ARG wish LS400 had stick!
12-30-02, 07:18 PM
#1
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ARG wish LS400 had stick!
After studying some sites on recommended shift points I looked at my dyno restuls from a while back and was trying to figure out optimal shift points for my car.
Then I realized..the LS400 transmission is super slow for gate shifting (1990-1994 - 1995 & up got a faster tranny ECU) and wouldn't to much for trying to race. The problem is the cars peak power points for torque and HP. They are at totally different RPMs. If you look in my graph peak torque occurs at around 4000RPM, while peak Hp is around 5000RPM.
So let's say the car WAS manual, would shifting at 5K RPM (for peak HP) be the best for street racing, or would trying to reach maximum torque at 4K RPM be optimal. Or would the middle point be best-4500?
Since gate shifting is slow, just flooring it and letting the car automatically do its thing, the car shifts at an insane 6K RPM. This is past peak power for torque and HP.
So it looks like a torque convertor set to stall at around 2200-2500 would be good. I wouldn'tgo for 2800rpm because the age and mileage of the tranny. 150K original motor and trany (recently fully'running' flushed w/ type IV.)
wish LS had stick!!
Then I realized..the LS400 transmission is super slow for gate shifting (1990-1994 - 1995 & up got a faster tranny ECU) and wouldn't to much for trying to race. The problem is the cars peak power points for torque and HP. They are at totally different RPMs. If you look in my graph peak torque occurs at around 4000RPM, while peak Hp is around 5000RPM.
So let's say the car WAS manual, would shifting at 5K RPM (for peak HP) be the best for street racing, or would trying to reach maximum torque at 4K RPM be optimal. Or would the middle point be best-4500?
Since gate shifting is slow, just flooring it and letting the car automatically do its thing, the car shifts at an insane 6K RPM. This is past peak power for torque and HP.
So it looks like a torque convertor set to stall at around 2200-2500 would be good. I wouldn'tgo for 2800rpm because the age and mileage of the tranny. 150K original motor and trany (recently fully'running' flushed w/ type IV.)
wish LS had stick!!
Last edited by Lvangundy; 12-30-02 at 07:19 PM.
12-31-02, 04:37 PM
#3
Super Moderator
on a stock transmission, it is USUALLY optimal to shift right before you hit redline. although it seems like you are ahead (behind?) of the power curve at this point, as long as you keep your rpms up, your car is already set in a motion between the engine, and tranny; it is quicker to just step on it and keep going past your torque and hp peak-your car can keep up with this "overload" quite fine. once you are in the next higher gear, your rpm will drop (duh) a few, right? this new initial drop-point in the rpm *should* ideally be a balanced point between your torque and hp peak ranges, so in your case, around 4500?? if you upshift and magically end up at 4500rpm then you are cool. if at this point, you are below 4000, then you are definitely behind the potential power curve, taking into consideration the "loss" you get from going over your hp/tq peaks, and from the drop in rpm from upshifting.
this is what Japanese textbooks say, and this is how i learned it, both from the book, in the chapter on optimal shifting, and from a toyota techie in japan.
just get your timer out and do some runs and see what works for your car.
if you change your exhaust/mufflers like the folks over in good ol japan, it'll feel really good going to redline!!!!!!
this is what Japanese textbooks say, and this is how i learned it, both from the book, in the chapter on optimal shifting, and from a toyota techie in japan.
just get your timer out and do some runs and see what works for your car.
if you change your exhaust/mufflers like the folks over in good ol japan, it'll feel really good going to redline!!!!!!
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