Tate

On my '01 M roadster, it's start and drive not going over 4k until proper temp has been reached. Driving in traffic and open roads in 2nd & 3rd was just fine while staying below 4k.
I see when my '84 Carrera gets here I'll be doing the same.

r911

you guys are likely to lug the engine & damage the main bearings

DARISC

??? Which guys?

Tate

Hence staying in 2nd or 3rd depending on the speed of traffic. Of course I did have a 3.73:1 diff in there too, so that helps to keep the revs between 3k & 4k.

theiceman

I just went out in my car after reading this thread and reralized I am not **** about watching everything. I get in it start it , when the engine settles I back it out of the driveway , I don't lug it or horse it with a cold engine and bring up the revs once I hit the highway , I noticed i drive between 3500 - 4500 on a cold engine. Have had no problems

rnln

whenever reading any thread regarding this topic, I always get confused.
In summary of this thread, I got:
1- Peter Zimmermann said start & go.
2- Steve Weiner said "so give it a 20 seconds idle and drive off keeping RPM's at or below 4000 "
3- Randywebb said "keep it higher than ~3k and lower than ~4500"

In the past, I alwasy idle the car to warm it up for a few seconds until the RPM comes down a bit, engine quiet down a bit. After reading this topic on this board several months ago, I start and go immediately and keep my RPM as low as I can, between 2k to 3k RPM for maybe 10 mins. Now, according to the above, I got 3 different methods. Which is more correct?

Daniel Dudley

It's like cookies. Different recipes, all make cookies. What I'm getting is that you don't want to let the cylinders get real hot while the rest of the engine is relatively cold. This won't happen in two min. but ten is a long time. Under 4K, 1/8 throttle or 1/4 throttle, moderation is the key.

You know when you are letting your motor sit at idle, and you know when you are beating on it from cold. Moderation in all things, including moderation. These are pretty tough cars. I can't see the ordinary day to day as killing them. From what I see, they like to be used. Just not for constant five min. jaunts in the dead of winter. When I see temp on the gauge, like 120, I give it half throttle. At 180, your engines, she is mine. As always, YMMV.

DARISC

You have to realize that the above three luminaries are "KNOW-IT-ALLS"!

That's because, between the three of them, when it comes to our cars they pretty much in fact do know it all (although each would probably modestly claim that they certainly do not - well, maybe Pete wouldn't ).

My take on their comments is that they are each saying the same thing:

Get in, start it and go.

Keep a light foot on the gas until temp. starts to build.

Keep the revs more or less in the 3k to 4k/4.5k range during that time.

Don't lug the engine (applies at any temp.).

As far as 20 or 30 seconds idle at start-up goes, crank the engine and by the time you fasten your seat belt as you're checking your oil pressure gauge and waiting for your garage door to finish opening, well, there it went.

I believe this applies to all gas engines and that there's nothing special about the 911 that makes this general start-up routine any more or less important.

From reading Daniel Dudley's last post, I suspect he agrees. Whatever the slight variations in the 911 cookie recipes used, don't half bake or burn.

These cars stimulate a mythical wonder for many enthusiasts and spelling out every little detail of every aspect of their care and operation is important to them, and that's all well and good.

My opinion regarding this cold start detail is, treat your 911 as you would any other car.

r911

I wouldn't say I know nearly as much as PZ & SW. Other than that, Darisc gives an excellent summary.

All 3 _are_ saying the same thing. I did not repeat what they (PZ & SW) said since I assumed everybody would "read & heed" based on who they are and what they know (or, alternatively, what they've seen -- which how you know what you know, eh?).

- I just added the admonition to not let the motor lug. At idle there is no load so there is little chance of that. Once you start driving tho, there can be problems and you may not hear them.

"the revs between 3k & 4k" - that should be fine, BTW
- If you need a little larger band or rpms to operate in, I would expand it on the high side, rather then the lower side.

2,500 can be fine too - it depends on the load and on other engine operating conditions.

BMW now has a little band that glows red I think on the tach when the motor is cold to show you what is allowed. That requires a lot of electronics to monitor various things, and a computer to put it all together. It should be the most accurate thing to use on their engines.

4,500 or 5k is not going to suddenly blow up the motor - these are all approximations. Yes, just cookie recipes. But, I would say not to treat the 911 like you would a huge displacement (lotsa torque) Amer. car - those motors are much less susceptible to lugging -- and a LOT cheaper to fix.

