Best shift point: Torque Versus Horsepower in a GT350

[GT30fan]

This had to have been discussed before, and if it had, I am sorry, but I did not find it

If you are trying to max out the GT350 in the stock factory set up (like a 1/4 mile drag race, or even gunning it from a rolling stop) it seems as you rev higher and higher, the torque starts to drop off

What is going to move the car fastest? Despite the car CAN rev to 8250 rpm, is that even a good idea? Especially if the torque is dropping, not rising?

Also, the dash board shift light.... does it change depending on mode? Will it tell you the best time to shift for speed, and if so, is that sometimes before the 8250?

And while this newby is dumping the stupid questions on you guys, when you set the exhaust mode to the louder setting, is it just that....louder...or is there more flow so is the power boosted?

thx

Sponsored

 

[EFI]

What is going to move the car fastest? Despite the car CAN rev to 8250 rpm, is that even a good idea? Especially if the torque is dropping, not rising?

HP. If the shiftpoint would be shortly after peak torque, everyone would be shifting at 5500-6000rpm. Those are shift points for your granddads 1960s pushrod engine powered Cadillac, not 2019 flat plane crank pinnacles of engineering.

Ford chose that shift point based on power curve, it's not some random number. And they certainly wouldn't choose that shift point if it was well past optimum eg. car is slower.

General consensus is that you should be shifting a couple hundred RPM past peak HP. The stock power curve peaks at around 7700 and stays relatively flat after that (doesn't drop like a rock) so there's no issue shifting at the stock rev limiter.

 

[GT30fan]

Does the heads up shift light "know" whats best for speed, or is it thinking MPG, etc as well?

And I assume when the car is put in loud mode, it must by-pass some baffles, therefore more power?

 

[gregsdart]

I would start by trying shifts at about 7900 and see how it goes. Tach lag, and time to complete the shift can raise the shift rpm some so without a data logger it is tough to tell what the true rpm is that you shift at. Basically reving it close to redline should produce the best times, but if it shuts fuel off, well, you get the idead.

 

[NightmareMoon]

Even if torque or hp is falling a little before redline, its going to fall /a lot more than that/ after the shift due to higher gearing in the next gear. Its rare to see a sports car today that is going to gain from short shifting, and if it happens, it would be in higher gears where the delta between gear ratios is smaller.

If Ford could have made a car faster by simply lowering redline, they would have done that. Your fastest times will be shifting at redline. If you still feel shifting at redline (8250) feels too strange, I’ll be happy to trade your GT350 for my GT (premium leather w/ recaros, its a nice car!) with a much more manageable 7000 redline.

 

[Shifting_Gears]

Spin that Voodoo to the moon!!

Everyone already covered why, so that’s my contribution.

 

[GT30fan]

I have 5 miles on it since she is hibernating. Once she's awake, I need to break it in.

I was asking all these questions because you hear all this 'no torque down low' speak. Yet, can run a 1/4 mile in the 12's. Wondering how. Think I've been told

 

[Idaho2018GTPremium]

The key is the torque at the wheels. The engine torque is multiplied by the trans and rear-end. So, for example, if the torque at 8000 rpm is 15% less than the torque at 6000 rpm, but the next gear down is a 20% reduction, the torque at the wheels will be higher at 8000 rpm in the lower gear than 6000 rpm in the higher gear, because the engine torque at the crank drops off slower than the gear change. Even though the engine is making less torque, it is still putting more torque at the wheels in the lower gear because it's at a higher multiplication in the lower gear. Do not confuse that with the fact that for a given gear, the max. acceleration does occur at peak torque. So, the acceleration in a given gear is quicker at 6000 rpm than 8000 rpm. However, that doesn't mean the acceleration of the next gear up is stronger at 6000 rpm than the lower gear at 8000 rpm.

The above is why a car like the Porsche 911 GT3 RS with 520 hp but only 346 ft-lbs can trap 129 mph in the 1/4 mile and do 0-60 in 2.9 seconds. High rpms = low gearing = high torque at the wheels even if the engine itself doesn't make that much torque.

