Warming Up With Forged Pistons

[Mitz]

The builder of my engine has set a minimum idle rpm to a little over 2000 when the car warms up, which usually takes about 10 minutes until it drops down to normal idle and is completely warmed up.

Until a few days ago I've had no problems with this, but lately I've been hearing more and more about how it's bad to let the car warm up by just idling and the better alternative is slowly driving it till it's warmed up.

So my question is would it be alright if I just let it warm up the way I have been, by letting it idle until the revs go down to normal like it has been tuned ? Or just start driving but at low rpm ?

Sorry if this is in the wrong section !

Thanks.

[Piggaz]

Start and drive around nice and gently. No point sitting there for a million years.

[zebra]

Just drive it and take it easy

[Mitz]

Thanks for your input, appreciated !

[Mitz]

Sorry double post

Edited September 16, 2012 by Mitz

[t_revz]

I start my car while it's rolling down the driveway so I can get away quickly and not annoy the neighbours at 430 in the morning. Steady steady til I reach the highway.

[Cowboy1600]

To expand a little on why warming up on idle is bad, at idle (even 2000rpm) your oil pump isn't moving a lot of oil meaning poor supply to the top of the engine which in turn leads to poor oil circulation to everything else which in turn leads to increased wear.

[Husky33]

and also by idling you are not warming up your gearbox/diff fluid, driving gently you are.

[TurboMick]

It's actually because at idle the rings aren't sealing very well compared to driving with a bit of load, so fuel can get past and contaminate the oil, and on new engines It will glaze the bores too.

Not to mention it takes 5 times longer to get to temp by idling.

[Mitz]

That's great to know guys, I guess I'll start doing it that way now

[discopotato03]

I don't think it takes too long for most engines to get the chill out of their pistons , pistons don't have a real lot of thermal mass and being aluminium means they absorb combustion heat pretty quickly . Obviously the most important thing at start up is getting oil circulating everywhere and good oils lubricate pretty well even when cold . I reckon somewhere between the oil flowing properly from cold and everything expanding as it heats up uniformy enough are the important factors here .

Running an engine fast from cold is obviously intended to generate enough extra heat to warm an engine up faster than it would just idling at say 9-1200 revs . The only logic I can see in this is performance if you want to drive it hard from the first turn of the wheels . As was mentioned things like gearboxes and diffs don't heat their fluids standing still .

The thing to remember is that most current production cars are pretty well sorted nowdays and they start and run well . Many cars that have been played with particularly engine management wise don't run so well from cold start and can have all sorts of drivability issues . I'd say because they don't run perfectly when cold is part of the reason many petrol heads like to warm them up a bit before driving away .

Anyway everyone has their own ideas but I think everyone feels better when the temp gauge climbs off its peg .

IMO oil circulation is no 1 priority and what you do just after your engine fires up should probably take oil formulation and viscosity into account . Heavy grade oils won't heat or become more "fluid" as quickly as lighter grade ones so if using say a 10W60 you may need to soft pedal a bit longer than if you were using something like a 0 or 10W40 .

Some engines take longer to warm up than others and if yours is like this I suggest you check and renew your coolant thermostat , I also resist the temptation to run cooler than std thermostats because a cooler running engine takes longer to get its oil up to temp . To me 76C is fine .

There may be some cold start tuning strategies that help an engine generate a bit extra heat to warm up quickly , if anyone knows of any I'm all ears .

A .

[AngryRB]

when the engines cold i dont think driving off straight away makes sense, piston to bore clearance is at its greatest, turbo and top end maybe thin films,

so i wait till i see 50degrees on the power fc takes about 5 mins, probably takes about 25mins before any big boost..

a warm up is like foreplay, it gets her well lubed before the action.

Edited September 16, 2012 by SliverS2

[blind_elk]

So, you would rather sit there idling, wasting fuel, for 5 minutes with a large piston - bore clearance, than drive for 2 minutes with a large piston - bore clearance after which the engine will be at 50, and you will be 2 minutes closer to you destination.