_________
On a more general note, if you look at what the experts tell you (and I have been doing that for several years) there is rarely a difference. "Experts" I'll define as people who have service and/or hotrodded and/or raced a large number of Porsches and their motors for many years. PZ& SW, Jeff Gamroth, Dick Elverud, Jerry & Bruce, Henry Schmidt, John Walker -- and I'm leaving out many others, including manfs. & specialists (wevo, SRP, both Erp's, Loren and others). Only once have I ever seen a disagreement among them (and it dealt with whether you "need" to have 2 separate msd boxes to run twin msd coils on a twin-plugged motor -- jury is still out, tho it will work for at least several hundred engine hours, the reliability & longevity is unknown). That's the only thing I've seen a difference on.

Treated even halfway decently, these motors should give you what they've given many others -- high performance for 200,000 or even 300,000 miles.

And keep the oil changed....

livi

Totally agree with the general views in this thread, but I would like to add one detail;

I always felt I could judge the load/ "stress" on the engine from sensory input to my right foot. What ?? Yes, the throttle pedal resistance feels stronger the more load the engine is put under. For example, going down hill, wind in the back, no matter what gear and revs - the loud pedal will feel easier to push down than during the opposite circumstances.

Hence, I do not only rely on the rev counter when starting out with cold engine, I try to select a combination of gear and revs that under the specific road- and traffic circumstanses (up/down hill etc) result in an as light as possible "pedal-resistance feel".

I also feel it is possible to simultaneously judge by the sound of the engine if the load /stress on the engine is low or high. High loads sounds more 'painful' as it were.

Anyone else have the same notion or am I just being delusional ?

Mike Murphy

Randy, I'm not sure I agree with this. Oil can take quite some time to flow when the engine is cold. RPMs above 3k can push the pressure-side of the oil pump's bypass valve open because the oil pressure is so high - a result that puts a lot of stress on the oil pump (++5bar).

Oil that doesn't reach the piston rings right away will allow the rings to score or quickly heat up the cylinder walls. This will happen twice as fast at 4,000 RPM than at 2,000 RPM.

But you're right about the possibility of lugging the engine, which is why Porsche specifies to keep the RPMs about 1,500 RPMs.

r911

the 1,500 number is for a warmed up motor, right?

The oil flow might be an issue - Chicago cold is a lot lower than W. Or. cold... but a good synthetic should flow well if the wt. range is chosen properly.

At a guess, scoring or heating will be a sig. damage issue even at low rpm if there is no oil flow.

Having seen many drivers (esp. those who are familiar with big Detroit iron, even as kids then switch to small Euro sports car motors) I fear lugging the most. But everyone gets to drive their own car.

Maybe Steve can comment on the issues you raised. I have not heard of a lot of oil pump failures on street cars.

sig_a

My '87 3.2 lets me know when it's ready to go. I start without touching the throttle. Engine starts and revs to 1100 rpm. I let it idle usually less than 2 minutes until rpm drops to spec. idle rpm of +/- 870. Drive off and shift at minimum 2700 rpm until up to temperature. That's the way it's engineered to work. No?

rnln

Thanks very much. I have to say that I have learned a lot from many people here especially Pete Z, Steve W, Randy... especially after I bought my P car. It's not that I didn't learn from other cars boards, but most other cars I had, people didn't get as low and detail level as you guys do. After reading this thread more than once, I think I got the idea but still have some confusions/doubts so I am going to ask anyway. Hope no one get tired of my questions.
1- start the car and go, meaningg drive right away or after a few seconds. Just do not wait for too long as 3 minutes or longer.
2- for proximately 1 mile or 2, do not over rev the engine (4k RPM is the max). After 1 mile or 2, kick down if you want.
3- Do not under load the engine, meaning do not run the engine below 2k RPM. Or someone say take it easy on the engine.
Questions:
1: so the best way is shifting at around between 2.5k rpm to 3k rpm?
2: Randy said he affraid the most at lugging (too low rpm). Maybe I ask what exactly mean lugging? Does it mean... for example when I shift too early, the engine want to die but I manage to keep it up and the engine sluggish. Am I correct?
3: what mechanically happen when the engine lugging?
Thanks in advance.

gerry100

Just to add my 2 cents-

Isn't the warm up even more critical in an aircooled motor?

My feeling is that it doesn't relay close up the wider tolerances and "fit together" optimally until the components are warm. That being said the parts run togehter beter under light load than idling.

I start and go ( 3k-3500 rpm for 5-10 miles), except when I'm gridding for a DE session when I idle a cold motor for afew minuntes.