ICE horsepower and torque curves
#13
04-29-2006, 03:26 PM
Re: ICE horsepower and torque curves
Hi All –
Most of you have been keeping up with Gary’s post on Hypermiling and his point of using 1,800 and/or 2,400 RPM for acceleration because of the peak in the torque curve at those points.
I came across this article in ACURAZINE and it gives a pretty good explanation between HP and Torque. Kind of long and detailed – and since it talks a lot about gearing it doesn’t exactly follow CVT protocol.
Happy reading
Phillip
Most of you have been keeping up with Gary’s post on Hypermiling and his point of using 1,800 and/or 2,400 RPM for acceleration because of the peak in the torque curve at those points.
Originally Posted by GaryG
The torque curve starts to slow at about 1800 rpm's to about 2200 rpm's, picks up at 2200 rpm's to 2450 rpm's. After that, it slows to 3,000 rpm's where it is flat to 3,500 rpm's. It shoots up from 3,500 rpm's to 4,000 rpm's and starts dropping slowly to 6,000. All down hill after that. This is based on a graph I have comparing Engine Torque (Nm) to Engine Speed (RPM) in a torque comparison of the Otto Cycle and the Atkinson Cycle we have.
For acceleration in the FEH, there is not much torque at low RPM's period. Watch your Assist/Charge needle start to move to Assist and your at the Max load of the ICE. This can be far below 2,000 rpm's depending on your throttle angle (requested torque). Ford designed the electric motors to begin assistance at Max load on the ICE. If you need assist, its there, but thats not where good MPG can be found IMHO.
If I need to get out fast, there is not much gained after 2,450 from the ICE during acceleration for FE. My goal is to hold at 1,800 or fake shift at 2,000 rpm's during acceleration while keeping the load under 90% on the scangauge. The slower the acceleration, the better for Max FE. If I can, I accelerate between 70-80% Load. If you are using Assist, you are wasting mpg IMHO.
GaryG
For acceleration in the FEH, there is not much torque at low RPM's period. Watch your Assist/Charge needle start to move to Assist and your at the Max load of the ICE. This can be far below 2,000 rpm's depending on your throttle angle (requested torque). Ford designed the electric motors to begin assistance at Max load on the ICE. If you need assist, its there, but thats not where good MPG can be found IMHO.
If I need to get out fast, there is not much gained after 2,450 from the ICE during acceleration for FE. My goal is to hold at 1,800 or fake shift at 2,000 rpm's during acceleration while keeping the load under 90% on the scangauge. The slower the acceleration, the better for Max FE. If I can, I accelerate between 70-80% Load. If you are using Assist, you are wasting mpg IMHO.
GaryG
Happy reading
Phillip
Last edited by VietVet'67; 04-29-2006 at 03:43 PM.
#14
05-04-2006, 02:34 PM
Re: ICE horsepower and torque curves
Hey Phillip
Your getting it all together and your mileage is showing it!
As far as acceleration and torque, you can feel the RPM's and hear the engine run away starting at 1900rpm's till it slows down at 2300rpm's. It feels like a clutch slipping in a manual transmission. This is why at 65-70mph is an inefficent speed. If the FEH is cruising at this speed, the RPM's are all over the place tring to hold 2100rpm's at 65-70mph. Now if you get a good draft at 70mph, the rpm's will drop too and hold at 1800rpm's very well. On the scangauge, the instant mpg starts playing with 50mpg @ 70mph with a draft. Xcel was going crazy in my FEH when he started hitting 70mpg (instant) at 60-65mph while drafting.
Everyday, I watch where my rpm's are to stay in the torque sweet spots. If I have someone on my tail while accelerating, I jump to 2450rpm's and hold. That's all I will give them and most of the time, that is when I'm going up a bridge in traffic.
GaryG
Your getting it all together and your mileage is showing it!
As far as acceleration and torque, you can feel the RPM's and hear the engine run away starting at 1900rpm's till it slows down at 2300rpm's. It feels like a clutch slipping in a manual transmission. This is why at 65-70mph is an inefficent speed. If the FEH is cruising at this speed, the RPM's are all over the place tring to hold 2100rpm's at 65-70mph. Now if you get a good draft at 70mph, the rpm's will drop too and hold at 1800rpm's very well. On the scangauge, the instant mpg starts playing with 50mpg @ 70mph with a draft. Xcel was going crazy in my FEH when he started hitting 70mpg (instant) at 60-65mph while drafting.
Everyday, I watch where my rpm's are to stay in the torque sweet spots. If I have someone on my tail while accelerating, I jump to 2450rpm's and hold. That's all I will give them and most of the time, that is when I'm going up a bridge in traffic.
GaryG
#15
06-01-2006, 11:59 AM
Re: ICE horsepower and torque curves
Hey fellow FEH owners,
You seem to know a lot regarding RPMs and hp. I'm still a novice, but learning everyday through your very informative responses.
I'd like to get your opinion on what the minimum rpm value you find the electric engine takes over after being in gas engine mode. In my 7 months experience driving my FEH'06 4WD, the transfer from gas to electric engine, while cruising under 30mph, ONLY occurs when the rpms are under 1,000 rpms. Never above 1,000 rpms. As a result, I either have to apply the breaks to lower the rpms or accelerate very very slowly to keep the rpms under 1,000 from a starting position (i.e. traffic light or stop sign) to reach the maximum electric cruising speed of speed of 30mph (although I have been able at tims to reach almost 35mph in electric mode).
