but after a while, the carbon deposits will build up on the pistons and eventually cause problems.

Benefits I can see from winding the car every once in a while:

1) Blow out all the carbon deposits.
2) Really heat up the converter and clean it out.
3) Clear the mufflers out of any interior rust/scale.

You'll notice, I'm sure, that if you only kick it every once and again, you'll get some smoke out the tailpipes. This is normal with every car and is indicative of the carbon and the rust blowing out. If you do this more often (like many times each day), you won't see this smoke anymore.

The transmission is strong (4T80-E) and can handle the power. If it couldn't, Caddy would have put it behind the Northstar. It's the strongest TFWD transmission GM Hydramatic makes. WOT upshifts won't hurt the tranny at all (unless something else is wrong, like you're low on fluid or something).

Katshot
01-30-03, 10:37 AM
The higher velocity of the airflow during full-throttle runs can help clear deposits that have accumulated in the combustion chambers, and exhaust system. That, combined with the sudden expansion of several items along the way due to the excess heat brought on by the full-throttle run helps loosen deposits too.
So bottom line, the heat loosens the deposits, and the increased airflow helps blow it out.
Hopefully this explains it a little better.

Cbody
01-30-03, 07:44 PM
I'll have to stick by my assertion from before, I'm just not seeing any carbon buildup, nor any other deposits accumulating on any EFI engines to the degree seen on older carburated engines. As long as the engine is operated for a long enough time for the engine to reach operating temp and actually driven at anything approaching a normal RPM range then you shouldn't have any problems with any foreign buildup, either in the combustion chamber or in the catalytic convertor (exhaust).

If there is actually a buildup of either carbon or other particulate in the engine, or exhaust then I'd suspect that it's not actually a problem with how it was driven, but more likely a problem with maintenence, ie. oil change intervals, leaking injectors, etc.

Of course, *if* the engine is literally only run for a few minutes at a time, or continually short tripped, then you will encounter problems, mainly due to the buildup of condensation internally which will destroy the oil in short order. But again, that's more of a temperature, or maintenence issue than it is a rpm issue, and no ammount of full throttle blasts will cure that.

I would have to wonder though, that if you're seeing smoke exiting the exhaust during full throttle blasts, that perhaps what you're seeing is actually excess fuel, or more likely burned oil, than carbon and rust deposits. Carbon and rust deposits really aren't smoke, nor to they resemble smoke upon exit.

End result, as long as the engine is kept in top shape, and driven normally, there shouldn't be any buildup of either carbon or rust to a degree that would hinder engine performance/mileage.
Jay

jadcock
01-30-03, 09:26 PM
It's true that newer MPFI engines will get "less" dirty inside, but the fact is, a byproduct of combustion is carbon and the engine WILL get dirty inside. In fact, a de-carboning procedure is a VERY common procedure for a dealership to perform on a Northstar. In fact, there's even a TSB out about carbon deposits doing so much as to unseat the rings during "normal driving":

http://www.nhtsa.gov/TSBScans/sb631313.pdf

You are correct -- much of the smoke at WOT is excess fuel, since the engine runs rich at WOT to protect the pistons and engine from detonation. But this will appear as a brown "smoke". Oil burning is usually a bluish smoke, pretty distinguishable from excess fuel in the exhaust. And when I say "smoke", I don't mean a plume...I mean a light dusting. Pretty much every car I've seen on the road will "dust" a little bit at WOT.

In summary, the amount of deposits in your engine is certainly related to the state of tune your engine is in. Having said that, it's never a bad idea to go ahead a wind out your engine every now and again. The Northstar engine has a very aggressive hatch pattern on the cylinder walls to retain oil for good lubrication during high-RPM operation. This is there as a design feature and has the unfortunate downside of increased oil consumption and combustion chamber depositing. The upside is the rings and cylinder walls are lubricated VERY well and engine wear is brought to an absolute minumum. The Northstar isn't your average small block Chevy. ;)

jadcock
01-30-03, 09:39 PM
As an aside, someone could convince me that WOT blasts can help dry out the exhaust. Normal exhaust temperatures are in the 600-800 degree range. Way back at the muffler, this may or may not be enough to keep away the condensation. At WOT, exhaust temperatures can sky-rocket -- to upwards of 1500 degrees. This will certainly burn away/blast away any stray molecule of H2O in the exhaust system somewhere. :)

elwesso
01-30-03, 09:51 PM
I will have to semi- agree on both points. There are tons of old people that never push their cadillacs, and they run just fine. Also, there are people that drive their cadillacs really hard, and still run fine. I suppose pushing it once in a while cant really hurt it, i dont really see the need to do it a lot. I can see the benefit of that extra pressure to blow all the crap out of the exaust. Personally, i dont think that doing this will make your car run longer and make it more reliable, although i do think it helps more than it hurts.

