Start and drive or warm up

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turbo2256b
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Start and drive or warm up

Post by turbo2256b » Sat Dec 30, 2017 7:15 am

News here is hammering for people letting their cars warm up in this cold weather and walking back in the house while it does.

They claim its best for the engine to just start it and drive off as warming the engine causes damage to it. Myself have always warmed my engines to around 140* in most any weather before driving off. I do sit in the vehicle while warming up as part of the news is about thefts.
What are your thoughts about warming and engine and damage.

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Re: Start and drive or warm up

Post by mitch » Sat Dec 30, 2017 8:33 am

Race motor forged pistons tight clearance let warm up, run of the mill factory vehicle start an drive
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Re: Start and drive or warm up

Post by PackardV8 » Sat Dec 30, 2017 12:21 pm

In fifty years of building engines and being around large fleet service, I've never seen any problems starting from cold and driving away gently until the engine is warm versus sitting idling until warm. Only those rigs which will immediately be pulling to max need to be fully warmed, i.e. a max GVW loaded truck pulling away from the dock.

FWIW, idling until the dash temp guage getting to the middle is not an indication of being ready to romp. Usually, engine oil takes twice as long to get up to operating temperature as does coolant. Oil may never warm enough at idle. It takes some load and some circulation to warm oil.

One oddity is the trans temp gauge on my Ford Super Duty. It comes up to mid-temp more quickly than does the coolant gauge.
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Re: Start and drive or warm up

Post by turbo2256b » Sat Dec 30, 2017 5:23 pm

I also run oil and trany temp gauges in a coupe of my cars. Oil does take the longest to heat up. Allso oil at low temps mabe bypassing flow untill warm enough.

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Re: Start and drive or warm up

Post by emsvitil » Sat Dec 30, 2017 9:39 pm

Warm up until there's enough defrost to see out the front window.
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Re: Start and drive or warm up

Post by SupStk » Sat Dec 30, 2017 9:58 pm

PackardV8 wrote:
Sat Dec 30, 2017 12:21 pm
In fifty years of building engines and being around large fleet service, I've never seen any problems starting from cold and driving away gently until the engine is warm versus sitting idling until warm. Only those rigs which will immediately be pulling to max need to be fully warmed, i.e. a max GVW loaded truck pulling away from the dock.

FWIW, idling until the dash temp guage getting to the middle is not an indication of being ready to romp. Usually, engine oil takes twice as long to get up to operating temperature as does coolant. Oil may never warm enough at idle. It takes some load and some circulation to warm oil.

One oddity is the trans temp gauge on my Ford Super Duty. It comes up to mid-temp more quickly than does the coolant gauge.
I've noticed the same on my Super Duty. Wonder if the same system that cools the oil also heats it to operating temp?
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Re: Start and drive or warm up

Post by woody b » Sun Dec 31, 2017 11:17 am

Modern gasoline fueled direct injection engines inject massive amounts of fuel on cold starts to warm up the catalytic converters. This is supposed to warm up the catalyst quicker, resulting in lower emissions. Starting and driving will result in the catalysts warming quicker. Less fuel is dumped into the engine. Letting it idle and warm up will result in fuel dilution of oil.
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Re: Start and drive or warm up

Post by peejay » Sun Dec 31, 2017 9:19 pm

emsvitil wrote:
Sat Dec 30, 2017 9:39 pm
Warm up until there's enough defrost to see out the front window.
So, start it with the remote starter, then take a shower, have breakfast, etc.

It's not so bad now with it hovering a couple dozen degrees below freezing. But when it is right around freezing with super high humidity, flash freezing of the windshield as soon as you start moving is pretty common.

The Hummer H1 is a pretty ridiculous piece of machinery but it does have something practical that I wish all cars had: Electric defrost grid in the windshield. There's a company in the UK that makes them for popular motorsports vehicles (Audi Quattros, Mazda MX-5s, etc) but they're right around $1000 and then you have to have it shipped across the puddle.

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Re: Start and drive or warm up

Post by peejay » Sun Dec 31, 2017 9:30 pm

woody b wrote:
Sun Dec 31, 2017 11:17 am
Modern gasoline fueled direct injection engines inject massive amounts of fuel on cold starts to warm up the catalytic converters. This is supposed to warm up the catalyst quicker, resulting in lower emissions. Starting and driving will result in the catalysts warming quicker. Less fuel is dumped into the engine. Letting it idle and warm up will result in fuel dilution of oil.
Are you sure about that? An engineer I talk to on occasion said that once nice thing about DI is that there are no cold enrichments, they will run in closed loop as soon as the O2 sensors give a reading.

Dumping fuel won't make a cat light off faster anyway. Rich mixtures put them to sleep. Most of the reason for power enrichment nowadays is to keep the cats from slagging.

