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Discussion Starter · #1 ·
So I am a mechanical engineering student doing a research project on waste heat recovery on my 91 CRX DPFI.. and also aiming to drastically increase the fuel economy. If anyone can answer some of these questions it would be a big help...

1) In what manner do the primary and secondary injectors operate?
2) Where can I find information about the effect of various common modifcations on the gas mileage of D-series engines, especially for turbo and high compression setups? A link to nice Dyno test results for various mods would be nice too..
3) Will the AEM computer work for the DPFI? If not, what will? And if it does, or others do, will it be able to display the fuel economy or give me information to calculate it?
4) Can anyone think of a better, or cheaper way to accurately measure the fuel economy while driving other than with two flow meters (one on main fuel line, and other on return line), and output from the VSS? Also, is there a way to get a voltage out of the VSS indirectly (like through the guage cluster)?

Thanks guys! Pictures and more coming soon...
 

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Well here's the proper way of testing fuel mileage.

Get your ECU chipped with a USB output. Then have a laptop read, and register, these following things:

- Speed (VSS)
- Throttle angle (TPS)
- MAP
- Heat
- Record your own driving conditions such as hills, traffic, highway, stop and go, dustiness and what not.
-Keep the tires at 32psi, check everytime you drive
- Put 5 gallons of fuel in, and drive until she runs out, everytime.

Do the calculations to get a full tank. Trust me, I'm a mech eng student too, and doing MPG research is VERY hard on a car you drive everyday as you need to run it out of fuel everytime because you can't have an unknown amount of fuel consummed. What you can do, is mount a fuel cell, and run it out of fuel, and switch over to your regular tank with a 5 gal reserve. Aswell, you should get a HF MPFI setup to improove mileage, with an HF tranny and if you really cared, HF head or engine.

Trying to find a valid use for heat is to create steam, unfortunatly our cars have no use for anything steam powered (generator). If we had an electrical motor assisted engine, we could use the steam, and regenative braking. The best way to use heat loss is the exhaust manifold, lots of wasted energy there. People have been getting 50mpg in heavier cars with SOHC VTEC-E motors aswell, so maybe look into those engines.

I wanted to do the MPG project for year 2, but instead I figured I would do something that I would be able to patent after my studies.
 

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Discussion Starter · #4 ·
I didn't even think about those vtec-e engines... damn.. thats my backup plan then.. So let me tell you guys a bit more about this project now..

The exhaust is going to be rerouted as a heat exchanger/boiler under the hood.. water will be boiled to create low pressure steam. The steam will be used for useful mechanical energy on demand or continuously via a steam motor at the factory A/C compressor location and will assist the engine directly. Another option is to install a turbocharger and shoot high pressure steam into the pre-turbine exhaust to create more boost. I am also looking into ways to elimate the compressor side of the turbo and use a gearbox or the like to make ~25:1 gear ratio and use that to power an alternator..

Some of these ideas are old, and some are new.. and there are a lot of things im not mentioning. I will be using an old waste heat recovery muffler to preheat the water; a custom made shell and tube heat exchanger to boil the preheated water, and eventually, use the exhaust manifold itself as the final heat exchanger which will ensure high pressure, superheated steam.

As for the gas mileage measurements.. I need a way to measure the fuel economy accurately and continuously, that is why I am leaning towards a pair of $450 Omega fuel flow meters, and measuring fuel consumption directly.

So whats been done so far is:

auto to manual trans swap
7lb lightweight flywheel
relocated battery
relocated factory intake to other side of engine
Civic half size radiator installed
A/C temporarily removed
New engine/trans mounts
obtained most components of the new exhaust including waste heat recovery muffler, catalytic converter, manifold
in the process of custom fabricating the solid copper shell and tube heat exchanger
and getting the 200k mile engine back up to speed..

Id be interested in sharing ideas as well.. if youve got some suggestions or want to contribute in some way, please email me at [email protected] .. thanks everyone!
 

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Remember, energy in = energy out - friction. Your belt ideas won't work. The most efficient way of running an alternator is thru the belt. The AC idea would only destroy belts at an alarming rate, and create an amazing noise when the belt is forced to slip.

