The tricks up my sleeve... Methods I may implement for better FE.

[omgwtfbyobbq]

Originally Posted by trebuchet03

Which is why comparing thermal efficiency of two engines VIA mileage can't happen for engines that have different power ratings (unless adjusted by the ratio of power generated - which is not linear).

Semantics (or categorization theory ) aside, isn't that what the EPA test does? Provided the comparison is between the same cars with different engine configurations... All they do iirc is put the car on a dyno that simulates the force the car should experience driving over the cycle. So, shouldn't the same car, have the same dyno configuration, and require the same amount of power regardless of engine cycle? Which would then allow for a comparison of BTE of both engines during that cycle, vera?

[trebuchet03]

Originally Posted by omgwtfbyobbq

Semantics (or categorization theory ) aside...

and require the same amount of power regardless of engine cycle? Which would then allow for a comparison of BTE of both engines during that cycle, vera?

It's not semantics

Fuel Economy = The amount of fuel required to achieve the task at hand (that is, make power).
Thermal Efficiency = The amount of heat/energy (in this case chemical) required to achieve a certain amount of work.


While momentum, energy, force etc. are conserved - power is not conservative and therefore must be controlled when doing a comparison. A heat engine that is more efficient, but generates much more power is not expected to need less heat than a heat engine that makes less power and slightly less efficient. That is what I'm trying to get across.

I have a perfect example (complete with P-v T-s diagrams) from my thermodynamics text book on this very subject... Unfortunately - I think I left it at home (200 miles away) because it's not on the book shelf :/

Again, I'm not saying this particular case goes either way... I'm saying that the system models are different and thus comparing the systems is a fallacy.

If put a carb'd engine and a more powerful poorly tuned fuel injected engine (both with the same displacement) on a bench test we can't make the conclusion that carb'd engines have a higher thermal efficiency because the carb'd engine sipped less fuel

[omgwtfbyobbq]

Power is controlled during the EPA comparison...
All things being equal, the engine that consumes the least fuel to make however much power, is the most efficient, right?

I don't see how comparing a turbocharged, diesel, NA, carb'ed etc... engine in terms of BTC can be a fallacy as long as the fuel is corrected for energy content, they are making the same amount of power, etc... I.e. the one that makes the required amount of power with the least amount of energy is the most efficient. I suppose we can even go to an extreme and have the FI'ed engine run so rich, and the carb'ed engine run so lean, that the carb'ed engine uses less energy to make however much power.

[trebuchet03]

Originally Posted by omgwtfbyobbq

Power is controlled during the EPA comparison...
All things being equal, the engine that consumes the least fuel to make however much power, is the most efficient, right?

I don't see how comparing a turbocharged, diesel, NA, carb'ed etc... engine in terms of BTC can be a fallacy as long as the fuel is corrected for energy content, they are making the same amount of power, etc... I.e. the one that makes the required amount of power with the least amount of energy is the most efficient.

Yes... again - I'm not saying either way with the specific reference you gave...

I am saying, taking that one example and making it a rule is a fallacy (rule = result however result != rule) of the slippery slope variety (a specific result was a consequence of a step). Which is why I said the statement was "quite easily a fallacy" when this specific discussion started

Another perfect example are turbo diesels which have higher thermal efficiency than their NA counterparts. Thermodynamically, efficiency is calculated in the same manner -- 1 - heatout/heatin because the diesel cycle is simply a heat engine.

Perhaps we're not meeting eye to eye because I'm speaking in the general sense you you're relating to the 95' Mitsu.? Re-reading my posts, I don't think I was very clear that I was speaking "in general" (such as my first post on it ) and I failed (until just now) to realize that you are not

[omgwtfbyobbq]

I should have qualified that in the sentence instead of spitting out some stream of information prior to the statement. It'sallgoodneway.

[cfg83]

DrivenByNothing -

Originally Posted by DrivenByNothing

The ECU will receive a modified voltage from the O2 sensor in order to lean out during closed loop operation. Detonation is obviously a realistic problem. To combat this, I will be implementing water injection. Water injection is very effective at preventing detonation and has several other benefits.

Water Injection Benefits:
Raises octane of the mixtue
Increases compression (water is incompressible)
Cools incoming air
Steam cleans cylinders

I'm sure I'm missing some. Water injection is much easier to implement on a turbocharged engine.

Another reason for the turbo, is to allow for higher compression to be created in the motor in order to test E85.

So the reasons for boosting are a) Ease of implementation of water injection b) Ease of creating a higher air to fuel ratio, c) Gain of some extra power for a small displacement engine, and d) Increasing of compression for alternative fuel applications.

If it doesn't work out, most of my investment will still have progressed me forward.

Is the 02 sensor modifier the EFIE? I ordered one as part of my hydrogen boost gizmo. I have not installed it yet, though, because life is messy right now.

And welcome to GS!

CarloSW2

[DrivenByNothing]

Yes, I have built the circuit, but need to work out some of the kinks.

I don't know how effective Eagle-Research's fuel savers are, but I bought the manuals for the HyCO and EFIE and they are full of incredibly useful information.

If I can't get the EFIE to work, I'll look at designing my own circuit to obtain the modified O2 signal I need.

Matt

[brucepick]

I have mechanic friends who've owned turbos.
Same engine displacement will give you more power
BUT mpg when using the available power is not likely to be any better than a NA engine capable of the same power.

Case in point:
my 2.3l NA Volvo 240 wagon, stock exhaust vs.
my frineds 2.3. Turbo Volvo 240 wagon, 3" cat-back exhaust, no muffler.

Mine is auto, his is standard.

Before I began hypermiling I got about 24-25 mpg summer.
He reports about 20.
Volvo 240 wagon with stick usually gets about 29-30 mpg but he's getting 20 with a modified, high-output turbo.

Gotta burn some gas to get all that acceleration.

[cfg83]

Matt -

Originally Posted by DrivenByNothing

Yes, I have built the circuit, but need to work out some of the kinks.

I don't know how effective Eagle-Research's fuel savers are, but I bought the manuals for the HyCO and EFIE and they are full of incredibly useful information.

If I can't get the EFIE to work, I'll look at designing my own circuit to obtain the modified O2 signal I need.

Matt

Cool. I have a digital A/F gauge that I will install with the EFIE to see it in action, but I came up with this hypothesis in the meantime ...

Assumption : At Idle + Closed Loop + Neutral at a stop, the ECU/PCM will be running the engine at 14.7 to 1.

Under my assumption, I can look at my LPH (liters per hour) and see that it is at 1.0 (or 0.3 GPH). Therefore, for my car, the 1 LPH represents the magic ratio. I used that to glean the following for my Saturn :

Air/Fuel Ratios from Scangauge for 1999 Saturn SW2 Only :
Attachment 395

When I run under my assumption, I will tweak the EFIE and watch the ScanGauge, looking look for the LPH to go from 1.0 to 0.9. When this happens, I know I will be running at a little more than 16 to 1.

Question : Since you have the EFIE docs, can you tell me how many amps it draws? I have the EFIE but I didn't order the docs. I want to put a fuse on it's power. The Eagle Research people told me it doesn't need it, but I would like to do it anyway.

Question : Also, since you have the docs, can you tell if it will act as a "pass through" if there is no power going to the EFIE? If yes, then I can put a switch on it in order to switch between real and faked 02 sensor input.

I can probably figure all of this out, but if you have the time, that would be great.

Thank You,

CarloSW2 the mooch

[omgwtfbyobbq]

I'd also be less inclined to kill the engine at stops or while coasting with a turbo, which takes some of the driver side of FE out of the equation. Not good for gassers imo.