Hellcat vs GT350 from a roll, who wins?

[Angry50]

You're partially right in understanding what I was saying. Not 7k shifting, but it's very possible that shifting at 7400 is faster than 8250. The idea being that HP falls off after peak RPM of 7400, and that since the next gear (ie, 2nd gear) actually has a little higher torque at the slightly lower RPM, it maybe be faster or at least negligible. I too would like to see testing of a GT350 on the track using varying shift points.

I came from Pontiac muscle cars. Those cars were big torque monsters. On mine peak HP was reached around 5000 RPM, with a redline of 6000 RPM. MOST pontiacs were the same ET time and speed when they shifted anywhere from 4800 to 5400 rpm, and went slower the more they revved before shifting.

Now, again, these old cars always had more torque than HP, so they're different than Voodoo motors, but in looking at the Ford dyno charts, it makes me wonder how much difference there is to going the extra 800 RPM. It all likely happens so fast that it's hard to even know for sure, at least in the 1-2 shift, but if anyone is a regular at the track, inquiring minds want to know!

think its quite a bit different, HP is a calculation of tq and RPM. which is why more modern motors make higher HP than tq due to the ability to spin them faster and flow the air. shifting for peak HP i think would be better goal as HP is "speed at which work is done". and i wager the gear advantage of the lower gear is more beneficial.

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[TDC]

Gt350 slightly noses over above 8k. Also bouncing off rev limiter = no acceleration. Better to shift a few hundred rpm earlier.

 

[Niz55]

I ran charger hellcat from a 40 roll with 4 people in the hellcat and got walked about 5 cars and he was still pulling.

 

[Angry50]

Gt350 slightly noses over above 8k. Also bouncing off rev limiter = no acceleration. Better to shift a few hundred rpm earlier.

for sure.. lol i set my shift light at 8k so i can be sure not to hit it lol

 

[AdamIsAdam]

I have my shift light at 7400 for the street. I figure for 1st gear especially, the RPM's come so fast, that by the time I actually shift, I'll be nearly 8k anyway! LOL

 

[key01]

Yeah, mine is set at 7800

 

[Zombo]

I created this chart - I think it was the first post I ever made here several years ago.

The chart indicates that, for maximum acceleration for the Voodoo, you shift at redline. The engine torque x gearing, which ultimately determines the tractive force at the rear tires, is always maximized in the lower gear (vs. upshifting). This is not always the case with all drivetrains, as it is a function of the gear ratios and specific shape of the torque curve. It is for the Voodoo.

I set my shift indicator 8000, for a little buffer.

 

[AdamIsAdam]

I created this chart - I think it was the first post I ever made here several years ago.

The chart indicates that, for maximum acceleration for the Voodoo, you shift at redline. The engine torque x gearing, which ultimately determines the tractive force at the rear tires, is always maximized in the lower gear (vs. upshifting). This is not always the case with all drivetrains, as it is a function of the gear ratios and specific shape of the torque curve. It is for the Voodoo.

I set my shift indicator 8000, for a little buffer.

Cool! Nice to see people read your work, right?

Have you actually tested your theories on the track with this car?

 

[JT1]

The HP "calculation" does all the work for you. If you notice the shape of the curve, as the HP is dropping, you want to shift when the HP in the next gear will be equal to what you just had.

 

[nastang87xx]

Umm.............Hellcat all day every day?

And forget even the power, by the time the 350 gets through first gear, the Hellcat is done with almost two if it's a ZF8 car.

 

[Hack]

The HP "calculation" does all the work for you. If you notice the shape of the curve, as the HP is dropping, you want to shift when the HP in the next gear will be equal to what you just had.

Not right.

You should really be calculating torque at the wheels to determine when to shift. Gearing is a torque multiplier, so when you shift to a higher gear, your torque at the wheels drops.

Engine HP alone doesn't help you determine when to shift because it doesn't take into account gearing.

 

[firestarter2]

Not sure why this is even a question

 

[Hack]

Not sure why this is even a question

I agree. It's more of a drag race thing - optimizing acceleration.

 

[DCShelby]

You can always do a roll-on.....and then get the Hellcat to attempt to take a moderate turn at high speed with you....cause while you can slice through.....the big Cat will get a bit......wobbly....

 

[JT1]

Not right.

You should really be calculating torque at the wheels to determine when to shift. Gearing is a torque multiplier, so when you shift to a higher gear, your torque at the wheels drops.

Engine HP alone doesn't help you determine when to shift because it doesn't take into account gearing.

Ummm, yes it is. Power is conserved, physics 101. You can do the math with gear ratios and calculate torque at the rear wheels, I assure you the math checks out.

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