I like option ONE because the increased cylinder pressure forces the piston rings out against the cylinder walls, thus seating the rings, cleaning the cylinder walls. I'm jealous. There are no hills on Long Island.
Your Opinion Wanted - RPMs vs Engine Load
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For everyone voting option 1, doesn't it seem like heading uphill at 2400 RPM would lug the engine? I've never driven an ecotec, but that just seems a little low for a hill climb.
Originally Posted By: ClarkB
coast down the other side in neutral.
If the hill is steep enough, rolling down in 5th with the foot off the accelerator pedal will prevent him from gaining too much speed while resulting in "0" fuel consumption. On the other hand, in neutral he'll burn as much fuel as if he was standing idle.
coast down the other side in neutral.
If the hill is steep enough, rolling down in 5th with the foot off the accelerator pedal will prevent him from gaining too much speed while resulting in "0" fuel consumption. On the other hand, in neutral he'll burn as much fuel as if he was standing idle.
Originally Posted By: Quattro Pete
Originally Posted By: ClarkB
coast down the other side in neutral.
If the hill is steep enough, rolling down in 5th with the foot off the accelerator pedal will prevent him from gaining too much speed while resulting in "0" fuel consumption. On the other hand, in neutral he'll burn as much fuel as if he was standing idle.
Why not just go up the 1st hill WOT in 3rd, then when you hit the top of the hill, shift into 4th, back to WOT, then to 5th, still at WOT and just let the momentum take u up the next hill.
Originally Posted By: ClarkB
coast down the other side in neutral.
If the hill is steep enough, rolling down in 5th with the foot off the accelerator pedal will prevent him from gaining too much speed while resulting in "0" fuel consumption. On the other hand, in neutral he'll burn as much fuel as if he was standing idle.
Why not just go up the 1st hill WOT in 3rd, then when you hit the top of the hill, shift into 4th, back to WOT, then to 5th, still at WOT and just let the momentum take u up the next hill.
Originally Posted By: rationull
For everyone voting option 1, doesn't it seem like heading uphill at 2400 RPM would lug the engine? I've never driven an ecotec, but that just seems a little low for a hill climb.
I've never owned anything but V8's. Now that I think about it, I may be uninformed on this subject.
For everyone voting option 1, doesn't it seem like heading uphill at 2400 RPM would lug the engine? I've never driven an ecotec, but that just seems a little low for a hill climb.
I've never owned anything but V8's. Now that I think about it, I may be uninformed on this subject.
Yes, 2400 rpms seems to lugging but not quite. I recently started experimenting going up the hill slower in 4th gear - engine seems to like it better.
How? In 5th gear at 89-92% engine LOD the temperature goes up to 200F (but never over). In 4th gear at 69-72% engine LOD - temperature stays down to 186F (normal operating temperature).
On the comments about going downhill. Scanguage says this:
In neutral I get 269MPG at 22% Engine LOD at 900 RPMS.
In 5th gear I get 160MPG at 9% Engine LOD at 3,000 RPMs (usually go down at 70-80mph).
I like going in neutral because you get down the hill faster. Why would scanguage show more MPG for neutral than in gear if I'm burning 0 fuel?
Many thanks for all the comments folks. Much appreciated! If you haven't commented yet - would love to hear your opinion - additional thoughts are very welcome.
How? In 5th gear at 89-92% engine LOD the temperature goes up to 200F (but never over). In 4th gear at 69-72% engine LOD - temperature stays down to 186F (normal operating temperature).
On the comments about going downhill. Scanguage says this:
In neutral I get 269MPG at 22% Engine LOD at 900 RPMS.
In 5th gear I get 160MPG at 9% Engine LOD at 3,000 RPMs (usually go down at 70-80mph).
I like going in neutral because you get down the hill faster. Why would scanguage show more MPG for neutral than in gear if I'm burning 0 fuel?
Many thanks for all the comments folks. Much appreciated! If you haven't commented yet - would love to hear your opinion - additional thoughts are very welcome.
My question is, why would there still be any engine load if you were in 5th and with your foot off the gas?
Good question - No idea, but Scanguage II definitely registers 9-12% engine LOD when in 5th gear with foot off of gas going down hill.
In Neutral - I average 22-26% engine LOD.
In Neutral - I average 22-26% engine LOD.
