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Blanking off radiator in winter?

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Ribenapigeon
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PostPosted: 12:49 - 30 Oct 2019    Post subject: Blanking off radiator in winter? Reply with quote
My fuel economy noticeably drops with the temprature. Is it ok to blank off a bit of the radiator like i used to do with cars years ago?
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Nobby the Bastard
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PostPosted: 13:05 - 30 Oct 2019    Post subject: Re: Blanking off radiator in winter? Reply with quote
Ribenapigeon wrote:
My fuel economy noticeably drops with the temprature. Is it ok to blank off a bit of the radiator like i used to do with cars years ago?


Doesn't your thermostat work?
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Ribenapigeon
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PostPosted: 13:24 - 30 Oct 2019    Post subject: Reply with quote
Thermostat is fine. Ive noticed it every winter. In the summer the bike will hit 100 miles before the last bar on the fuel indicator but when the temps get cold its under 100. Im probably ridung more efficiently as well, not caning it and short shifting more.
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Polarbear
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PostPosted: 13:43 - 30 Oct 2019    Post subject: Reply with quote
Ribenapigeon wrote:
Thermostat is fine. Ive noticed it every winter. In the summer the bike will hit 100 miles before the last bar on the fuel indicator but when the temps get cold its under 100. Im probably ridung more efficiently as well, not caning it and short shifting more.


Watercooled with a working thermostat I struggle to work out why there would be a noticeable difference from the cooling side.

Maybe something to do with cold fuel? Carb icing or something similar?
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weasley
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PostPosted: 13:50 - 30 Oct 2019    Post subject: Reply with quote
Polarbear wrote:
Watercooled with a working thermostat I struggle to work out why there would be a noticeable difference from the cooling side.

Exactly this.

Drop in fuel economy could be for many reasons:

- different riding style
- different route or journey length
- different traffic
- different weather
- different tyres/pressures
- different chain maintenance
- different air density - more drag
- different road surface - more water being displaced
- different load - luggage, clothing
- heated equipment use
- more time on choke/start-up enrichment
- and so on

If your thermostat is working and it is still running cold, then maybe lagging the engine will help, but in this weather I would doubt this.
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Pete.
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PostPosted: 14:09 - 30 Oct 2019    Post subject: Reply with quote
Fuel injection normal behaviour.

The air intake temperature sensor tells the ECU what the air temperature is and the ECU derives air density from that and adds or removes fuel accordingly. Lower temperature = more dense air = more oxygen molecules = more fuel required.
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weasley
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PostPosted: 14:25 - 30 Oct 2019    Post subject: Reply with quote
Pete. wrote:
Fuel injection normal behaviour.

The air intake temperature sensor tells the ECU what the air temperature is and the ECU derives air density from that and adds or removes fuel accordingly. Lower temperature = more dense air = more oxygen molecules = more fuel required.


Yes, but also = bigger bang. Denser air generally contributes to more power and better efficiency (hence why we have intercoolers and charge air coolers).

Lower temperature = more dense air = more oxygen molecules = more fuel required = bigger bang = close throttle a little for same power output.

If you are going everywhere at full throttle then yes, you'll use more fuel and go faster.
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Ribenapigeon
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PostPosted: 14:29 - 30 Oct 2019    Post subject: Reply with quote
Pete. wrote:
Fuel injection normal behaviour.

The air intake temperature sensor tells the ECU what the air temperature is and the ECU derives air density from that and adds or removes fuel accordingly. Lower temperature = more dense air = more oxygen molecules = more fuel required.


So no point restricting air flow through the radiator then?
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ThunderGuts
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PostPosted: 14:59 - 30 Oct 2019    Post subject: Reply with quote
weasley wrote:


- more time on choke/start-up enrichment



This I'd say is a significant factor, at least for some bikes. For my 10 mile commute, in the summer the bike will be happy to run after 10 seconds of tickover and no choke applied. In cold temperatures it needs choke for 10 seconds and idling for a good minute. Idling uses quite a bit of fuel . . .
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steve the grease
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PostPosted: 18:34 - 30 Oct 2019    Post subject: Reply with quote
The thermostat regulates the minimum temperature of the engine. The fan ( if there is one ) the maximum. The reason there is a pressure cap is so the engine can run at over 100^c, it will never run at that temp in winter . The thermostat opens at about 88^c
It could well help the engine to run warmer if you blank off some of the rad.
Carnot efficiency any one ?
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The Shaggy D.A.
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PostPosted: 18:43 - 30 Oct 2019    Post subject: Reply with quote
Try a tinfoil wrap on the radiator for a tankful, and let us know Smile
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Sister Sledge
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PostPosted: 20:57 - 30 Oct 2019    Post subject: Reply with quote
The radiator wrapping thing was for when engines didn't have thermostats. Engines could never get to temperature in cold air and wrapping the radiator a little would help the engine get hotter and therefore run better.
People doing it to modern engines with thermostats will be the same people who beat carpets on a washing line each springtime. It's pointless with modern stuff.

