Engine pre-heaters

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Engine pre-heaters

Postby guilleracing » Sat Jan 01, 2011 11:05 am

This is my first post so I hope this is in the right place.

Does anyone have any experience of these?


Thank you!

Greg.

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Re: Engine pre-heaters

Postby tristancliffe » Sat Jan 01, 2011 1:24 pm

I have been thinking about these also. Trying to work out how to make a working oil heater (water is easy to heat just by idling), but don't have time to experiment yet. I was planning on making a aluminium tank, and having a small pump and an electric immersion heater element in it, connected to the car via the filling plugs on top of the engine tank.

The sort of heater in Demon Tweeks is meant for heating water, and I doubt that's a problem in Monoposto. I was told they aren't compatible with engine oil, but maybe that's just the grade of rubber used in the hoses...

I can't afford the ridiculous prices of commercial (water) heaters, so homemade is the only solution.
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Re: Engine pre-heaters

Postby guilleracing » Sat Jan 01, 2011 1:49 pm

Hi,

I have done a little bit of research on this already. A cheap 240v coffee cup heater is rated at 500 watts. I bought one to see how fast it heats water. The answer is it takes two minutes to put 50 Degrees celcius into one litre of water. A domestic water heating element is rated at 3000 watts.

One approach would be to put the coffee cup heater into the oil tank in through the filler neck, if it will fit.

(An engine block will absorb and radiate heat out quite a bit in cold weather so care must be taken not to loose the heat you put in, in the first place.)

I guess the next step would be to make up a heater with a 3 kw water heater and see how fast it will do an engine.

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Re: Engine pre-heaters

Postby tristancliffe » Sat Jan 01, 2011 3:15 pm

Interesting stuff already.

The main problems, as I see it, will be getting the heating element into the oil. I only have a small hole in the top of the tank. Hence thinking about drybreaks and pumps. Then the power source is another problem, but mains power or a generator should sort that. And finally, how long does it take to heat 5 litres of oil to 50 degrees at the same time as heating s block, gearbox, some water etc.

I think 3kW will be a bare minimum. How much is a 3kW element?!

But I'm glad I'm not the only one to think about stuff like this.
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Re: Engine pre-heaters

Postby Dermot Healy » Sat Jan 01, 2011 4:14 pm

Why would you want to do this with production derived engines in race cars that don't need to be started in very cold weather anyway?

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Re: Engine pre-heaters

Postby guilleracing » Sat Jan 01, 2011 4:20 pm

Hi Dermot,
I have tried to spin my ff2000 spec engine over cold. It is VERY tight.

Once warm there is a marked difference in the ease of cranking!

I have found a 12V 200 watt heater that will easily drop into the oil tank.

Good old ebay. There is also an Engine Block Heater for 99 quid.

I have ordered one up and will get back to you when it has been tested.

I have read that Engine oil needs 80 degree temperature for full protection.

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Re: Engine pre-heaters

Postby guilleracing » Sat Jan 01, 2011 4:27 pm

The heater I have ordered up is here

http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... K:MEWNX:IT

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Re: Engine pre-heaters

Postby tristancliffe » Sat Jan 01, 2011 6:23 pm

Dermot

We have 15 minute practice sessions. The first ~5 minutes of which is spent warming the engine oil so that it can withstand the pressures of racing speed. There are some drivers that don't bother - these are usually the ones with less engine reliability or less engine power. It really does make sense to preheat the oil (if it can be done on the cheap).

In a race, we have a green flag lap to warm the oil (and brakes and gearbox, but without overheating the coolant), and it just isn't possible to heat the oil with no (or very little) load on the engine. Hence we all start the race with an engine that isn't ready for it. Then people wonder when engines fail in Monoposto when they are meant to be standard engines capable of 250,000 miles. Either nobody can build an engine, or we're stressing them a lot more than in road use.

No need to reach 100 degrees, or heat the coolant really, as the engines aren't close tolerance types like in F1, but it all helps.

Our oil tank opening is about 18mm in diameter, so the element would have to be VERY SMALL!! Hence a tank, pump and pipes.
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Re: Engine pre-heaters

Postby Dermot Healy » Sat Jan 01, 2011 8:57 pm

No no no…..i’m not at all convinced by this

Believe me Tristan …I know all about blowing up engines. Your area of expertise is in winning races & championships & securing lots of fastest laps but MY expertise is in having those long depressing conversations that ensue whilst I look at my (or a customers) engines sitting forlorn, dripping oil, sometimes with a little hole in the side, or at the very least no longer rotating happily!

If I could only add the ‘…ah well, you see, you pushed it too hard when the oil wasn’t fully warm’ line to the litany of other excuses that I customarily use to disguise the fact that I have no real idea why the poor thing has gone bang then I would certainly do so.

But…my view would be that, sadly, engine failures in series like Mono never ever really have anything much to do with pushing too hard before the oil is warm. By the time you have got your single seater started, tried to drive it to the assembly area but have to wait whilst a 50ft motorhome is reversed , then waited again whilst the guy in a van stops to collect his mate with 38 burgers & 18 coffees (or was it 38 coffees & 18 burgers) from the café blocking the road, then wait idling until your pit crew arrive with the jump battery, started it up again as somebody wants to noise test it, let it idle whilst you argue with the noise tester, stopped & started it again as you thought they were moving off, started it again as a trigger happy marshal blows his whistle & waves his hands, waited whilst the guy in front is push started, finally get going down the pit lane only to stall, restart only to be stopped at the end by that cone with a red flag in it & now afraid to switch off you can be sure the oil will be up to 50-60 deg & the water temp (much more likely to be a problem) @ 110deg. Yes, of course oil temps don’t rise significantly until the engine is under load but they do creep up sufficiently as a general rule to mean that by the time you finally get out on track & have built up a tyre temp it will be safe enough to use the full rev range.

