All your fuel economy worries are over!

[billywight]

Check this out...

http://cgi.ebay.com/ebaymotors/Fuel-Saver-Gas-Saving-Device-Patented_W0QQcmdZViewItemQQcategoryZ50068QQitemZ45 72384724QQrdZ1QQsspagenameZWDVW

[D-Train]

Given the lengths most teams go to keep the charge cool (particularly in forced induction engines), i'd think it isn't really applicable in racing conditions. Besides, a cooler charge will combust better.

*Maybe* suitable for standard cars doing highway kilometres, etc but i really doubt we'll be seeing them in use in FSAE. But even then, most manufacturers (if not all) have their cars run rich for several reasons, including preventing detonation and providing cooling to the engine in some conditions.

Most power chips that you get for standard cars simply lean out the fuel ratios a bit, so the mixture is no longer excessively rich anymore, and more air can enter the chamber. Since there is more oxygen to react with, more petrol can be burnt, and hence you get a bigger bang. This tends to make me think that simply raising the fuel temp will not really aid fuel economy, but then again, there's a hell of a lot i don't know about engines.

[Agent4573]

actually its funny, cuz the colder the fuel charge the better and more efficient the engine runs.... gotta love ebay scams.

[Kamil S]

Originally posted by Agent4573:
actually its funny, cuz the colder the fuel charge the better and more efficient the engine runs.... gotta love ebay scams.

I agree... "cool" is the keyword for fuel/air entering the combustion chamber. I have yet to see an interheater on ebay, haha http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

[welder]

Might be worth having a squizz at the SAE paper on the Honda v6 turbo F1 motor,maybe not running pump fuel but definately counter-intuitive!

[Chris Davin]

I am generally highly suspicious of these types of devices, for the following reasons:

-The auto manufacturers employ some of the best automotive engineers in the world and spend millions of dollars every year on R&D. If there were a simple device that would improve fuel efficiency by 20% or more, the chances are pretty overwhelming that one of the OEM's would have discovered it first.

-These fuel economy-improving devices often rely on the psychological effect that if someone installs the device and thinks they are getting better fuel economy, they will tend to drive more conservatively, and this alone can reduce fuel consumption significantly (in street cars, driving habits can have a large effect on how quickly one goes through fuel). Of course, one might say, if the device reduces the vehicle's fuel consumption, it doesn't matter how it works, even if it's through such indirect means. But then this has ceased to be an engineering problem (tricking people into driving more conservatively).

This particular device heats fuel, which will heat the engine's charge air and reduce power output. In this respect, it works exactly like chopping off a cylinder or two - you're driving around with effectively a smaller engine! I'm sure that there are plenty of people out there that, with gas prices being what they are, are wishing they chose a smaller and less powerful engine when they bought their cars, but this is not the way the device is advertized.

It's not entirely unbelievable that pre-heating fuel in order to get better vaporization, and a more complete burn, will improve fuel efficiency. But most street engine injection systems are designed to maximize fuel vaporization anyway, so there is probably little room for improvement here. And, under load, I think most street engines are knock-limited in their spark timing, so artificially heating the charge could induce knock and cause the ECU to retard timing, which could actually hurt efficiency (and power too).

EDIT: The description incorrectly refers to unburned fuel in the exhaust as "blow-by." Blow-by is gas that leaks past the rings.

[VFR750R]

Heating fuel will increase efficency but decrease power.

I'd like to add a somewhat related example. It's amazing how different we set up our open cup engines vs. our restrictor plate engines. We try to run our restrictor pistons very hot which increases efficiency of the engine and since the air fuel mix is limited by the restrictor you can do more with less. But hot pistons heat the incoming air fuel charge reducing the volumetric effiency per cycle. So on an open engine big oil squirters are used to cool the piston and pick up VE, where power is limited by VE rather then the restrictor and thermal efficiency. It's amazing how many things I learned in college to increase the thermal efficiency of an engine actually reduce its output.

[Psychosis]

what a waste of time! if you want to heat your petrol, do what we do and fit your tank 1" away from your exhaust http://fsae.com/groupee_common/emoticons/icon_biggrin.gif and as to saving petrol, we know all about that over here, our petrol is £0.92 a litre, works out at $1.61 a litre ($7.25 a gallon). you guys would cry if you had to pay that! you'd probably also do what i do and drive everywhere with the clutch on the floor.

[Lukin]

I don't know why the Aussies teams just don't use a polarizer. It would make the technology of the UWA suspension look like leaf springs!

[BryanH]

I've used fuel temp compensation on Haltach installations.(Mazda,GM have fuel temp sensors) Can't remember exact figures but fuel density change from 20deg C to 85C was around 7%. this equates to change in A/F ratio of say 12.9:1 to 13.6:1. Prob give you a 5% improvement in economy if you drive an EFI car flat out everywhere (not in closed loop)
Btw the honda F1 engine ran a 85% toluene fuel that needed to be heated to coolant temp to actually vaporise.

[Cement Legs]

Originally posted by Psychosis:
... you'd probably also do what i do and drive everywhere with the clutch on the floor.

Or put it in neutral...... http://fsae.com/groupee_common/emoticons/icon_rolleyes.gif

[drivetrainUW-Platt]

WOW, thats prob the biggest claim in gas milage increase I have seen yet, and man at 45 bucks everyone should have one.....riiiiiiight. sounds like someone talking advantage of the fact that gas is so expensive and most ppl are just dumb when it comes to cars, I pitty the fool that spends the time installing one.

[Charlie]

Like Bryan said, it probably works. Hotter fuel means you get less in there. You'll lose power, but you'll save gas. It's like running a leaner mixture.

Of course, wouldn't say you'd necessarily get the advertised numbers, and there are more efficient ways of getting the same job done... Just install a throttle pedal stop at about 60%. http://fsae.com/groupee_common/emoticons/icon_wink.gif

[DaveC]

Yup, My A/F gauge reads leaner when I'm puttering around town on hot days (Carbed V8). I can tell when its about to vapor lock by the AF gauge. I need to get a bypass AFPR and run a return line... http://fsae.com/groupee_common/emoticons/icon_frown.gif

On most FI cars, it'll just compensate with fuel trims.