Fuel economy/Heat recovery

[amnonholland]

Hi all,

Im interested in tuning and achieving excellent fuel economy.
I have a 1994 Auto-V6 running duel fuel LPG system.(sequential multipoint injection)
Atm i have a dying auto trans so fuel econ isnt that good due to clutch slippage
Im getting 12.5L/100km on lpg eqivalent to about 9.5L/100km on petrol
(235.2146 ÷ x L/100km = y MPG (US liquid gallon)) - Conversion factor for those familiar with mpg

I have installed a fuel controller that voltage modulates the VAF sensor so i can lean out the mixtures slightly. It works reasonably well but there are a few problems with regards to, after a while the ecu runs back to stoic mixtures due to closed loop operation (input from O2 sensors)

1- if the O2 sensors are unplugged the system will go into open loop mode, i assume and possibly very rich
In this mode, will the ecu still make calculations based on VAF???
If so this would mean that i would be able to correctly adjust mixtures via VAF modulation without closed loop operation interfering

I monitor the mixtures via the the stock narrowband o2 sensor.
I monitor egts (pyrometer is located about 100mm past the 02 sensor on the front bank)

2- Is this to far down the exhaust manifold to give a correct readng?
would it loose approx 100K between extractors and current pyrometer location?
temps fluctuate between 300 to 400C under normal drving conditions and max out at 500C when flogging it.

There are no noticeable power losses when running lean, but throttle response is a little poorer. but i am getting fuel savings of about 10% with no real aggressive tuning. Also lpg has a high RON rating in excess of 100 hence it can be leaned out with out pre detonation occurring.

3-From a safety perspective how far can i push the lean mixtures? Will i be able to hear if knocking occurs or will it be inaudible because of the small engine components? Is it safe to lean it out to the point where any leaner could affect drivability?


HEAT RECOVERY TOPIC

IC engines are only ~30% max efficiency with the other 70% lost as heat. 30% power at the crank (very optimistic), 30% out radiator and 30% out Exhaust.
So when cruising the engine does output about 20Hp. This means there 40-50 Hp of heat in generated.
I have been thinking about some mechanism to transfer this heat into usable energy and have up with ideas that use steam to either provides power and/or increase FE

There would be a water tank onboard. Water passes through a heat exchanger with the radiator Heating from say 20C to 90C. This water is passed through a secondary heat exchanger with the exhaust creating a high pressure steam. This high tmp/pressure steam will spool a turbo that spins and runs an large alternator( complication: gearing would be required)

The alternators output could
-a- replace the alternator the runs off the engine (possibly reducing 1-2 hp worth of drag)
-b- power electric motors mounted in the wheels. complicated, but a host of information at http://www.evalbum.com/" onclick="window.open(this.href);return false; This option would be a way to increase your vehicles power output with no increase in fuel consumption
-c- alternator electrical output is consumed within a electrolysis cell where the resulting H2 and O2 are fed back-into the IC engine.
Option -c- has 2 advantages
1- range and mpg can be significantly improved as fuel is supplemented
2- Hydrogen catalyzed combustion in spark ignition engine increases combustion efficiency and improves emissions quality

Looking from a efficincy perspective

option -a- would have maybe a 5% increase in FE due to no alternator drag on engine
option -b- would have a round trip efficiency(heat to mechanical) of say
- 70% heat recovery
- 40% turbine efficiency
- 80% alternator efficiency
- 90% motor eff.
= 20% overall eff.
so when cruising you would have 0.2*50HP = 10Hp extra
thats a 50% increase in power!!!!!!!!!

what about when flooring it
for my klde 130HP (mechanical)
means 325 heat is generated
At 20% efficiency thats 65HP extra at no increase in fuel consumption

Option -c-
- 70% heat recovery
- 40% turbine efficiency
- 80% alternator efficiency
- 50% electrolysis eff.
= 11 % overall eff.

At 20Hp load when cruising 0.11*50Hp(heat)
= 5.5 Hp extra(in terms of fuel energy)
thats a 27.5 % increase in MPG or range

Please feel free to comment/ question
thanks

[Hoodzy]

After skimming over this. It seems you basically want to use steam energy from the heat. Given this where will you put all this water? This set up will add weight.

If you want to get better fuel economy. First switch to a manual. Ensure your tires are inflated properly. Get rid of all excess weight in the vehicle.
HAHAH

[RS_OBD'oh_2]

Wow, Ok. Looks like this is not your first bbq.

1 For your EGT/pyro the location for the sensor should be app specific and listed in the product manual.
2 Narrow band is no help at all, if you can drop some cash for an EGT, drop another 200 for a wide band. There is no way I would ever lean out my mix without a wide band. That's like building a house without a level.
3 What are you using for fuel control and vaf clamp?
4 If you are nearing detonation... you are risking your engine in hopes of 10% better fuel economy. You'll need something like the HKS(?) AF/knockamp for those slight indications.
Bottom line is that you don't have enough test equipment to ensure a good tune and safety of your engine.

And yes, I did stop reading the rest of your post.

[Mi|<E]

So just a quick question -

Why do you think the major car companies are going hybrid electric?


Steam is taking a 50 year step backwards, these are cars not trains.

[fowljesse]

This is all beyond me. You definitely need a manual transmission.
Try gassavers.org for answers to your questions.