kcnewell
01-30-03, 10:05 PM
This is a little off topic, But, I've got this engine in my shop today, the guy didn't want to ruin YES I said RUIN it with unleaded gas so he pulled it in the garage and parked it in 1988! NOW, He wants to drive it. Needless to say He did more damage to the engine by leaving it idle than he EVER would have driving it! The engine is totally shot,seals,rings everything. He left the gas in it for 14 years! ( You shoulda smelled THAT! ) OK, Back on topic....I like to run my engine kinda hard because I like the feel of the thing working hard. On the newer engines with all the computer controls you don't need to "BLOW THEM OUT" Bear in mind that no matter how good an engine is....Pushing it to its limit is ALWAYS a risk. It's a machine and when you use it hard it can and eventually will break! Your dealer knows that and is in fact talking out of his head as you say. The problem is...His head is firmly stuck in his ass! That's my opinion and is not intended to be construed as the opinion of Cadillac Forums.

Dead Sled
01-30-03, 10:14 PM
in a way its a warranty litigation in the making

BeelzeBob
01-31-03, 10:48 AM
Thanks for all the info here. Lots of good points made.. I learned a thing or two. :D

jadcock
01-31-03, 11:08 AM
Originally posted by kcnewell
On the newer engines with all the computer controls you don't need to "BLOW THEM OUT" Bear in mind that no matter how good an engine is....Pushing it to its limit is ALWAYS a risk.

This is true. The "limit" is not necessarily the "redline" of the engine, though. The engine can and will run at redline all day long. You'd be surprised at the testing and validation procedures that the Northstar engine went through. Here's one, for example, to validate the head gaskets' strength and durability:

A cooler chills a batch of engine coolant to very cold temperatures (I forgot the exact temperature, well below zero) and this coolant is pumped into the engine. The physical engine gets so cold, frost forms on the outside of the block. The engine is then started and immediately brought to WOT and run at 6000 rpm ("redline") until the coolant is near boiling (about 250 degrees). It's then immediately shut off and that coolant is cycled out and a new batch of subzero coolant is pumped in and the engine is shocked with this vast change in temperature. This is one cycle, and THREE HUNDRED CYCLES were performed consecutively and the engine was then disassembled for analysis. No head gasket failures. No mechanical failures. The thing performed exactly as designed.

When I heard of the many rigorous tests the Northstar went through to validate its design, I was utterly amazed. The worst thing you can do to a high-speed high-performance engine like the Northstar is to granny it around, never opening it up. Back in the days of pushrod V8s with 5000 rpm redlines, constant high speed was riskier because of the design and construction of components (cast iron cranks for instance). The Northstar is designed and built as a world-class engine, with an array of forged and cast alloys in use where appropriate. It is built to run and run hard! :)

peatea
01-31-03, 11:28 AM
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

jadcock
01-31-03, 11:51 AM
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! :thumbsup: 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.

elwesso
02-04-03, 04:31 PM
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.

Katshot
02-04-03, 04:44 PM
What GAS-BURNING engines do you know that are run at WOT constantly?

jadcock
02-04-03, 05:32 PM
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.

elwesso
02-04-03, 07:21 PM
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.

jadcock
02-04-03, 08:21 PM
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. :p

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! :thumbsup:

elwesso
02-04-03, 09:02 PM
Those really are tremendous results.

seduxion
02-05-03, 07:20 PM
yes very impressive... i wonder ho wmany other engines can do that.

Katshot
02-06-03, 09:22 AM
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.

Katshot
02-06-03, 09:24 AM
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.

jadcock
02-06-03, 09:51 AM
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"?

Katshot
02-06-03, 11:03 AM
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.

jadcock
02-06-03, 11:23 AM
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! :thumbsup: 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.

Katshot
02-06-03, 02:52 PM
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.

jadcock
02-06-03, 03:11 PM
The saying "they don't make them like they used to" is so true. Decades ago, the manufacturing process was so loose, they'd have three different piston sizes for one engine, A B and C. After the block was bored, they'd measure the bores and assign a size to it, either A B or C. Then they'd match the piston to that bore to ensure a proper fit. That's making three different parts to fit one hole, simply because the boring process wasn't accurate enough. Wow! Today, they can put that investment into superior metallurgy, better production processes, and more sophisticated designs.

elwesso
02-06-03, 04:17 PM
So what do you think the verdict is: Important to push the northstar or any engine, or are the risks of messing something up outweigh the benefits?

jadcock
02-06-03, 05:17 PM
I look at it this way. It's certainly not going to hurt the engine by pushing it hard every now and then. I'd agree much quicker to a statement like "it's good to wind the car out to keep the engine clean" than to a statement like "it's good to always idle the car around and be as easy on it as you can".

