When to stop the foreplay and go full out

[gundersen]

As the subject suggest, when is the engine ready to be really thoroughly used?

 

The ease the debate on, a multiple choice list:

1) From the get go

2) When the water temp is hot (80-90 degrees), 5-10 minutes, 3 miles

3) When the oil pressure stabilises (on my k, its 4 bar), 10 minutes, 4 miles

4) When the oil is hot (80-90 degrees), 20 minutes, 10+ miles

Items ordered in the sequence they happen when I drive.

[Stationary M25 Traveller]

No. 4

[glasgow]

I always believed it should be No. 4 and that is what i do (without having oil temp gauge though)... However, I notice in almost all the blats I have been to that the convoy just start engine, then drive and get hard acceleration with the first opportunity the road allows.... Errmm, may be I shouldn't go to blats with bad Westfield boys then 😬

 

Ahmed

[Stationary M25 Traveller]

If you want to enjoy driving rather than replacing head gaskets on a regular basis .... number 4 !

[The_ASH]

I've always applied point number 4, seems best and most mechanically sympathetic to try to get as many bits of the engine & drivetrain warm before stressing them too much.

[Chris Coxall]

What are the actual consequences of items 1 -4 ?

 

I can't see how not having your oil up to temp can cause a head gasket failure - surely it's just increased wear on bearings, cams etc

 

I'm sure somebody will enlighten me 😬

[gundersen]

Perhaps if the engine warms up unevenly the head will have reached a different level of expansion compared to the bottom, thus allowing for exhaust gas to escape from the cylinder if pressed too hard?

 

But that is just me guessing, indeed it would be very nice if somebody who actually knew something about it would enlighten us 😬

[myothercarsa2cv]

Ahmed, getting to the blat start point is your warm up time 😬

[Andy Lef]

🙆🏻 just my luck that it's 12.2miles to the office - guess my warm up starts at home?

[rj]

The K-series has steel bolts that goes from the top of the cylinder head to the bottom of the engine fixed in the oil rail.

 

Aluminium, which the engine is made from, has a thermal expansion coefficient of .000023, a 1 meter bar will grow 2.3 mm if its temperature increases 100 degrees C.

 

For steel the ciefficient is is .000013.

 

Imagine what happens to the clamping force that holds the headgasket in place when the engine is not warmed up properly.

 

No wonder the gasket will blow if you don't behave!

 

4 is the answer - and wait a little after that. Before the oil is warm the engine has not expaded.

 

Also let it run when you've been hooning it on a trackday before you stop it in the pit. Peter Carmichael made some tests with his car. If you stop it the pressure in the cooling system will raise to crazy levels. I learnt it the hard way - and changed the headgasket.

[Graham King]

I have always used 4 in any car, to be specific in the 7, I use a limit of 3-3500 RPM until the oil temp reaches ~ 60 degrees, then 4500 until it reaches approx 80 degrees, then I give it full beans. I'm not anal about it but use those as general guidelines. Water temp is largely irrelevant in all this.

 

Graham.

[Birkin S3 ZA.]

No 4 for me, but start to rev up to 5000 when oil is past 60 deg 😬

[AndrewGP]

Quoting Graham King: 

I have always used 4 in any car, to be specific in the 7, I use a limit of 3-3500 RPM until the oil temp reaches ~ 60 degrees, then 4500 until it reaches approx 80 degrees, then I give it full beans. I'm not anal about it but use those as general guidelines. Water temp is largely irrelevant in all this.

 

Graham.

 

Exactly what I do. Although I watch the water come up first, check it stabilises then flick the switch to watch the oil come up. When it's up at 80 degrees, I flick back to water and monitor that to check it's not overheating. Yes, I know it's a little bit anal 😬

[Roger Ford]

Sometimes when we're racing, there's a "no running engines" rule (either because it's at the start of the day, or it's just after some stupid "church break") until a couple of minutes before we head out on track for qualifying.

 

Nobody takes it gently, nobody (to my knowledge) has blown a head gasket doing it.

[glasgow]

Quoting myothercarsa2cv: 

Ahmed, getting to the blat start point is your warm up time 😬

 

In Scotland most of the blat start points are within 5 minutes drive... 😬

[Graham King]

Exactly what I do. Although I watch the water come up first, check it stabilises then flick the switch to watch the oil come up. When it's up at 80 degrees, I flick back to water and monitor that to check it's not overheating. Yes, I know it's a little bit anal

 

Ah when I said I wasn't anal I meant about the rpm, I do exactly the same as you, but until water is up to temp the oil won't be anyway, so water temp stabilises flick across to oil, when oil up to temp go back to water. 😬 Maybe I am anal after all.

[lavena]

RJ - never thought about it like that, however....

 

Surely. when the engine has been nicely warmed up - to an even 100degs then the expansions are different anyway? Isn't the problem more differential temperatures and the torque settings allow for the differential expansions?

 

Or am I missing something?

[Roger Ford]

It could be argued that the engine is only designed to work properly when the alu has expanded more than the steel. Though since it was created as a Metro engine, I doubt the designers expected Mrs Schoolrun to carefully run it up to temperature every times she used it. Then again, she probably didn't rag it too much either.

[CharlesElliott]

Not that I know what every person does to their engine, but it has always interested me that in 9 years of racing Caterhams, with up to 80 K series cars racing in a weekend, I don't know of *anyone* that has blown a head gasket.

[DaveMorris]

THe only time the oil in my Vx lump gets up to 90 degrees is during a reasonably a severe thrashing on the road (and not possible in the winter) or when on track.

 

I use 60 degrees - which is normally about 10 miles driving.

 

D

[Rob Walker]

I have two comments. Firstly most Caterhams will never see 80-90c oil temp on road use apart from a hot day if we ever get one or driving like a mad man. I drive my car keeping a careful eye on revs until I see at least 50c oil temp then start using more revs. Second whilst I agree with RJ on thermal expansion of ali vs steel you must consider that the K engine is a sandwich construction and held together with STRETCH bolts as the engine expands the expansion is accommodated by the bolts stretching and maintaining roughly the same clamping forces on the block and head gasket.

 

The other reason for not goosing the car from cold is that all modern fuel injected engines run fuel enrichment from start up cold until at least 60C water temp.

 

Rob

 

Edited by - Rob Walker on 4 May 2013 09:23:28

[Roger Ford]

Quoting Rob Walker: 

=The other reason for not goosing the car from cold is that all modern fuel injected engines run fuel enrichment from start up cold until at least 60C water temp.

Why is that a reason? Does the enrichment cause any problems? Or just waste fuel?

[johnv]

I wait until the oil temp is up and the pistons are the right size!

[rj]

Quoting Rob Walker: 

Second whilst I agree with RJ on thermal expansion of ali vs steel you must consider that the K engine is a sandwich construction and held together with STRETCH bolts as the engine expands the expansion is accommodated by the bolts stretching and maintaining roughly the same clamping forces on the block and head gasket.

 

 

Rob

 

Rob,

 

True, but the stretch is 1.25mm - cold (Thread is M9x1.25, bolts are tightened to 20Nm + 2x180 deg) if you remove the compression of the head gasket from the equation. My rough guess would be that the hot clamping force is at least twice the cold.

 

/regin

 

 

[Martin J]

No wonder so many head gaskets failed on early freelanders etc.

I can't imagine owners of these carefully warming the engine before hard use!