As above really - denser air methinks. Perhaps the auto choke thingy or whatever it does is on for longer in colder weather and that's drinking more fuel?
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Ribenapigeon
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PostPosted: 10:48 - 31 Oct 2019    Post subject: Reply with quote
Sister Sledge wrote:
The radiator wrapping thing was for when engines didn't have thermostats. Engines could never get to temperature in cold air and wrapping the radiator a little would help the engine get hotter and therefore run better.
People doing it to modern engines with thermostats will be the same people who beat carpets on a washing line each springtime. It's pointless with modern stuff.

As above really - denser air methinks. Perhaps the auto choke thingy or whatever it does is on for longer in colder weather and that's drinking more fuel?


My auto choke works fine. I keeo an eye on it as when the bike was newer it actually stuck a bit but a judicious tap of a hammer in the right place freed it up. It's never stuck since.
Im going to try making sure the engine has heated up before riding for the next tankful.

I did wonder if the tinfoil radiator trick was sonething from the old carbed engine pre Efi days. I had old Minis back in the day and in order to manage engine temp id have to have the heater on in the summer to cool and off in winter to keep temps up.
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MattJ
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PostPosted: 19:19 - 01 Nov 2019    Post subject: Reply with quote
Engines aren't as efficient when cold compared to when they get to operating temperature. When it's colder outside it takes the engine longer to get up to temperature so you will get worse fuel economy.

Fiddling with your radiator is a recipe for disaster, don't do it.
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Ribenapigeon
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PostPosted: 19:39 - 01 Nov 2019    Post subject: Reply with quote
MattJ wrote:


Fiddling with your radiator is a recipe for disaster, don't do it.


Im going to leave the radiator. I think just letting the engine warm up on idle before riding is worth a try.
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Fizzer Thou
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PostPosted: 21:47 - 01 Nov 2019    Post subject: Reply with quote
When was the coolant last replaced?

What ratio of anti-freeze/anti-corrosion inhibitor to distilled water are you using?
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Ribenapigeon
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PostPosted: 23:14 - 01 Nov 2019    Post subject: Reply with quote
Coolant was changed in june at the yearly service by the garage no idea what ratios of stuff. How important is that fir winter fuel economy
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Polarbear
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PostPosted: 01:09 - 02 Nov 2019    Post subject: Reply with quote
Ribenapigeon wrote:
Coolant was changed in june at the yearly service by the garage no idea what ratios of stuff. How important is that fir winter fuel economy


I don't know about fuel economy but for engine longevity you want the right mixture of antifreeze/water. Did your garage use a pre mix? Did they mix it themselves and what did they use?

You need to know for any top ups.
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Pete.
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PostPosted: 01:53 - 02 Nov 2019    Post subject: Reply with quote
Ribenapigeon wrote:
I think just letting the engine warm up on idle before riding is worth a try.


That'll do wonders for your fuel economy...
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Phoenix
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PostPosted: 05:39 - 02 Nov 2019    Post subject: Reply with quote
Sister Sledge wrote:
The radiator wrapping thing was for when engines didn't have thermostats. Engines could never get to temperature in cold air and wrapping the radiator a little would help the engine get hotter and therefore run better.
People doing it to modern engines with thermostats will be the same people who beat carpets on a washing line each springtime. It's pointless with modern stuff.

As above really - denser air methinks. Perhaps the auto choke thingy or whatever it does is on for longer in colder weather and that's drinking more fuel?


We still do it over here on modern engines but mostly diesel trucks but it's totally different because at -30/40 degrees C then even with the thermostat closed it won't reach operating temperature with the radiator fully exposed. In the UK it will never be cold enough to need to mask off the radiator on a modern vehicle, he hasn't said whether the bike is reaching normal operating temperature, if it's not then it could be that the thermostat is simply stuck open. I've never noticed decreased fuel efficiency in cold weather on fuel injected cars or bikes.
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Teflon-Mike
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PostPosted: 08:30 - 02 Nov 2019    Post subject: Reply with quote
Sister Sledge wrote:
The radiator wrapping thing was for when engines didn't have thermostats. Engines could never get to temperature in cold air and wrapping the radiator a little would help the engine get hotter and therefore run better.
People doing it to modern engines with thermostats will be the same people who beat carpets on a washing line each springtime. It's pointless with modern stuff.


Morris Minor's have a thermostat. Mini's with the same A-Series engine have a thermostat. folk blanked off the rad still.... On Minor there was a tendency to remove thermostats, especially in summer and or if towing, to raise the temp they boiled over at, hence blanking off the rad in winter to manually regulate engine temps, a bit. On Mini's with the engine mounted across the engine bay and the radiator up against the wheel arch, the cooling was a little overly good, for a 40bhp engine, so they would take heck of a long time to warm up in winter, hence rad-blanking, but mope often they got tin fol over the grill, NOT to stop air-flow through the rad, but to shield rain water from the Distributor shorting the HT leads and causing miscellaneous mis-fire.