Originally Posted By: OriginHacker21
Why would scanguage show more MPG for neutral than in gear if I'm burning 0 fuel?
The service manual for my civic clearly states that fuel is cut at zero throttle in gear above some engine speed (I think it's around 1200 RPM but I can't remember). However, I noticed the same scangauge behavior you mention here when descending my daily hill -- mpg numbers were much better in neutral than in gear (though they were both astronomical) and better in 5th gear than in 4th. I found this very curious.
I recently sent my scangauge in for a firmware upgrade (in case you haven't seen it, the newer system lets you add manufacturer-specific gauges). Now, when I descend the hill in gear (tried in both 4th and 5th) the MPG display goes to "9999" but in neutral it says something around 250 like you mentioned you were getting. Indeed, the display goes to 9999 for any off-throttle period above 1000 or so RPM.
I haven't e-mailed linear logic about it or anything, but I assume that this means the SG2 firmware can now detect the fuel-cut condition. If it couldn't before (or if it was calculating MPG differently in some other way) that would explain the numbers you're seeing in neutral vs in gear coasting.
EDIT: to address the post immediately above, I'm pretty sure the engine load is 0 too when off throttle with the new software, but I can't remember 100% if I checked it or not.
Why would scanguage show more MPG for neutral than in gear if I'm burning 0 fuel?
The service manual for my civic clearly states that fuel is cut at zero throttle in gear above some engine speed (I think it's around 1200 RPM but I can't remember). However, I noticed the same scangauge behavior you mention here when descending my daily hill -- mpg numbers were much better in neutral than in gear (though they were both astronomical) and better in 5th gear than in 4th. I found this very curious.
I recently sent my scangauge in for a firmware upgrade (in case you haven't seen it, the newer system lets you add manufacturer-specific gauges). Now, when I descend the hill in gear (tried in both 4th and 5th) the MPG display goes to "9999" but in neutral it says something around 250 like you mentioned you were getting. Indeed, the display goes to 9999 for any off-throttle period above 1000 or so RPM.
I haven't e-mailed linear logic about it or anything, but I assume that this means the SG2 firmware can now detect the fuel-cut condition. If it couldn't before (or if it was calculating MPG differently in some other way) that would explain the numbers you're seeing in neutral vs in gear coasting.
EDIT: to address the post immediately above, I'm pretty sure the engine load is 0 too when off throttle with the new software, but I can't remember 100% if I checked it or not.
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Wow thanks for the info rationull - that makes sense now. Awesome to know.
Originally Posted By: OriginHacker21
Yes, 2400 rpms seems to lugging but not quite. I recently started experimenting going up the hill slower in 4th gear - engine seems to like it better.
How? In 5th gear at 89-92% engine LOD the temperature goes up to 200F (but never over). In 4th gear at 69-72% engine LOD - temperature stays down to 186F (normal operating temperature).
On the comments about going downhill. Scanguage says this:
In neutral I get 269MPG at 22% Engine LOD at 900 RPMS.
In 5th gear I get 160MPG at 9% Engine LOD at 3,000 RPMs (usually go down at 70-80mph).
I like going in neutral because you get down the hill faster. Why would scanguage show more MPG for neutral than in gear if I'm burning 0 fuel?
The difference in temperature is because you are putting out the same amount of power in either case, but the water pump is turning slower in 5th. The engine is more efficient in 5th, so there is less waste heat generated and dumped into the cooling system. The cooling system just isn't as effective with the slower coolant flow.
Scanguage used to have a problem with zero fuel flow when you were at 0 throttle downhill. The one I got a month ago now compensates for that. Contact Scanguage for a better explanation. Do they do firmware upgrades?
Mine that I bought last November or December shows 9999 mpg when the fuel cuts off.
Yes, 2400 rpms seems to lugging but not quite. I recently started experimenting going up the hill slower in 4th gear - engine seems to like it better.
How? In 5th gear at 89-92% engine LOD the temperature goes up to 200F (but never over). In 4th gear at 69-72% engine LOD - temperature stays down to 186F (normal operating temperature).
On the comments about going downhill. Scanguage says this:
In neutral I get 269MPG at 22% Engine LOD at 900 RPMS.
In 5th gear I get 160MPG at 9% Engine LOD at 3,000 RPMs (usually go down at 70-80mph).
I like going in neutral because you get down the hill faster. Why would scanguage show more MPG for neutral than in gear if I'm burning 0 fuel?
