Warm Up Time / Oil Temp - When is it ok to cut loose?

**Preen59** · 02-09-2010, 06:50 PM

Aeroplane engines have propellers, this gives them a load straight away. Poor wording on my part.

Rotax engines are almost impossible to cold seize- They have a chrome bore. Half a lap and they're good to go. I raced karts for 10 years (stopped racing in '07). I have been involved in tuning/development and building (along with blueprinting) engines for one of the best engine builders in Australia for the last 8 or so and that is ongoing.

Every class i raced, without fail, the engine would be good to go after one lap. And i still lean on an engine straight out of the gate. I never, ever had a cold seizure. Nor has anyone else i have ever seen doing that. The only engines i was ever wary of were RESA's, piston ports and higher. Because of the large fin area and iron bores, they could be susceptible to cold seizure. A quick choke into the first corner on the start of the second lap to give it a mild quench and get some more oil into the bottom end fixes that. People that think they need 2 laps are either too scared to drive on cold tyres or kidding themselves.

**hooba** · 02-09-2010, 07:09 PM

Preen - the morning REX flight from Sydney to Orange loads the passengers, and then they fire up the engines and go through a warm up routine for 5-10 mins before the plane even moves, and QantasLink turboprops do the same thing for the first flight of the day.

**pologti18t** · 02-09-2010, 08:16 PM

Originally Posted by gerhard

Yes it's probably more dramatically evident in a 2 stroke that can rev to 22,000, but the fact is the pisron expands faster than the surrounding metal. Just like in your 4 stroke with a sump full of oil that only revs to 7000 or so, which can also destroy itself when overheated.

I've had a 4 stroke that revs to 18500 and a 750 that revs to 14500. Neither of them seized in a variety of conditions

I always thought that 2 stroke engines had far looser tolerances than a 4 stroke.

Several times mates have told of 2 stroke bike engines siezing when overheated/ oil starvation only to run again once cooled down. Not sure this is as common in a 4 stroke engine

**Preen59** · 02-09-2010, 09:00 PM

Originally Posted by hooba

Preen - the morning REX flight from Sydney to Orange loads the passengers, and then they fire up the engines and go through a warm up routine for 5-10 mins before the plane even moves, and QantasLink turboprops do the same thing for the first flight of the day.

Very true. But my point was that when they warm up a plane engine, the propeller provides the load. This is completely different than trying to warm the engine without a load. (I knew what i was talking about.. Haha.)

Originally Posted by pologti18t

I've had a 4 stroke that revs to 18500 and a 750 that revs to 14500. Neither of them seized in a variety of conditions

I always thought that 2 stroke engines had far looser tolerances than a 4 stroke.

Several times mates have told of 2 stroke bike engines siezing when overheated/ oil starvation only to run again once cooled down. Not sure this is as common in a 4 stroke engine

Once an engine seizes, it is quite possible for the piston to separate from the bore once it cools down.. But it's still shot and will need to be rebuilt. It scuffs the bore, damages the piston and sticks the ring in the groove. After a seizure, I've stripped an engine, cleaned up the bore with emery, dug the ring out, cleaned up the piston and ring groove, cleaned up the ring and had it back together for the next heat before.. But it will never be as good again.

**ethosguy** · 02-09-2010, 10:22 PM

Aircooled have larger clearences than watercooled, not so much a 2/4 st thing. Large clearances and the emissions they promote are the underlying cause for the demise of aircooled engines. Large clearances are essential buffer to the substantial differential thermal expansion and high differential temps in an air cooled engine. Your Golf R engine is a world leading low emission, close fit engine.

Any siezure is good reason for a disassembly inspection, hot or cold. Some might run but it won't be a healthy thing anmore. *****, my KTM 2st piston is óut of spec after 20 microns (on dia) are gone...and it'll wear those 20 microns in 50hrs of running. That's not even the surface roughness between peak and trough of the tool finish. It's a big bore too so I hardly have to flog it for my yaryars.

In cold places, like Canada, they have engine sump/block heaters...I have experienced an entire fleet of snow cats (12) that would not start, too cold to crank, after less than 75 minuts after parking from full operating temperature because the operators didn't plug them in to the mains engine heater between shifts. It was only -30deg F. But then big ol'industrial diesels aren't F1 so I can't imagine how they could relate?

I'm watching, currently, cold temp (-40 to + 60degC) testing for weapons gimbals because of differential thermal expansion causing cold temperature loading on opposed taper roller bearings to determine design changes. Grease played a role but now with super high end grease it is proving to be mostly about bearing clearance/preload at the moment and service life/performance tradeoffs and implications. Not pistons but still made of aluminium and steel.

VW engineers (or BMW or Ferarri or...) have no clue what they are talking about in their owners manuals...(sic).

When heat treating aluminium a rule of thumb is about 30 mins per inch thickness for thermal lag. Have a think about the wall thicknesses and conduction paths in an engine? Sounds like the emprical 5-10mins moderate use is about right.

Why do most watercooled engines have thermostatic coolant head/block recirculation control before allowing the cooling system into play?

This just gets more and more entertaining.

**rs73** · 02-09-2010, 10:24 PM

sometimes in traffic my oil temp can go to about 97-98C... is that still ok? that's according to the MFD, not sure how accurate it is

**Brian** · 02-09-2010, 11:45 PM

Originally Posted by Brian

I'm struggling here guys. I've read TFM backwards, tried every combination of MFD displays, but I cannot seem to get a readout of oil temp on my MFD (118TSI). Is it not applicable to the 118 or am I missing something?
All helpful criticism will be absorbed with thanks.
Brian

Any help here guys?
Thanks in advance

**OraQube** · 03-09-2010, 12:32 AM

Originally Posted by Brian

Any help here guys?
Thanks in advance

Pretty sure the MY09's can't show the oil temp on the MFD.

**Transporter** · 03-09-2010, 07:51 AM

Originally Posted by Brian

I'm struggling here guys. I've read TFM backwards, tried every combination of MFD displays, but I cannot seem to get a readout of oil temp on my MFD (118TSI). Is it not applicable to the 118 or am I missing something?
All helpful criticism will be absorbed with thanks.
Brian

In our Tiguan I can set up in MFD what you want to have on display - just scroll and press OK on every option that will take you to sub menus, until you find option what you want to have displayed. I don't have the car here (my wife's daily ride) or manual so I can't give you better instructions.

But maybe it is not a feature on your car - which I doubt it.