driving below 2800 RPM = trouble?
 

Snipped from the internets...
Ever since the last year's oil hijacking by the NYMEX speculators I picked up the habit of driving AT the speed limit. When gas crashed back to below $2 I continued my frugal driving, keeping the car in th 6th gear on highway and rarely keeping the RPM's above 3,500K. Not just to save gas but I figured I'd do the real driving at the autocross and cut down on engine wear. My car by the way, is only driven weekends and 90% of it on the highway the other 10% usually darting around lower Manhattan. Guess I'll have to keep it in 3rd gear more often.

I'm skipping Mobil 1 for the first time ever. I'm thinking of going with Castrol Syntec 5W40. I hear there are issues with Royal Purple "shearing".
Flamesuit on...

==============================================
"What do you all think, lower RPM's = less probability of IMS failure?"
__________________________________________________ ____

"Absolutely not.

The exact opposite has been true.

We have yet to see a single IMS failure from an engine that has been driven hard and thus far we have the biggest library of documented failures on this Continent.

Most IMS failures come in stop and go street driving, or in cars driven by Women.

The statistics prove that these engines like to be driven more aggressively, this information is included in the December 08 Excellence article on the M96 engine that features our development program.

The key to reducing IMS issues is to reduce the oil change intervals provided by Porsche by 1/2 and use an oil other than Mobil 1. If you coupkle this with a driving style that a Porsche is designed for your chances of having a failure are greatly reduced.

Do NOT drive at less than 2800 RPM and do not lug the engine!!!!!!!!! Nothing is worse and nothing has proven to kill the oil faster!

I have been TRYING to make the IMS fail in one of our test cars for the past 8 months or so. I hold the car WAO against the rev limiter for 2-3 minutes at a time, flog it in second gear against the limiter for as much as 5 solid miles at a time. When the car fires up, stone cold I hold it WAO for at least 45 seconds. There IS NOTHING that can be worse on an engine than this kind of abuse since the engine sees a huge temperature differential and it's not even well lubricated when it fires up and revs immediately to oblivion.

I have been doing this for almost 20K miles and have not changed the oil since I began the process of "flogging". The engine is equipped with full data acqusition as well as oil condition monitoring systems and the data has remained consistent since I began the torture. The engine has 75K miles on it now.

I'll post a durametrics data log over the weekend showing the RPM and abuse this baby has seen and you won't believe it.

It appears that Boost may be required to kill this engine before January when I'll be pulling it to swap one of my 2.9s into it. "


--------------------

Jake Raby
Raby Enterprises Inc
www.flat6innovations.com

You may have a point here. I blew my 3.2 last November driving it very nicely. But now I have a 3.6 :D And im broke lol.

Good news? I thought (obviously incorrectly) that since it was water cooled, then it wasn't necessary to keep the rpm's high. I usually try to keep it between 2500-3000.

I agree that driving properly will not only give the owner more fun while he or she owns the car, but seams to be proper for these engines.

However, I beat the bush pretty hard trying to find the right oil, and haven't heard of Royal Purple shearing. I'm not saying I didn't miss it, just haven't seen anything as of yet. BTW I'm using RP 5w-40 at this time.

What does "lug the engine" mean?

I've heard of this lower RPM's = IMS failure as well.

Thankfully I’m always driving between 4-7K RPM..I like using lower gears while cruising...3rd usually up to 65-75 MPH.

how much of this applies to Tiptronic transmission boxsters? (probably a dumb question)

also on my Tip, how long is it "safe" to stay in first when first starting the car?

i'm always in a rush to get it to 2nd (as it stays above first until you turn the car off)

I have no intent of flaming anyone, just increasing all of our collective knowledge. Just did a quick search concerning HTHS ratings, if your oil has an ACEA rating of A3, it should have a HTHS rating of 3.5 or greater. This is, I believe Porsche's requirement. :cheers:

I would also like to hear something on this as I have a tip. I thought I read somewhere that tips are not as prone to IMS failures as manuals are, but is that because there are more manual cars out there? I try to wind mine up as much as possible once she's warm, but I am in a lot of stop and go traffic.

That's like when you slow down to pay a highway toll and then you try to take off with the car still in 5 or 6th gear because you're too lazy to downshift.


My lazy move is skipping 5th gear. I go from 4th to 6th. So I think that's kinda like lugging..

p.s.
There's a case of RP 5W40 sitting at a local NAPA dealer. They're wanting like $12 a quart. I don't mind the price but Castrol Syntec is like half the price. Is it really twice as good? I've seen the load machine tests but I'm not sure how real world they are. And of the dozens of oils that Porsche has tested and recommeded why isn't RP in there? Is it purely business?

The Tiptronic cars are less prone to RMS failure... NOT IMS failure.

