The dirty cost of one man's hypermiling?

[ProDarwin]

Originally Posted by dcb

Test	RPM	%CO2	%O2	%HC	%CO	%NO	mph	hp	torque
1	1735	14.8	0.0	62	0.06	101
1	2800	14.6	0.3	16	0.02	89
2	1698	11.8	4.4	39	0.02	105
2	2752	11.4	4.9	14	0.01	74
3		11.7	4.5	2	0.0	75	6.1	5.3	117.4
3		12.1	3.8	6	0.0	544	7.8	6.7	116
3		12.1	4.2	11	0.1	195	9.8	8.6	117.5
3		12.3	3.4	3	0.0	76	14.6	12.8	117.3
3		12.5	3.1	1	0.0	71	14.9	13.0	117.3
3		12.2	3.3	1	0.0	90	20.6	10.9	70.9
3		12.3	3.5	0	0.0	78	25.0	13.1	70.2

This is an odd bit of data... does the dyno record tq or hp in non-standard units (I know the pictures say ft-lb and hp) but 5.3hp w/ 117.4 ft-lb would be ~237rpm. All of the hp/tq values are pretty far off what I would expect from this test.

I think Sentra's approach is fairly scientific thus far and his conclusions are not unreasonable.

[cfg83]

SentraSE-R

[EDIT: I guess you already have a way to measure the cat temps]

This may be the thing for you :

High Range Adjustable Temperature Switch with LCD - Jaycar Electronics

Heat can be a major problem with any car, especially modified and performance cars. the more power, the more heat, so you need to ensure you have adequate cooling systems in place. This temperature switch can be set anywhere up to 1200 degrees celsius, so it is extremely versatile. The relay can be used to trigger an extra thermo fan on an intercooler, mount a sensor near your turbo manifold and trigger water spray cooling, or a simple buzzer or light to warn you of a high temperature. The LCD, which can easily be dash mounted, displays the temperature all the time. kit supplied with a quality solder masked PCB with overlay, LCD panel, temperature probe and all electronic components. Probe does NOT have isolated case. Kit requires probe with insulated case, if mounted to common ground.

The idea would be to install this in your Cat to determine it's warm-up/cool-off time period.

CarloSW2

[dcb]

Sentra, can you summarize the events a bit more (without foregone conclusion bias if possible)? I cannot confirm or deny your assertion of HC returning to normal, I don't know why they are so different in test 3 and test 2.


What happened before test 1?

What happened after test 1?

What happened after test 2?

Thx!

[ProDarwin]

Originally Posted by ProDarwin

This is an odd bit of data... does the dyno record tq or hp in non-standard units (I know the pictures say ft-lb and hp) but 5.3hp w/ 117.4 ft-lb would be ~237rpm. All of the hp/tq values are pretty far off what I would expect from this test.

Oops. If this is wheel hp and wheel tq, that isn't unreasonable... 237rpm with a 24" tire would be approx 17mph. I must've had a brain fart last night.

[user removed]

Originally Posted by SentraSE-R

It's been a long time since I did NICE-on P&G, but IIRC, I got mid-40s mpg averaging ~30 mph. I got mid-50s mpg @32 mph in 5th gear cruise control on the same drive.

Are the data there to support an assumption that my engine is an average polluter when run normally (smog test 3)?

Are there any alternate theories with equal likelihood to dethrone P&G from being the cause of the above-average air pollution test results? I realize 4 months of relative inactivity, or one month of complete inactivity alone could be the cause, but given my P&G history, and the return to normal HC results after my 900 mile "normal" driving, is there another theory with equal likelihood?

Does anyone see any major logic flaw in my suspicion that I'm dumping 15-75X the average xB's HC into the air with unlit cat P&G? FWIW, my constantly-lit-cat drive today saw the cat temps staying between 985 and 1339 degrees F.

Mech, I was driving 100 miles/night looking for rattlesnakes in the desert when I was that age. Gas was 18.9 cents/gallon. Life was good. When I was younger, midday LA smog looked like nighttime Central Valley Tule Fog. We'd play touch football in air so foul, it gave us shortness of breath. I don't want my gaming behavior to swing us back in that direction.

dcb, I wish I could make more sense out of those data. The NOx spike seems strange. I'm happy to see the HC back to normal.

