1.4T Hill Climbing
- Thread starter yamura
- Start date
RichieRocket
New member
yamura, I don't have my 1.4T yet, hopefully this week.
The thing that stikes me about your question is that "it depends!".
What grade of hill? 1% or 6%?
Steady speed or accelerating?
What speed? 45 or 85 mph?
Right now I have a '98 Civic 1.6L, it has
Horsepower: 106 hp @ 6200 rpm
Torque: 103 ft-lbs. @ 4600 rpm
At 70 mph in 5th gear, it turns 3000 rpm (I'm guessing 40 hp max @ 3000rpm)
I routinely go up 3-4% grades on the highway, that's steep enough that they have to add a slow lane for trucks. The civic has no problem in 5th.
The 1.4T has a 6-spd manual, 2100 rpm at 70 mph,at that engine speed, because of the good low-end torque, it produces >60 hp max. Of course you don't want to be lugging uphill with your foot on the floor, but even at, say 3/4 throttle, 40 hp, that's plenty to maintain 75 mph (steady speed) up a 3% hill.
The proof will be driving the thing!
The thing that stikes me about your question is that "it depends!".
What grade of hill? 1% or 6%?
Steady speed or accelerating?
What speed? 45 or 85 mph?
Right now I have a '98 Civic 1.6L, it has
Horsepower: 106 hp @ 6200 rpm
Torque: 103 ft-lbs. @ 4600 rpm
At 70 mph in 5th gear, it turns 3000 rpm (I'm guessing 40 hp max @ 3000rpm)
I routinely go up 3-4% grades on the highway, that's steep enough that they have to add a slow lane for trucks. The civic has no problem in 5th.
The 1.4T has a 6-spd manual, 2100 rpm at 70 mph,at that engine speed, because of the good low-end torque, it produces >60 hp max. Of course you don't want to be lugging uphill with your foot on the floor, but even at, say 3/4 throttle, 40 hp, that's plenty to maintain 75 mph (steady speed) up a 3% hill.
The proof will be driving the thing!
Danny5
Its over 39000!
My wife climbs 4000ft everyday on the way to work. Our interstate has a 6% uphill, with no slow lane for tractor trucks, that climbs almost 2000ft.
The speedlimit is 65, but just before the hill, and right after, its 75.
6th gear is worthless for climbing this hill! Maybe its because we start at 2800ft. But she tried climbing in 6th, and dropped to about 45mph. She is learning that a shift to 4th, or possible even 3rd may be required!
YMMV
The speedlimit is 65, but just before the hill, and right after, its 75.
6th gear is worthless for climbing this hill! Maybe its because we start at 2800ft. But she tried climbing in 6th, and dropped to about 45mph. She is learning that a shift to 4th, or possible even 3rd may be required!
YMMV
RichieRocket
New member
yamura, of course I have not actually driven one yet...come on Chevy, deliver my car already!!!
I put together a engine rpm vs. road speed chart on another thread:
http://www.sonicownersforum.com/forum/t640/
1500 rpm in 6th is only 50 mph...
Others have commented on the hill pulling.
RichieRocket
New member
Here's a thought experiment on the hill climb stuff.
I wish I had real data on aero drag...anyone in the auto industry, can you tell us what the drag coeffcient/frontal area of the Sonic are? Either that or what is the aero drag force at a certain speed?
Anyway, the hill I used as an example (you guys out west are gonna laugh!) is CT state Rte 2 thru Glastonbury, it climbs 200 ft in 4200 ft distance....OK, stop laughing!!! The highest point in our entire state is only 2300 ft! That is a grade of 4.7%, in CT that requires a slow truck climbing lane. We must have wimpy trucks...
For a 3000 lb empty car plus driver to maintain 75 mph up a 4.7% grade (2.7 degrees), it takes 28.5 hp at-the-wheel(atw).
Let's assume the Sonic uses 25 hp (atw) to overcome the aero drag at 75 mph.