You talk of “….warming the engine oil so that it can withstand the pressures of racing speed” ….And yes 50-60 deg is not perhaps the optimum oil temp but my suspicion is that oil at that temp will be perfectly able to maintain satisfactory lubrication in a production derived engine subjected to race usage assuming everything else is as it should be. Oil at 100 deg does not possess any additional properties that allow it to lubricate better than oil at 50-60 deg, and the difference in viscosity displayed by a synthetic multigrade oil at those two temperatures will be quite small and quite compatible with the oil system design to allow adequate lubrication to be maintained. You are the engineer and love a good Google, but I’d be surprised if you come up with anything showing significant differences in oil film strength or oil film adhesion (probably not the correct technical terms but you know what I mean) within the temperature ranges we are talking about. With modified, exotic or older engines other factors come into play but for Mono stuff I don’t see it as a great problem

For what it is worth my view is that engine failures in (non bike engined) Mono cars are much more likely to be the result of (a) being cooked/water loss whilst sitting in pit lanes or on the grid whilst things are delayed (b) having engines rebuilt – newly rebuit engines are the ones which go bang (c) silicone sealant floating around (d) oil pipes crushed on chassis stands/jacks/ or whilst loading (e) detonation … or if XE vauxhalls (f) crank pulley/timing belt idlers undoing (g) valve spring caps cracking (h) or bits of valve guide trying to make a bid for freedom.

The appeal of the ‘ warm it up correctly’ line is that it appeals to our moral sense (just like the changing the oil and filter after every race)…it allows us to really feel we are doing the ‘right thing’ & that we have some control over what happens. We will be ‘rewarded’ for our good behaviour & the wicked (yes yes Jeremy Timms) will be punished.

You can see I am very very bored!

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Re: Engine pre-heaters

Postby mexican » Sat Jan 01, 2011 10:39 pm

Dermot, you didn't mention my personal favourite of selecting 2nd gear instead of 4th on the way up the box!

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Re: Engine pre-heaters

Postby broadside » Sat Jan 01, 2011 10:54 pm

Whereas I managed to select 4th instead of 2nd off the line at Silverstone :oops:

Dermot, I think its time you wrote a book....................
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Re: Engine pre-heaters

Postby tristancliffe » Sat Jan 01, 2011 11:08 pm

Well Dermot, I agree with more of what you say than I would care to admit!! My point is that preheating the oil slightly can only help. We've had oil pump belts strip teeth because of asking too much of the oil pump on cold, thick oil. We think. Maybe it isn't.

But for a homemade £50 preheater I would feel happier. And I could do with a new mini-project. Well, I could up until Jeremy's car arrived here for a 3 month rebuild.

Oh, and Jeremy had the annoying habit of only skipping the oil warmup laps when it was useful - Snetterton's Saturday qualifying etc. That wasn't lack of mechanical sympathy, but an awareness of track conditions that bordered on irritating.

Far more pressing for me is working out how I have injectors open for 18ms at high revs when there is only 16ms between each cylinder's cycles. Odd.
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Re: Engine pre-heaters

Postby Nick Harrison » Sun Jan 02, 2011 7:11 am

Experience would suggest to me that far more damage is done in the oil getting too hot during a race rather than having it too cold at the start. So why exacerbate the problem?

Forty years ago in wet sump cars I have let two inches into the sump to increase the capacity for this reason and even in Mark's time of competing have put oil in the fridge and during qualifying used a large oil syringe to take some out of the dry sump tank and replace with chilled. If you are tempted to do this a tip. Insulate the syringe and wear gloves, it gets v hot!!

Certainly when we were running Mugen F3000 engines we never started the engine without pre heating the water. That however was not to do with operating temperature whilst running as such but to align the main bearing journals before firing.

Pre heating the oil in the gearbox..........now that is worth doing. Good for a few horse power at the wheels, a particular advantage on the first lap. Or infact running the box without oil even better. Favourite F3/F Renault trick.

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Re: Engine pre-heaters

Postby guilleracing » Sun Jan 02, 2011 11:24 am

Well, If you remember my initial question was do you have any experience of these?

What a brilliant debate! My personal opinion would be to have the engine oil maintained within a range where it was the giving the best lubrication properties without getting too hot. I must confess my own application is not circuit racing but long distance hillclimbing in Europe. The tracks are in the mountains and often VERY cold. Sometimes below 0deg. We suffer from over cooling in the higher regions of a climb.

My reason for asking is that I like to run the engines of my cars over the winter to make sure the valve gear gets rotated. I just thought it would be kinder to the engine to start is once the fluids etc had reached a certain temperature. It was not really my plan to get everything "stinking hot" and then go out and race 20 minutes on a track.

Thanks for all the replies, I look forward to many more lively debates to come!

Greg.

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Re: Engine pre-heaters

Postby samier » Mon Jan 03, 2011 9:09 am

ArtyB wrote:
Pre heating the oil in the gearbox..........now that is worth doing. Good for a few horse power at the wheels, a particular advantage on the first lap. Or infact running the box without oil even better. Favourite F3/F Renault trick.


I have been trying to figure this out, I have seen a few cars if on stands, you can freely rotate the wheels with out any effort at all, while some you need you put a bit of effort. Not sure exactly what they are doing to reduce the friction. Are you saying they run no oil? or maybe a different grade or engine oil?


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