Veloce Raptor

And the hits keep coming....







Professional Racing and Driving Coach

ew928

Please don't mention Torque Multiplication.

I've been told slushboxes have a torque multiplication effect due to their torque converters.
Me no understand.

Fred R. C4S

I'm damn glad the none of you are Mechanical Engineers responsible for any mode of transportation I might use. I think torque and power are covered in ME101 or perhaps it was ME102. It's been 40 years ago for me. But from some of the rather strange arguments put forth, most of you don't know what torque and power actually are. It all gets even more confusing when a mistaken understanding of torque vs power is thrown into a discussion of the practical application of both (or either) in a road car. Do any of you work in the financial sector?

Cheers,

2BWise

This thread is on cruise control now....I predict 32 pages. Torque multiplication? My head might explode. I think that horsepower and torque were covered way back in Physics 1 or 2.

I will be the first to admit that I am not good with technical writing and most likely did a crappy job of conveying my thoughts. It would be so much easier to do this in person and would have ended, I don't know, the equivalent of like twenty pages ago.

Veloce Raptor

Our American gladiator seems to be MIA....







Professional Racing and Driving Coach

ew928

He slipped on some torque whilst coming back from the fridge with a brewski.

mark kibort

I heard the heads are better, lighter valve train, stock. I forgot that the S54 was the e46 motor. I heard, that some of them can make 330rwhp with only good exhaust and aftermarket ecu.

mk

mark kibort

I wasnt able to watch it, but if it is anything like the Tesla drag videos Ive seen and read about, it is amazing. as much as the flat torque curve is interesting, the range of HP over the rpm available is even more amazing. basically, its like piston engine that can rev to 14,000rpm, with a flat torque to about 8,000rpm. If you look at the HP curve, it is very wide, but falls off at the end pretty dramatically. If they had a sequential 1 speed shift at about 80mph to keep the hp up, it would be even faster. HP to weight ratios are pretty good with the electric car, and its launch is phenominal due to no clutch and max torque at 0rpm.

Also remember, we are talking about a 300hp vehicle at 2600lbs running 12 second quarters vs vets and M3s that are 350 to 400hp but weigh over 3300lbs and run low 13s if they are lucky.

Coming from the industrial world using high powered electric motors and controls, it would be a dream to have an electric Tesla racer! I dont think the drive electronics could handle 50% duty cycle and 10second ratings for 30min. (i.e full power 10 seconds, 10 seconds rest , repeat for 30min. The batteries could almost handle it now, and someday will.

mk

mark kibort

You didnt like my two graphs and descriptions addressing the title subject?

Your right, in ME101 doesnt address Force, power, acceleration in a race car. pretty simple concepts, on a relatively complex application. Varied power, efficiency losses, gear reductions, varying jerk, all sorts of variables. Thats why I broke it down into basic elements. acceleration being directly proportioal to power at any speed, since that is what the main goal is, to maximize and compare acceleration at any vehicle speed, right?

Dust off the old books and come out and play!

mk

mark kibort

i got the video this way. http://www.youtube.com/watch?v=UAYrsEOxqYc

Actually saw it a while ago.

Hp to weight folks. something like 300hp, 1900lbs with the Lithium batteries. lots of torque is not really the issue here, as it needs lots of torque, to get the power at the higher speeds when it falls off. remember, these things are geared like our first gears. imagine the acceleration if you could keep your foot in 1st gear all the way to 110mph!
Even if the torque falls off, the HP is actually rising with every revolution up to near 80mph.

In this case, you can still determine acceleration by the power output at any speed. Of course now, since there is no gears, you can just take the 300ft-llbs, multiply it by 8:1 and get the rear wheel torque for most of its run in the 1/4mile.

That was amazing. I want a electric road race car with 2 gears!

There is a huge advantage off the line with launch not having to deal with clutch dumping.

Here is the tesla 270+ hp HP /torque curve. (I like the marketing how they compare it to some 120hp lotus.
(by the way, 200Kw is about 270hp)

mk

A.Wayne

Hacker wins .............................................................

wanna911

A major blow to the Torque side of this arguement IMO is the ACURA LMP1 car that just entered ALMS. It's on the pole with short developement times. Has only 370 ft lbs compared to the Audis and Peugeots turbo diesels with tons of torque (like 800 ft-lbs).

If torque was so much better the Acura wouldn't have a chance with such a huge deficit. The Acura seems to get off the corners just fine despite a lack of torque.

Seems like I said that if you were to even the hp/weight restrictions between LMP1 and LMP2 that the Porsches and Acuras would REALLY own the Audis, seems like that is coming true. And this is on a high speed track where the torque will have the best chance. Too bad Audi isn't running the whole season.

I don't see how anyone can say definitively one way or the other, because it will vary. But there is no way that torque is the deciding factor when these cars have nearly identical hp. Trying to say the Acura handles that much better to overcome over 400 ft lbs of torque deficit is reaching for straws.

sjfehr

I've been trying to stay out of this debate as it's so heated... But power and Torque are both limiting factors. It's a two-part equation; torque is required for momentum, power for kinetic energy- depending on the engine, gear and conditions, either could be the car's limiting factor at any given time. Engines/transmission systems are designed so that both these factors are addressed simultaneously, though, otherwise you might end up with hp you can't use or massive torque that tops out at 5mph. Assuming good transmission gear ratios:

1st gear is generally torque limited, especially from a stop. You simply can't make use of all that high-end horsepower when your engine is only running at low RPM, and it's not practical for a lower end 1st gear. At higher rpms, rote hp is generally more important as torque can be geared for, hp can't.

They sure do. The variable input/output ratio of the torque converter very effectively makes up for any slop in the torque/hp tradeoff and gives a better gear ratio in 1st gear and smoother shifts. Unfortunately, it also introduces a bunch of weight and other inefficiencies.

Veloce Raptor

Dez, just to be crystal clear: my being on the torque "side" of this argument is only in the specific example you gave in your original query which started these 400+ endless threads months ago. Of those 2 cars with 400hp, I would prefer the one making more torque (all other things being equal/optimized) for a technical road course.

In racing, all sorts of other factors come into play which can equalize a high TQ car like the Audis and a high HP car like the Acuras.







Professional Racing and Driving Coach

mark kibort

I think we all know your preference, but Ive already proved that when comparing two equal HP cars, that a lower torque engine can produce more REAR wheel torque at any speed. The fact of the mater is, is that rear wheel torque. (that made at the rear wheels , applying force to the ground) is inextricably tied to power! YOU are absolutely right to generalize that a higher torque engine is an INDICATION of a flatter hp curve. But, Dez's question was pretty clear. Ive shown factual evidence showing with his guidlines, actually, the lower torque engine might work better on all road courses.
(because of a broader HP curve)

VR, this picture shows one possiblity of Dez's requirment of two equal HP engines. which one would you pick?
This graphically shows why any of the 37 that selected that higher torque is always better, should review the curves and change their vote. Clearly, this shows that a lower torque engine can be better off turns and down straights.
also shown here with two other real case, equal HP cars.
https://rennlist.com/forums/6397709-post321.htmlmk