350z Manual Tip
10-07-2014, 07:07 AM
#1
Registered User
Thread Starter
350z Manual Tip
I have the most random and probably the most stupid basic question ever.
my 350z is my first manual car so bear with me.
I always overdrive my gears to make sure they stay between 1.5-2.0 RPM to save as much gas as possible.
Now someone told me if I keep overdriving my gear (when I get to 40mph and above, and always stick to 6th gear) it will wear down that specific gear.
Should this even matter...
let alone I have no idea what I'm asking. Just need some manual driving advice on saving gas..
All in all I try to go the most highest gear to keep the RPM on the low numbers I mentioned above.
my 350z is my first manual car so bear with me.
I always overdrive my gears to make sure they stay between 1.5-2.0 RPM to save as much gas as possible.
Now someone told me if I keep overdriving my gear (when I get to 40mph and above, and always stick to 6th gear) it will wear down that specific gear.
Should this even matter...
let alone I have no idea what I'm asking. Just need some manual driving advice on saving gas..
All in all I try to go the most highest gear to keep the RPM on the low numbers I mentioned above.
10-07-2014, 07:34 AM
#3
dont even worry about it. no matter what gear you are in all the gears are meshed (constant-mesh transmission) and are moving, and therefore wearing. i read something about how 5th is the only gear that constantly does something because its a reduction gear for all the other gears, except for 6th, but dont quote me on that.
just drive it and be happy. i usually shift around 2-2.2k and will stay in 5th unless im on a level road. if i drop below 2k and am going up an incline i will go to 5th. the car has around 200 lb/ft of torque at 2k rpms, so there is no lack of grunt at lower revs, no need to rev it to the moon to get going.
just make sure you dont slip the clutch any more than you need to when starting off, dont hold the car on a hill with the clutch, and for gods sakes put it in neutral and take your foot off the clutch pedal at a stop! oh, and dont rest your foot on the clutch either while driving, use the dead pedal
just figured since its your first manual car id give you a few pointers that ive had drilled into me when i started driving.
just drive it and be happy. i usually shift around 2-2.2k and will stay in 5th unless im on a level road. if i drop below 2k and am going up an incline i will go to 5th. the car has around 200 lb/ft of torque at 2k rpms, so there is no lack of grunt at lower revs, no need to rev it to the moon to get going.
just make sure you dont slip the clutch any more than you need to when starting off, dont hold the car on a hill with the clutch, and for gods sakes put it in neutral and take your foot off the clutch pedal at a stop! oh, and dont rest your foot on the clutch either while driving, use the dead pedal
just figured since its your first manual car id give you a few pointers that ive had drilled into me when i started driving.
10-07-2014, 07:36 AM
#5
open her up and have fun at times, but wasting gas for no good reason is stupid. no need to race the engine 24/7 imo.
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10-07-2014, 07:52 AM
#8
New Member
6th at 40mph isn't stupid. As mentioned, it's great on flat roads. And it's not always about saving gas or saving money, sometimes I see it as an achievement. Also it's nice to see what the Z can do and proves that going hybrid or getting another car isn't always necessary.
10-07-2014, 08:00 AM
#9
I have the most random and probably the most stupid basic question ever.
my 350z is my first manual car so bear with me.
I always overdrive my gears to make sure they stay between 1.5-2.0 RPM to save as much gas as possible.
Now someone told me if I keep overdriving my gear (when I get to 40mph and above, and always stick to 6th gear) it will wear down that specific gear.
Should this even matter...
let alone I have no idea what I'm asking. Just need some manual driving advice on saving gas..
All in all I try to go the most highest gear to keep the RPM on the low numbers I mentioned above.
my 350z is my first manual car so bear with me.
I always overdrive my gears to make sure they stay between 1.5-2.0 RPM to save as much gas as possible.
Now someone told me if I keep overdriving my gear (when I get to 40mph and above, and always stick to 6th gear) it will wear down that specific gear.
Should this even matter...
let alone I have no idea what I'm asking. Just need some manual driving advice on saving gas..
All in all I try to go the most highest gear to keep the RPM on the low numbers I mentioned above.
10-07-2014, 09:08 AM
#10
Registered User
Thread Starter
Thank you all for your answers.
That's what my theory was. Keep the RPMS down between the numbers I mention but when I have to gain up the hill I switch to a lower gear to gain up back onto a flat road and continue cruising in 6.