There's certainly a middleground there that will be different for everyone. On gmforums.com, IceHeart400 has a nitrous kit on his Northstar-powered Eldorado and races it often. He'd agree in a heartbeat that revving it to the moon is good for it. There are some other folks who would rather drive it slowly to moderately and call that good, perhaps nervous to push it to its limit. I'm used to engines with redlines of 4500 or 5000. The Northstar made me nervous at first to push it all the way to 6000, but after conversing with this powertrain engineer at GM, I'm convinced of the capability and durability of this engine. It's been bulletproof so far for me.

I guess that's all I can say. After my own experiences and discussions, I know the engine was designed for that and it can handle that. I think the worst thing you can do for any given engine is never drive it hard. Running at redline all day is not necessarily good for any given engine either. Moderation is key, just like with everything in life. :)

Cbody
02-07-03, 09:30 AM
Well said Jason, I would agree with that.
Jay

elwesso
02-07-03, 06:20 PM
I can agree to a certain extent. I dont think that it is good for the engine, but on the other side it doesnt really hurt it.

mike97sls
02-10-03, 08:16 PM
I will shed my experiences on this topic. The Audi 5000 and Acura that I had before were always driven as hard as they would possible go. The Audi was my first car and it had gone through two transmission rebuilds. When I first got my license I drove it as fast as it would go everywhere I went. I thought I was invincible. It was a great car it would top out in third gear (3 speed auto) at a little over 120 on the 120mph speedo and that was about 400 rpm into the red on the tach (approx. 6000). That 5 cylinder 20 valve engine was fun and I never had any problems with that car burning any oil. The 1990 Acura Legend coupe I had was another story. My uncle got it in as a trade and I ended up with it. It was faster but the handling was definitely not GERMAN and it smoked a little when it sat idling. I sold it to a friend after I bottomed it out over a stupid man hole cover and cracked the tranny casing after having the transmission rebuilt. I put every piece of aftermarket performance equipment I could buy on that car. That car lead to me losing my license for doubling the speed limit because some cop decided to "play games" with me when I had the flu. I now have a 97 sls and that is due to the fact that my uncle is a Cadillac Sales Manager. He knows how I beat on four wheelers, my father's big block boat (MerCruiser 454 loves redline 4400-4600rpm), and all the Automobiles I drive. Which car does he think will hold up to my abuse? A Northstar which was defnitely not my first choice. BTW, he has also told me to make sure that I "clean it out" every once in a while. I assured him that this would not be a problem and he laughed.

BeelzeBob
02-11-03, 10:01 AM
Welcome aboard, Mike! Thanks for signing up.. Well, I bet your Father knows what he's talking about being a Cadillac Sales Manager.. I'm sure he hears a lot of stuff around the showroom and repair bay.. And if he tells his Son to "clean it out" every once in a while, he can't mean any harm.. I still have to wonder - just a little - if the service people are actually made to think this and believe it.. But, I have a feeling it's the right thing to do. It just makes too much sense to me..

elwesso
02-11-03, 04:18 PM
I agree. The thing that concerns me is not the engine, but the tranny. If you do it constantly then it could really mess it up, or definitely shorten its life span.

jadcock
02-12-03, 04:50 PM
Some more input:

Drive it, keep the carbon cleaned out with frequent applications of throttle as you describe. Heavy throttle and higher PRM all tend to keep the ring grooves cleaned out of carbon as the higher RPM operation tends to cause the rings to move and rotate in the grooves which keeps them mobile and free. Babying it too much will allow the rings to stay stationary and eventually stick from the carbon buildup.

That is from my GM engineer friend, this time, posted at the message board at caddyinfo.com. Thought this was interesting, given our recent discussion.

elwesso
02-12-03, 05:35 PM
Well, cant go wrong with that. Next time I get to my fleetwood, and there isnt a fricken foot of snow on the road, ill open her up!

Either that or donuts......

Roswell256
02-27-04, 06:11 PM
See here is what I don't get. Everyone opens them up on the road right? What about opening it up sitting in the parking lot in park. That can't be bad on the transmission and other then putting a load on it is equivilent to running it on the road. Correct me if I'm wrong but won't a few redline throttle pumps in the parkinglot do the same?

-Roswell-

Anthony Cipriano
02-27-04, 06:54 PM
See here is what I don't get. Everyone opens them up on the road right? What about opening it up sitting in the parking lot in park. That can't be bad on the transmission and other then putting a load on it is equivilent to running it on the road. Correct me if I'm wrong but won't a few redline throttle pumps in the parkinglot do the same?

-Roswell-

Revving the engine up in neutral does little or nothing helpful. The time at WOT is so brief that there is little or no chance to build any cylinder pressure and heat before the engine is bouncing off the rev limiter. Revving it at part throttle puts little or no gas pressure load on the engine and pistons - it puts a lot of inertial loads into the crank, bearings, rods, etcetera - but nothing that does any good to the engine. Forget it. Put the car in gear and go drive it.