The difference in temperature is because you are putting out the same amount of power in either case, but the water pump is turning slower in 5th. The engine is more efficient in 5th, so there is less waste heat generated and dumped into the cooling system. The cooling system just isn't as effective with the slower coolant flow.
Scanguage used to have a problem with zero fuel flow when you were at 0 throttle downhill. The one I got a month ago now compensates for that. Contact Scanguage for a better explanation. Do they do firmware upgrades?
Mine that I bought last November or December shows 9999 mpg when the fuel cuts off.
Fuel economy gives some indication of how hard the engine is working. That was why I asked since his question did not ask how to save gas.
Yeah, since I do all the driving my co-workers pay for all the gas (those that ride with me). So saving gas is a good thing but not necessarily something I'll put over making it easier for the engine.
So to increase engine life and load - Option 2 would be better - going uphill in 4th gear at a slower speed = less engine LOD and temperature.
Then going downhill - I see now it is better to leave it in gear.
Everyone agree with that?
So to increase engine life and load - Option 2 would be better - going uphill in 4th gear at a slower speed = less engine LOD and temperature.
Then going downhill - I see now it is better to leave it in gear.
Everyone agree with that?
Originally Posted By: OriginHacker21
Yeah, since I do all the driving my co-workers pay for all the gas (those that ride with me). So saving gas is a good thing but not necessarily something I'll put over making it easier for the engine.
So to increase engine life and load - Option 2 would be better - going uphill in 4th gear at a slower speed = less engine LOD and temperature.
Then going downhill - I see now it is better to leave it in gear.
Everyone agree with that?
The leaving it in gear question doesn't have a simple answer except for old ladies that say it's dangerous to coast out of gear.
If leaving it in gear slows you done enough that you have to use power sooner, than it depends on whether you save more fuel by leaving it in gear or by coasting further.
What does GM say about towing your car with the drive wheels on the ground. That's the condition you are operating under when you coast in neutral.
Yeah, since I do all the driving my co-workers pay for all the gas (those that ride with me). So saving gas is a good thing but not necessarily something I'll put over making it easier for the engine.
So to increase engine life and load - Option 2 would be better - going uphill in 4th gear at a slower speed = less engine LOD and temperature.
Then going downhill - I see now it is better to leave it in gear.
Everyone agree with that?
The leaving it in gear question doesn't have a simple answer except for old ladies that say it's dangerous to coast out of gear.
If leaving it in gear slows you done enough that you have to use power sooner, than it depends on whether you save more fuel by leaving it in gear or by coasting further.
What does GM say about towing your car with the drive wheels on the ground. That's the condition you are operating under when you coast in neutral.
If your situation is like mine and leaving it in gear down the hill slows your acceleration, but does not actually slow the car down then yes I totally agree that leaving it in gear is the way to go. As to the 4th vs 5th I also believe that 4th is better for the engine as I stated above but this post has got me thinking more about the "what's better for the engine" question.
We have two situations:
One in which the engine is operating at high load, low engine speed. This is more efficient presumably because there's less frictional loss at lower speeds and less parasitic throttle drag. However, stress on internals is higher because the engine is operating closer to peak power (shown as a higher throttle opening and higher LOD number on the SG2).
And one in which the engine is operating at lower load, higher engine speed. This is less efficient because of higher frictional losses and more parasitic throttle drag, and causes more friction-related wear on the engine. But it's less stressful on the internals because there's less load being put on them (operating further from peak power).
So what we're insinuating here is that operating an engine with higher load but lower frictional wear is more stressful on it than operating with higher frictional wear but lower load stress on the internals.
This makes some sense because while the oil can protect the engine from frictional wear to a degree, we have only the materials engineering of the internal components to protect against high load stress.
So it seems to me that what we're really asking is (with some exaggeration): Is an engine more likely to become a gutless, oil burning pig due to ring and cylinder bore wear from higher frictional wear over the years, or is it more likely to snap a con-rod or wear out a bearing due to higher load stress over the years?
I'm still in the "option 2" camp, but when I phrase the question this way it makes me realize that I have no engineering basis to vote one way or another. Anyone have any better information, or can anyone poke holes in my logic?
