Whats better on cold start? High RPM Low Throttle v. Full Throttle Low RPM?

[MRSSIIM3]

As the title says, I'm curious to see what people think is better/worse for our Ms during cold start:


1. Flooring it from stop to 3k rpm and shifting and cycling through the gears this way?

2. Light throttle, like 20% lets say, but letting it go up to 5-6k?

If someone could chime in and give some sort of scientific reason why they come up with their reasoning, that would be best. Otherwise, just say what you think is best and why.

[X2Board]

Just take it easy, less then 4K until it's warmed up.

[MRSSIIM3]

Originally Posted by X2Board

Just take it easy, less then 4K until it's warmed up.

i never go more than 2.5k when its cold or give it more than 1/4 throttle. im just genuinely curious as to which is better/worse

[AshyLarryMP]

I'm guessing high rpm is worse. There is a rev limiter, not an acceleration limiter. Higher revs has higher forces on everything. If things are unbalanced from not heating up evenly the forces are amplified.

I work at a gas turbine power plant. On start up the thing accelerates really fast up to speed and then holds there for a while to warm up before electrical loading.

[meko]

Oil is thick when cold obviously. Even when it's warm out the oil is thick until engine has fully warmed up. This is an easy one, keep RPM as low as possible without bogging it and wait till oil temp get up and allows full RPM with light throttle. I stay below 3500 BTW until fully warmed. I also drive right away after starting, as opposed to letting it sit and warm up. All fluids warm up quicker this way.

[Titanium Silver]

I would think high RPM is worse than high throttle. If you can compare the two...

Revving the car to 8000 RPM when the engine is cold seems like it would be worse than throwing it in 6th gear on the highway going slow (around 50 mph) and giving it a generous amount of throttle (and maintaining low RPMs).

[MRSSIIM3]

thats what i was thinking. makes sense. thanks guys!

[BPMSport]

RPM is definitely a factor, but the amount of load is also an important part of the equation.

The answer is neither is good on cold start.

[FVM3]

I always start up my car 10 mins before i go out

[Ezio]

Originally Posted by MRSSIIM3

i never go more than 2.5k when its cold or give it more than 1/4 throttle. im just genuinely curious as to which is better/worse

thats overkill. I think its kind of funny when people baby a OEM motor that much. I mean ya its not good practice to be rough. but you don't have to baby it either.

You would be surprised how much stress OEM internals can handle. Once you start to mess with internals of a engine, thats when you start to worry.

[BPMSport]

Originally Posted by FVM3

I always start up my car 10 mins before i go out

This isn't good either. I would suggest leaving within a minute of start and driving moderately.

[AshyLarryMP]

Originally Posted by Mike Benvo

This isn't good either. I would suggest leaving within a minute of start and driving moderately.

Yeah, the owners manual says not to do that. I guess the engine doesn't warm up fast enough at idle.

[SenorFunkyPants]

The owners manual says not to let it stand idling because its a pollution issue.
Aircraft piston engines are warmed up at idle.
I let my car idle until the secondary air pump has finished its initial cold start cycle then drive very easy until the oil temp gauge needle moves, then no full revs until at normal oil temp.
Engine wear it at its highest when its cold.
Engine wear increases with rpms.
Combine the two for maximum wear rate.

[gatorfast]

This is like asking would you rather die by fire or drown. There is no good answer.

[Majin Buu]

Both methods will increase wear and tear. They also help build up pressure within the engine, and you also have to keep in mind the seals are still cold. So that pressure also increases the risk of oil leaks, and not just mechanical wear on the engine.

[AshyLarryMP]

Originally Posted by gatorfast

This is like asking would you rather die by fire or drown. There is no good answer.

Drown, because fire would hurt more.

You learn more when you ask questions.

[W///]

Originally Posted by gatorfast

This is like asking would you rather die by fire or drown. There is no good answer.

Well since you asked, drown. No questions.

OP, the answer is neither. Keep the RPM low as well as the load until oil is warm.

[mdosu]

I think you might be confused, and here's the clarification:

When the oil is cold, RPM is the major concern here. When cold, you need to keep the RPM down below 4k. I use the M3's rotating oil temp gauge and the meter to measure when I can use the full rev range. I also usually wait until oil temp is at the first tick mark, which is around 175 degrees.

In terms of throttle, regardless of oil temperature, you cannot go full throttle (heavy load) at low RPMs (below 2k) in any of the gears #2-7. This puts strain on the transmission. Again, this is regardless of "cold start"....

So that's why I think you're confused with the question you posed. You need to operate with the above description in mind. So if you're cold, and you're in 1st gear, and you want to stomp on the gas, just don't go above 4k.

[mdosu]

Originally Posted by FVM3

I always start up my car 10 mins before i go out

that's excessive and actually creates extra wear on your engine as your engine is not receiving the proper cooling from air flow. Your engine is also running longer than the mileage counter indicates. The CBS likely adjusts for this in our cars regarding oil change intervals, but the air flow issue cannot be discounted.

You'll see that the quickest way to warm up your car is to drive it, it's also the most fuel efficient, and creates less oil consumption (or oil breakdown).

This also applies to "cool down" process too. Aside from track conditions where you're literally going from track loads to stop, the 5 minutes you're driving in your neighborhood and parking provides sufficient engine oil and water cooling. There's no need to idle your car afterwards, even if it was a spirited drive (cavet, actual track conditions where you're literally going from full load to stop in less than a minute). Idling in this case actually creates even more restrictive air flow issues....

I don't think most people understand how important air flow is to the car's cooling systems and processes. That's why you also NEVER put a front license plate over an air inlet.

[Chriskm3]

?????

[Millie]

Originally Posted by FVM3

I always start up my car 10 mins before i go out

Location: Los Angeles.

You love burning gas, don't you.

I've started my cars in -40 for over 5 years now and let them "warm-up" for a minute max. Never had an issue.

[WRXXX]

Originally Posted by FVM3

I always start up my car 10 mins before i go out

Just curious, what do you think about while waiting for 10 long minutes? That's an eternity when idling.