So the total hp required is 53.5 hp (atw). At 75 mph, the 1.4T is turning 2250 rpm. Looking at Trifecta's dyno chart for the Cruze (gearing is a little different, but close enough) for the STOCK 1.4T.
http://www.trifectaperformance.com/DynoSheets/2011ChevyCruzeLUJDyno.jpg
Ahhh crap, the trifecta dyno run starts at 2400 and they are not at full throttle until 2700 rpm
Extrapolating the STOCK hp line down to 2250 rpm, there should be ~60 hp available (at full throttle, of course)... So the car "should" be able to make it up the hill, BUT full throttle at 2250 rpm for ~45 seconds long kinda makes me un-easy.
That's for an empty car plus driver, if you add a couple passengers and a couple suit cases, it'll be even worse!
Comments?
I wish I had real data on aero drag...anyone in the auto industry, can you tell us what the drag coeffcient/frontal area of the Sonic are? Either that or what is the aero drag force at a certain speed?
Anyway, the hill I used as an example (you guys out west are gonna laugh!) is CT state Rte 2 thru Glastonbury, it climbs 200 ft in 4200 ft distance....OK, stop laughing!!! The highest point in our entire state is only 2300 ft! That is a grade of 4.7%, in CT that requires a slow truck climbing lane. We must have wimpy trucks...
For a 3000 lb empty car plus driver to maintain 75 mph up a 4.7% grade (2.7 degrees), it takes 28.5 hp at-the-wheel(atw).
Let's assume the Sonic uses 25 hp (atw) to overcome the aero drag at 75 mph.
So the total hp required is 53.5 hp (atw). At 75 mph, the 1.4T is turning 2250 rpm. Looking at Trifecta's dyno chart for the Cruze (gearing is a little different, but close enough) for the STOCK 1.4T.
http://www.trifectaperformance.com/DynoSheets/2011ChevyCruzeLUJDyno.jpg
Ahhh crap, the trifecta dyno run starts at 2400 and they are not at full throttle until 2700 rpm
Extrapolating the STOCK hp line down to 2250 rpm, there should be ~60 hp available (at full throttle, of course)... So the car "should" be able to make it up the hill, BUT full throttle at 2250 rpm for ~45 seconds long kinda makes me un-easy.
That's for an empty car plus driver, if you add a couple passengers and a couple suit cases, it'll be even worse!
Comments?
Gimpster
New member
Good work.
I can't speak for how this particular PCM works, but on my previous GM's they had a COT (Catalyst Over Temperature) table. Essentially its a value (no temp sender involved) determined by a slew of engine variables designed to protect the catalysts from melting into blobs. When it reaches the temperature threshold the PCM's response is basically to dump fuel in.
So where I'm going with this is, and I can't prove without datalogging, I doubt we could keep the car at WOT going up a hill for 45 seconds without hitting the COT. I sure as heck couldn't on the Cobalt SS's I had. Once you hit COT the power starts to hit the dirt.
Also to your point charge temps will get pretty darn high too.
So in closing.... shift gears
I can't speak for how this particular PCM works, but on my previous GM's they had a COT (Catalyst Over Temperature) table. Essentially its a value (no temp sender involved) determined by a slew of engine variables designed to protect the catalysts from melting into blobs. When it reaches the temperature threshold the PCM's response is basically to dump fuel in.
So where I'm going with this is, and I can't prove without datalogging, I doubt we could keep the car at WOT going up a hill for 45 seconds without hitting the COT. I sure as heck couldn't on the Cobalt SS's I had. Once you hit COT the power starts to hit the dirt.
Also to your point charge temps will get pretty darn high too.
So in closing.... shift gears
RichieRocket
New member
Driving the car will show how it behaves...but they won't ship my car, booo-hooo
Today, work is really slow, more than half the people are out before the holiday. So I spent a few minutes working out the numbers...