I P&Ged, I failed to light the cat, and my emission values were abnormally high.

I lit the cat for 100 miles, my emission values dropped, and were still abnormally high.

I lit the cat for 900 miles, my emission values returned to normal. Is there any other cause and effect relationship going on here?

In my posts 36 and 40 on this thread, you have experienced what I speculated in those two threads. The manufacturers design a car for "normal" operation. EOC during 50-75% of a driving cycle falls out of that parameter.
Now that you have the two extremes and a fairly conclusive set of data, maybe there is a point of compromise that you can reach where you have the desirable emissions readings and close to the same mileage as before.

I watched your video showing your technique and appreciate the effort to show all of us how it's done. Looks like you might just need to adjust the technique to maintain cat function to the greatest extent possible to have the best of both worlds.

Since you can monitor cat temps, the remaining unknown is how long does it take serious techniques to affect emissions. It would seem like the longer trip "undid" the effects of years of previous driving for best mileage. Now the question is how do you sacrifice some economy, as little as possible, in order to produce the lowest emissions that will satisfy your opposing goal of normal percentages.

The 100 mile trip that reduced, versus the 900 mile trip that brought them to normal. What is required now to maintain the reduction?

That is the unanswered question.

Is it a maintain the low emissions issue, or a take a trip issue? You have the results of the extremes of to little and too much, meaning do you have to take a trip frequently or will the shorter trip be all that is necessary to maintain ideal function? I think there is a balance between the two, but if the longer trip "repaired' the system then maybe the shorter trip, or possibly just a change in technique be all that is necessary?

My speculation would be to drive with engine on and monitor cat temps, with the objective of keeping temps in the range above the cat function threshold.
Can cat temps be maintained with a reasonable amount of EOC? Would just driving with engine on to warm everything up, then manitaining a minumum effective cat temp be the solution?

Sadly increasing average cat temps requires wasting more heat energy, which means the choice is best mileage or lowest emissions, which is why I have always been opposed to adding "stuff" to control emissions, but that is a topic for another thread.

regards
Mech

[SentraSE-R]

^^^ My thoughts exactly, Mech. I've been driving to keep the cat lit, and observing FE with engine-on P&G. The UG's cat temp display must be an estimate, based on its observed behavior. I started with a cold engine, with cat temperature starting <100F. Within 3 blocks, the cat was supposedly up to 900F. If I kill the engine, the cat temp displayed (900F, for example) doesn't drop. When I restart the engine, the cat temp display always starts recounting at ~100F, even when it was showing 1200F 30 seconds earlier. So, it's not very believable.

Since I didn't EOC on highway trips, I won't see any FE loss there. I just tanked up in preparation for such a trip. The UG indicated 43.2 mpg estimated, with the entire 215 mile tank driven engine-on. I always err on the conservative side, so every tank is at least as high as the UG estimate. Actual FE for the tank was 50 mpg! It was probably a short fill.

dcb, sorry I haven't gotten back to you. I've been busy the past 2 days, and won't have Internet again until Sunday night.

[Arragonis]

Just a quick thought, my 2p.

I had a cracked windscreen in George a couple of months ago. When it was being replaced the guy insisted on disconnecting the battery - "health and safety" - no idea why.

Afterwards George ran rough for a little while. I checked out the handy Haynes book and it suggested that removing power resets the ECU, and that it has to "relearn" its settings - fuel quality, timing etc. Mr Haynes recommended a quick blast at different speeds for about 20 minutes and its been fine since.

Just wondered if a long period of inactivity - even if the battery was still in the car - if the same thing happened ?

The cat on George is the next bit of pipe from the manifold which is lucky because the rear silencers have a reputation for rusting very quickly

[user removed]

How about the advertised exhaust wrap for the converter, and possibly a temp probe that would read the temp of the outer converter heat shield. Then you could drive normally where you know the cat is lit and get a reliable reading for the external temp of the heat shield.

Maybe a new tactic for operation while still retaining high efficiency.

I know an inexpensive laser thermometer will read up to 500 degrees, which makes it a very useful tool for auto diagnosis.

