Shift Point for Gas Mileage????
04-06-2008, 05:07 PM
#42
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I'm guessing you have an auto, and maybe with a high stall? On another note, I've noticed people claiming high mpg tend to have upgraded heads. Any ideas on mpg increase for better heads and/or any other mods that might significantly improve mpg? Anybody notice significant mpg upgrade with a heads upgrade? Maybe it would pay for itself over the life of the car. Of course probably take the savings back on drivetrain wear though due to more hp. How about a mild or agressive cam upgrade, better or worse mpg?
04-06-2008, 05:10 PM
#43
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I do take short trips and i live in a real city city environment, stoplights and stop signs every 100ft, etc so the car doesn't warm up at times, but i should get at least 13mpg or something, but the mileage just kept going down. The worse part about it is the car doesn't get beat on or see high rpms since i live in a city so i can't imagine if i actually put my foot into it how low the mileage could go.
05-31-2008, 10:22 PM
#44
In a previous post, someone said that "lugging doesn't hurt the engine." I think the problem is that some are confusing lugging with bogging. I believe bogging is refers to driving at a low RPM when accelerating. It's bad for gas mileage at this point because you're not optimizing the full potential of the engine's ability to accelerate; thus, taking longer and spending more gas to reach the cruising speed. On the other hand, lugging is when the gear ratio is too out of proportion with the speed and load at which the car is under. In this case, the engine will vibrate and shake, and is unmistakable. This should be avoided at all times because it erodes the components inside the combustion chamber. The vibration itself may not be damaging, but it's what causes the vibration, which is explosion taking place under a reduced combustion volume due to the slower moving pistons. In other words, you're forcing more compression than the designated volume was designed to handle. And the worst part is that the amount of savings on gas may not even be substantial enough to be worth the whole trouble.
05-31-2008, 11:33 PM
#45
If you bought one of these cars for gas mileage you bought the wrong car. Maybe look at a Honda.
I have 4.11 gears in the rear. In town I usually cruise at about 40-50 depending on speed limit in 5th gear. On the highway I go between 60-70 in 6th gear depending on speed limits. I get better with this than I do in my SUV so Im not to concerned. I just drive it and have fun with it and dont worry about the mileage.
I have 4.11 gears in the rear. In town I usually cruise at about 40-50 depending on speed limit in 5th gear. On the highway I go between 60-70 in 6th gear depending on speed limits. I get better with this than I do in my SUV so Im not to concerned. I just drive it and have fun with it and dont worry about the mileage.
no to steal this away but i have 4.11s what would be a good cruising speed it seems if i run 65 i can pass everyone without touching the throttle i try to stay with the shift a 2k
06-01-2008, 05:32 AM
#46
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If this isn't an exaggeration, then I must insist that you avoid this. I'm not saying to not do this just because of some misunderstood precaution, but at this big of an RPM/gear ratio gap, you've gotta be hearing vibrations from the engine, in which case is lugging.
In a previous post, someone said that "lugging doesn't hurt the engine." I think the problem is that some are confusing lugging with bogging. I believe bogging is refers to driving at a low RPM when accelerating. It's bad for gas mileage at this point because you're not optimizing the full potential of the engine's ability to accelerate; thus, taking longer and spending more gas to reach the cruising speed. On the other hand, lugging is when the gear ratio is too out of proportion with the speed and load at which the car is under. In this case, the engine will vibrate and shake, and is unmistakable. This should be avoided at all times because it erodes the components inside the combustion chamber. The vibration itself may not be damaging, but it's what causes the vibration, which is explosion taking place under a reduced combustion volume due to the slower moving pistons. In other words, you're forcing more compression than the designated volume was designed to handle. And the worst part is that the amount of savings on gas may not even be substantial enough to be worth the whole trouble.
In a previous post, someone said that "lugging doesn't hurt the engine." I think the problem is that some are confusing lugging with bogging. I believe bogging is refers to driving at a low RPM when accelerating. It's bad for gas mileage at this point because you're not optimizing the full potential of the engine's ability to accelerate; thus, taking longer and spending more gas to reach the cruising speed. On the other hand, lugging is when the gear ratio is too out of proportion with the speed and load at which the car is under. In this case, the engine will vibrate and shake, and is unmistakable. This should be avoided at all times because it erodes the components inside the combustion chamber. The vibration itself may not be damaging, but it's what causes the vibration, which is explosion taking place under a reduced combustion volume due to the slower moving pistons. In other words, you're forcing more compression than the designated volume was designed to handle. And the worst part is that the amount of savings on gas may not even be substantial enough to be worth the whole trouble.
