Fuel & coolant temp effect on power?
Fuel & coolant temp effect on power?
(OP)
Hi All,
Just wondering if anyone has any calculations, rules of thumb, resources etc for showing the power loss/gain based on the temperature of fuel and coolant?
I'm also looking for some resources for radiator design based on a known heat rejection required, I know there are some good spreadsheets around but can't find any.
Cheers,
Just wondering if anyone has any calculations, rules of thumb, resources etc for showing the power loss/gain based on the temperature of fuel and coolant?
I'm also looking for some resources for radiator design based on a known heat rejection required, I know there are some good spreadsheets around but can't find any.
Cheers,





RE: Fuel & coolant temp effect on power?
Fuel temperature has an insignificant influence due to the low mass of fuel in the charge relative to the mass of air. The very small amount could be very inaccurately calculated by specific heat and mass and temperature difference, but the amount of heat transfer from fuel to the air between the time the fuel is injected into the charge and the inlet valve closes would be very difficult to calculate.
Influence of coolant temperature depends on many other factors such as surface area to volume ratio, compression ratio, engine speed, to name a few.
Regards
Pat
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RE: Fuel & coolant temp effect on power?
The realities of designing and manufacturing just about anything with any degree of complexity to it, such as a radiator, are such that no-one is going to get it right the very first time. You'll have to experiment, and feed the results into subsequent designs.
You might consider shopping for an off-the-shelf radiator, for your your known heat rejection case.
I forgot what I was going to say
RE: Fuel & coolant temp effect on power?
On a turbocharged diesel air temp can affect cylinder pressure in an important fashion (because charge density is higher) even if output power isn't much changed (constant fueling). This can be a problem with diesels operating near their limits in cold climates, or on/near startup of just about anything in an extremely cold climate.
RE: Fuel & coolant temp effect on power?
Having said that I worked on a gasoline->diesel conversion and the fuel consumption was ridiculous as the head was too cold.
Cheers
Greg Locock
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RE: Fuel & coolant temp effect on power?
I said to cold can inhibit ignition, but to hot can induce detonation or preignition.
Regards
Pat
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RE: Fuel & coolant temp effect on power?
I don't have a PDF version of this but your local CAT dealer may give or sell you a copy.
Hope that helps, Mike L.
RE: Fuel & coolant temp effect on power?
RE: Fuel & coolant temp effect on power?
Fuel temperature is pretty much irrelevant unless you are trying to squeeze more into a restricted tank size to reduce the number of fuel stops.
Increasing coolant temperature increases power if detonation is not an issue, however I suspect it is and I would expect you need to test your specific set up to determine a:f vs ignition timing vs coolant for the optimum compromise. I am sorry I can't be more help.
Even if hotter coolant with richer mixture allows you to not pull timing so you do increase power, you need to weigh the power gin vs the extra average fuel load.
Regards
Pat
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RE: Fuel & coolant temp effect on power?
- Steve
RE: Fuel & coolant temp effect on power?
It's rear engined with the radiators sitting in side pods, we're looking to minimise the size of the opening in the side pods if at all possible to reduce the drag.
The fuel tank is ridiculously oversized for the duration of the races so there's no need to increase the density in order to fit more in, your point about it being such a minute amount in comparison to the volume of air does make quite a bit of sense Pat.
Timing cannot be changed so I don't know that running it too much hotter is an option.