There are many advantages to occasional full throttle accelerations with a Northstar and any engine. It keeps the carbon cleaned out of the combustion chamber. This is maybe a little more important with the Northstar than some other engines due to the tight squish volumes between the piston and the cylinder head. This is designed this way to promote good incylinder mixture motion (good combustion) but it has the down side of providing a ready place for carbon build up to touch the piston causing noise. Ever heard of the Northstar "cold carbon rap" problem? Simply put you'll hear a rythmic, piston slap like noise when the engine is cold. Very prominent and very annoying. Cause: excessive carbon build up causing the the piston to contact the carbon on the head causing it to rock in the bore and "slap" - much more evident when the engine is cold and the pistons haven't expanded to full diameter yet. Simplest and easiest "fix" for this: A few good WOT accelerations to clear the carbon out. That is all it takes to eliminate the problem and prevent it from re-occurring.

Occasional WOT accelerations also help seat the rings to the ring lands and exercise the rings and keep them mobile and from becoming stuck in carbon in the ring lands. At high RPM and WOT the rings move around on the piston. They actually rotate on the piston and will polish away any carbon and seat themselves to the sides of the ring grooves. This is especially important on the 2000 and later Northstars which had hard anodized top ring lands on the pistons. Very hard and wear resistant. Also harder to breakin and seat the rings to the sides of the ring lands to promote the best possible seal. Many oil consumption complaints on the 2000 and later engines are related to some extent with the rings never seating to the sides of the ring grooves due to lack of load as the engine was babied around forever. Even engines with rings stuck in the ring grooves due to carbon build up can eventually be freed up with enough high RPM operation.

WOTs warm up the engine thoroughly and clean out the exhaust due to temperature in the exhaust and high flow rates blasting particulates, rust and such out of the system.

Frequent WOT operation will not hurt the engine or the transmission. It's designed for that. The healthiest engines that I have seen at high miles are always the ones that are run the hardest. Rings are free on the pistons and sealing. No carbon buildup.

The exercise that I think works best for many things is to select manual 2nd gear on an isolated stretch of expressway. This takes the trans shifting out of the question if you are worried about hurting the transmission, also. Start at 55 MPH or so and go to WOT in 2nd gear and hold it until the RPM reaches near the normal shift point ie 6500rpm for an L37 and 6000rpm for an LD8. Hold the throttle wide open until the engine reaches, say, 6200rpm for your STS and then just let completely off the throttle. Leave the transmission in 2nd so that the engine brakes the car and creates some pretty heavy overrun conditions at high vacuum levels. Let it slow until it is about 55 or so and then go to WOT again and repeat. This exercise really loads the rings, allows variable RPM operation at WOT for several seconds continuously, creates heavy overrun which tends to unload the rings and make them move and thus exercise them in the ring grooves and it will blow out carbon and the exhaust - all without creating a spectical of yourself and attracting the attention of the cops. You can do it on most any freeway and stay within the 70-75 MPH range allowable. Once a week like this will keep the engine cleaned out and healthy and is DEFINITELY recommended for the Northstar in particular.

The Northstar engine was designed, developed and validated to be run hard. It was expected that people would use the performance of the engine, though few seem to do so. The biggest single problem that many issues stem from is lack of use at full throttle by the owners. It just doesn't like to be babied around. The rings are low tension by design for good high RPM operating characteristics and low friction/good power. They work best if "used" and kept free.

In every conversation with owners I've had, once the owner started doing the WOTs and using the power and the engine they report no more carbon rap, better oil economy, no "smoke" when they do light it up (keep the exhaust cleaned out. If you notice a "cloud" when you do a wot you are not doing enough WOTs) etcetera. A bit of judicious use of the other end of the throttle travel is a good thing.

Anthony Cipriano
02-27-04, 06:57 PM
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.
.


Katshot. Where and when does this happen. I want to go. This is a figment of your imagination. Ridiculous. Who would fund such an endeavor, what would it prove and why would anyone do it? Nothing like this happens but if it did a Northstar would do very good at it.

Ralph
02-27-04, 07:01 PM
Revving the engine up in neutral does little or nothing helpful. The time at WOT is so brief that there is little or no chance to build any cylinder pressure and heat before the engine is bouncing off the rev limiter. Revving it at part throttle puts little or no gas pressure load on the engine and pistons - it puts a lot of inertial loads into the crank, bearings, rods, etcetera - but nothing that does any good to the engine. Forget it. Put the car in gear and go drive it.

There are many advantages to occasional full throttle accelerations with a Northstar and any engine. It keeps the carbon cleaned out of the combustion chamber. This is maybe a little more important with the Northstar than some other engines due to the tight squish volumes between the piston and the cylinder head. This is designed this way to promote good incylinder mixture motion (good combustion) but it has the down side of providing a ready place for carbon build up to touch the piston causing noise. Ever heard of the Northstar "cold carbon rap" problem? Simply put you'll hear a rythmic, piston slap like noise when the engine is cold. Very prominent and very annoying. Cause: excessive carbon build up causing the the piston to contact the carbon on the head causing it to rock in the bore and "slap" - much more evident when the engine is cold and the pistons haven't expanded to full diameter yet. Simplest and easiest "fix" for this: A few good WOT accelerations to clear the carbon out. That is all it takes to eliminate the problem and prevent it from re-occurring.