The turbo idea is the only good one I've read. If you make it happen remember to control the steam, having 100% steam efficiency (impossible due to heat loss) would make a turbo spin at an alarming rate, either killing it, or over boosting the motor. You would need to calculate the heat efficiency, the steam capability and the pipe sizing, ontop of all the regular turbo crap you need to deal with. Remember if you use steam to keep it in an isolated unit, have the steam collect back to water to be reused, no sense in always fill the car with water. It would require alot of engineering for a pretty flinsy idea.

A 25:1 gear ratio would require a very big gear just so you know. I took a course on just gears and power transfer thru belts, chains, gears, sprocket, including friction in bearings and shafts. It's alot more work then you think.
 

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Discussion Starter · #6 ·
Another thing I forgot to mention... the most important thing right now is a proof of concept. I already have a $1000 grant, but I need more funding desperately...if I physically show that my ideas work in basic form.. then I can get the funding I need to take things to the next level. I am well aware of the faultiness of the belt idea.. but think of it like this : if it squeels, its producing substantially more power than is lost due to friction (when in use), and seeing and hearing the belt slip and squeel would be a great way to convince myself and others that appreciable gains can be recognized.

The difficulty in gearing the turbo is the reason for it being my second option (or next step).. I would need to impose virtually no loads on the turbo shaft other than torsion... leading me to a planetary gear box. If I could get one donated, as well as a turbo, and some other parts.. things might change a bit. So until then, I am probably going to attempt to use the factory a/c compressor, or at least the housing, to function as my steam motor.. but its still up in the air. And steam comes first.

So do you have any more insight into obtaining an accurate, continuous fuel economy readout.. since that might be what I am forced to spend the grant money on?

oh and im a junior in ME so if you throw some lingo at me ill probably be able to handle it. Thanks!
 

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If you're going to go the flow sensor route, I assume the reason you need two is that you need one for the return line since the stock fuel pressure regulator is a bypass regulator. However newer cars use nonreturn regulators because pumping the fuel back to the tank warms up the fuel in the tank and increases fuel vapor emissions. So if you can substitute a regulator from a newer civic (not sure where that change occurred but 2001 and up have it for sure) you would only need one $450 flow meter.

The output of the VSS in the speedometer is 4 pulses per revolution of the speedo cable. Not sure what the ratio is between the speedo cable and the axle but that's an easy enough experiment to do.

If you have a waste heat -> steam -> generator -> electrical power path, you could consider doing what the Saturn Vue Green Line does and replace the alternator with a motor/generator. (they used a bigger than normal belt if I recall correctly.) Then you just need a motor controller that controls the output torque of the motor. Should be less complicated than gearing your steam engine directly to the motor.
 

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'9445 said:
If you're going to go the flow sensor route, I assume the reason you need two is that you need one for the return line since the stock fuel pressure regulator is a bypass regulator. However newer cars use nonreturn regulators because pumping the fuel back to the tank warms up the fuel in the tank and increases fuel vapor emissions. So if you can substitute a regulator from a newer civic (not sure where that change occurred but 2001 and up have it for sure) you would only need one $450 flow meter.

The output of the VSS in the speedometer is 4 pulses per revolution of the speedo cable. Not sure what the ratio is between the speedo cable and the axle but that's an easy enough experiment to do.

If you have a waste heat -> steam -> generator -> electrical power path, you could consider doing what the Saturn Vue Green Line does and replace the alternator with a motor/generator. (they used a bigger than normal belt if I recall correctly.) Then you just need a motor controller that controls the output torque of the motor. Should be less complicated than gearing your steam engine directly to the motor.
An alternator is an electric motor, Reverse the polarity (feed it current ratter then receive current) and they will start spinning (not recommend, they are design to be used like that). Your best bet would be to use a timing belt style (notched belt) so you have maximum efficiency out of that belt (no flat/V belt slip).

You said you wanted torsion only on a turbo shaft? Then buy a new ball bearing turbo and end it. The shafts on good turbos will withstand anything you try and throw at them. Planetary gear boxes are garbage. They are best suited for automatic transmissions with internal clutches. Ever designed a planetary gear box? It's more work then they are worth in my opinion (I fully designed a 4 speed + reverse gear box, froms gears to shafts to bearings to casing).
 

