Does warming up harm your engine?

[tomphot]

Originally Posted by spuggy

Short answer to the OP's question is that the owner's manual specifically states you should not idle the car to warm it up, but should drive it instead, keeping the revs down and load light until it's hot. At least, the one for my car does. Any more questions?

Could this be because it's against the law to idle you car in Germany?

I was dressed down once while warming up a rental car in the winter.

[dshepp806]

Originally Posted by spuggy

Short answer to the OP's question is that the owner's manual specifically states you should not idle the car to warm it up, but should drive it instead, keeping the revs down and load light until it's hot. At least, the one for my car does. Any more questions?


I believe that oil flow is the absolute lowest when the oil is thick and cold. Pressure is relatively high, but flow is at the minimum.

So idling when the oil is cold means that the oil flow is at the lowest it'll ever be. Idling is when the car is making the least heat (no work) - so it'll take longer to warm up as well.

A long time ago, I was taught that you started a vehicle, ran it long enough that you could pull away without sputtering and knocked any manual choke off as soon as possible. It's worked pretty well for me for many years.

Like some others here, I fast-idle for a minute or so to get some heat into the top-end (this is enough to open the internal engine thermostat maybe 3-4 times, which you can see with a 140 PSI pressure gauge), and then take off, keeping revs down and load light until the oil starts to warm up.

On the 911, I use a "3000 limit until 80 degrees, 4000 until 190 degrees, no slogging ever, no boost until 190 degrees" regime.

+1 on what the German boys wrote in my 89 owners manual,..get to driving (lightly) soon after cranking her up.....no long term idling.


20-30 minutes of idling? no frikin' way. I can get the cabin heat up MUCH quicker when I'm driving her,..it doesn't take long at all.

My regiment is much like Spuggy's.


Best,

Doyle

[RoninLB]

different strokes for different folks



during cold winters I start and keep rpms as low as possible till the 90-100#'s low rpms oil psi starts to come down.

I also start with clutch engaged so I'm not loading engine thrust bearing without oil psi. Swepco is not an issue at 20F doing this.

Then I raise rpms till cylinder head temps [CHT] raises to 175F degrees. Manual throttle is a great install.

If at a warm idle I'll raise rpms to 1,200-1,500 to keep alternator and cam lubrication ok.

The act of glazing cold start spark plug carbon is a consideration with carbs. Don't whack the throttle when cold, gently raise rpms. FI is more forgiving.

[ErVikingo]

Perhaps worst of all is you commit the typical mistake of warming up the engine and taking off like a bat out of hell when the rest of your drivetrain is " cold".

A lot of us think about bringing the engine up to temp but never think twice about the tranny for example.

[RWebb]

Originally Posted by tomphot

Could this be because it's against the law to idle you car in Germany?

Doubt it - the advice pre-dates all pollution laws.

The advice -- given by the engineers who created the car -- is based on the simple fact that the 911 motor will take almost forever to warm up at idle, not to mention the damage from idling a cold motor.

That does not mean that you cannot get away with it. But if you are buying a used 911, try to avoid buying one from a guy who does this sort of thing to his car.

[J P Stein]

I'm kind of between the rock & the hard spot on this subject.
Mine is an AX only car, not street legal and putting around on slicks (not R specs)on access roads is a good way to get flat....those are usually crudier than city streets. There are no "warm up laps" at AX.

I have sat in the car idling with a blips, elevated revs, yada.....this takes about 10 minutes just to get the temp gauge off the peg (50C), much less to operating temp.

I have tried throwing a towel over the air intake grill...leaving some space for air flow..... and this seems to work most quickly....but doing this seems wrong somehow. Probably not as wrong as beating on a cold engine, tho.

Comments?

[old man neri]

Originally Posted by J P Stein

Comments?

Oil preheater of some kind?

[J P Stein]

Originally Posted by old man neri

Oil preheater of some kind?

How much do they weigh?

A portable one would seem impractical in the staging lanes....not to mention the ribbing I would get....but I'll think on it.