We have two situations:
One in which the engine is operating at high load, low engine speed. This is more efficient presumably because there's less frictional loss at lower speeds and less parasitic throttle drag. However, stress on internals is higher because the engine is operating closer to peak power (shown as a higher throttle opening and higher LOD number on the SG2).
And one in which the engine is operating at lower load, higher engine speed. This is less efficient because of higher frictional losses and more parasitic throttle drag, and causes more friction-related wear on the engine. But it's less stressful on the internals because there's less load being put on them (operating further from peak power).
So what we're insinuating here is that operating an engine with higher load but lower frictional wear is more stressful on it than operating with higher frictional wear but lower load stress on the internals.
This makes some sense because while the oil can protect the engine from frictional wear to a degree, we have only the materials engineering of the internal components to protect against high load stress.
So it seems to me that what we're really asking is (with some exaggeration): Is an engine more likely to become a gutless, oil burning pig due to ring and cylinder bore wear from higher frictional wear over the years, or is it more likely to snap a con-rod or wear out a bearing due to higher load stress over the years?
I'm still in the "option 2" camp, but when I phrase the question this way it makes me realize that I have no engineering basis to vote one way or another. Anyone have any better information, or can anyone poke holes in my logic?
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I think this is an easy one. Wear is both load and RPM dependent. The load is exactly the same in both cases. You are pushing the car at the same speed. You will have less wear with lower RPM.
We all talk about lugging an engine. I have never seen any data to suggest this condition increases wear and in your event I do not think you are lugging it anyway.
aehaas
We all talk about lugging an engine. I have never seen any data to suggest this condition increases wear and in your event I do not think you are lugging it anyway.
aehaas
Interesting, your fourth and fifth gear ratios are farther apart than any MT I've driven. I guess that tells you that I have never driven a GM vehicle with a MT. (They are rare.) I expect 2,400rpm in 5th to become about 3,100rpm in 4th on my MTs.
Back on topic, I'd use 5th unless it requires so much throttle opening to get up the hill that the fuel mapping goes to a WOT power mode. From the scangauge it looks like 5th is the best. I wouldn't worry about bearings at 2,400rpm, but it is your car.
And, if you don't shift you'll save wear on your clutch and it's master/slave cylinders, and your left foot, and your shift linkages...
Back on topic, I'd use 5th unless it requires so much throttle opening to get up the hill that the fuel mapping goes to a WOT power mode. From the scangauge it looks like 5th is the best. I wouldn't worry about bearings at 2,400rpm, but it is your car.
And, if you don't shift you'll save wear on your clutch and it's master/slave cylinders, and your left foot, and your shift linkages...
Define "Engine Load". How exactly is it calculated ?
Originally Posted By: AEHaas
The load is exactly the same in both cases. You are pushing the car at the same speed.
You are correct that thrust is the same here at both engine speeds. But at 2400 RPM each power stroke must be doing more work (in the physics sense) than at 3500, since there are fewer power strokes per second to do the same amount of work. My logic is that if the engine is doing more work in each power stroke, the engine is under more load (which implies that I'm not using load as a synonym for thrust or motive force).
youdontwannaknow:
I believe that engine load as defined by the scan gauge is the ratio of power output to max power output at current engine speed, given as a percentage.
Note that with this definition of load, the load is not the same at these two different engine speeds, since the max power output at 3500 is higher than the max power output at 2400 (I assume .. I don't have an ecotec dyno graph or anything...)
EDIT: I'm not exactly sure how the OBD2 system or the scangauge arrives at the load number, however. Maybe it's inferred based on the throttle position?
The load is exactly the same in both cases. You are pushing the car at the same speed.
You are correct that thrust is the same here at both engine speeds. But at 2400 RPM each power stroke must be doing more work (in the physics sense) than at 3500, since there are fewer power strokes per second to do the same amount of work. My logic is that if the engine is doing more work in each power stroke, the engine is under more load (which implies that I'm not using load as a synonym for thrust or motive force).
youdontwannaknow:
I believe that engine load as defined by the scan gauge is the ratio of power output to max power output at current engine speed, given as a percentage.
Note that with this definition of load, the load is not the same at these two different engine speeds, since the max power output at 3500 is higher than the max power output at 2400 (I assume .. I don't have an ecotec dyno graph or anything...)
EDIT: I'm not exactly sure how the OBD2 system or the scangauge arrives at the load number, however. Maybe it's inferred based on the throttle position?
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