 

[GT30fan]

The key is the torque at the wheels. The engine torque is multiplied by the trans and rear-end. So, for example, if the torque at 8000 rpm is 15% less than the torque at 6000 rpm, but the next gear down is a 20% reduction, the torque at the wheels will be higher at 8000 rpm in the lower gear than 6000 rpm in the higher gear, because the engine torque at the crank drops off slower than the gear change. Even though the engine is making less torque, it is still putting more torque at the wheels in the lower gear because it's at a higher multiplication in the lower gear. Do not confuse that with the fact that for a given gear, the max. acceleration does occur at peak torque. So, the acceleration in a given gear is quicker at 6000 rpm than 8000 rpm. However, that doesn't mean the acceleration of the next gear up is stronger at 6000 rpm than the lower gear at 8000 rpm.

The above is why a car like the Porsche 911 GT3 RS with 520 hp but only 346 ft-lbs can trap 129 mph in the 1/4 mile and do 0-60 in 2.9 seconds. High rpms = low gearing = high torque at the wheels even if the engine itself doesn't make that much torque.

Nice!!! But alot of the 'no low torque' comments come from members here even, mostly the guys that want a Whipple supercharger.
Maybe it's more of a feel thing?

I am guessing if the RPM's are kept high, I am not going to be hurting ....

 

[Idaho2018GTPremium]

Nice!!! But alot of the 'no low torque' comments come from members here even, mostly the guys that want a Whipple supercharger.
Maybe it's more of a feel thing?

I am guessing if the RPM's are kept high, I am not going to be hurting ....

The rpms don't even have to be that high. It pulls more than decent at 3k rpm in most gears, really hard at 4k rpm.

The Gen 3 Coyote has less low end torque than an LT1 in the Camaro SS, for example, and feels less torquey under light throttle (a running joke on this site) of many turbocharged engines since turbos create a lot of low end torque with light throttle applications.

 

[Idaho2018GTPremium]

Nice!!! But alot of the 'no low torque' comments come from members here even, mostly the guys that want a Whipple supercharger.
Maybe it's more of a feel thing?

I am guessing if the RPM's are kept high, I am not going to be hurting ....

I just realized you were referring to the Voodoo. I think the Voodoo has less torque below 3500 rpm than the Gen 3 Coyote. The Voodoo has a large jump in torque around that engine speed.

 

[NoVaGT]

I have 5 miles on it since she is hibernating. Once she's awake, I need to break it in.

I was asking all these questions because you hear all this 'no torque down low' speak. Yet, can run a 1/4 mile in the 12's. Wondering how. Think I've been told

You keep mentioning torque. But if torque is what you wanted, you dun bought the wrong car. You bought a car with a high RPM HP hit, not a down-low torque hit.

You rev the nuts off that car to accelerate hard, that's what it's engineered and built for.

 

[Grintch]

Compare the torque at 8000 rpm to 6000. Now consider the extra torque multiplication form being in the lower gear. Does that clear up why racers don't shift 2000 rpm early? And why HP is really what matters?

 

[GT30fan]

These are questions on clarification of comments I am reading from others

No reqrets on the purchase whatsoever

My wife and kid will also drive this car on occasion. A rocket launcher at a light when off to get a gallon of milk might even be a negative. Like the idea it IS there waiting on tap WHEN you want it, but perhaps not in the way when you don't (hello officer). My past 69 charger hi rise mega cam build was fast as hell, but it was so aggressive it either lit the tires or would stall, take your pick

 

[Balr14]

Nice!!! But alot of the 'no low torque' comments come from members here even, mostly the guys that want a Whipple supercharger.
Maybe it's more of a feel thing?

Unless you are drag racing, there are situations where you would like more low-end without revving the crap out of the engine. Aside from that, more low-end just gives more flexible performance. On the plus side, the lack of low-end tends to be easier on the drive train.

Sponsored