The two biggest factors to pay attention to for fuel consumption are engine speed and throttle position. Yeah if you're in a high gear at a relatively low speed it will keep your RPM's down, but if you have to bury the throttle all the time to compensate for being in an inappropriate gear your efforts will be counter productive.
10-07-2014, 09:09 AM
#11
I floor it in 1st to bounce the rev limiter then skip to 6th to cruise the strip. Sometimes I feel more chill and start in 3rd let it bog then shift to 4th to cruise PCH. The best is to start in 6th then no other gears gets any wear and tear. Skipping gears will add unnecessary wear on the synchros. Last part is true.
10-07-2014, 02:57 PM
#12
Hell I almost never use 6th gear. i have a really loud exhaust that drones a good bit in 6th below 55-60 mph. My car is just a weekend fun car so i don't really care about gas mileage and withe the turbos and built fuel system if you even get into it one or twice your fuel milage is toast anyway.
10-07-2014, 03:04 PM
#13
Blanqshot, I am a mechanical engineer and I can help answer your question with science.
The engine's brake specific fuel consumption (BSFC) is the measure of how much fuel it burns per the amount of power it generates. This article explains BSFC decently and is consistent with what I learned in my Engine Performance & Design classes as part of my degree: http://en.wikipedia.org/wiki/Brake_specific_fuel_consumption
Pay special attention to the section with the map on the right. The red line that limits the map on the vertical axis is the WOT power curve, as measured at the crankshaft. This is what's normally shown on a dyno sheet. The limit on the right side of the horizontal axis is the engine's max RPM. All combinations of RPM and power generated by the engine are shown on the map, with the contour-map-style islands formed by the changes in observed BSFC at that operating condition. BSFC maps are generally only recorded by OEM's when they're developing a vehicle, although with the right instrumentation it could be done privately.
In order to maximize a vehicle's cruising MPG (fixed load & RPM), you'd want to operate it in the island of lowest BSFC. To achieve this practically, you could change the loaded drive tire radius with a different tire size, or change the transmission or final drive gearing. As an example, the differences in BSFC are responsible for the MPG increase that some cars see when changing to a numerically higher final drive gear ratio. The engine is operating at a higher RPM, but lower load to travel at the same ground speed. This would move the operating point on the BSFC map down and to the right. Also consider that throttle position is less open and the injector duty cycle is reduced. Normally people would expect to have worse MPG numbers after changing to a numerically higher final ratio, for example changing from the factory manual 3.5 ratio gears to the 4.08 ratio gears, due to the increased engine speed that this entails. In many cases this is not correct.
A related discussion can be found here: http://www.eng-tips.com/viewthread.cfm?qid=339585
Let me know if you have any further questions. I hope this helps.
The engine's brake specific fuel consumption (BSFC) is the measure of how much fuel it burns per the amount of power it generates. This article explains BSFC decently and is consistent with what I learned in my Engine Performance & Design classes as part of my degree: http://en.wikipedia.org/wiki/Brake_specific_fuel_consumption
Pay special attention to the section with the map on the right. The red line that limits the map on the vertical axis is the WOT power curve, as measured at the crankshaft. This is what's normally shown on a dyno sheet. The limit on the right side of the horizontal axis is the engine's max RPM. All combinations of RPM and power generated by the engine are shown on the map, with the contour-map-style islands formed by the changes in observed BSFC at that operating condition. BSFC maps are generally only recorded by OEM's when they're developing a vehicle, although with the right instrumentation it could be done privately.
In order to maximize a vehicle's cruising MPG (fixed load & RPM), you'd want to operate it in the island of lowest BSFC. To achieve this practically, you could change the loaded drive tire radius with a different tire size, or change the transmission or final drive gearing. As an example, the differences in BSFC are responsible for the MPG increase that some cars see when changing to a numerically higher final drive gear ratio. The engine is operating at a higher RPM, but lower load to travel at the same ground speed. This would move the operating point on the BSFC map down and to the right. Also consider that throttle position is less open and the injector duty cycle is reduced. Normally people would expect to have worse MPG numbers after changing to a numerically higher final ratio, for example changing from the factory manual 3.5 ratio gears to the 4.08 ratio gears, due to the increased engine speed that this entails. In many cases this is not correct.
A related discussion can be found here: http://www.eng-tips.com/viewthread.cfm?qid=339585
Let me know if you have any further questions. I hope this helps.
Last edited by 1973camarolt; 10-07-2014 at 03:07 PM.
