How to increase torque curve above 70mph

[ron570]

Is there a way to increase the power torque curve above 70mph in 6th gear? There is plenty of low & mid range power, but very little high end.

 

[paul_858]

What RPM are you at? You probably haven't hit peak torque @70mph. Perhaps you need more low end? Unlike low gears, you're hitting the wonderful coefficient of drag of the FJ which is about as good as a scion xb, albeit not as bad as the MB G500.

 

[ron570]

on hills above 70mph I loose power. Granted I could maintain speed, but its very weak and sluggish. At 85, and over 3000rpm, it almsot no power.

 

[ron570]

compared to my Ram Cummins, at same speed and above, I have all the power in the world to accelerate in 6th gear. Is there a way to re-tune the 4.0 to have a better high end curve?

 

[Zack1978]

compared to my Ram Cummins, at same speed and above, I have all the power in the world to accelerate in 6th gear. Is there a way to re-tune the 4.0 to have a better high end curve?

Apple orange?

 

[ron570]

Apple orange?

Not true, even my 2003 4runner which I sold had more power same conditions.

There has to be a way to re-program the rpm & touque curve.

 

[Isotel]

v6 vs 6 cyl Turbo Diesel
i belive thats what he means my apples to oranges..


in a 6 speed the 6th speed is only to be used while cruising down the highway.. Put her in 5th while pulling hills!


Yea a Cummins can do it in 6th because it puts out 500+ ftlb Tourqe at Supper Low RPM.. not true with a gas v6

 

[pulse98]

According to the rpm/gear/speed chart I found for the FJC, for the 5 speed auto tranny, you should be at:
3rd gear: 3850 rpm at 70 mph
4th gear: 2800 rpm at 70 mph
5th gear: 2000 rpm at 70 mph

Which gear do you want more power in? That will determine the rpm that you want to target for your torque improvements.

 

[ron570]

According to the rpm/gear/speed chart I found for the FJC, for the 5 speed auto tranny, you should be at:
3rd gear: 3850 rpm at 70 mph
4th gear: 2800 rpm at 70 mph
5th gear: 2000 rpm at 70 mph

Which gear do you want more power in? That will determine the rpm that you want to target for your torque improvements.

6th gear (M/T), not auto. On straight roads it has plenty of power. I'm refering to up steep inclines at over 75mph.

 

[Blues Dawg]

6th gear (M/T), not auto. On straight roads it has plenty of power. I'm refering to up steep inclines at over 75mph.

Downshift. If you improve high end, you will likely decrease low end, which you (probably) do not want. If you had an auto it would downshift for you.

 

[pulse98]

According to the rpm/gear/speed chart I found for the FJC, for the 6 speed auto tranny, you should be at:
3rd gear: 4300 rpm at 70 mph
4th gear: 3450 rpm at 70 mph
5th gear: 2900 rpm at 70 mph
6th gear: 2300 rpm at 70 mph, 2500 rpm at 75 mph

So that means you want more power/torque around 2300 to 2500 rpm. In terms of engine rpm, that is considered low rpm range.

This rpm range is difficult to improve without hurting your mid and high rpm power and tq.

If you look at the www.unichip.us (ecu's) website and look up the 2005 4.0L Tundra Engine gains, you will see next to no improvement (less than 2%) at your desired rpm range.

I recommend:
1. Free: Downshift for more power and torque
2. $3000+: forced induction

 

[ron570]

I recommend:
1. Free: Downshift for more power and torque
2. $3000+: forced induction

downshifting at that speed straighns the motor, & looses throttle responce until you regain. The idea of giving up some low & mide range rpm sound interesting. The problem with forced induction that I forsee, is the 2 cat's just off and on each side of the exhaust manifold. It's interesting that Toyota still hasn't produced a TRD super charger for the 4.0, yet they do for the 4.7V8.

 

[jgordon]

I'm not familiar with the torque curve of the FJ, but generally downshifting actually puts less strain on the engine (provided you downshift properly - double clutch etc). It puts the engine up into the sweet spot, so to speak. It's trying to accellerate up hills or with load at too low an rpm that generally will wreak havoc with an engine.

 

[powdr7]

I know for most cars/trucks you can get an ECU reflash. Not sur eif t would help in this case, but it ususally gains some performance when done on certain rides. There might also be a company you can contact and see if they can or already are making a program you can actually hook up to the computer and make some changes.

 

[k_os]

downshifting at that speed straighns the motor, & looses throttle responce until you regain. The idea of giving up some low & mide range rpm sound interesting. The problem with forced induction that I forsee, is the 2 cat's just off and on each side of the exhaust manifold. It's interesting that Toyota still hasn't produced a TRD super charger for the 4.0, yet they do for the 4.7V8.

4.0 Blower is coming out very soon. They're either finishing it up or it's in production.

 

[ron570]

4.0 Blower is coming out very soon. They're either finishing it up or it's in production.

Per TRD USA

Thank you for your interest in TRD, The 4.0 Supercharger is currently under development. Please check back in about 6 months.




Thank you,
Ronald Halasz