I was thinking about fuel

"Joe_Limon" (Joe_Limon) 05/13/2014 at 00:59 • Filed to: None

0

35

If you preheat your fuel using heat from your exhaust pipes (keeping the fuel liquid since it is under pressure), then have the fuel immediately vaporize when it is injected/loses the pressure keeping it liquid. Would you get a boost in fuel economy? I could see netting less power/volumetric efficiency as the air heats up and expands. But what about fuel efficiency? Would you be able to gain a more complete burn at higher engine speeds? Or even extract more energy out of a given amount of fuel since the fuel would be closer to its ignition point.

hollanddjw 1 > Joe_Limon 05/13/2014 at 01:07

0

...or causing a fire

Birddog > Joe_Limon 05/13/2014 at 01:14

4

That sounds like a goodrecipe for detonation (pre-ignition).

claramag, Mustaco Master > hollanddjw 1 05/13/2014 at 01:15

0

^x2

You want fuel to heat up in a controlled environment, like the combustion chamber. You introduce a heat source like that before the fuel rail, you're just begging for all the gas in your tank to go kaburst

claramag, Mustaco Master > claramag, Mustaco Master 05/13/2014 at 01:15

0

But keep thinking outside the box

CRider > Joe_Limon 05/13/2014 at 01:21

2

Yeah, try wrapping your fuel line around your exhaust manifold a few times. That should do something. I'm not saying what it''ll do, but it'll definitely do something .

Squid > Joe_Limon 05/13/2014 at 01:27

1

You wouldn't get good atomization and metal parts would break and your motor would be no more. It isn't vaporization that the fuel undergoes, but atomization and being mixed with the air in a calculated stoichiometric ratio for optimum combustion. The high pressure of the fuel combined with the fan nozzles on the injectors are what help with combustion, you might be better off cooling the fuel down rather than heating it up, but I'm not an engineer that deals with internal combustion engines, and my brain is too full of silly putty to even try to look up the benefits (if there are any) of cooling fuel down to help with combustion. The density would change and it might only have a marginal effect on cooling the air charge down so I think it is more than likely a moot point, but bottom line is that heating fuel does nothing good for your motor. Unless Satan is your motor. . . . . . . .

GhostZ > Joe_Limon 05/13/2014 at 01:30

0

Hotter fuel is usually bad because it means hotter air, which is less dense. If you're suggesting heating the fuel separately away from the intake air, then there MIGHT be some advantage, but you'd have to proportionally reduce compression ratio or change spark timing in order to prevent predetonation, since the fuel will ignite a lot easier. You'd be trading mechanical compression energy for (much less efficient) thermal energy, but I'm sure a real engineer can probably answer this much better than I can.

The power in combustion, from what I've understood, comes from the heat expansion and reaction with oxygen, NOT from just the heating of the fuel or ignition of the fuel. This means that icy cold air and icy cold fuel that ignites is going to have the greatest expansive force, and also take proportionally more force to ignite. So the tradeoff doesn't really work.

Singhjr96 > Squid 05/13/2014 at 01:48

1

(sorry for the bad grammar, i'm trying to crank out a research paper right now)

To add onto what squid said, there is quite a few benefits to cooling down the fuel. Take water methanol injection in forced induction engines for example. It inject a water methanol mixture into the cylinder along with the gasoline. (to thwart common misconceptions, there is such little solution and the solution is atomized because of how high pressure it is injected under, that it is actually beneficial to your engine) after injection the mist begins to vaporize which sucks away heat in the process therefore cooling it down(same idea as sweat or water evaporating off of your skin). It cools down the fuel which help reduce pre detonation. Compression can also be even higher. since the cooler air is denser more oxygen can be shoved into the cylinder. and as we know, more oxygen also means more fuel, which means more power.