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ludesrv said:
An alternator is an electric motor, Reverse the polarity (feed it current ratter then receive current) and they will start spinning (not recommend, they are design to be used like that). Your best bet would be to use a timing belt style (notched belt) so you have maximum efficiency out of that belt (no flat/V belt slip).
Yep, that would be the cheapest route ... you'd need to make new control electronics to replace the rectifier and voltage regulator on the alternator to control the field coil and modulate the current input/output to the alternator.

My thought was that if you used a standard ac induction motor you might be able to use one of the motor controllers used for electric vehicles. With the motor connected to the crank via a pulley it looks to the controller like a motor in a vehicle being pushed at various speeds. Tell the controller to supply power to accellerate and it assists the motor, tell it to go into regenerative braking mode and you generate power instead.
 

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Discussion Starter · #10 ·
Yeah I like the alternator idea... Ive worked with the GM 'BAS' (Belt-alternator-starter) system on a 'hybrid' vehicle and actually may be able to get one donated.. but the crankshaft pulley is a limiting factor.. I could get creative with it but the bottom line is that if its not balanced properly.. problems emerge quickly. Maybe I could weld a notched ring on the circumference of the pulley... but thats another thing thats going to have to wait.

So I really appreciate the input so far.. Im definitly going to consider the returnless system.. thats a damn good idea and you might have just saved me some considerable cash! This is my next step in the project, so if you have any more ideas about it.. please do.

As for gearing the turbo (If I go that route).. I definitely don't plan on designing a planetary gearbox.. people mass produce those and maybe I could get one for free! As for the shaft.. thats not what im worried about.. im sure the shaft can take a hell of a load but the bearings can't.. thats why I can't add any radial or axial forces on the shaft(especially the end of it).
 

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'9445 said:
If you're going to go the flow sensor route, I assume the reason you need two is that you need one for the return line since the stock fuel pressure regulator is a bypass regulator. However newer cars use nonreturn regulators because pumping the fuel back to the tank warms up the fuel in the tank and increases fuel vapor emissions. So if you can substitute a regulator from a newer civic (not sure where that change occurred but 2001 and up have it for sure) you would only need one $450 flow meter.
Well I dug out the 2001 manual last night ... not sure how much good newer civic parts would do you. It is a non-bypass system, but it works by putting the regulator and fuel filter in the fuel tank with the fuel pump. So, it's still a bypass regulator, it's just been moved back into the tank so the line going up to the fuel rail has regulated pressure, not full pump pressure. The other issue is that there is no manifold vacuum reference for the regulator so the fuel pressure is constant relative to atmospheric and the pressure drop across the injectors varies as manifold pressure changes. I'm not sure whether somebody has a program to generate an ECU chip that's set up for this.
 

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Discussion Starter · #13 ·
Thanks for the good info.. I actually have found (although haven't been able to contact yet).. a guy who makes a MPG meter for obd-0 that calculates the fuel economy from injector pulse width and VSS input. I will be trying to get my hands on that, especially since some of my professors have strongly advised against using flow meter/s on the fuel line/s for various reasons.. I am still somewhat open to both approaches, as I know both CAN work.. but whichever is the more time consuming and expensive approach may have to be thrown out. I would be interested to hear any more suggestions, especially since you seem to be more fuel savvy than me. Thanks!
 

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theCRXproject said:
Thanks for the good info.. I actually have found (although haven't been able to contact yet).. a guy who makes a MPG meter for obd-0 that calculates the fuel economy from injector pulse width and VSS input. I will be trying to get my hands on that, especially since some of my professors have strongly advised against using flow meter/s on the fuel line/s for various reasons.. I am still somewhat open to both approaches, as I know both CAN work.. but whichever is the more time consuming and expensive approach may have to be thrown out. I would be interested to hear any more suggestions, especially since you seem to be more fuel savvy than me. Thanks!
Yeah doing it based on the injector pulse width is a good idea. Although I think for example Consumer Reports uses the flow meter approach on everything they review as they do their own accurate mpg tests.

You should be able to find some place that will flow test your injectors or sell you a new set that is tested so you know exactly what the flow at working pressure is (with old injectors ... who knows?).

Also bear in mind if you are a bit of a computer hacker or have access to somebody who is, the technology for hacking the OBD0 and OBD1 Honda ECU programs is pretty well developed (pgmfi.org and other places). I believe you can get hacked ECU code that generates serial output you can use for data logging which should include injector pulse width. Then you just have to have a laptop plugged in to log the data.
 
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