This is most likely because there is no direct mechanical link to the crankshaft. With a torque convertor, the link is fluid, with a clutch, it's mechanical.

:cheers:

Ahhh, thanks for the clarification. Wishful thinking on my part:rolleyes: But, I guess if you are running a tip car in the Drive mode the transmission will keep the engine from "lugging" with the downshifts. Which from the sound of it is a good thing.

Good point. In fact, I'm in Drive about 99% of the time unless I get in slow traffic, or on a 25MPH Pkwy. Then I go manual and usually stay a gear below what the dme would otherwise do in order to keep the revs up.

Don't forget, both your oil pump and your waterpump are rpm dependent!

:cheers:

Here I am checking the forum on Saturday morning at 5:45 am waiting for the wife to order me around to set up tables for her garage sale and I read this thread.

It warms my heart to no end that my gut feeling is right when I'm behind the wheel of my Boxster:

DRIVE IT LIKE YOU STOLE IT ... it's good for the motor.

I'd rather wear out the motor from increased friction than have an IMS failure because I babied the thing. When my motor blows, it had better be due to being thrashed for many many miles, not babied too much.

Now I must go out and set up tables in the dark and take orders from "the Boss."

"Whipping Boy reporting for duty, Ma'am!"

How much for this coffee pot? And for these garden tools? And what about the plastic pig holding flowers? I don't see a price on the Boxster?

6:47 am

Tables set up, many many loads of crap taken to front yard.

burned out boxster is only $500. Price is negotiable

I have done my morning duty and will now wash dog, bmw, porsche, and do a 15 gallon water change on the marine aquarium at my office.

Then I'm off to a funeral of a distant friend (very close to my older brother, but not me) who was murdered on Monday morning and his body was set ablaze like the Boxster in this thread to cover up the beating he received. (No need to post "I'm sorry for your loss" comments. I just thought it was odd that I'd be commenting on a thread for a burned out Porsche and the same thing happened to this guy!)

Heck of a day, this!

Wow. Interesting story. I guess I should change my driving style. I was shifting pretty early and also skipping gears like going 1-3-5. That was to save my clutch mostly. Or can I still do this just rev higher?

Unless you are lugging the engine, I would like someone to explain to me how the RPMs contribute to IMS failure? Are you suggesting that a flawed engine design responds BETTER to more internal stress and friction?

How can that be, please enlighten me.

Again, I am not talking about lugging the motor, although I am not sure how the Tip will allow you to lug it if you are in auto mode.

I am open but skeptical!

:rolleyes:

Hey Brucelee, I just watched Enter the Dragon a few days ago on TV, it never gets old. You really can't lug the engine if it is in auto mode, but if you are in manual mode and you are in 4th gear and have to slow down due to traffic, etc. and don't downshift manually, you can definitely lug the engine in that scenario.

If I've understood Jake Raby and Charles Navarro's comments correctly, the higher rpm translates to higher oil pressure which feeds the IMS bearings at a greater volume, reducing friction (I know, the bearing is supposed to be sealed, but likely leaks).

This is also why they recommend removing the outer seal to allow greater oil flow.

And for what it's worth, I only use Royal Purple in my Box S. Tried it in my '73 911, but leaked too much; so back to good 'ol 20W50 Castrol GTX Dino juice (though it's looks like Brad Penn going forward).

From everything that I have gathered from the information presented on several other Boxster forums, here's what I understand as being the issue:

At lower RPMs, the Vario-Cam system is actuating the valves at certain rpm ranges.
During the period that the VC system is being actuated, this places an additional load on the IMS, as the IMS is what connects the Camshafts to the Crankshaft.

During high rpms, the cams are already in their maximum position, so they don't place any greater load on the IMS and its bearing. At lower rpms, there is a much greater strain.

Lugging the engine, which technically qualifies as any event that start out at a low rpm in a high transmission gear, with large throttle opening, places a large strain on any engine, but on this engine, because of the design using an IMS, and the weak bearing, this wind up becoming a weak link in the engine.

If you think about most other engine designs, the camshafts are directly actuated by the crankshaft either by a timing chain, a timing belt, or by timing gears. This engine is different, and presents a weak link between the two.

So, here is the most simple way to explain the current thinking on why Boxster engines are having a high rate of IMS bearing failures:

Basically, lugging the engine places a greater load on the IMS and its bearing than is healthy. Excess load on the bearing leads to seal failure. Seal failure leads to oil intrusion, which washes away the lubricating grease in the bearing. Long oil change intervals combined with lugging and cold running lead to fuel contamination of the oil, which leads to fuel contamination of the IMS bearing, which then leads to its failure.

So several things can help lessen the chances of IMS failure:

More frequent oil changes with top quality oils. Somewhere in the 5k to 7500 range is being claimed as the best.