The harder the engine works, the more heat it produces. The more heat it produces, the faster it gets to the correct operating temperature (which should be as the manufacturer designed it to be, so don't go installing "cooler" thermostats). The maximum wear rate in an engine is during the warm-up period. Taxi engines basically last for ever, because they rarely get cold.

Any good engineer, with the exception of Adam Gilchrist's father, will tell you to drive from the get-go. Trying to get the engine warm by idling is a waste of fuel (and therefore money).

[AngryRB]

i doubt id waste much fuel, id rather look after the motor than have it operating under load when its stone cold..

Im never in a rush with my engine cold, why is there so much concern over a short idle time, are you that short of a dollar? The issue is not wasting a dollar here or there on fuel , its the longevity of the motor. After spending a few thousand dollars on a brand new turbo, im not going to take off at the turn of a key.

My brother did that in his rotary he had and it blew some seals somwhere, turnt into a smoker.. so in that case it did need warm up time.

i take 5mins just to get out the front gate, theres a notable difference after 5mins, the motor is free'd up a bit rather than cold and groggy..

Edited September 16, 2012 by SliverS2

[StevenCJR31]

i doubt id waste much fuel, id rather look after the motor than have it operating under load when its stone cold..

Im never in a rush with my engine cold, why is there so much concern over a short idle time, are you that short of a dollar? The issue is not wasting a dollar here or there on fuel , its the longevity of the motor. After spending a few thousand dollars on a brand new turbo, im not going to take off at the turn of a key.

My brother did that in his rotary he had and it blew some seals somwhere, turnt into a smoker.. so in that case it did need warm up time.

i take 5mins just to get out the front gate, theres a notable difference after 5mins, the motor is free'd up a bit rather than cold and groggy..

cant compare a rotary engine to a skyline engine, rotarys are fragile at best and intolerant of detonation, with the engine running/idling you will get a SMALL amount of heat getting blown onto the gearbox via the engine fan

[t_revz]

^^^ rotaries always blow seals, nothing to do with warm up

It's not about money why people do it. Idling at 2-3% load compared to driving it at 10% load can more than halve warm up period.

Even heavy truck engines alternate cylinders so only half are firing to load up and warm the engine faster

[m.j.h]

There may be some cold start tuning strategies that help an engine generate a bit extra heat to warm up quickly , if anyone knows of any I'm all ears .

By the time I've got the car out onto the road it has been idleing for a few minutes and I take it easy till the first hill when I drag the brakes and load the motor up slightly to zero on the boost gauge. By the time I'm at the top of the hill temp gauge has moved up to close to normal

EDIT

Same with the truck I drive

If I let it idle it takes a good 10 mins to even move the gauge but if I let it idle while I sort the paperwork pump up air etc then leave the yard and cruise up the hill it is up to a quarter on the gauge and off the fast idle

Edited September 16, 2012 by m.j.h

[AngryRB]

i dont think the guage is a very good indicator, when the power fc gives 50degrees, the needle is still under the line

^^^ rotaries always blow seals, nothing to do with warm up

It's not about money why people do it. Idling at 2-3% load compared to driving it at 10% load can more than halve warm up period.

Even heavy truck engines alternate cylinders so only half are firing to load up and warm the engine faster

its a personal thing, to me its zero load for 3-5mins to let the parts expand and lube up, 50deg is better than 10deg and drive off.. my opinon only..

[AngryRB]

double post

Edited September 16, 2012 by SliverS2

[GTSBoy]

I subscribe to both ideas. I start the car and push it out of its spot (to make getting to the passenger door easier to put my laptop bag, lunch, etc in) then go back inside to say goodbye to everyone. The car gets a couple of minutes of idling so that I don't have to drive it up my 45° driveway* and 35° residential street** dead cold. It absolutely goes up those hills better if it is let run for a couple of minutes than if thrown at them cold. And there is no way to avoid making boost up the driveway even in first, and the street can oonly be done if willing to drive at 10km/h the whole way up.

There are reasons for everything.

* exageration, yes, but it is bloody steep.

** also exageration.

Edited September 16, 2012 by GTSBoy