An analogy is your radiator, both it and the cat are designed for the worst case scenario which is climbing a steep grade with a fully loaded car at 70+ MPH. In that scenario the exhaust system is probably glowing red from the manifold back to the point where the factory heat shielding ends. I remember climbing a mountain in West Virginia in my AT XB and the engine was running at over 4k RPM for 6 miles to the top of the mountain. If ever the cat was going to melt it would have been on that climb! Likewise the radiator is designed to keep the engine from overheating under the same circumstances.
Both the cooling and cat systems have to be designed for the worst possible scenario, something you will never see at 50 MPG. Hypermiling basically amounts to trading the heat energy normally wasted for useful work moving the vehicle.

If you can find a happy medium, you might be able to keep the cat lit in all but the most severe engine off P&G scenarios. Who knows maybe even all of the scenarios of your technique.

Maybe you get the picture about me, NEVER SURRENDER, NEVER SAY NEVER, there is always a way to make something work. Even at double the mileage of the average XB driver you still have enormous amounts of heat energy wasted. Maybe not two thirds, but still at least 40-50 percent.

With that amount of heat energy available, even though it is much lower than a normal driver, you can still make every effort to focus it on the one component that depends on waste heat to function properly. Grille blocks increase the return coolant temp, Cat wraps increase the internal converter temperature. Heck even DFCO is about the same as engine off, except the engine is pumping fairly cool air through the cat, which would make it cool off much faster than shutting the engine off altogether, so that is a positive and probably a big one.

Both of those will directly (cat wrap) and indirectly (grille block) focus your much lower average wasted heat energy to the one place where it is essential to maintain proper emissions function.

Tell you what, if I was Sentra, I would not surrender quite yet, You may find that you can actually improve both mileage and emissions beyond what you were achieving before you suffered this "catch 22" situation. In doing so you will be way ahead of any other extreme mileage driver who just rationalizes the cost of higher emissions with the statement "I'm producing lower CO, so that is my justification".

I think this may be one of the most important threads I have ever read on this site, and I know this. You are correct to have a high sense of personal responsibility and integrity. To be willing to sacrifice technique for emissions is a high standard followed by few.

It will be very interesting to see if you can come very close to your previous mileage and meet emissions standards. What would be even more fantastic would be to see if you could actually equal your prior average WHILE not sacrificing emissions in the process.

While the design of your emissions system may make that impossible, I would never give up the pursuit, just remember, even the heat energy you are not wasting contributes directly to global warming, so you, by driving more efficiently, are directly heating the atmosphere to a much lesser degree than 99.999999% of every other driver. It's not a rationalization to pollute, just a point to remember.

regards
Mech

[dcb]

Has anyone read this? It discusses causes and effects of contamination of o2 sensors and cat converters and lots of other good info, i.e. monitoring both o2 sensors for performance (front sensor should be richer than rear), perhaps that can be quantified:
http://www.autoshop101.com/forms/h64.pdf

[Vekke]

If you are so much scared about your emissions how can you withstand the fact that everytime you make the first start you will pollute a lot before the catalysator is fully warm up? You can only fasten that process by putting the catalysator closer the exhaust manifold and by using exhaust wrap around the pipe. You can also install smaller diameter catalysator but that is illegal because its not designed for your car at least in europe. So it does not matter how good your intentions are...

Only real choice would be EV.

Good points has also being made about the fact that fuel does not come up clean from soil. First you need to pump it process it and also haul to the fuel station. Usually those machines arent the most eco friendly at all.

In Finland test is made so that they first rev the catalysator hot about 30 seconds and measure the values from the pipe first at high revs about 3000RPM and after that with idle revs. If values arent good tehy rev it little bit more to make the the cat hotter. If you have hypermiled the car and never revved it properly you need to drive up to 7 miles with second gear revs on the redline to clear the catalysator. Go back to measuring place and see if the catalysator is clear.

If you get proper values your catalysator still works like it should. If you cannot reach the target values you need to change the CAT.

So you do need sometimes to rev the engine like you stole the car to work properly. Usually I do that in motorway incoming ramps flat out rev each gear to redline.

I would say in each case its better to burn less fuel than produce few HC, NOX, particles of pollution less.