Occasional WOT accelerations also help seat the rings to the ring lands and exercise the rings and keep them mobile and from becoming stuck in carbon in the ring lands. At high RPM and WOT the rings move around on the piston. They actually rotate on the piston and will polish away any carbon and seat themselves to the sides of the ring grooves. This is especially important on the 2000 and later Northstars which had hard anodized top ring lands on the pistons. Very hard and wear resistant. Also harder to breakin and seat the rings to the sides of the ring lands to promote the best possible seal. Many oil consumption complaints on the 2000 and later engines are related to some extent with the rings never seating to the sides of the ring grooves due to lack of load as the engine was babied around forever. Even engines with rings stuck in the ring grooves due to carbon build up can eventually be freed up with enough high RPM operation.

WOTs warm up the engine thoroughly and clean out the exhaust due to temperature in the exhaust and high flow rates blasting particulates, rust and such out of the system.

Frequent WOT operation will not hurt the engine or the transmission. It's designed for that. The healthiest engines that I have seen at high miles are always the ones that are run the hardest. Rings are free on the pistons and sealing. No carbon buildup.

The exercise that I think works best for many things is to select manual 2nd gear on an isolated stretch of expressway. This takes the trans shifting out of the question if you are worried about hurting the transmission, also. Start at 55 MPH or so and go to WOT in 2nd gear and hold it until the RPM reaches near the normal shift point ie 6500rpm for an L37 and 6000rpm for an LD8. Hold the throttle wide open until the engine reaches, say, 6200rpm for your STS and then just let completely off the throttle. Leave the transmission in 2nd so that the engine brakes the car and creates some pretty heavy overrun conditions at high vacuum levels. Let it slow until it is about 55 or so and then go to WOT again and repeat. This exercise really loads the rings, allows variable RPM operation at WOT for several seconds continuously, creates heavy overrun which tends to unload the rings and make them move and thus exercise them in the ring grooves and it will blow out carbon and the exhaust - all without creating a spectical of yourself and attracting the attention of the cops. You can do it on most any freeway and stay within the 70-75 MPH range allowable. Once a week like this will keep the engine cleaned out and healthy and is DEFINITELY recommended for the Northstar in particular.

The Northstar engine was designed, developed and validated to be run hard. It was expected that people would use the performance of the engine, though few seem to do so. The biggest single problem that many issues stem from is lack of use at full throttle by the owners. It just doesn't like to be babied around. The rings are low tension by design for good high RPM operating characteristics and low friction/good power. They work best if "used" and kept free.

In every conversation with owners I've had, once the owner started doing the WOTs and using the power and the engine they report no more carbon rap, better oil economy, no "smoke" when they do light it up (keep the exhaust cleaned out. If you notice a "cloud" when you do a wot you are not doing enough WOTs) etcetera. A bit of judicious use of the other end of the throttle travel is a good thing.

Anthony, my dad never drives his cars hard. How many miles would you guess before the carbon is built up to be a disadvantage to an engine like the N*? IE, every few thousand miles, etc.?

Lawrence
02-27-04, 09:53 PM
Katshot. Where and when does this happen. I want to go. This is a figment of your imagination. Ridiculous. Who would fund such an endeavor, what would it prove and why would anyone do it? Nothing like this happens but if it did a Northstar would do very good at it.

It would be interesting to see. Never heard of it from an auto manufacturer. But Mercury Marine does it, at least used to at their privately owned Lake X in FL. They ran outboards non stop, some models literally ran for years. There was one model, can't remember which one, they tied up to a dock and ran WOT for a reported 3 yrs, until it finally quit. They do it just to see what would break first. They would repair the failed part, start it back up and see what would break next. And on and on. And probably the reason they won so many Formula 1 Championships.

Here is a link to a Media Player Video. Check Part 3.
http://www.screamandfly.com/home/features/mercury_video_history/mercury_video_history.htm

Vesicant
02-27-04, 10:46 PM
For one, Marine engines dont run at WOT as said... an example, boss owns a new 30 ft Carver mariner 350, full throttle on it was both the engines at 4,000 rpms.

Our truck, Silverado 1500 w/Z71 (1998) is driven very lightly by mum and occasionally when I or someone else is in it, we have to floor it and man.. can you see the dust and griime flow out of that exhaust. Now its been needing a tune up and gets more of that carbon build up because the explosions arent as effectiant anymore. The catera, on the other hand; is driven quite hard but only because the engine like the Northstar was built to run hard. High-Rpms

Anthony Cipriano
02-27-04, 10:58 PM
For one, Marine engines dont run at WOT as said... an example, boss owns a new 30 ft Carver mariner 350, full throttle on it was both the engines at 4,000 rpms.




