drummerdimitri

Hey guys,

I've been interested in knowing how much torque a stock C63 has from 1k rpm. All the graphs and dyno results I've seen start at 2000-2500 rpm but I am actually more interested in knowing how much torque/hp this car makes just above idle since I always tend to **** into a higher gear at 2000 rpm.

Cheers!

roadtalontsi

ya mine starts at 2500

drummerdimitri

Exactly. Assuming the engine idles at 750 rpm, wouldn't people be willing to know the power/torque of the engine from idle to 2500 rpm? Why ignore that part of the power band when it is mostly used in bumper to bumper traffic?

Merc63

Cause you're lugging the **** out of the engine hammering it off idle in 5th gear at the dyno. And no not many care what power their engine makes at that rpm wot cause you shouldn't be wot at that rpm.

drummerdimitri

I have a bad habit of shifting up all the time and let the low end power do all the pulling in high gears at low speed. Is that really bad for the engine? That's why I am asking about low end power.

Merc63

You don't want to give it too much throttle in a high gear low rpm. It puts a lot of pressure on the rods and crank. Anything under 2500rpm is for part throttle cruising.

drummerdimitri

I see what you mean, but for some reason I really enjoy flooring the car in 7th gear at 1000 rpm and pass other cars. I'm sure a turbocharged or diesel car is better suited for this sort of thing.

Ingenieur

The torque will be 5.25 x the HP at 1000 rpm
And HP is linear with rpm
And at 0 rpm power is 0
What is hp/ torque at
2500 or lowest recorded
3500
???

We can estimate it
Assuming torque droops below <2500

drummerdimitri

I don't know what you are asking but you simply cannot estimate the power and torque at 1000 rpm if you only have dyno graphs that start at 2500 rpm. Every engine differs in its output pattern so you can make an educated guess but it will never be spot on.

Ingenieur

That is why I said 'estimate' it captain obvious
Lol

Everything is an estimate with varying degrees of precision
Except integer math


The power is proportional to rpm, fuel/air ratio & qty
And air qty (and therefor fuel) is proportional to displacement
We can safely assume torque output is optimized for throttle position/load
And the eff is > in a well engineered system like this
And eff is not overall fuel to power conversion eff but practical eff based on the bat or best available technology

drummerdimitri

I had no clue what you were asking to be honest. I'd like to see some dyno graphs that starts at around 1000 rpm if there are any out there.

Anatoli

Ingenieur

Using the first curve I estimate
1000 rpm
75 HP
390 lb ft

Ingenieur

Second curve
65 HP
340 lb ft

Assuming graph units
Power = kW
Torque = N-m

drummerdimitri

That's a crap load of power at 1000 rpm! This thing must explode off the start in first or second gear.

roadtalontsi

no way an N/a makes 300tq at 1000rpm. i could see 350+ with a blower. that is too the wheels.
no love for 500wtqs on my first one
here's my old slk55 dyno

Ingenieur

The stock graph above shows 340 lb ft at 1500
95 HP At 1500 rpm

At the crank
Loss was measured at 15%
Wheels at 1500
290 lb ft
80 HP

It made more at 1500 than the slk55 did at 2500!
Impressive

My previous estmates were all crank numbers

149max

Using AMG performance media it looked to be about 400tq @ 2000rpm to me.

That's almost 90% tq at just above idle!!!

Ingenieur

That equates to 150 HP
HP is ~ to rpm so at 1000 ~ 75 hp
Torque at 1000 = 5252/1000 x 75 = 390 lb ft
At the crank

Engines at full throttle approximate constant torque machine
And variable power which makes sense since P = t x w (w = 2 pi n rev/sec)

Its fairly linear too
2000 = 150 hp
6000/2000 x 150 = 450 hp basically the engine rating
T at 6000 = 5252/6000 x 450 hp = 400 lb ft
Basically the same as 2000

drummerdimitri

According to this engine output graph from the AMG website, it is clear that the stock engine produces 500 NM or 369 lb-ft of torque at 2000 rpm at crank. For some reason though, the SLS engine output graph starts at 1500 rpm so we can better estimate the power/torque at 1000 rpm assuming both the 6.3 engine in the C63 and the SLS have similar low end grunt. I did my homework and based on those two graphs, my best estimate for the power and torque at 1000 rpm came out to be 55.6 HP and 396 NM respectively.

whoover

I think you meant to say the SLS torque at 1,500 is 460 NM. Even so, I think it falls off more quickly below that and the 396 NM estimate for 1,000 seems high. One of my complaints with the C63 transmission is that in C-mode it sometimes lugs at 1,000 rpm or so when driving in slow traffic. I hate that vibration and there's no way the engine is delivering almost 400 NM. Don't forget that the peak torque for a base Jetta is 170 NM.

Ingenieur

The 300 lb ft is imo low but close
Torque = displacement V x Mean effective pressure Pme / 4 Pi
V, 4 and Pi are constants
Pme ~ comp ratio x vol eff x boost (if applicable)
Comp ratio is constant
So if cam, fuel ratio/qty, etc are optimized as they are with modern controls
The only real variable is vol eff
Note engine speed is not a direct variable
It falls as rpm decreases due to less pumping effeciency
And falls as rpm increases due to air friction or pumping losses
It is max in the middle hence peak T in the mid range

Therefor in a perfect engine torque will be the same at 1000 or 6000
And this engine is at lesst 70-75% 'perfect'
So 300 to 350 lb ft at 1000 rpm is a good estimate crank for a stock C63

Ingenieur

Porsche used to post grade vs rpm curves for each gear in their owners manuals
From this torque could calculated
The force required to lift the car against gravity

Ingenieur

This is an actual stock C63
1500 rpm Crank
340 lb ft
95 HP

Even if hp is only 2/3 at 1000 (1000/1500 = 2/3)
Power IS prportional to speed p = t x w with t being fairly constant
65 hp
T = 5252/1000 x 65 = 340 lb ft

At 1000 definitely between 300 to 350

drummerdimitri

In that case what would you think is a correct estimation of torque at 1000 rpm? This is a 6.2 liter V8 after all, so 400 NM just above idle can't be too far off...