Thread: Why??

All my cars get the best fuel economy when it's stinking hot. Doesn't matter if they're petrol EFI or diesel. Even with AC cranking the fuel economy is still great.

I think it's shorter warmup and warmer air gives less aerodynamic drag.

More likely the thermostat does not work properly and it never reaches optimum operating temperature except when the weather is very hot.

John

Hi Guys,

it has a new thermostat, it warms quickly (within 5minutes) to full operating temperature, even with the heater running when it's bloody cold. it runs much better with a sniff of choke.

It always feels like it's running lean to me I'm not sure how to check though ... If there was a way of adjusting the carbs, I'd just turn/move both adjusters by a specific amount and see what happens (that way I could always put it back where it was).

Would old carby diaphrams cause marginally lean running

seeya,
Shane L.

I bought one of these: MTX-L Wideband O2 Digital Air/fuel Ratio Gauge

No more guessing ever.

Originally Posted by Dougal

I bought one of these: MTX-L Wideband O2 Digital Air/fuel Ratio Gauge

No more guessing ever.

How sweet would that be if you were fitting aftermarket injection

Is there a way of adjusting the twin carbs on it though? The fact it runs a lot better with a sniff of choke tells me is running lean. I guess I'll hit the carby tuning sites and see if I can find how to slightly richen up the mixtures

seeya,
Sahne L.

Originally Posted by DoubleChevron

How sweet would that be if you were fitting aftermarket injection

Is there a way of adjusting the twin carbs on it though? The fact it runs a lot better with a sniff of choke tells me is running lean. I guess I'll hit the carby tuning sites and see if I can find how to slightly richen up the mixtures

seeya,
Sahne L.

Or indeed trying to get Lucas 14CUX to not drown your engine and bankrupt you.

I figure, once you know the exact problem, a solution can always be found. It's nailing down and defining the problem that is the hard part.

Gee's it running well... Not just a little bit .... a LOT. Bloody bizarre. There's not bi-metalic strips or weird cold running diaphrams/setups anywhere on these things are there If there is ... I reckon there stuck at the "full hot" position.

Originally Posted by Dougal

...warmer air gives less aerodynamic drag.

Umm - sure you have an engineering degree Dougal?


http://www.ce.utexas.edu/prof/kinnas...IFS/kinair.gif


http://upload.wikimedia.org/wikipedi...emperature.svg

So the higher viscosity will lead to lower Re at higher temperatures, which will reduce skin friction drag but increase wake drag (the dominant form of drag for a bluff body like a Land Rover). You cannot make a statement like that unless you have done a study of the flow around a RRC.

Experimental studies of vehicle acceleration show a general trend of increased drag and decreased engine performance with temperature.


http://www.scielo.br/img/revistas/jb...3/a10fig02.gif

http://www.scielo.br/scielo.php?pid=...pt=sci_arttext