I however do not know if you can use this with a standard setup where there is no forced induction. You possibly could, but it would possibly be more detrimental because even though there is air being sucked in, not enough of it is being forced into the cylinder during the injection process to be efficient. Also, the problem of the fuel not even detonation at all can be a concern. Even though the system would only inject the water during high heat, high throttle situations, it may cool down the fuel too much to spark. The system does take off about a 100 degrees or even more heat out of the inlet fuel mixture. Bottom line, no point in using this system if you are not using a turbo or supercharger.

pdthedeuce > Joe_Limon 05/13/2014 at 01:50

0

if that were true , this wouldn't exist ... http://www.jegs.com/p/Mr-Gasket/Mr…

AMGtech - now with more recalls! > Joe_Limon 05/13/2014 at 01:51

1

I'm not an engineer but in my experience gasoline isn't nearly volatile enough to be ignited by exhaust heat, especially in the lines or tank, there just isn't enough oxygen and no spark. The auto-ignition temperature of gasoline is over 530 degrees Fahrenheit if I remember correctly. Most properly functioning naturally aspirated gasoline engine exhaust systems rarely exceed 500. Not only that but the fuel will have been heated by the engine before being injected. If you were to take an engine that runs more than 30psi (probably even less) fuel pressure and disconnect the main feed to the engine at operating temperature, the fuel that would spill out would boil as a result of losing pressure. We're not even talking about the pressures inside of the combustion chamber yet, or direct injection which runs thousands of PSI fuel pressure. My meager knowledge of the subject tells me that as far as optimizing efficiency from a gasoline engined vehicle, best current technologies would be small displacement turbocharging with direct injection Atkinson cycle. And of course, this is oppo, ADD LIGHTNESS!

Squid > Singhjr96 05/13/2014 at 02:08

0

There is a video of an M3 with ITB's running a methanol injection system. I think it comes down to actually tuning the car to run with it and using a wideband sensor to perform your engine calibrations.

But you pretty much got it, my only thoughts are that actually cooling your fuel down wouldn't do much because there are too many opportunities for it to heat up before it gets to the injectors. A methanol system is way more effective at maintaining cooler inlet charge temperatures and you see massive power gains on F/I motors.

I feel you, I had two finals today and zero sleep, my brain is mush and only being fueled by hot sauce right now. . Good luck on your paper.

Singhjr96 > Squid 05/13/2014 at 02:19

0

I just took an a.p. physics test today, and mush is not a good enough word to describe my grade. Possibly super heated liquid dripping out of my ears. Even though I know I failed the physics test, I know I passed the a.p. lang test. But on the bright side, the only class I even need to worry about now is precalc honors, and this paper. After I catch up on my work in precalc i'm golden.

Somebody just posted a video earlier on oppo about velocity stacks with methanol injection. But the thing is it doesn't matter if the fuel heats up before it gets into the cylinder, that is going to happen anyway, the mixture is directly injected with the fuel into the cylinder so it is cooled down right before it is compressed. But with stacks I can see what you mean.

Squid > Singhjr96 05/13/2014 at 02:26

0

I was saying to actually cool the fuel down and forgo the meth injection. Just cooling the fuel rather than heating it like the OP suggested would most likely be a futile attempt. I was half asleep when I wrote that first post. . . I really need to get to sleep.

Singhjr96 > Squid 05/13/2014 at 02:28

0

Oh, lol. I need to sleep too man. BUT TOO MUCH DAMN HW. The struggles of actually wanting to go to college, and giving a shit about your grades.

Squid > Singhjr96 05/13/2014 at 02:33

0

I feel you, just wait until you get there. It took me about 7 years after highschool to decide I wanted to do college and now I finally made it to university and shits pretty tough man. Good luck finishing your homework.

Singhjr96 > Squid 05/13/2014 at 02:38

0

I just know already i'm going to college right away after school. A lot of that decision was influenced by my parents, but i've also come to realize that's just the best way to go about it because it will just make life so much easier once you graduate. More money=easier life.

Squid > Singhjr96 05/13/2014 at 02:47

0

Meh, do what makes YOU happy. If you want to go to college do it. I fucked around too much when I first started college and never should have attempted it. But since you are in the AP classes you should be fine at university. I figured my early 20's were better spent with me working and having a good time partying rather than getting an education I would forget. . .

Singhjr96 > Squid 05/13/2014 at 02:50

0

Well my dream is a car related job in mechanical engineering, or automotive engineering. It was to become a particle physicist but there isn't enough cars in that to be a viable career. lol

Squid > Singhjr96 05/13/2014 at 03:02

0

Hahaha, Keep at it and make sure you find a school with a FSAE team! If you want to work in automotive engineering there is no better extra curricular activity than that.

Singhjr96 > Squid 05/13/2014 at 03:04

0

OHH I will definitely join the FSAE team at UW (University of Washington). They have about 200 or so people on their team.