Run the engine up through the rpm range in every gear, and stay away from the 2300 to 3000 rpm range for long periods of time (don't drive cross country at exactly 55 mph).

Have the IMS bearing seals removed to allow constant oil access to lubricate it.

Buy a 2009 Boxster instead. :)

BC.

I think there's a happy medium...don't stay below 3k and maybe don't keep it up too high either. I'm guessing if your Boxer engine stays between 3-5K RPM 90% of the time and you go no longer than six months or 7.5K miles on the same oil you should have a long lasting engine. and of course keeping the RPMs no higher than 3k before the oil temp is up too

p.s.
Advanced Auto Parts has a special sale on Castrol Syntec, 5 quarts and a K&N oil filter for $25. Pep Boys sells it for $7 each. I plan to buy four of these lots, go with Honda Civic filters and sell the four of them for $15 or whatever. They sell for $13 each without the sale. That ought cover the two Mahle Boxster filters I picked up for $20. I'm going to go with 5w40. Hasta la vista Mobil1 and short shifting.

FWIW, I feel sorry for any owner who is so concerned about IMS failure that they feel they have to drive at over 3K all the time. If you really believe the motor is that poorly engineered, either spend a wad of cash to get Jake to fix it for you or get rid of it.

I drive the cars I own for my pleasure, if they can't take the way I want to drive them, then I'll get something else.

This is worrying, the two people that mostly drive my Box keeps the RPM's between 2-3k almost 90% of the time. I think my sister also lugs the engine a lot, keeping in higher gears when slowing down then booting the throttle.

I always thought it being ricey to always keep the RPM's blisteringly high, but if the cops catch me for making too much noise, I can always tell him I'm saving my car from destruction :P.

Here, Here.
Ed

I think Perfectlap's suggestion for driving is ideal. No sacrifice at all, and no guilt for pushing it a bit. I do not see it as being overworried about IMS - just doing what you can to avoid an unlikley issue (like taking an aspirin every day for my healthy heart).

I have read on the LNE Engineering site that 5-40 oil is best, but it wasn't clear (at least to me) if that helped even if the seal to the IMS bearing had not been removed. I am going to increase the frequency of oil changes to 5,000 and use Castrol or RP.

I may be one of the people Pbanders feels sorry for, but I drive at the RPM I want, and use some common sense too.

The last thing I want is to mess my car up but I really can't imagine me ever lugging the engine, it runs too good to shift that soon. I'm going to just drive it the way I am comfortable driving it and let what ever happens happen. :cheers:

This part makes me laugh because all of the men who have driven my car shift waaaay lower than I do, even my dad. I love the sound of the engine rev. I do a lot of stop-and-go city driving though so that sort of sucks.

Lets try this.

Yes, one should avoid lugging the engine. There is no exact RPM rule for this, as in first gear, you should not be able to LUG the engine, and in 6th gear, it is quite easy.

Second. The engine should be able to run safely between just above lugging and to just about red line. So, any exact RPM rule is clearly not appropriate for the issue of grenading the engine. The engine SHOULD NOT grenade.

Re: The IMS, Porsche should just fix the issue if it has not already.

Regarding wear: Higher RPMS cause greater wear than lower RPMs. Any auto engineer will tell you that, assuming you are NOT lugging the engine.

The whole drive it like you stole it advice is purely infantile, if you are talking about engine wear.

Having said that, if you want to trash your engine, be my guest. Just go to the track and beat it until it dies.

:D

Have you actually talked to an auto engineer who told you this? Different parts wear for different reasons, load is the leader in wear, not speed. Any mechanical engineer will tell you that.

Both lead to wear on the engine. As I said, if you are not lugging the engine, you are not loading it unduly with low RPMs. If you are flooring the accelerator all the time, you ARE loading the engine unduly. Would you want to take you car to the drag races every day? Would it comfort you to know that you are not lugging the engine?

If you are running at 6000 RPMS all the time, you are elevating friction, heat. and wear. Pistons have to reciprocate. When you move them at 6000 rpms rather than 3000 RPMs, and they have to reverse direction, at which RPM do you think there is more stress on the cranshaft and the pistons?

Think about it.

Ah Bruce, we've had this discussion before, I've shown you data, and you still ask the same questions. There's nothing else I can do for you.

Repost the data. I don't recall. Again, explain please how load, friction, heat, are all lower at higher rpms. Explain why running your engine at near redline reduces wear than say at 3000 rpms. Are you suggesting that if I drive 90 MPH that the load on the engine is lower than if I drive at 65? If my MPG is lower at the higher speed, does that not reflect the extra energy consumed by the engine to push the air away to attain that speed? Does the extra load lead to extra wear?

If the laws of physics have been changed, I would like to know.

BTW-I too have posted information from engineers on this topic before.