What do you think running at full throttle at 4000rpm? It's operating at Wide Open Throttle. Marine engines run at full throttle most all the time. That or they idle while the owner trolls. Anyone who has spent any time in a boat has held the throttle wide open for long periods of time. Especially any sort of sport boat. Marine engines are run the hardest of most any engines on the planet. Even to keep a large boat on plane the engines are deep into the throttle. Very deep. Put a vacuum gauge on a marine engine and you will see that they run at zero vacuum a lot. Zero vacuum is unthrottled and the only difference between that and true WOT is theoretical. Practically it is exactly the same thing. Boat engines are just usually rated for a specific power at a lower RPM than the equivalent engine in a car. With the propping and gearing in the boat the operating RPM can be kept lower to make the engines live longer even though they are at WOT a great deal of the time.

The Northstar engine was marinized for MasterCraft ski boats several years ago. It was exactly the same motor as was installed in cars. It was also propped and geared to run 6000rpm at full throttle in the boat - which it does frequently.

Anthony Cipriano
02-27-04, 11:11 PM
It would be interesting to see. Never heard of it from an auto manufacturer. But Mercury Marine does it, at least used to at their privately owned Lake X in FL. They ran outboards non stop, some models literally ran for years.


All automotive manufacturers do limit endurance testing of the cars and the engines. Just no one runs a bunch of different cars WOT on a track to see which blows up the first. All the engine durability testing takes place on an engine dyno. As an example, the Northstar engine is validated on a test on an engine dyno where the engine is run at full throttle, 6000rpm, making 300hp for 300 hours continously. The engine is shut down occasionally for checks and oil changes and such but when it's running it's full throttle at 6000 flat out. And it lasts 300 hours. In 300 hours at 6000rpm in a car that would be about 150 miles an hour and the car could go 50,000 miles. Twice around the world. It would be impossible, practically speaking, to accomplish this on a track so vehcile testing to the point that the engine would fail would be pointless. You would run out of tires and gas and such.

Dock testing by the marine manufacturers is very common. Everyone does that. GM Powertrain is a major supplier of marine engines and tests the same way but on a dyno. The main reason to "dock test" (tie it to the dock and leave it on wide open) is to test the cooling sytems in the boat and such. The engine testing on a dyno ensures that the engine will take it.

gman2153
02-28-04, 03:15 PM
I find the fact that you blame a cop for playing games when he nails you for double the speed limit quite amuzing... I bet the judge thought so also.

c_a_s_2
02-28-04, 08:30 PM
In my opinion, what's more sensible than occasionally rodding your caddy is to keep the oil and filters and plugs NEW, AND only place the shifter in fourth gear when you want to do extended cruising -- over 55. That prevents the car from loping along at low rpm (in fourth) in town, which contributes to carbonizing the intake, cyinders, and plugs !!!! I found quite a performance (and mileage) boost in new platinum plugs, (car only has 42k on it) but I just bought thew eldo from a little old lady. SO --- run you plugs for 100k if you want to, but I recommend you instead replace then about every 50k -- with the best plugs you can get (Like Bosch Quad Platinums) Style on, Ride On.
cs

Anthony Cipriano
02-28-04, 08:54 PM
..........................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.

There are a lot of engines designed to run continously at WOT... Every engine is designed with a certain duty cycle in mind. Engines that power heavy trucks run wide open at peak power all the time. They are designed to do that and can do it for thousands of hours. Dedicated marine engines are designed for a "rated" power and can run that way for thousands of hours. Even simple engines like a 5hp Briggs and Stratton on a portable generator runs wide open all the time as long as the generator is loaded. It is designed to run that way.

A diesel engine in a commercial 18 wheeler can run at WOT maximum power for millions of miles. It was designed for that kind of constant power output. It runs at a relatively low RPM (below 1800rpm all the time) to keep the inertia loads low and makes the power/torque with compression, displacement and a lot of turbo boost and very very robust internal parts - allowed due to the low RPM it operates at.

A passenger car engine is at the other end of the spectrum. It will idle through life almost never running at full throttle. It will last hundreds of thousands of miles running at part load. It is designed to make a lot more power to accelerate and pull loads on an intermittant basis. Generally, an automotive engine will live at full load, full throttle for several hundred hours - not the thousands and thousands of hours that a marine or truck or aircraft engine might see under these conditions. It all depends on the duty cycle of the engine and what it was designed for.

You run your weed eater engine or leaf blower engine at WOT for extended periods - those were made for that. They are relatively low specific output engines for that very purpose - to live at a continous WOT duty cycle.