BiTurbo228 - Dr Frankenstein of Spitfires > Joe_Limon 05/13/2014 at 04:36

0

This sounds like something that happens on the Fiat X1/9's engine. There's a little metal bar that connects the exhaust manifolds to the carburettor, but also a fan that cuts in to cool the carb when it gets up to temperature.

Maybe that helps with cold-running fuel economy or something, I can't remember.

Old-Busted-Hotness > Joe_Limon 05/13/2014 at 05:57

0

Smokey tried it, and made it work:

http://www.gafiero.org/smokey.shtml

The DeLorean was supposed to get a hot-vapor engine, but the deal didn't go thru because of John Z's coke bust.

Joe_Limon > Squid 05/13/2014 at 08:15

0

I agree that cooling your fuel is a great way to increase the power of an engine. But where my idea differs is that the goal to preheating your fuel would mean you would use less fuel at the expense of performance. Think of it this way, engines produce more power in colder situations right? But they are farr less efficient, to get optimum fuel efficiency, you want to be driving on a hot summer day.

Also, I am not sure of your point regarding metal parts breaking... We aren't talking about turning the fuel into a plasma or crazy high temperatures. The fuel would still be liquid under the pressure of the delivery system.

Joe_Limon > Singhjr96 05/13/2014 at 08:20

0

See now those are methods to produce more power, I am talking about fuel efficiency regardless of power output. The more energy you are pulling from your fuel to heat your engine, the less it converts to mechanical. Since it will be extracting more thermal energy from the fuel due to a larger heat differential.

Joe_Limon > Squid 05/13/2014 at 08:23

0

cooling your fuel down is a method for increasing the power of an engine and since the fuel is vapourized when it hits the top of the hot valve all cooling does is allow a little denser air to enter the engine. Again however, this idea wasn't to help with performance, it was to solely benefit fuel efficiency.

Joe_Limon > Singhjr96 05/13/2014 at 08:26

0

I agree that it happens anyway, the point was that by extracting the heat from the engine, more of your fuels energy is going into heating the engine back up. Methanol/cooling methods work so you can burn more fuel by getting denser air into the engine but my idea wasn't an idea to make more power.

Joe_Limon > GhostZ 05/13/2014 at 08:29

0

I am well aware of the air density issue in regard to power output. And I thought I stated it pretty clear that power output was not a goal of this design... But anyway, the idea is to lose less thermal energy from your energy so a higher percentage per amount of fuel burnt goes toward mechanical output. But yes, cold air more power.

Joe_Limon > Old-Busted-Hotness 05/13/2014 at 08:29

0

thanks!

Joe_Limon > pdthedeuce 05/13/2014 at 08:30

0

not talking about power ... Talking about fuel economy

Joe_Limon > hollanddjw 1 05/13/2014 at 08:31

0

engineered to happen in your cylinder :) not hacked together in a shed.

AMGtech - now with more recalls! > Old-Busted-Hotness 05/13/2014 at 09:55

0

That is very interesting. They would have either had to lower the compression or use a higher octane fuel to prevent detonation. Detonation can and does cause catastrophic failure, I.e. breakage of metal parts. I doubt this would work on a fuel injected motor due to the heat created by pressurizing. And then obviously there is the trade off of poor cold runability. But I bet that engine is super clean inside!

pdthedeuce > Joe_Limon 05/13/2014 at 11:13

0

"Or even extract more energy out of a given amount of fuel since the fuel would be closer to its ignition point."... this is what I was referring to .

Old-Busted-Hotness > AMGtech - now with more recalls! 05/13/2014 at 14:19

0

They got around detonation by homogenizing the mixture, and were able to run it super lean (20:1). But ole Smoke took the secret with him when he checked out in 2001.

Apparently the "danger zone" for detonation is around 2200F combustion temp. Somehow they got the engine to live past that and had no problems running much much hotter. No doubt the pistons and chambers had a special coating, but it's likely we'll never know.

You could probably make it work with EFI using a throttle-body injector, if you knew all the secrets.

Singhjr96 > Joe_Limon 05/13/2014 at 16:23

0

I was just adding onto the benefits of cooling down the inlet air temperature and fuel.

Squid > Joe_Limon 05/13/2014 at 17:01

0

The part about metal breaking was in reference to vaporized fuel causing detonation which would cause stuff to break.