Regaining 30 HP / 20 TQ - Interesting Video post 37s and power loss

[Rocksalty]

Saw this video, from stock tires to 37s, noted the power loss, was wondering how would one get that power back? (w/o Turbo/SC)

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[Bowerss2]

Well, to be more accurate it didn't loose any power. It did however loose power to the ground. Re-gearing is needed with 37s, especially if you have the 3.73 gears. Plenty of threads on what gears are good for what tires.

 

[Rocksalty]

Well, to be more accurate it didn't loose any power. It did however loose power to the ground. Re-gearing is needed with 37s, especially if you have the 3.73 gears. Plenty of threads on what gears are good for what tires.

Yup, all known, this is with 4.10s, and this is in regards to the at the wheel power. So the question was how to make it up?

 

[Bowerss2]

Yup, all known, this is with 4.10s, and this is in regards to the at the wheel power. So the question was how to make it up?

Without forced induction?

Cam, Retune and maybe Intake and Exhaust. Doing intake and exhaust alone is a waste of money. 30HP and 20Tq is too much for simple bolt on stuff. I have no idea if anyone makes / re-profiles cams for the pentastar. But it could be done. The key would be the tune.

Either that or forced induction.

Price you pay for getting bigger / heavier wheels and tires. Rotating mass = Powertrain loss. Physics is a harsh mistress.

I know its not what you asked but best bang for your buck for drivability, reliability, and MPGs will be dropping in 4.88 or 5.13 gearsets.

 

[Rocksalty]

Without forced induction?

Cam, Retune and maybe Intake and Exhaust. Doing intake and exhaust alone is a waste of money. 30HP and 20Tq is too much for simple bolt on stuff. I have no idea if anyone makes / re-profiles cams for the pentastar. But it could be done. The key would be the tune.

Either that or forced induction.

Price you pay for getting bigger / heavier wheels and tires. Rotating mass = Powertrain loss. Physics is a harsh mistress.

I know its not what you asked but best bang for your buck for drivability, reliability, and MPGs will be dropping in 4.88 or 5.13 gearsets.

thanks brother, its more of a though experiment but my thoughts are in line with yours, simple bolt ons wouldn't cut it. Gearing is always a great idea.

 

[bgenlvtex]

There are literally no free rides.

Those who believe there are, are destined to be disappointed.

Re-gear, do what you can to free up exhaust and improve intake temperature without sacrificing filtration, keep tire and wheel weight as low as possible.

From there determine if the juice is worth the squeeze.

 

[Factoid]

The depth of your performance improvement is directly related to the depth of your pocketbook. No more, no less.

 

[endurojeep]

Ok so I understand somewhat driveline loss hp and torque. so mathematically is it not so that you can not increase horsepower by changing gear ratio as this would only provide torque amplification. You would either have to increase horsepower at the source or reduce the drag of the large tires and wheels to increase the brake horsepower a simple gear change should not accomplish this as the drag(loss) will not change

 

[bgenlvtex]

Ok so I understand somewhat driveline loss hp and torque. so mathematically is it not so that you can not increase horsepower by changing gear ratio as this would only provide torque amplification. You would either have to increase horsepower at the source or reduce the drag of the large tires and wheels to increase the brake horsepower a simple gear change should not accomplish this as the drag(loss) will not change

Correct, re-gearing will only perceptibly mitigate loss of hp/tq when increasing rotating/un-sprung mass.

To replace the lost hp/tq due to an increase in un-sprung/rotating mass something will have to be done to the engine to effect that change.

All the cold air intake and free flowing exhaust you can muster won't give to 10hp/tq

 

[LaterGator]

Who cares about losing 30 hp / 20 tq at 6000 rpm. Up to 5000 rpm there is little to no difference. The power between 1000 and 3500 rpm is what matters for drivability on and offroad.

Just put on the 37's and enjoy. Regearing is way less expensive than a turbo or supercharger and you still use 87 octane.

 

[MadMax]

Ok so I understand somewhat driveline loss hp and torque. so mathematically is it not so that you can not increase horsepower by changing gear ratio as this would only provide torque amplification. You would either have to increase horsepower at the source or reduce the drag of the large tires and wheels to increase the brake horsepower a simple gear change should not accomplish this as the drag(loss) will not change

Re-gearing applies more leverage for the power of the system. so no power is gained or lost just the application at which the gears manipulate the power.

 

[MadMax]

Saw this video, from stock tires to 37s, noted the power loss, was wondering how would one get that power back? (w/o Turbo/SC)

But when you used 93 octane, did you drain the gas tank before adding the 93 octane?

 

[Jeeperjamie]

One of the reasons why I'll probably stick to 35's on mine. Still getting 18.5 MPGs average with 4:10 gears on the Max tow and driveability hasn't changed at all with the 2.5" lift. This is a whole other animal when compared to the JKs on 35's and even 37's I would imagine. I'm 100% please with the performance on 37's, but if I could find a set of 37's that weighed pretty close to my BFGs I may would consider them.

 

[ACAD_Cowboy]

Cubic dollars is how you make that back. Take it down to castings and milk every last bit out of the stock setup through porting and polishing on both sides, reducing as much component mass as you can, hunting every occluding turn and convolution you can find and putting the truck on a diet to earn back as many ounces as you can.

And as a helping hand, torque is the rotational force exerted by the crankshaft, horsepower is torque over time. Torque is what lets you lift the front wheels, horsepower is what keeps them up. A loss of 30hp probably isn't that noticable as its a loss from peak numbers. I would be much more interested in know what the change is to the area under the curve, what the net hp change across all engine speeds.

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