Have you actually talked to an auto engineer who told you this? Different parts wear for different reasons, load is the leader in wear, not speed. Any mechanical engineer will tell you that.


Are you suggesting that load is lower at higher speeds?? How can that happen in normal aggressive driving?

Is the concept of "lugging" an engine even relevant with fuel injection? I mean in the good ole days, you could feed the car too much fuel. Now, the car will only feed what it knows it can burn.

What exactly is stressed more at low RPM? The engine has less torque.

Is driving a BMW 135i at 1500 RPM lugging the engine... when it is near the peak torque there?

Let me offer a few scenarios as to what I believe it means to lug the engine.

Lets say you floor the car off the line in first gear. The engine will move the car forward in a happy manner. Now floor the car off the line in 4th, 5h, or even 6th gear. The engine will not sound happy and in my mind is akin to lugging the engine.

Here's another scenario: have the car in 6th gear as you brake for red light. Don't press the clutch in, just use the brakes... the engine will not be happy at anything less than about 15 mpg heading toward zero... that's lugging the engine. This also gets back to flooring the car in 6th without shifting to a lower gear to accelerate should the light turn green... that's lugging the engine.

So I believe that in the context of the above, as a happy medium between lugging the engine and driving it like you stole it, avoid mashing the gas pedal in a higher gear when under 3K rpms to keep the engine happy. Use a gear appropriate for the speed you are going, as well as how much you are accelerating.

That's not very scientific. How is it more difficult for the engine at 2000RPM in 6th gear than 4500RPM in 6th gear, other than at the higher speed there is even more friction to overcome in the engine and from the air resistance of the car moving forward??

If the car couldn't adjust timing or fuel and was detonating before TDC, I can see that being real bad... maybe that's what happened in the good ol' days.

So I can see WOT at 1800RPM not being very exciting, but I don't see how it is bad.

Think of it as riding a bicycle.
Travelling @ 5mph in your lowest gear your legs will be revolving rapidly - not a lot of pressure on your leg muscles but you will run out of breath & tire quite quickly.
Now try pushing the same bike in top gear @ 5mph - you will probably give yourself a hernia & rupture your knees trying to turn the pedals - thats the same as lugging the engine. With low revs & WO throttle position the load on the lower engine componants (crankshaft, big end bearings & crankshaft main bearings) will be severe.
And don't compare a high compression, high revving sports car engine like a Porsche (who's max torque is @ about 4500rpm) with a diesel engine designed for low rev power who's torque curve is virtually flat from 2000rpm to 5000rpm. They are a different animal all together.

Originally, this thread noted that according to Jake Raby, in essence, operating at low rpms caused IMS failures (or increased the risk of failure).

So far as lugging the engine, there is a definite definition. The British use the term 'Labouring' in the US, it's 'Lugging'.

It means that the rpms have been allowed to fall out of the powerband of the engine for a particular load/selected gear. You are slowly stalling the engine.

An example would be having the transmission in a higher gear than the road speed or load requires, such as not downshifting when going uphill.

When this happens, things heat up very quickly internally and the engine will detonate or ping. This leads to shockwaves in the reciprocating parts (rods, pistons) and the crankshaft, and cause piston slap, scoring of cylinder walls, bearing wear, excess loads on timing gear (chains, belts, gears, or in this case - the intermediate shaft).

In concert with this, because the rpms are low, coolant and oil are not flowing at their optimal rates or pressures further compounding the effects and/or damage.

I agree that theoretically, running the at higher rpms can create more wear. I say theoretically because these higher rpms also allow greater flow and pressures for the oil and coolant which can now better protect against wear.

But, the point here was the IMS. And it is at low rpms that the oil pressure and flow are at such a low point that the inherent weakness of this part is more readily realized - it fails more easily and perhaps more quickly.

Drive it 'harder' and you may take say 10-20k mi. more off the life of your bearings and such over time than if you drove at lower rpms.

I think the point Jake is making though is that by doing so, at least your car will actually reach that kind of mileage, where without it, the IMS will grenade the motor much sooner.

But, I think we need to distinguish between the early cars and the later ones when in '03 Porsche re-designed the IMS.

IMS failure in the early cars is virtually unheard of, in fact, I can't think of a single instance being reported in the pre-'00 cars (though I'm sure there must have been some).

:cheers:

I drove the whole weekend shifting above 5-7K RPM downshifting about oh....300% more. Man this car moves! LOL

With the weather we had here last weekend, I decided to take out the Box to "teach it the meaning of the word respect". I love that line from Carl the grounds keeper http://www.youtube.com/watch?v=JObTMW3RVf4&feature=related . Anyway, the opposite was true, I forgot just how fast that car can fly and just when I think I'm getting in trouble those big Brembos bring me back to subsonic speeds, I LOVE IT. :dance:

This much fun must be illegal is some Middle Eastern country's.