Max Speed in Each Gear for 5 speed man. Yaris with no tach??

[09TRD]

Originally Posted by justjesus

You wont achieve max accel from redlining these motors.

I'd love to see you prove that empirically.

Peak HP occurs at 6,000 RPM. Redline occurs at 6,500 RPM.

You'll want to shift at or near red-line for peak performance, even though engine horsepower falls off after 6,000 RPM. Why? Because doing so will put the engine closer to its horsepower peak in the next gear (immediately after the up-shift) while ensuring peak obtainable drive-wheel torque at all vehicle speeds.

Precise shift points would be determined in the fashion discussed in this link:

http://www.allpar.com/eek/hp-vs-torque.html

Generally speaking, shifting at red-line is a good "rule of thumb" for maximizing acceleration. That tends to be especially true for higher revving, small displacement DOHC engines (e.g. Yaris engine).

I've been told that the Yaris's owner's manual recommends the following shift points for maximum acceleration:

1 to 2: 31 MPH

2 to 3: 59 MPH

3 to 4: 86 MPH

Assuming that's true, I suspect that each of those shift points corresponds to engine red-line in the Yaris models equipped with tachs.

[09TRD]

Originally Posted by PK198105

if you like i could scan the page relating to this from the actual manual. let me know.

as for max power best way would be to do a dyno run and see the RPMs at which power peaks, Garm i believe has acces to a dyno

Please scan that page of the manual if you don't mind.


Peak power (106 HP @ the flywheel) occurs at 6,000 RPM - just like Toyota says it does. Peak power will be less when measured on a chassis dyno, though the RPM at which it occurs will be identical.

That says little about determining shift points for optimal acceleration, though, as explained here:

http://www.allpar.com/eek/hp-vs-torque.html

Generally speaking, one wants to shift at engine red-line (ABOVE PEAK HP RPM) in order to maximize acceleration. That's particularly true with "peaky," small displacement, DOHC engines (e.g. Yaris 1.5 liter).

[ROCKLAND TOYOTA]

Originally Posted by 09TRD

Peak power (106 HP @ the flywheel) occurs at 6,000 RPM - just like Toyota says it does. That says little about determining shift points for optimal acceleration, though, as explained here:

http://www.allpar.com/eek/hp-vs-torque.html

Generally speaking, one wants to shift at engine red-line (ABOVE PEAK HP RPM) in order to maximize acceleration. That's particularly true with "peaky," small displacement, DOHC engines (e.g. Yaris 1.5 liter).

i have no tach and hence rely on engine sound so i can attest to to the claim about peak power. i say this cause when i shift at redline i notice a slight bog in power but when i shift JUST before im spinning 18inch tires in second gear and third doesn't have that lag you get around 60 mph........

[09TRD]

Originally Posted by ROCKLAND TOYOTA

i have no tach and hence rely on engine sound so i can attest to to the claim about peak power. i say this cause when i shift at redline i notice a slight bog in power but when i shift JUST before im spinning 18inch tires in second gear and third doesn't have that lag you get around 60 mph........

How does the rolling diameter of 18" set-up compare with the OEM set-up?

If it's off, indicated speed will differ from actual speed.

[justjesus]

Originally Posted by 09TRD

I'd love to see you prove that empirically.

Peak HP occurs at 6,000 RPM. Redline occurs at 6,500 RPM.

You'll want to shift at or near red-line for peak performance, even though engine horsepower falls off after 6,000 RPM. Why? Because doing so will put the engine closer to its horsepower peak in the next gear (immediately after the up-shift) while ensuring peak obtainable drive-wheel torque at all vehicle speeds.

Precise shift points would be determined in the fashion discussed in this link:

http://www.allpar.com/eek/hp-vs-torque.html

Generally speaking, shifting at red-line is a good "rule of thumb" for maximizing acceleration. That tends to be especially true for higher revving, small displacement DOHC engines (e.g. Yaris engine).

I've been told that the Yaris's owner's manual recommends the following shift points for maximum acceleration:

1 to 2: 31 MPH
2 to 3: 59 MPH
3 to 4: 86 MPH

.

And I'd love to prove it as well. If i had easier access to a track, I'd do it. Would you settle for a measured distance (1/4 mile) vs time (stopwatch)?

It's nice to have peak HP so close to redline, as it makes your point that much easier to work with. And, for most people (as well as the common point of view), shifting at redline would be best.