Fuel warming for fuel economy 2

[Blob97]

The radiator that I am currently running is set up to also function as a tranny cooler. Because I have a manual tranny I have no need for this function. Would there be any fuel economy benefit to running the fuel through this core in the radiator?

The vehicle is a 1996 Dodge Neon
198K Miles

 

[kenre]

That diagram is a good example of trying to overcome the shortcomings of a draw through carby turbo instalation.

By heating the air fuel mixture it will reduce fuel puddling and promote vapourisation. These can be big probs with old school technology as shown.

Ken

 

[mattsooty]

PFI gasoline engines inject onto a closed valve - almost never on an open valve (except at high load/high speed). To do otherwise greatly increases HC emissions.

Cooling the fuel: While it is tempting to imagine that this might decrease the intake systems temperature it will only be by a miniscule amount - consider the amount of air that is in that system!

Any gain that is made will be outweighed by the fact that your droplet size will be much greater and a larger proportion of your fuel simply *does not burn*. It just sails out of the exhaust port as HC emissions.

Also all of these last droplets of fuel splashing about will mean that there is plenty of oppurtunity for wetting the spark plug - hardly the stuff that fuel economy & power gains comes from!

Might I also mention that driveability is going to be badly affected - as said before the situation sort of replicates having a very low RVP fuel.

MS

 

[patprimmer]

What has fuel temperature got to do with particle or droplet size?

They are both independent factors that each has an effect on vaporisation rates.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[mattsooty]

I think the key here is that we are talking about a PFI engine here, not DI.

The mixture preparation that is occuring on the back of the intake valve consists of the gasoline components changing from a liquid to vapour state - with the lightest end of the fuel vaporising first.

As soon as the valve opens the jet action that occurs between seat & valve causes a certain 'spray pattern' of fuel droplets to enter the chamber with the vapourised charge.

For a start with a lower temp there is going to be more fuel that is still in the liquid state (the heavier ends).

As this fuel enters the chamber the evaporation of the smaller droplets will occur as they pass from liquid to vapour, however since the fuel started at a lower initial temp there will be more energy required (time) to evaporate the remaining droplets.

Since there are more droplets about for longer there will be more coalescence & impingement and therefore more HC emissions.

MS

 

[patprimmer]

OK, I can see your point.

Is it supposition or do you have data.

I can also see the possibility that depending on valve and injector timing, that as the inlet valve opens some time before TDC, the air flow as the valve cracks off the seat at low RPM might be very slow and do little to disperse and atomise the fuel.

As in a modern engine, virtually all fuel is burnt during the power stroke, I still do not see any meaningfull gains in fuel economy, especially as the Engine Managment System will be calibrated or mapped for metering fuel at normal temperature.

Regards

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Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[Fabrico]

That cool fuel cool works by cooling intake air could be a big supposition.

The diagram above is of something far more than a turbo setup. "No, not a turbo! It's a homogenizer!"

 

[mattsooty]

I do not hold data like that personally but companies I have worked before do.

Although as you know nothing in this world is for sure so the mechanism I described mightn't be whats happening - no way of telling for absolute sure.

As for heating or cooling the fuel, I must agree with Pat here - leave it alone!

MS

 

[GunMuse]

This is a "AGED" problem. Everyone has heard of the "vapor carb" problem with this is well (enviromental law) Today's fuel versus the day of "vapor carb" has to be heated to a higher point to become a vapor and how that is done is what is part of the state to state laws that create "boutique fuels".

Living out in the Oil fields we can still get our hands on "drip gas" which is gasoline before the government gets a hold of it. The good ol' stuff that leaves vapors on the ground on a mildly warm day. The octane of gas is not as such to make vaporization delivery a safe reality without major modifications to laws. You have to keep in mind that the lawyer in the congress will engineer the engine before you do and blame someone else for static movement forward in technology.

Look at LPG 40% cheaper to start. Has huge tax breaks for using it.