Now, one thing that they DO do is retard ignition timing and advance the exhaust cam so the valves open earlier. Even non-DI cars will do this. My last Volvo had variable exhaust cam timing strictly to warm up the converter faster, and the cat was bolted straight to the turbo outlet. My current Volvo has variable intake and exhaust cams, and since it is their fancy high performance model (S60R) it has a huge turbo and the catalyst is mounted halfway down the exhaust stream. It has extremely poor fuel economy when cold. It also spools the turbo up at idle like my friend's WRX with antilag.

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Re: Start and drive or warm up

Post by In-Tech » Sun Dec 31, 2017 9:47 pm

Uhhhhhh huht huht...he said do do :mrgreen:
Obviously none of us can speak for all OEM's, what I see with GM, and agree with the strategy, is retarded timing to heat the exhaust and achieve closed loop asap but even then I still see a programmed lambda blend of ~.9 tapering to 1 within a few seconds/minutes to light the cat. It's truly quite impressive and a good learning experience studying what OEM's do for emissions during warmup.

My personal thoughts are to start and drive within a few seconds once I feel oil pressure/flow has stabilized and drive as normal and not "rev" the engine much during its shifting patterns until I feel oil temp is "normalized" as well.

I do quite a bit of MEFI/Delphi tuning for sand cars. One of the things I do when the aluminum blocks are used is a rpm limiter based on engine temp(can be oil temp too if customer pays to have added features, most don't :roll: ) Of course then I get the call that it's misfiring occasionally. No it's not, your dumb shite's get drunk then sit by the campfire till 4am and decide to go race to someone elses camp and I just saved your engine. :lol:
Heat is energy, energy is horsepower...but you gotta control the heat.
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Re: Start and drive or warm up

Post by Geoff2 » Mon Jan 01, 2018 5:10 am

This will get debated....forever. For me, I like to drive off straight away because I feel the engine will get up to operating temp quicker, which reduces wear.

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Re: Start and drive or warm up

Post by peejay » Mon Jan 01, 2018 7:54 am

Geoff2 wrote:
Mon Jan 01, 2018 5:10 am
This will get debated....forever. For me, I like to drive off straight away because I feel the engine will get up to operating temp quicker, which reduces wear.
It's generally worse for the engine if you wreck the car because you can't see where you are going :D

I don't disagree with you, but "straight away" has practical limitations when engine heat is required to be able to see out of the car.

Intech: Are you looking at applications with an air pump? I can see rich mixture + air pump being used to get a light afterburner effect. .9 Lambda is nowhere near as rich as I've seen port EFI run when cold though!

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Re: Start and drive or warm up

Post by PackardV8 » Mon Jan 01, 2018 4:46 pm

It's generally worse for the engine if you wreck the car because you can't see where you are going. . . . I don't disagree with you, but "straight away" has practical limitations when engine heat is required to be able to see out of the car.
For true and no one here would suggest driving without clearing 360-degree vision, but that's not what the OP asked:
What are your thoughts about warming and engine and damage.
Once we begin adding in "but if/when" there's no bottom to that rabbit hole: Some additional digressions - Remember to disconnect the battery charger and block heater and remove the cover from the windshield. Before driving away, does one shovel the driveway or just keep driving on more new snow? What about when the snowplow has put an ice berm at the end of the drive way? Check snow depth and decide to install chains? Shovel the front walk for the postman? How does one determine the oil is warm enough for a strong freeway entry dash?

How about my own off-topic suggestion - buy an electric car. Our new Chevrolet Bolt can be plugged in overnight, and programmed to warm and top off the battery and warm the car interior at the same time every morning or warm-up can be activated remotely via smartphone or nearby using the key fob.

Things only extreme lunatic fringe EV owners would ever consider - determined to maximize battery range they will drive wearing a lap robe instead of using the resistance heater to keep the interior warm. They consider anyone utilizing the heated steering wheel and seats to be a wimp.
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Re: Start and drive or warm up

Post by pdq67 » Mon Jan 01, 2018 8:53 pm

Cold starts.

1st. Clean all glass off outside. As well as the hood and tops of the front fenders and roof.

2nd. Start engine and let the oil pressure normalize, then idle away easy-like until she starts to warm up.

As for defrost, I learned a long time ago to run my heater on it's, "down low/floorboard", setting and let the windshield stay cold until my car was totally warm! The rising under dash heat will help keep the windshield clear. Then once warm, switch to defrost if I wanted it. Oh, and crack the drivers side window down a skosh.. And it seemed that the cheaper the car, the worse the defroster worked!

Works for me!

The main thing is to NOT beat on your cold engine regardless until it heats up!

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Re: Start and drive or warm up

Post by Geoff2 » Tue Jan 02, 2018 4:23 am

Where I live, I don't need a heater...

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