10-08-2014, 04:13 AM
#14
Registered User
Thread Starter
Blanqshot, I am a mechanical engineer and I can help answer your question with science.
The engine's brake specific fuel consumption (BSFC) is the measure of how much fuel it burns per the amount of power it generates. This article explains BSFC decently and is consistent with what I learned in my Engine Performance & Design classes as part of my degree: Brake specific fuel consumption - Wikipedia, the free encyclopedia
Pay special attention to the section with the map on the right. The red line that limits the map on the vertical axis is the WOT power curve, as measured at the crankshaft. This is what's normally shown on a dyno sheet. The limit on the right side of the horizontal axis is the engine's max RPM. All combinations of RPM and power generated by the engine are shown on the map, with the contour-map-style islands formed by the changes in observed BSFC at that operating condition. BSFC maps are generally only recorded by OEM's when they're developing a vehicle, although with the right instrumentation it could be done privately.
In order to maximize a vehicle's cruising MPG (fixed load & RPM), you'd want to operate it in the island of lowest BSFC. To achieve this practically, you could change the loaded drive tire radius with a different tire size, or change the transmission or final drive gearing. As an example, the differences in BSFC are responsible for the MPG increase that some cars see when changing to a numerically higher final drive gear ratio. The engine is operating at a higher RPM, but lower load to travel at the same ground speed. This would move the operating point on the BSFC map down and to the right. Also consider that throttle position is less open and the injector duty cycle is reduced. Normally people would expect to have worse MPG numbers after changing to a numerically higher final ratio, for example changing from the factory manual 3.5 ratio gears to the 4.08 ratio gears, due to the increased engine speed that this entails. In many cases this is not correct.
A related discussion can be found here: http://www.eng-tips.com/viewthread.cfm?qid=339585
Let me know if you have any further questions. I hope this helps.
The engine's brake specific fuel consumption (BSFC) is the measure of how much fuel it burns per the amount of power it generates. This article explains BSFC decently and is consistent with what I learned in my Engine Performance & Design classes as part of my degree: Brake specific fuel consumption - Wikipedia, the free encyclopedia
Pay special attention to the section with the map on the right. The red line that limits the map on the vertical axis is the WOT power curve, as measured at the crankshaft. This is what's normally shown on a dyno sheet. The limit on the right side of the horizontal axis is the engine's max RPM. All combinations of RPM and power generated by the engine are shown on the map, with the contour-map-style islands formed by the changes in observed BSFC at that operating condition. BSFC maps are generally only recorded by OEM's when they're developing a vehicle, although with the right instrumentation it could be done privately.
In order to maximize a vehicle's cruising MPG (fixed load & RPM), you'd want to operate it in the island of lowest BSFC. To achieve this practically, you could change the loaded drive tire radius with a different tire size, or change the transmission or final drive gearing. As an example, the differences in BSFC are responsible for the MPG increase that some cars see when changing to a numerically higher final drive gear ratio. The engine is operating at a higher RPM, but lower load to travel at the same ground speed. This would move the operating point on the BSFC map down and to the right. Also consider that throttle position is less open and the injector duty cycle is reduced. Normally people would expect to have worse MPG numbers after changing to a numerically higher final ratio, for example changing from the factory manual 3.5 ratio gears to the 4.08 ratio gears, due to the increased engine speed that this entails. In many cases this is not correct.
A related discussion can be found here: http://www.eng-tips.com/viewthread.cfm?qid=339585
Let me know if you have any further questions. I hope this helps.
However you lost me at the part "As an example, the differences in BSFC are responsible for the MPG increase that some cars see when changing to a numerically higher final drive gear ratio. The engine is operating at a higher RPM, but lower load to travel at the same ground speed. This would move the operating point on the BSFC map down and to the right. Also consider that throttle position is less open and the injector duty cycle is reduced. Normally people would expect to have worse MPG numbers after changing to a numerically higher final ratio, for example changing from the factory manual 3.5 ratio gears to the 4.08 ratio gears, due to the increased engine speed that this entails. In many cases this is not correct."
Are you stating its possible to achieve a higher MPG even at a higher RPM rate?
10-08-2014, 06:02 AM
#15
LOL "science" great answer,
However you lost me at the part "As an example, the differences in BSFC are responsible for the MPG increase that some cars see when changing to a numerically higher final drive gear ratio. The engine is operating at a higher RPM, but lower load to travel at the same ground speed. This would move the operating point on the BSFC map down and to the right. Also consider that throttle position is less open and the injector duty cycle is reduced. Normally people would expect to have worse MPG numbers after changing to a numerically higher final ratio, for example changing from the factory manual 3.5 ratio gears to the 4.08 ratio gears, due to the increased engine speed that this entails. In many cases this is not correct."