Many engines are rated at different power levels based on the duty cycle that they must endure. Gas truck engines are commonly rated at a number like 350hp in a light duty truck (an 8.1 GM gas engine in a suburban or pickup) or that same exact engine (same internal parts) would be rated at 280hp in a heavy duty truck that would tow 16000 pounds all the time. Or haul rocks out of the quarry in low gear and full throttle all the time. That same engine might be rated at 220 in a Kodiack truck that tows semi trailers short distances. But at full throttle all the time to keep them rolling. The engine is derated to be able to perform at it's rated power (WOT for that application) for thousands of hours that would be required instead of the hundreds of hours that it might see at WOT in the light duty pickup truck. The key to understanding is that there are many different duty cycles and each engine is designed, optimized and rated for that application. Many of the heavy duty engines spend all their lives at full throttle both gas and diesel varieties.

Ralph
09-07-04, 01:59 AM
OK Anthony, my Dad did your expressway trick to help break-in the rings, etc. and so far so good. No problems. The DTS only has 500 miles on it so I don't suppose it has to be done too often. He has always babied his cars engines. I still would like to know how often carbon build-up might become a problem, roughly. Say every 5,000 miles? 10,000 miles? It might be good to know so he could do this again to avoid carbon buildup with the smaller ports, etc.

Anthony Cipriano
09-07-04, 12:36 PM
OK Anthony, my Dad did your expressway trick to help break-in the rings, etc. and so far so good. No problems. The DTS only has 500 miles on it so I don't suppose it has to be done too often. He has always babied his cars engines. I still would like to know how often carbon build-up might become a problem, roughly. Say every 5,000 miles? 10,000 miles? It might be good to know so he could do this again to avoid carbon buildup with the smaller ports, etc.


If it were my car I would take every opportunity to do a WOT blast to keep the carbon cleaned out. Not that you have to go out of your way to do this - just merging onto the expressway is an excellent opportunity to give it a shot of WOT. At least once per week I would recommend to keep the combustion chambers clean and the exhaust cleaned out of particulates.

ljklaiber
09-07-04, 08:44 PM
I try not to post too much but as an old hotrodder and engine builder, I gotta say that my 95sls gets wailed on ALL the time, and it has over 142k miles. I take care of it and I 'drive it like I stole it'.

If ya worry about honkin a Northstar...(Yes they keep ya busy at the wheel), just buy a V6malibu.

Don't blame yer ride...look in the mirror......(Wat we said in 1955)

ljk age 63

Dan 2000 STS
12-29-06, 01:10 PM
What GAS-BURNING engines do you know that are run at WOT constantly?


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.

I have to bring this one out of the archives just to add my $.02 with regards to aircraft engines.
I'll keep it very simple. A safe takeoff requires that the aircraft achieve as much altitude and airspeed in the shortest amount of time possible. Basically you want to attain enough altitude and airspeed that if you experience a loss of power you would be able to turn back and glide to the airfield that you just departed. With that concept in mind it's easy to understand why aircraft engines are run at 100% power on each and every take-off. This is the safest way to operate and therefore it is also the manufacturers recommendation.

If you look at a typical Cessna 172 used for flight training at any relatively busy trainig facility you could expect to see a airplane that endures upwards of 30 practice takeoffs and landings on any given day. A typical climbout in a 172 would be about 4-6 minutes before the throttle is cut to a 65-80% power, cruise setting. Using those figures you'd be looking at a plane that runs 3 full hours per day at 100% power....when was the last time you did that in your Caddy??

In actuality, it's an apples to oranges comparison because aircraft engines are subject to MANDATORY maintainence on a routine basis as well as scheduled overhauls (rebuilds) each 2000 hours or so. This sort of maintainence is a good idea when your wheels are frequently 5000 ft off the ground and you spend 3hrs a day at max power.

GreenMachine
12-29-06, 04:37 PM
I think it's not really a problem, hot rodders with custom PCMs and what not are certainly running these things hard...exception being the trailer queens :P

There's a post on this forum somewhere that discusses the stock northstar can run higher 6500, could get to 7000 or 8000 no problem.

I think that is shown well in the new RWD Northstars that redline runs from 6500-7000 rpms.

Lets not forget Mark and his turbo STS. It certainly may not last as long as a non-blown but that will get him some excitement and shows that the northstar can take a beating, and so can the trans considering he is running more power threw than what we can.

I think it all goes back to general maintenance. If you going to pushing this thing hard, don't go 100,000 miles between tranny fluid changes. My 98 deville has had its share of heavy throttle applications, and has 95,000 miles on it, it's probibly overdue for a tranny fluid change, so in the next couple weeks I'm going to go ahead and do that.

dp102288
12-29-06, 09:54 PM
:yeah: I believe the Northstar has a small amount of untapped potential. Because it can run to near 8000 rpms without too much of a problem, and a fellow member has sc'ed their Seville, undoubtly this engine is stronger than utilized.