AS FOR THE COOL FUEL. its for stability not performance an engine that misses on a car 4 ft wide at high speed the shimmy would kill the guy. Its to help prevent predetentation and prevent fuel temp from changing during the run. Mattsmooty gave great explanation on why it would pollute more but not even on topic.

http://www.prnewsnow.com

 

[Fabrico]

GunMuse, respectfully, you need to watch those vapors. It's not likely that anyone could post something more incorrect.

 

[mattsooty]

No serious like,

Its the government that's making all this fuel that is so hard to vapourize...

MS

 

[patprimmer]

mattsooty and Fabrico

I have been around these fora for quite a few years now.

I have noticed that when aggressive or non respectful arguments, rather than rational debate evolve, people and threads disappear.

When someone looking for an argument for whatever reason starts baiting with stupid comments, they, along with those who took the bait and the thread all go together.

Best first step is to respectfully post a correction, then ignore any attempts to wind you up.

Anyone who belongs here will quickly see which argument is valid and which is ranting raving bunkum.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[Fabrico]

Anyone who belongs here will quickly see which argument is valid and which is ranting raving bunkum.

I've been thinking that but until now was not convinced of it.
Thank you Pat
Apologies GunMuse.

 

[mattsooty]

Yes, good point Pat - an error of judgement on my part....

Apologies GunMuse.

MS

 

[LordMalaK]

Having been a drivability tech for some 20 odd years, I tend to agree that although heating the fuel will make it vaporize faster, fuel is a chemical which makes the oxygen in air burn, and thats where the power comes from. If you cool the intake air it becomes denser and will let you get more into the cylinder- so if your crafty enough to have heated fuel introduced directly into the cylinder AFTER the intake valve closes you may see some efficiency gains from the combustion process. Otherwise your just reheating the cooler air, which will negate the gains your seeking.

just my 2 cents worth.

 

[LordMalaK]

oops, I have to add to my previous post:

You can't inject gasoline directly into the cylinder because gasoline will detonate in the fuel rails under the pressure needed to get it into the cylinder.
I'd imagine sequential port injection with warmer fuel might work, but warmer fuel won't work in anything else because as stated earlier it'll only rewarm the cooler air- which will reduce the air density.

Fuel injected directly into the cylinder is called a diesel engine.

 

[mattsooty]

LordMalak

"Fuel injected directly into the cylinder is called a diesel engine"

.....not a Gasoline Direct Injection engine then?

"You can't inject gasoline directly into the cylinder because gasoline will detonate in the fuel rails under the pressure needed to get it into the cylinder"

Soooooo what about the Mitusbishi GDI engines, VW FSI engines etc....?

"Having been a drivability tech for some 20 odd years"

Really???


MS

 

[patprimmer]

How does the oxygen get into the fuel rail to give the fuel something to react with?

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[LordMalaK]

ok, ok, I've been out of it for a couple of years. But I was taught that gasoline will detonate under extreme pressures, not the 100 or so psi its under now, but thousands psi used in diesels. Sorry I haven't kept up on current tech as I retired an am quite happy with my carburated 25 year old oldsmobile. An I haven't worked on a bishi in 10 years and VW's we're scarce as we specialized in Benz and BMW's.

I'll dig out my calculator as it occurs to me that at a 12:1 compression ratio you'll only need a few hundred psi to inject directly into a cylinder (gasoline), and as I'm not a chemist I can only guess at the stability of gasoline under those pressures. If mitsubishi and VW can do it I guess it's reletavily safe, but I've never laid eyes on either system.

again, sorry. It was only my opinion based on years of consumer vehicle service, not special vehicle development.

 

[bobqzzi04]

During the latter years fo the Formula 1 turbo era, when the rules introduced fuel quantity restrictions, Honda started to heat the fuel to achieve better BSFC. It was one of their main advantages.

 

[turbocohen]

yamaha di 700psi, mitsu thousands of psi, gdi pressures over 10000 in the works. Fact is, heating fuel is not good for durability, aggravates deposit formation.