I fully agree with you, Crimsonnaire. Lugging hammers the main bearings especially. Shooter_Jay, no disrepect intended, but I'm willing to bet you'll end up spinning a bearing and be scratching your head wondering why, since you thought you were being "easy" on the engine.
Just as you can run an engine at too high of rpm's, you can also run them at too low. Idle speed is just what it says, it's for idling the motor, not driving it under load. As always, everyone can drive their car the way they see fit, as for me, I'll make sure mine is in the proper rpm operating range. When I got my TA, one of the first things I did was look up the price of replacement parts. Ouch! Motors are kind of expensive!
Ok, that being said, I found out for optimum fuel economy for my particular TA:
I accelerate moderately, and don't skip gears. I shift at 2500 rpms. I keep it in the appropriate gear for the speed the car is going. Cruising thru town, I stay at 1500 to 1800 rpm. I stay in gear during coasting or deccelerating.
This method gets me 27+ mpg on the highway (haven't tried the interstate yet), 18 mpg in town. Cruising around with the wife on the weekend, town and highway, I'll still hit 20+ mpg. That's with a little playing around/showing off thrown in there.
Last edited by johnnybravo; 06-01-2008 at 05:36 AM. Reason: spelling
06-01-2008, 08:18 AM
#47
Not good to lug the engine, I don't let mine go below 1500rpm if I want to maintain speed or accelerate. Only in highway situations on flat levels or downhill will I let it go below 1500. I'm cammed now, so down low is even worse than before, but still manageable.
Outside the powerband, you will put a LOT of strain on the engine's internal parts. Fuel economy would be terrible due to inefficiency of the cam, air velocity would be too slow, and the load being high.
there's no way you can lug around in 6th with a 3.42 gear at 600 rpm. The stock cam can barely lug the car around at idle let alone in 6th with such a load and only 600rpm. That's just asking for a bearing to go.
To get the most of your mileage, add a extra bit of air to the rears and fronts. 32PSI won't harm city handling much and give a bit more mileage from the added tire height and reduced friction. Stay OUT of the power band. Stock and mild cams (up to 230 duration) will have their torque bands start around 3000rpm. Below that all the way to the "lugging" rpm is still usable torque. I would say from 1500-2500 is the ideal range for mileage and all you really need for city/highway driving. If you've ever seen how much fuel gets dumped in after 2500rpm in HP Tuner's you'll understand why I mention to keep away from blipping past that rpm. Skip gears. 1-3-5, use a high gear when the road is flat or you are just maintaining speed. 6th isn't recommended the closer you get to idle, but at 1500 with 3.42 gears, you're already doing roughly 55 mph.
Outside the powerband, you will put a LOT of strain on the engine's internal parts. Fuel economy would be terrible due to inefficiency of the cam, air velocity would be too slow, and the load being high.
there's no way you can lug around in 6th with a 3.42 gear at 600 rpm. The stock cam can barely lug the car around at idle let alone in 6th with such a load and only 600rpm. That's just asking for a bearing to go.
To get the most of your mileage, add a extra bit of air to the rears and fronts. 32PSI won't harm city handling much and give a bit more mileage from the added tire height and reduced friction. Stay OUT of the power band. Stock and mild cams (up to 230 duration) will have their torque bands start around 3000rpm. Below that all the way to the "lugging" rpm is still usable torque. I would say from 1500-2500 is the ideal range for mileage and all you really need for city/highway driving. If you've ever seen how much fuel gets dumped in after 2500rpm in HP Tuner's you'll understand why I mention to keep away from blipping past that rpm. Skip gears. 1-3-5, use a high gear when the road is flat or you are just maintaining speed. 6th isn't recommended the closer you get to idle, but at 1500 with 3.42 gears, you're already doing roughly 55 mph.
Last edited by SladeX; 06-01-2008 at 08:24 AM.
06-02-2008, 02:13 AM
#48
I've got a 99 Z28 with 132k on it and i get low 20's in the city, i usually shift at around 1600 or so and hit 1-2-4-5 or 6 depending on speed. I'll do all the gears on the highway. I've gotten 29+ on the highway running about 72 mph multiple times.
jk
06-02-2008, 02:50 AM
#50
This reminds me. When the Top Gear driver took off in 5th with the Z06, he essentially lugged up until he got past 30mph. This is unless he was slipping the clutch the whole time.
