srf506

Okay folks, on another web site we were discussing whether or not you should, or shouldn't, warm-up a turbo before driving off into the sunset, and whether you really need to let it idle in a "cool-down" mode before shut-down. My comment was way back in my youth when I was part of the Brumos over-the-wall crew on their 962s we always warmed it up before going on track and always took a good "cool-down" lap and let her idle for a couple of minutes in the pits before shutting it down. I was told it was a longevity thing with the turbo. Get it warmed-up and lubed at low-speed before you started turning a couple of hundred thousand RPMs with it on boost, and, let the temps stabilize in the engine bay and get cool oil running through the turbo before shutting down. Evidently the oil pressure took a while to bleed off and you'd pump cool oil into a "hot" turbo and it would coke up around the bearings which could cause the turbo to fail if you just shut it down. Made sense to me then, so I've always given my engine a minute or two to warm-up (let the oil volume gauge get to about the half-way point and the temp needle off the peg and in the warm-up bar) before backing her out of the garage. Now I have almost a mile of twenty-mile-per-hour neighborhood street to traverse before I get to a major road so I'm really just idling down the road for another few minutes before I even think about getting on the boost. Likewise, I idle down the road to the house and then let the engine idle another minute or two (usually I listen to one song on the radio or CD) before turning her off. What's the overall sentiment about this? I know turbo technology has moved on a lot since those mid 80's time units. Other than wasting gasoline and adding hours on the motor is there still a reason to do this? Someone pointed out that if that was really necessary Porsche would've put a turbo timer on the cars. I just was curious. Thanks for your consideration.

Kevin

I always allow the engine to warm up for a few minutes before leaving when it's cold..

Two minute coll down for the K27 series turbochargers.. Porsche has even written this in it's later owners manuals.. What we want is the fuel on the idle circuit to cool down the turbine wheel..

With the prices of rebuilds and new turbochargers spending some time letting your turbochargers cool down pays off in the end..

38D

The single turbos didn't really change much from 78 up to 94 (at least in terms of cooling the turbine). I always warm up and cool down.

UDPride

Well heres what I do, then heres what i think:

what I do: start car and let it idle until the revs level out at about 800rpms. Usually about a minute or so. On the other side, if Im driving normally, I'll let the car idle 15-20 seconds, then turn off. Rarely have I just pulled in somewhere where I was driving real hard. If I drive hard, I take it easy before I end up wherever Im going.

what I think: any car designed so that you have to sit around with your thumb up your butt and let it idle when you turn it on and turn it off is a poorly-designed vehicle. If someone asked you to do this in pretty much any other car it would be called a design flaw. "Im sorry I have to let my MR2 Turbo idle for a couple minutes before we drive to the bank." Its kind of ridiculous. If you are paying $80,000 MSRP for one of these 930s brand new, you damn well better not have to idle the thing every time you want to drive it. Other car companies manage to not require this problem to keep the car running fine, so I dont think you should have to in a Porsche either. I dont care how many horses it has and how much it cost. Engines and trannies have been around forever. You should be able to get into your car, turn the key, and drive off.

I feel the same way about cars like Ferraris where owners have to open and close things with a diaper so they dont break. Its like the more you pay, the more fragile the car is. To me, thats poor quality and design. Cars should be designed to work well and sensible from the start. I dont think Porsche should get a pass on things like this just because they sell sports cars.

Sorry for the rant.

nathanUK '81 930 G50

I have a turbo timer built into the alarm, push a button on the remote, remove the ignition key, lock the car (I removed central locking), set the alarm and the engine auto switches off itself after a few minutes. Simple.

Cajun

Nathan,

How much does a system like that cost???

I have never looked into turbo timers...but then again, this is the first turbo I have ever owned...

911rudy

I have always subscribed to the theory that a normal start up and drive away is the same as letting the car idle. Infact, engine specialist suggest that letting an engine warm up at idle is a complete waste of time. However, if you are going to race or otherwise push an engine right away, then a warm up is advised. On turbo cool down I agree with all of you only if you stop abruptly after being on boost. If you drive sedately through your neighborhood on your way home, then your turbo has already had its cool down period. All of that being said, turbos do have a useful life and will fail eventually no matter what you do. If the parts were from NASA maybe not. I saw a Ferrari docu on TV and it said that they had to use an external engine oil warmer and circulate it through the engine before it was STARTED! This was on an F-1 race car. This was due to engine tolarances.
Rudy

nathanUK '81 930 G50

I know you can buy timers seperately made by Blitz and those other Japanese companies. They shouldn't be too expensive.

Mine is controlled by the Category 1 alarm/immobiliser, this would be quite expensive to do unless of course you need a new alarm anyway for insurance purposes. I would not be able to insure the car unless it had a Cat 1 alarm.

My 3.2 carrera only has a Cat 2 immobiliser but that has no major mods. Can't get insurance for that either unless it has at least a Cat 2.