Is this standard or normal for an FEH???
You seem to know a lot regarding RPMs and hp. I'm still a novice, but learning everyday through your very informative responses.
I'd like to get your opinion on what the minimum rpm value you find the electric engine takes over after being in gas engine mode. In my 7 months experience driving my FEH'06 4WD, the transfer from gas to electric engine, while cruising under 30mph, ONLY occurs when the rpms are under 1,000 rpms. Never above 1,000 rpms. As a result, I either have to apply the breaks to lower the rpms or accelerate very very slowly to keep the rpms under 1,000 from a starting position (i.e. traffic light or stop sign) to reach the maximum electric cruising speed of speed of 30mph (although I have been able at tims to reach almost 35mph in electric mode).
Is this standard or normal for an FEH???
#16
06-01-2006, 05:09 PM
Re: ICE horsepower and torque curves
Hi Haskellf
Most of us use the term electric motor because electric engine is confusing to the gas engine which we refer to as ICE. Anyway, it's hard to understand, myself included, all the terms that get bounced around without adding new ones.
The only time the RPM's go under 1,000 is when the ICE is shutting off. A good signal the ICE is going to shut down for EV mode is a RPM between 1000-1100rpm's. Sometimes, there is a slight bump to 1100rpm's just before the tach drops to zero for EV mode. Seeing the little bump means the computer is made up it's program (mind) to go EV. I use this signal to shift to neutral ("N") to stop any further regen for a smooth transfer into coasting.
It sounds like you need to read some of the terms Pravus Prime has put together in the first thread in the FEH section. It's much easier to go EV with "L" and tapping the brakes than what your doing. As far as reaching 30mph accelerating in EV, your doing great. Reaching 35mph in EV with the AWD is excellent. I suggest keeping the tires at the max sidewall pressure of 44psi also.
GaryG
Most of us use the term electric motor because electric engine is confusing to the gas engine which we refer to as ICE. Anyway, it's hard to understand, myself included, all the terms that get bounced around without adding new ones.
The only time the RPM's go under 1,000 is when the ICE is shutting off. A good signal the ICE is going to shut down for EV mode is a RPM between 1000-1100rpm's. Sometimes, there is a slight bump to 1100rpm's just before the tach drops to zero for EV mode. Seeing the little bump means the computer is made up it's program (mind) to go EV. I use this signal to shift to neutral ("N") to stop any further regen for a smooth transfer into coasting.
It sounds like you need to read some of the terms Pravus Prime has put together in the first thread in the FEH section. It's much easier to go EV with "L" and tapping the brakes than what your doing. As far as reaching 30mph accelerating in EV, your doing great. Reaching 35mph in EV with the AWD is excellent. I suggest keeping the tires at the max sidewall pressure of 44psi also.
GaryG
#17
06-02-2006, 11:01 AM
Re: ICE horsepower and torque curves
Thanks Gary,
I asked the same question to the service dept yesterday during my routine maintenance and they just kept replying that there are no RPMs while in EV mode. I tried to explain to them that I was talking about the ICE, but they kept stressing that in EV mode there are no RPMs. I asked to talk to a technician and they flat out refused. I let the question drop and accepted that the service rep didn't know anything about a FEH.
Thank you for the info and I feel much better knowing that there was an answer to my question.
I asked the same question to the service dept yesterday during my routine maintenance and they just kept replying that there are no RPMs while in EV mode. I tried to explain to them that I was talking about the ICE, but they kept stressing that in EV mode there are no RPMs. I asked to talk to a technician and they flat out refused. I let the question drop and accepted that the service rep didn't know anything about a FEH.
Thank you for the info and I feel much better knowing that there was an answer to my question.
#18
06-02-2006, 11:13 AM
Re: ICE horsepower and torque curves
Just to be really clear, if you are operating in EV mode, the ICE is off, and the tach will show zero rpms. If the tach comes up off the bottom of the dial, you have started the ICE.
It IS possible to start from rest and get to 35-38 mph without ever having the tach move off the bottom of the dial while in EV mode. It ISN'T easy...
When coasting down from above 40 there seem to be two accepted methods to get the ICE to shut down. One is to bump the brake pedal twice, with more space between the bumps than a double click on a mouse. The other is to pull the gear lever to L. I am begining to think that sticking the car in neutral for a bit before going to Low while coasting down through 40 mph will cause the ICE to idle down and make the transition to EV happen at a higher speed than just pulling it into low at 43 or so.
Haven't had enough repititions to be certain.
Lots of babble there, hope some is helpful.
MM
It IS possible to start from rest and get to 35-38 mph without ever having the tach move off the bottom of the dial while in EV mode. It ISN'T easy...
When coasting down from above 40 there seem to be two accepted methods to get the ICE to shut down. One is to bump the brake pedal twice, with more space between the bumps than a double click on a mouse. The other is to pull the gear lever to L. I am begining to think that sticking the car in neutral for a bit before going to Low while coasting down through 40 mph will cause the ICE to idle down and make the transition to EV happen at a higher speed than just pulling it into low at 43 or so.
Haven't had enough repititions to be certain.
Lots of babble there, hope some is helpful.
MM
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