[amnonholland]

Yes i do intend on a ATX to MTX ASAP when i can come by a MTX trans (theres not all that many of them in sydney australia)

Given this where will you put all this water?

I would assume it be in the order 20-50L water per tank gas

I do plan on getting a wide-band O2 sensor. I definitely wouldn't be leaning out 90RON fuels, but lpg with 106RON gives a larger safety margin.

3 What are you using for fuel control and vaf clamp?

using jaycar fuel adjuster. simple to program, nothing special
http://autospeed.com.au/cms/title_The-D ... ticle.html" onclick="window.open(this.href);return false;

Why do you think the major car companies are going hybrid electric

Yes but but they still don't seem to be addressing the fundamental issue that there still using a ICE engine that derates 70% of the input energy in the fuel to waste heat.

Not trying to have a go at anyone.
Just purely ideas for thought.

[RS_OBD'oh_2]

http://www.jaycar.com.au/productResults ... RM=KEYWORD" onclick="window.open(this.href);return false;

did you really get something from these guys? My wideband sensor is worth more than anything they sell. Get real electronics. If you want engine management, go with a reliable source and not hippie carp.

You sir have smoked yourself silly.

[amnonholland]

take it easy mate, the cars only worth 2 k anyway

lol its not engine management, its merely tricking the ecu via VAF

[fowljesse]

I would really love to see a worklog for your car! I'm interested in your progress, too.
I'm tuning mine for both power and fuel economy. I'd like to be able to run LPG.

[RS_OBD'oh_2]

take it easy mate, the cars only worth 2 k anyway

lol its not engine management, its merely tricking the ecu via VAF

Ya, I'm not sure you are aware of where you are posting... this is MX-3.com. We don't care about the price of the car.

So, you've managed to buy a 20 dollar piggy back. If you only control the VAF you are missing some important issues with any engine. Enjoy your detonation.

NOTE: My lunch was worth more than your electronics.

[Newfie_dan]

you are talking about adding some 20-50 kg of water to the weight of the car plus the weight of a steam based system, in addition you are also going to have to add a steam turbine to move the alternator. Yes it is true that the ice is one of the most ineffecient means of moving a vehicle and steam power is much more effecient but for what you would spend in time engineering such a system and money on making the system work its just as well to do an electrical conversion and make the car an electric vehicle making it some 80% effecient. Why not just convert it to a hydostatically driven system and eleminate the trans while your at it to covert the drive system and reduce the lost power from the crank to the wheels. Just so you know you can add an electric turbo to up your volumetric effeciency and thereby make more power right? (and yes guys that last shot was a shot of sarcasm there in case you lost it) There is no replacement for good electronics to up the fuel effeciency, that junk you bought was just that junk. Get a fmu and engine management if you really want to up the fuel economy and squeeze more mileage out of the fuel. Weight reduction and engine management will acheive this, as well as learning how to hypermile when you drive.

[fowljesse]

As this IS a forum, it's a good oportunity to give facts and opinions, such as what he should do about his electronics, if they're inferior.

I like the forward thinking, and you amnonholland came here for opinions, so don't let them bother you. I recommend getting an engine management system with a wideband O2 sensor, if you really want to push the mixture. With MegaSquirt, you can have 2 different fuel and spark maps; 1 for each fuel. Long ago, I thought extensively about the inefficiency of the ICE, and how to recoup the heat loss, and concluded that I can't. I get about 35mpg HWY right now running at about 13.5:1 (I haven't tuned it for FE yet) running MegaSquirt and Spark on my DE making around 200whp.
I know the offset of the investment in gas price will take a long time to catch up, but I'm tuning mine for power, also (mostly a hobby, not investment). I get many returns in quality of life, just driving it.
I would seriously like to see a worklog for your car. There was a guy a cuople yeqars ago on here with a LPG conversion, and I "made" him do a worklog. You can do a search for his posts. I don't remember his name, but you can try LPG, etc...

Oh yeah, and you can get a 626 tranny for lower HWY rpm.
Good luck with it all!

[Newfie_dan]

Forward thinking is to be applauded, it does help ppl out with options down the road and I was not trying to be entirely scarcastic, but the options of an electric mx-3 does appeal to me because of the instant torque factor and dollar for dollar its probably 1 of the most economic conversions a person can do to a lightweight car like the mx-3, not to mention the visual appeal of the car to the eye. I have given some time to consider this option and may realistically approach such a project in a few years time. But yes fowljesse has made the same point that I made in that upgrading the engine management is your best dollar for dollar bet for fuel economy vs heat reclamation. I apologize if I came across as being to sarcastic and rude in my previous post I was in a bit of a foul mood at the time, but either way this is an open forum and I do not want to discourage you from posting your thoughts.

[RS_OBD'oh_2]

I drink and post sometimes.. but I am not sorry for anything I have said. New ideas are great, but when you fail on the tried and true methods, I get pissed. Damage to any engine based on ignorance and cheap mods are just sad.

[Ryan]

I think the bottom line is, the amount of money you spend on synthesizing a turbine generator to an internal combustion engine in a small metal engine bay that wasn't designed to hold anything else will cost MUCH more than your fuel or energy savings.

and if its about the environment, get a bike.

and if its a personal vendetta to try and out-engineer the rest of the specialist engineers in the world using the budgets of auto manufacturing companies, I wish you the best of luck, but won't be watching your worklog.