On Land-Rovers and for a lot of North-American cars, you used to actually be able to buy 'Rad-Muffs' that hung over the radiator grill, and had flaps you could roll up or drop down to help regulate air-flow, hence cooling. On the Landy, it was mostly rather like the mini, and the cooling was set up; for tropical climates so as to not over heat, so in typical UK summer, sorry, winter, they never got up to temperature, and the muffs were sold as an economy aid to reduce time on choke. On North American cars and trucks, the range of climates they could be expected to work in was from the burning desert of Arizona to the frozen waste lands of Alaska... or Canada.... so again, the cooling tended to be arranged on the conservative side and, especially with a big, as in 5litre engine, not thrashed very hard or very often to get it warm, they never would. Hence muffs used to aid warm-up.

These days... most cars are front-=wheel drive and have transverse mounted engine like the old Mini, BUT the cooling radiators have usually been portioned conventionally 'in-line' behind the grill, with an electric fan, that doesn't depend on the engine and a belt to drive it.

B-U-T, probably the most significant 'thing' is cheap plastic mouldings.

The old mini or Landy, had a bit of bent tin bolted to a pulley that drove the water-pump. It was neither very effective, or particularly efficient. With the advent of electric fans came injection-moulded fan blades that could easily and cheaply have an aerofoil section and shift an awful lot of air for their diameter and speed. The same cheap plastic mouldings also allowed radiators to be shrouded and engine bays ducted for much more efficient air-flow.

Curiously, the technology in the trusty car thermostat has NOT significantly changes much. Essentially a spring loaded pin expands with temperature to open the port to let more water flow. It has never been particularly elaborate or sophisticated, or even accurate.

Fuel injection, is another matter. In the fuelling 'map', there is basically a set of instructions to =over ride or lift the base map, and enrich the fuel/air ratio when the engine jacket, and/or air temperature is cooler, to replicate what an old fasioned 'Choke' did.

This then begs a couple of conundrums.

In days of yore, in the UK, in moderately 'usual' weather, there shouldn't have been any need for rad masking. It was most often a bodge to get around a silted up rad and or dodgy thermostat. On a more modern, carburated car, it still shouldn't be particularly needed, and the cooling system should be a lot more efficient and not need any help, if in good order.

While on anything with EFI, the electric brain should effectively automatically compensate, and rad masking REALLY shouldn't be needed.

On a bike engine, with a typically small rad to start with, and these days optimised most often for warmer climes, and summer only use, there REALLY should be no need, and blanking the rad is a good way to risk overheating when you do open the taps.

Yup. With the colder weather you will spend more time on choke, or with the EFI enriching the mixture, and you will likely be gingering the throttle a bit more in reduced grip. Which could account for the better summer MPG recorded. BUT if you have more serious issues, it suggests that there is something 'wrong' with the bike, and like the old Morris Minors, rad-blanking is NOT a fix for that, its a bodge.
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weasley
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PostPosted: 10:30 - 02 Nov 2019    Post subject: Reply with quote
Phoenix wrote:
...at -30/40 degrees C then even with the thermostat closed it won't reach operating temperature with the radiator fully exposed.


When the thermostat is closed the radiator is irrelevant - it may as well be removed. In very cold climates it is worth blanking off the grille to stop cold air getting around the engine itself and overcooling it.
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Polarbear
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PostPosted: 11:19 - 02 Nov 2019    Post subject: Reply with quote
Another thing to remember on old vehicles, the radiator fan was turned by the fan belt, still the name we oldies give to the alternator belt even though fans have been electric for years.

So even when stone cold the fan was operating so old engines relied on solely the thermostat for temperature control.
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Phoenix
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PostPosted: 21:43 - 02 Nov 2019    Post subject: Reply with quote
weasley wrote:
Phoenix wrote:
...at -30/40 degrees C then even with the thermostat closed it won't reach operating temperature with the radiator fully exposed.


When the thermostat is closed the radiator is irrelevant - it may as well be removed. In very cold climates it is worth blanking off the grille to stop cold air getting around the engine itself and overcooling it.


You are correct, with the thermostat closed nothing flows through the radiator, however with the radiator fully exposed at -40 what happens is that the thermostat will start to open but the cooling is so rapid that it is stuck at the barely open stage and you will not reach operating temperature but be stuck at 80 degrees or whatever thermostat it has, the other side effect is then you get barely any cab heating. It's not about airflow around the radiator to the engine itself, these are semi trucks so the engine bays are not enclosed or insulated like a car, airflow gets to them from the sides, vents and most if it from below.
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Nobby the Bastard
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PostPosted: 21:53 - 02 Nov 2019    Post subject: Reply with quote
A typical bike cooling system only holds a couple of litres of water so it'll always get to temp regardless of the outside temp.

My kettle holds that much water and can boil it in a minute or two.
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