At 75 mph,
6th gear 2250 rpm ~60hp available max at-the-wheel
5th gear 2700 rpm ~70hp max
4th gear 3550 rpm ~90hp max
Wow, I gonna be downshifting...maybe I should have waited for the automatic
Today, work is really slow, more than half the people are out before the holiday. So I spent a few minutes working out the numbers...
At 75 mph,
6th gear 2250 rpm ~60hp available max at-the-wheel
5th gear 2700 rpm ~70hp max
4th gear 3550 rpm ~90hp max
Wow, I gonna be downshifting...maybe I should have waited for the automatic
Sonic Boomer
New member
Hmmm, I live in moderately hilly country and driving ~50MPH on secondary roads I suspect that I will probably end up living in 4th gear. I can't see shifting back and forth every 0.5 miles (which is my guess at the average length of a hill).
Wonder how bad that will screw my MPG...
Wonder how bad that will screw my MPG...
Gimpster
New member
I just finished driving to San Franciso from Kansas via I80, so obviously I went through some pretty big climbs. I did have to put it into 4th a couple times, in particular on the climb around Echo, UT. Never did I have to make a shift to 3rd. Otherwise I REALLY can't complain, it wasn't any worse than having to shift from 5th to 4th on my Mustang when I make this trip. When it got bad I'd just skip from 6 to 4.
I left the car in 6th on that climb just to see what it would do. I had cruise set to 75 and it slowly dropped speed, but I could tell the cruise had it WOT ... or close to it. After the car dropped below 65 the cruise gave up and turned off hehe.
On another climb I left it in 5th and floored it for at LEAST a minute, and I never felt it chop power or hear any detonation.
I left the car in 6th on that climb just to see what it would do. I had cruise set to 75 and it slowly dropped speed, but I could tell the cruise had it WOT ... or close to it. After the car dropped below 65 the cruise gave up and turned off hehe.
On another climb I left it in 5th and floored it for at LEAST a minute, and I never felt it chop power or hear any detonation.
RockTheShazbot
New member
RichieRocket
New member
Hmmm, I live in moderately hilly country and driving ~50MPH on secondary roads I suspect that I will probably end up living in 4th gear. I can't see shifting back and forth every 0.5 miles (which is my guess at the average length of a hill).
Wonder how bad that will screw my MPG...
To the contrary, Sonic Boomer, 4th gear at 50 mph is 2300 rpm....that's the mpg sweet spot! At 50 mph, don't even think about 5th or 6th in hills...
Danny5
Its over 39000!
I don't think that's the MPG sweet spot. My car wants me to be in 6th cruising at 50mph. Thats when you start to see phenomenal gas mileage. Like close to 50mpg.
By 2300rpm, you should be in full boost, which definitely wouldn't contribute to gas mileage...
Sonic Boomer
New member
I forgot, but with the torque of the turbo at 148 ft-lb starting at 2500RPM will make a big difference. Acceleration up hill may not be too strong in the higher gears, but I would expect it to hold speed up a reasonable grade.
RichieRocket
New member
I don't think that's the MPG sweet spot. My car wants me to be in 6th cruising at 50mph. Thats when you start to see phenomenal gas mileage. Like close to 50mpg.
By 2300rpm, you should be in full boost, which definitely wouldn't contribute to gas mileage...
Danny5, I don't think you understood my posting. I agree that on flat road, you want the rpms as low as possible...BUT Sonic Boomer was not talking about a flat road, he was driving in hilly terrain. 6th gear at 50 mph is 1500 rpm!!!!
50 mph + 6th gear + 1500 rpm + steep hill =
I don't think the 1.4T would do well pulling up a steep hill at those conditions!!! When I used the phrase 'sweet spot', I meant only for that particular condition, steep hill and 50 mph.
Also, Chevy claims the 1.4T has 148 ft-lbs starting at 1900 rpms, not 2300 as you stated.