Are you stating its possible to achieve a higher MPG even at a higher RPM rate?
However you lost me at the part "As an example, the differences in BSFC are responsible for the MPG increase that some cars see when changing to a numerically higher final drive gear ratio. The engine is operating at a higher RPM, but lower load to travel at the same ground speed. This would move the operating point on the BSFC map down and to the right. Also consider that throttle position is less open and the injector duty cycle is reduced. Normally people would expect to have worse MPG numbers after changing to a numerically higher final ratio, for example changing from the factory manual 3.5 ratio gears to the 4.08 ratio gears, due to the increased engine speed that this entails. In many cases this is not correct."
Are you stating its possible to achieve a higher MPG even at a higher RPM rate?
10-08-2014, 08:14 AM
#16
dont even worry about it. no matter what gear you are in all the gears are meshed (constant-mesh transmission) and are moving, and therefore wearing. i read something about how 5th is the only gear that constantly does something because its a reduction gear for all the other gears, except for 6th, but dont quote me on that.
just drive it and be happy. i usually shift around 2-2.2k and will stay in 5th unless im on a level road. if i drop below 2k and am going up an incline i will go to 5th. the car has around 200 lb/ft of torque at 2k rpms, so there is no lack of grunt at lower revs, no need to rev it to the moon to get going.
just make sure you dont slip the clutch any more than you need to when starting off, dont hold the car on a hill with the clutch, and for gods sakes put it in neutral and take your foot off the clutch pedal at a stop! oh, and dont rest your foot on the clutch either while driving, use the dead pedal just figured since its your first manual car id give you a few pointers that ive had drilled into me when i started driving.
just drive it and be happy. i usually shift around 2-2.2k and will stay in 5th unless im on a level road. if i drop below 2k and am going up an incline i will go to 5th. the car has around 200 lb/ft of torque at 2k rpms, so there is no lack of grunt at lower revs, no need to rev it to the moon to get going.
just make sure you dont slip the clutch any more than you need to when starting off, dont hold the car on a hill with the clutch, and for gods sakes put it in neutral and take your foot off the clutch pedal at a stop! oh, and dont rest your foot on the clutch either while driving, use the dead pedal
just figured since its your first manual car id give you a few pointers that ive had drilled into me when i started driving.
10-08-2014, 10:16 AM
#17
Blanqshot, the answer to your question at the end is yes. Higher RPM does not always mean higher fuel consumption. The load is defined as the engine power needed to generate the correct amount of force at the tire contact patch to maintain the vehicle's speed. This power is taken from the engine's flywheel and multiplied by the transmission and final drive gear ratios. Selecting a lower transmission gear (5th instead of 6th) means that the engine power is multiplied by a higher number, producing more force at the contact patch than is necessary to maintain the vehicle's speed. In order to reduce the force to the target amount, the engine's fuel burn rate can be reduced, which is normally achieved by reducing throttle position. Reduced throttle position means reduced mass air flow and reduced fueling to keep the air/fuel ratio correct. To find out if this means lower fuel consumption per distance traveled (MPG), you must refer to the BSFC map and compare the two operating points.
Years ago, I changed the final drive ratio in my Camaro from a 2.7 to a 3.7 and the car's MPG was the same in both cases. This sparked my curiosity and so I studied the related topics until I understood them.
Phenom, you're correct as long as the load you're referring to is engine load. Does this help clarify?
Years ago, I changed the final drive ratio in my Camaro from a 2.7 to a 3.7 and the car's MPG was the same in both cases. This sparked my curiosity and so I studied the related topics until I understood them.
Phenom, you're correct as long as the load you're referring to is engine load. Does this help clarify?
10-08-2014, 01:06 PM
#18
New Member
Who worries about MPG driving a Z....if you want to save gas,buy a Civic and call it a day.The Z does pretty well on gas for a sportscar just under normal driving conditions.
10-10-2014, 05:00 AM
#20
One thing I always like about my '03 is I can put it in 4th gear from 30-90 with no lugging and no rev limiter. I would downshift while accelerating but for straight line cruising, set it and forget it. Maybe that's why I have 145,000 on my original clutch, and no noise whatsoever.