what rpm to really shift at?
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what rpm to really shift at?
yea guys i was wondering.. i was looking at the specs for my daewoo and it said 130hp @5400 rpms.. now does this mean for best hp and best time do i shift at 5400 rpms? or do i shift right before redline? i need to know this so when i can actually drive im taking down to thw drag strip to see what it can do
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BosnianLanos
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Shift at redline, right before the fuel cut if you can time it well. That way, when your RPM drop for the next gear, they'll be closer to the sweet spot for max TQ/HP, and you won't loose as much forward momentum.
If you're running down to the drag strip. Take some of the unnecessary crap out of your car. I.E : Interior panels, seats (leave drivers, lol) spare tire, jack, tool kit, random trash, etc. 100 lbs lighter means about 10 hp more, probably even more in our light low powered cars.
If you're running down to the drag strip. Take some of the unnecessary crap out of your car. I.E : Interior panels, seats (leave drivers, lol) spare tire, jack, tool kit, random trash, etc. 100 lbs lighter means about 10 hp more, probably even more in our light low powered cars.
well idk about taking off door panels and seats..lol... i can take out the spare tire and crap like that... and i've been experimenting with what rpm to launch at... so far i can do 3000-3500 rpms with a bit of tire spin but not much.. i will try to bring it up later on but thats what i got so far.. not trying to tare the engine apart lol
max hp at 5400 rpm is just that, and doesn't really mean all that much by itself.
To really know when the best time to shift is, you need a combination of a dyno and your gear ratios. What you essentially want to do is shift at an RPM such that the torque going to the wheels (which is why you need to know the gear ratio) is the same or increases from lower gear to the next gear. It's virtually impossible on a 4 cylinder low displacement engine (i.e. your torque will usually always drop), so the only thing you can do is minimize that drop, which basically means you need to shift at redline.
If you google optimal shift points or whatever, you can find more details in the matter.
To really know when the best time to shift is, you need a combination of a dyno and your gear ratios. What you essentially want to do is shift at an RPM such that the torque going to the wheels (which is why you need to know the gear ratio) is the same or increases from lower gear to the next gear. It's virtually impossible on a 4 cylinder low displacement engine (i.e. your torque will usually always drop), so the only thing you can do is minimize that drop, which basically means you need to shift at redline.
If you google optimal shift points or whatever, you can find more details in the matter.
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PrecisionBoost
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Or you could simply do a search with my name and find the information that I posted with regards to the Dyno diagram for the 2.0L, gear ratios, optimal shift points and calculated physical torque to wheels.
Sometimes the search engine doesn't pick up the exact thread..... but if you use me as an author you should be able to find it.
When you do.... post it here..... I'd look myself but I'm short on time.
I was going through optimal shift points with Kinkyllama to help him with lap times.
Basicly the power will go up as you come to 5400RPM and then drop off sharply.
The optimal shift point is where the power in the gear your in matches the power in the next gear ( technically this is more related to torque but I'm just trying to make this simple )
Due to the 2.0L design power drops like a rock as you approach redline..... so you need to shift just before redline to match power levels and get the optimal shift point.
Sometimes the search engine doesn't pick up the exact thread..... but if you use me as an author you should be able to find it.
When you do.... post it here..... I'd look myself but I'm short on time.
I was going through optimal shift points with Kinkyllama to help him with lap times.
Basicly the power will go up as you come to 5400RPM and then drop off sharply.
The optimal shift point is where the power in the gear your in matches the power in the next gear ( technically this is more related to torque but I'm just trying to make this simple )
Due to the 2.0L design power drops like a rock as you approach redline..... so you need to shift just before redline to match power levels and get the optimal shift point.
2010 BMW 335D
1994 Opel Calibra 4X4 turbo ( C20LET 2.0L Turbo )
2002 Daewoo lanos
1994 Opel Calibra 4X4 turbo ( C20LET 2.0L Turbo )
2002 Daewoo lanos
Here's the link
http://www.daewootech.com/forum/viewtop ... hift#19927
unfortunately the dyno isn't show... I thought it was better to go by torque and not hp but regardless it's good info.
http://www.daewootech.com/forum/viewtop ... hift#19927
unfortunately the dyno isn't show... I thought it was better to go by torque and not hp but regardless it's good info.
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PrecisionBoost
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- Joined: Thu Jun 19, 2003 5:59 am
- Location: Edmonton, Alberta, Canada
Well.... horsepower = ( RPM X torque) / 5252 ..... so they are directy related.
Think of it this way.... if your creating 100 lbft of torque at 1000 RPM and 100lbft at 6000 RPM.... which one requires more energy transfer.... the answer is 100lbft at 6000 RPM.
Or here's a simpler way.... if your lifting 10 lbs with your hand at a rate of 6 repetitions per minute you would be doing 10 times less work than if you were lifting the weight 60 times a minute.
Think of it from an energy transfer point of view.... your exerting more energy on the tires when you make similar torque levels at higher RPM.
Torque is defined as a force at a particular distance.... so if you apply one pound of force at two feet from a center point you are producing a torque of 2 ft-lb
When you start to include rotational velocity ( RPM ) then it converts that torque number into power..... which is the real world effort used to push the car forwards.
At the wheels the torque provided by the drive shaft converts that rotational energy into forward motion.
I don't know how to explain it in simpler terms.... because it's actually much more complex.... the torque is better described as angular accleration multiplied by the moment of inertia within the engine.
I have the U20SED 2.0L 16V dyno graphs in a couple of places.... here's a post showing the torque..... looks like I screwed up and loaded the torque curve twice..... so horsepower isn't shown here
http://www.daewootech.com/forum/viewtop ... yno+intake
If you were to choose torque for your shift point you'd be shifting way too low since the peak torque is around 3700RPM
So......... in closing..... you use the horsepower of the engine to then figure out the transfer of energy between the wheels and the road.
Think of it this way.... if your creating 100 lbft of torque at 1000 RPM and 100lbft at 6000 RPM.... which one requires more energy transfer.... the answer is 100lbft at 6000 RPM.
Or here's a simpler way.... if your lifting 10 lbs with your hand at a rate of 6 repetitions per minute you would be doing 10 times less work than if you were lifting the weight 60 times a minute.
Think of it from an energy transfer point of view.... your exerting more energy on the tires when you make similar torque levels at higher RPM.
Torque is defined as a force at a particular distance.... so if you apply one pound of force at two feet from a center point you are producing a torque of 2 ft-lb
When you start to include rotational velocity ( RPM ) then it converts that torque number into power..... which is the real world effort used to push the car forwards.
At the wheels the torque provided by the drive shaft converts that rotational energy into forward motion.
I don't know how to explain it in simpler terms.... because it's actually much more complex.... the torque is better described as angular accleration multiplied by the moment of inertia within the engine.
I have the U20SED 2.0L 16V dyno graphs in a couple of places.... here's a post showing the torque..... looks like I screwed up and loaded the torque curve twice..... so horsepower isn't shown here
http://www.daewootech.com/forum/viewtop ... yno+intake
If you were to choose torque for your shift point you'd be shifting way too low since the peak torque is around 3700RPM
So......... in closing..... you use the horsepower of the engine to then figure out the transfer of energy between the wheels and the road.
2010 BMW 335D
1994 Opel Calibra 4X4 turbo ( C20LET 2.0L Turbo )
2002 Daewoo lanos
1994 Opel Calibra 4X4 turbo ( C20LET 2.0L Turbo )
2002 Daewoo lanos