Tippy

Just some thoughts I had about what Raby and Macster have beens saying in the "IMS bearing" thread.

You know, I used to do this (redline @ cold) all the time in all my V8's. I didnt think twice about it and always found the motors had peak HP when ice cold (obviously).

On 50 degrees or colder nights, I would let my cars sit for hours before I raced if I drove it earlier.

Once I got into sportbikes, I stopped doing this and let the engine warm before nailing the throttle.

Then, I got my first Porsche (996) and became really **** about letting the engine come to full operating temperature before even going over 1/4 throttle.

My thoughts are this: an engine should not blow up from redlining cold. If it does, it is on the ragged edge of failure at operating temperature - which we all know Porsche is FAR from.

Wear on a cold engine at redline, well thats a whole 'nuther story.

Not saying to do what Raby did but jeez, the motor should not be grenaded by this.

End of thoughts. Comments, fire suit on.

1999Porsche911

It is always more risky to redline an engine that has not warmed up. The tighter the engine, the more the risk until all components have expanded to normal. A runner who starts out in a sprint without warmig up has more risk of pulling a muscle, and so does a car. IMO, an engine is ready for redline when oil temperature reaches 150F.

However, if the purpose of redlining is to produce power, you are losing a huge amount of power until the transmission has been engaged for at least 20 minutes due to the drag from the cold gear lube.

Tippy

Totally agree on the tolerances, but it shouldnt fail. Wear, yes.

On the trans fluid drag, I think the parasitic drag is more than out done from higher hp/tq IMO. This opinion comes from lots of testing.

ivangene

Well, this is a new theory for me. I have never run cold engines hard (well fast is a better word) in anything I have owned. I do agree with the thinking. I suppose the reason we dont comes from some old tale from North Dakota where a guy rev'd his tractor in -50 degree winter and the oil didnt lube the motor causing it to seize... then the "warm it up" theory was born and we all just do it without knowing why ?

When I first read the manual for the P-car and it said "start the car and drive, do not idle the engine to warm up the engine to operating temp" I was really surprised and it was hard to make that change.. but I have tried - still, I wont be out there reving it up while its cold

of course in EU if you just let the engine idle to warm up, meanwhile finish getting your things ready in the house it is illegal (unattended, running vehicle) and even your best friend will turn you into the police (in some countries)

1999Porsche911

What puts the car at risk is not wear but the potential of the looseness of certain components to not follow the designed path of movement and seize or break.

Marc Gelefsky

I only do that on rental cars

(But than I feel guilty..damn)

Tippy

Im not advocating to do it (and will never do again), it is just I did it in the past without ever screwing up an engine. My '95 'vette I had, had 126,000 miles on it and I regularly stabbed it cold. It maybe used about a quart every 5k miles.

To your point, I think cold wear patterns are established after dozens of runs. There is a "cold" path established over time. I could see a new motor seizing instantly when cold at redline as I have witnessed my dad doing but over time, I think the risk is lowered IMO.

HAHA, yeah, done the same.

ivangene

LOL @ rentals, and yet there is exsists a culture that thinks rental cars are great to buy since they always have excellent service records.

(I knew you didnt mean go do it - )

Dave!

Buddy of mine caught air over train tracks driving a rental on a business trip. Why anyone would willingly buy one of those things is beyond me.

chriswaxman

[QUOTE=ivangene;6965597]


When I first read the manual for the P-car and it said "start the car and drive, do not idle the engine to warm up the engine to operating temp" I was really surprised and it was hard to make that change.. but I have tried - still, I wont be out there reving it up while its cold

QUOTE]

The owner's manaul I've had for every German vehicle I've owned has said this. In addition to Porsche an early 70s BMW car and BMW bikes from the 70s, 80s and 90s, air, oil and water cooled alike.

I think what is intended by this instruction is what is being advocated by most here and for the same reasons -- start driving but go easy on the throttle until warmed up.

Someone will have to explain to me the downside to idling until warm. I can see the downside in certain circumstances, e.g. overheating if you do it for too long, or leaving a boxer motorcycle engine idling while leaned over on the side stand. But barring things like that I don't know what the harm could be. Regardless, I do what the manual says.

chsu74

+1 and then I think of the money I paid to rent it and the guilt goes away. Same with doing stunt tricks in icy parking lots after its warm of course...

chsu74

The engine may be warm but the rest of the car is not.

Orient Express

I have seen a 996 engine with only 500 miles on it, with a thrown rod from redlining it when before it fully warmed up.

Dave!

Wear is increased while the engine is cold. The engine will warm much faster if it's running around 3000rpm under load than at 800rpm with no load. So to idle to operating temp will take much longer and result in more wear--at least that's the reason I've always seen.

Also, didn't something on 993s get gummed up if you idled too long while cold?

chriswaxman

Nor is your brain, sometimes. Seriously though, there's something to be said for getting everything set before mashing your foot down, especially in a car with power. No need for a quick getaway, it's not like I'm practicing to pull pulled a bank job.