With some modifications, this same engine is now making 330 hp and is being supercharged in the STS-V and XLR-V (well slightly different in the XLR-V).

davesdeville
12-30-06, 07:14 AM
Wow talk about a necropost (old thread being brought back up again.) Anyway if you worry about the trans put a big aftermarket trans cooler on it. Heat buildup in the fluid is the biggest reason for trans failures.

dp102288
12-30-06, 01:06 PM
^^ Yeah at old thread! :p

For a Northstar/4T80-E is there a special kind of trans cooler, or does one size fit all cars?

davesdeville
12-30-06, 07:27 PM
There's not really a special cooler... you'd have to measure the space you want to put it and find a unit that's the right size. I know on Mark VIIIs the cooler from newer (02+ or something like that) powerstroke diesels will fit well.

dp102288
12-30-06, 10:02 PM
^^ Okay, just wondering. Thanks! :thumbsup:

VinnyT
12-30-06, 10:06 PM
Before ANYONE does the WOT thing, make sure you do not have any bottom end problems. There was a member here(sorry can't remember his name)that was having the "knock" noise. Many told him to do the WOT thinking it was carbon....it wasn't. He threw a rod. Instantly toasted engine. While I admit it is rare for the N*, it can happen. Make sure the car is in good mechanical condition before mashing the gas.

I myself use Seafoam before every oil change. I SLOWLY pour it through the PCV hose while at 100-1200 RPMs(just enough to prevent stalling). I let it sit for 30 min, then run it moderately hard for a few miles. I immediately change the oil. This seems to work very well.

Everyone has their own opinions on what to do with the carbon issue. I like the Seafoam way, but I still do the WOT thing, however its not because of the carbon.:devil:

dp102288
12-31-06, 12:50 PM
^^ Point well taken. I also remember that thread, and many said the WOTs only sped up the problem that was already there. The rods would have been thrown later. Maybe not, but I think as long as you warm the engine up enough, WOTs shouldn't be too much of a problem.

You seem to know how to use seafoam, but for most people, WOTs are safer because if you pour it in too fast, you hydrolock the engine up. The spray is supposed to be very safe though since it can't go in too fast.

turbocad6
12-31-06, 10:13 PM
I just bought a dts with high milage... it's got over 130k on it, & was owned by someone who musta never pushed the thing.... when I got it, the first thing I noticed was that it had a shake/stutter/stumble at idle... so on my way home with it I punched it hard for a bit..... clouds of black smoke out the tailpipe...... did it again for a few seconds longer... still black smoke....

the ride home was 2 hours & at speed on the NJ tpke, & I wot'd it many times before there was no black clouds.... by the time I got home, the engine stumbled about half as much as it did..... I have since ran a fuel injector flush machine on it, & added some injector cleaner to the fuel.... I'm still punching her daily & still clearing out all the carbon built up over the 5 years of *****footing this thing around.... BUT...

there is a flipside.... because the car was never abused or pushed hard, it is extremely tight... the tranny & all the suspension bushings & axles are all the better for it... so now, after I clear out the carbon, it'll be in better shape than if it was driven by someone like me to begin with:D

beating a car alot does loosen up & wear suspension & drive axles, & transmission, so the best way to "clean it out" is on the highway at higher speeds... the car will not suffer nearly as much as if you were to go around punching it from a rolling start at a light.... that causes stress & wear... I'll admit that I do punch it & accelerate hard with it too, but I've never been one to baby a car.... I go by the philosophy of, if it breaks it wasn't strong enough to begin with & needed to be replaced or upgraded anyway... I say beat the hell out of it to let it show you what's not good enough... if nothing breaks, then every things fine;)

MonzaRacer
12-31-06, 11:16 PM
OK as a tech I do like to see a person periodicly take a spirited trip down the road ,let the tranny do its upshift at full throttle, etc.
As for blowing the carbon out of the engine itdoes work. I know of 2 identical last year Camaros one lady driven (ie putting around the town) and her hubby ran the pee diddling crap out of it.
Well his had around 140k on it and hers around 100k and both got sugared and when we tore them down and went through both. did a great build up and hers had MASSIVE amounts of crud around the valves and severe carbon in the engine. The slime inside the intake and the engine was pretty bad. Then we pulled his down and it looked great carbon wise. Both got rebuilt and now she does do some spirited driving now and again and sine we put the Air Ride on her car she loves on/off ramps as she will slam a lower gear and floor it on them.
They are building a street rod and I am trying to getthem to try an Aurora 4.0 (basicly a Northstar)but i am not sure what the bell housing shape is yet.
I dont recommend it to go foot to the floor for miles and lay rubber all the time but a little hard running lets the engine develope some better numbers on long term fuel too.
Heck a Ford with a MAF will forget its BARO setting if you dont give it a boot some times.
Besdies if your Cadillac is so whimpy you cant hump it once in while they should restart Olds and kill Caddy.
Just use some common sense.
Lee

AlBundy
01-01-07, 07:31 PM
MonzaRacer I see you got the link. I just wanted you to read a good thread that had alot of Bbob's info.